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WhistleStop
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Reged: 09/07/07

Loc: Grafton, Ontario
"Lessons from the Masters"...first impressions
      #6078367 - 09/13/13 09:01 AM

The book arrived yesterday and I had a wonderful night time read (it was cloudy). Being left handed I went to some of the back chapters first .
What a delight !!...read with much interest Rob Gendler's chapter on framing objects and Babak Tafreshi's chapter on Earth and Sky photography. Top knotch writing and advice !
This book hits all the right notes...excellent text for those that dream of migrating from one aspect of astrophotography to another...all in one source.
I'm impressed ! I will probably buy another copy (as any astrophotographer knows you need two of everything). Will also get a digital copy for my tablet.
I bow to the masters ...thanks for the wealth of information.
Cheers
Lynn


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vpcirc
Post Laureate


Reged: 12/09/09

Loc: Merced CA
Re: "Lessons from the Masters"...first impressions new [Re: WhistleStop]
      #6078800 - 09/13/13 01:55 PM

I'm glad I, the guy who knows nothing, recommended it on here when I saw it. I will always take my advice from those who've gone before me and their results show me they know what they're talking about. No sense trying to reinvent the wheel when so many top professionals are willing to share their practices to produce such beautiful images!

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Rick J
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Reged: 03/01/08

Loc: Mantrap Lake, MN
Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6079489 - 09/13/13 10:02 PM

So the March 2014 shipping date was an error by Amazon? Or did you sail across the lake and get one here? Or did the publisher get the problem solved?

Rick


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vpcirc
Post Laureate


Reged: 12/09/09

Loc: Merced CA
Re: "Lessons from the Masters"...first impressions new [Re: Rick J]
      #6079945 - 09/14/13 08:19 AM

Rick I contacted Rob Gendler, his publisher contacted Amazon Canada to get it corrected

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WhistleStop
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Reged: 09/07/07

Loc: Grafton, Ontario
Re: "Lessons from the Masters"...first impressions new [Re: Rick J]
      #6079954 - 09/14/13 08:23 AM

Hi Rick
I was in contact with Rob Gendler (as were others) and mentioned the issue with Amazon.ca. He kindly contact the publisher and within 48 hours the book was on its way. Hopefully all the Canadian orders get the same treatment. The book is a delight... gems at every turn.
Cheers
Lynn


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Rick J
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Reged: 03/01/08

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Re: "Lessons from the Masters"...first impressions new [Re: WhistleStop]
      #6080689 - 09/14/13 04:14 PM

I was told my copy wouldn't arrive until the 18th of the month but it came today. Now to find time to read it. A rainy day here but I'm so far behind on the "honey do" chores I better do a few of those first. At least mine wasn't "abridged" by cutting off the top inch or two.

Rick


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WhistleStop
Pooh-Bah
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Reged: 09/07/07

Loc: Grafton, Ontario
Re: "Lessons from the Masters"...first impressions new [Re: Rick J]
      #6080794 - 09/14/13 05:28 PM

I think the book is great...Chapter One however can be skipped as it made my eyes cross ( don't do math ! )...the gems lie in Chapter 2 and beyond.... It is very well written.
Glad you didn't get an 'abridged' edition .
Enjoy the read .
A MUST book in my humble opinion... long overdue.
Cheers
Lynn


Edited by WhistleStop (09/14/13 05:35 PM)


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pfile
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Reged: 06/14/09

Re: "Lessons from the Masters"...first impressions new [Re: WhistleStop]
      #6080811 - 09/14/13 05:39 PM

looks pretty good, i just read the "look inside" on amazon and had been expecting another "here's how to do xyz in photoshop" but it looks like it covers lots of things in general and the examples use lots of different software.

ordered...

rob


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andysea
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Reged: 09/03/10

Loc: Seattle, WA
Re: "Lessons from the Masters"...first impressions new [Re: pfile]
      #6080943 - 09/14/13 07:18 PM

Not sure how I missed this. I will order it soon!
Thanks for the pointer

Andy


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psandelle
professor emeritus


Reged: 06/18/08

Loc: Los Angeles
Re: "Lessons from the Masters"...first impressions new [Re: andysea]
      #6081160 - 09/14/13 09:49 PM

Thanks for the reminder; completely forgot about it coming out. Just ordered it from Amazon. I love my ebooks, but my astro books are all old school paper.

Paul


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kozzina
super member


Reged: 09/28/09

Loc: Czech Republic, Prague
Re: "Lessons from the Masters"...first impressions new [Re: psandelle]
      #6081484 - 09/15/13 03:41 AM

I bought this book in before few days for kindle. Its great book, i can recommend it to everyone

Edited by kozzina (09/15/13 03:41 AM)


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vdb
sage


Reged: 12/08/09

Re: "Lessons from the Masters"...first impressions new [Re: kozzina]
      #6081756 - 09/15/13 09:48 AM

Is there an iPad version?

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raf1
scholastic sledgehammer
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Reged: 11/18/05

Loc: south Texas
Re: "Lessons from the Masters"...first impressions new [Re: vdb]
      #6081771 - 09/15/13 10:00 AM

Install the Kindle app for iPad and you are gtg.

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Ken Crawford
sage


Reged: 06/02/09

Re: "Lessons from the Masters"...first impressions new [Re: raf1]
      #6081811 - 09/15/13 10:34 AM

Rob worked very hard on this book in not only coming up with the concept but also working with all the authors. You can imagine what that took alone but there is the editing of each chapter, getting the images correct, content laid out, and the list goes on and on. Then the long hours of working with the publisher for the final result. Rob's countess hours of this labor of love have paid off and I am very proud of what he has put together.

I look forward to hosting him at AIC2013 next month . . .


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Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: "Lessons from the Masters"...first impressions new [Re: Ken Crawford]
      #6082023 - 09/15/13 12:55 PM

Quote:

you can imagine what that took alone but there is the editing of each chapter, getting the images correct, content laid out, and the list goes on and on.



I wish he did a better job editing chapter 1. The inclusion of f-ratio myth mumblings is inexcusable. This goes to show that one shouldn't take seriously books written by amateurs for amateurs.


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Ken Crawford
sage


Reged: 06/02/09

Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6082050 - 09/15/13 01:18 PM

Of course you are free to disagree with any or all of what is written in any of the chapters. The “reality” is that Stan has contributed more to amateur astrophotography that most of us here!

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vpcirc
Post Laureate


Reged: 12/09/09

Loc: Merced CA
Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6082168 - 09/15/13 02:26 PM

Quote:

Quote:

you can imagine what that took alone but there is the editing of each chapter, getting the images correct, content laid out, and the list goes on and on.



I wish he did a better job editing chapter 1. The inclusion of f-ratio myth mumblings is inexcusable. This goes to show that one shouldn't take seriously books written by amateurs for amateurs.




Are you saying Robert Gendler is an amateur? just because you don't agree with Stan Moore is hardly a reason to make that comment. Gendler is one of the top and most respected imagers in the world. NASA sure seems to think he knows what he's doing.


http://www.nasa.gov/mission_pages/hubble/science/m106.html


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Peter in Reno
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Reged: 07/15/08

Loc: Reno, NV
Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6082591 - 09/15/13 06:34 PM

I took the risk and ordered a Kindle version. This book seems to be more dedicated to Photoshop users. I use PixInsight and don't know PS. I wish each chapter used at least two processing tools since PixInsight is getting extremely popular and I have a hard time understanding PS tools described in this book.

If you are a heavy PS users, this book may be good for you. Not sure about heavy PixInsight users. I hope Amazon has a refund policy for Kindle users.

Peter


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vpcirc
Post Laureate


Reged: 12/09/09

Loc: Merced CA
Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6082659 - 09/15/13 07:23 PM

Peter, very few people are trying to finish a complete image in PI yet. Many use GIMP as an alternative to PS, but PS isn't quite ready for final finishing work. The nice thing is, book teaches you how to use those tools in PS that you didn't know how to use.

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6082691 - 09/15/13 07:42 PM

Still I think the description about the book should have been more accurate before purchasing the book. Anyway I was able to get a refund for the Kindle version. I guess I'll have to wait for another book that's more dedicated to PixInsight.

Peter


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JWalk
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Reged: 06/06/10

Loc: San Antonio, TX
Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6082753 - 09/15/13 08:23 PM

I really think PS gives you more control over what you want to do. I start with PI and finish in PS. Starting in PI seems nice. I do the heavy lifting in PI and decon. I know PS is expensive but it really works. Lightroom also has some amazing features to "finish" an image, especially with respect to color.

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pfile
Post Laureate


Reged: 06/14/09

Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6082763 - 09/15/13 08:25 PM

mike, that's just wrong.

the 'look inside' didn't seem so PS-centric. that's too bad. anyway i'm sure i'll still learn something reading it.. i hope


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RandallK
Carpal Tunnel


Reged: 11/10/06

Loc: Nanaimo, B. C. Canada
Re: "Lessons from the Masters"...first impressions new [Re: pfile]
      #6082796 - 09/15/13 08:50 PM

I received mine after a lengthy wait. It was sent priority post by Amazon.ca and I got a decent letter of apology from Amazon.

The main reason I purchased Photoshop (CS 5, then 6) was because most tutorials, whether it be on YouTube or via publication are based on Photoshop. PaintShopPro and PixInSight can probably do all that the astro imager needs but the lack of tutorials is what hampers the use of these programs.

I have skimmed through the book in the "reading room" a few times and have deemed it to be a very handy companion in furthering my astro imaging processing.

A great thank you to Robert Gendler & Co. for the great work for a great hobby!


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vpcirc
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Reged: 12/09/09

Loc: Merced CA
Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6082838 - 09/15/13 09:23 PM

Quote:

Still I think the description about the book should have been more accurate before purchasing the book. Anyway I was able to get a refund for the Kindle version. I guess I'll have to wait for another book that's more dedicated to PixInsight.

Peter




Last year Wodaski said he was working on one, but the program is so powerful and complex I wouldn't expect it anytime soon. The program is also still evolving, so maybe you can't write a book yet? I do believe when the program is done, nothing will touch it.


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pfile
Post Laureate


Reged: 06/14/09

Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6082850 - 09/15/13 09:29 PM

i think the core paradigm of PI has not changed "that much" since v 1.6. the changes since then have been the addition of a bunch of new processes, lots of very useful 3rd party scripts, and of course the project save/restore feature which is IMO completely awesome. my sky conditions dictate multi-night projects and it's great to be able to come right back to exactly where i left off on one project or other.

so someone totally could write a book at this point.


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hytham
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Reged: 12/25/12

Loc: Canadian in the US
Re: "Lessons from the Masters"...first impressions new [Re: JWalk]
      #6084460 - 09/16/13 06:16 PM

Quote:

I really think PS gives you more control over what you want to do. I start with PI and finish in PS. Starting in PI seems nice. I do the heavy lifting in PI and decon. I know PS is expensive but it really works. Lightroom also has some amazing features to "finish" an image, especially with respect to color.




I echo these sentiments.

Only recently have I discovered that LightRoom and PS are an extremely amazing compliment to PI especially in colour enhancing and contrasting arenas.


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PGW Steve
Pooh-Bah


Reged: 10/03/06

Loc: Winnipeg, Canada
Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6088149 - 09/18/13 02:17 PM

Quote:

Quote:

you can imagine what that took alone but there is the editing of each chapter, getting the images correct, content laid out, and the list goes on and on.



I wish he did a better job editing chapter 1. The inclusion of f-ratio myth mumblings is inexcusable. This goes to show that one shouldn't take seriously books written by amateurs for amateurs.




And one should take seriously things written by you?? Whenever I see a post from you, I know it is going to be confrontational. I skimmed through the posts you made in the last year, and they are rife with conflict. Of all the posts you made in the last year, you started two threads. One was locked. The other you asked for help and a bunch of people replied and you didn't even offer up a thank you.


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pfile
Post Laureate


Reged: 06/14/09

Re: "Lessons from the Masters"...first impressions new [Re: PGW Steve]
      #6088243 - 09/18/13 03:09 PM

there is a machine in alph's house that pees in his cornflakes EVERY MORNING. oh god make it stop

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hytham
Pooh-Bah
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Reged: 12/25/12

Loc: Canadian in the US
Re: "Lessons from the Masters"...first impressions new [Re: pfile]
      #6088330 - 09/18/13 03:56 PM

I downloaded the book from Amazon and so far I have not learned anything new that I have not already seen available (in text or video) on the Internet. (Settle down. I'm not saying I'm a master by any means, I'm very clearly stating that I have seen the techniques described in this book online - nothing new or ground breaking).

What it does have going for it; centralized form factor.

Good read so far and I have (re)learned a great deal.

Thanks to all involved in the book.


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DNTash
scholastic sledgehammer
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Reged: 09/02/07

Loc: GMT+2
Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6089317 - 09/19/13 02:04 AM

Quote:


I wish he did a better job editing chapter 1. The inclusion of f-ratio myth mumblings is inexcusable. This goes to show that one shouldn't take seriously books written by amateurs for amateurs.




A vote for reading Chapter 1. Stating first that I am new to AP, not an expert by any means, as many here, at least not yet , and by no means a math-lete, I personally found Chapter 1 to be quite useful as the basis for understanding procedures described in later chapters. In Chapter 1, he explains concepts very well, even for the less experienced, and particularly for the stated purpose of the chapter. And, the math wasn't difficult to understand, given his examples. As for the short discussion of what he referred to as the f-ratio myth, which was new to me, I personally found it quite interesting and it made sense in the context of his discussion, a discussion that itself provides context for the rest of the book and makes it that much better of a read. Five stars.

Oh, and to the OP, thanks for the tip on the book!

Edited by DNTash (09/19/13 02:07 AM)


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: DNTash]
      #6089331 - 09/19/13 02:46 AM

If you are a beginner, read this book, became a firm believer in Stan Moore's focal ratio myth and replaced your small aperture/short focal ratio scope with larger aperture/larger focal ratio scope, you will be very disappointed. Before you do that, please do a thorough research by reading professional papers and articles first. I don't believe Stan's focal ratio myth was ever checked or approved by the professionals.

Several years ago, I imaged NGC6946 two consecutive nights using C-8 at F/10 one night and F/6.3 focal reducer the other night. I compared F/10 and F/6.3 images (raw and unprocessed) by measuring the ADU of same unsaturated stars and found the ADUs in F/6.3 image more than double than at F/10 image. This is using same aperture size of 8" or 200mm. This proved that focal ratio matters, not aperture. This was taken with same CCD camera. The seeing conditions of both nights appeared to be identical.

I uploaded calibrated and un-processed subs using F/10 and F/6.3 in FIT format for comparison. They were taken with SXVR-M25C OSC camera and each sub was 10 minutes.

F/10:
https://www.dropbox.com/s/qd3k8ttrmfeljry/NGC6946_F10.fit

F/6.3:
https://www.dropbox.com/s/6esxwpl7mfno78c/NGC6946_F63.fit

Judge them for yourself. If you think my experiment is invalid, please explain why.

Some people may say that when you reduced the focal ratio with a focal reducer that you effectively increased the FOV thus you gathered more light which makes it "appear" to be faster light gathering because more photons are striking the same number of pixels on the chip, thus only the aperture really matters. Well, that's how focal ratio works!!!!

It looks like to me that focal ratio DOES matter.

Peter


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DNTash
scholastic sledgehammer
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Reged: 09/02/07

Loc: GMT+2
Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6089338 - 09/19/13 03:10 AM

Good info, and a valuable comment, Peter. I don't think your comment was directed to me specifically, as a beginning APer, but it is an important point. You won't be seeing me giving up my smaller, faster scopes for more AP aperture, and the chapter didn't suggest that to me. I read it as useful and interesting context to the wider discussion in the book. But, I do find the concepts of aperture and f-ratio, and the debate, interesting to try and understand -- as a newbie APer.

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: DNTash]
      #6089343 - 09/19/13 03:20 AM

Hi DNTash,

My post was not necessarily directed to you but to everyone else as well.

You said it yourself by describing your scope as a "faster" scope by meaning your scope has short focal ratio. By "faster" means shorter exposure time regardless of aperture size.

Peter


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Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: "Lessons from the Masters"...first impressions new [Re: DNTash]
      #6089351 - 09/19/13 03:57 AM

Quote:

As for the short discussion of what he referred to as the f-ratio myth, which was new to me, I personally found it quite interesting and it made sense in the context of his discussion, a discussion that itself provides context for the rest of the book and makes



No book should fool anyone especially a beginner who buys a book to learn. I have never seen/read a single academic source that agreed with or even mentioned Mr Moore's f-ratio theory. If you can find one, please let me know.


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Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: "Lessons from the Masters"...first impressions new [Re: PGW Steve]
      #6089353 - 09/19/13 04:02 AM

Geez! You are obsessed. You should seek professional help.

Quote:

Quote:

Quote:

you can imagine what that took alone but there is the editing of each chapter, getting the images correct, content laid out, and the list goes on and on.



I wish he did a better job editing chapter 1. The inclusion of f-ratio myth mumblings is inexcusable. This goes to show that one shouldn't take seriously books written by amateurs for amateurs.




And one should take seriously things written by you?? Whenever I see a post from you, I know it is going to be confrontational. I skimmed through the posts you made in the last year, and they are rife with conflict. Of all the posts you made in the last year, you started two threads. One was locked. The other you asked for help and a bunch of people replied and you didn't even offer up a thank you.




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mmalik
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Reged: 01/13/12

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Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6089397 - 09/19/13 05:48 AM

Folks, let's stop picking on Alph or anyone else. I for one appreciate all point of views; open discussion after all, no need to suppress opinions.

Talking of masters, here... is something I wrote in light of what I learned from the masters of ImagesPlus and PixInsight in this... and this... thread, respectively. Regards


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vpcirc
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Reged: 12/09/09

Loc: Merced CA
Re: "Lessons from the Masters"...first impressions new [Re: mmalik]
      #6089416 - 09/19/13 06:31 AM

Aperture is king will always be king, no doubt focal ratio plays a role in your ability to image given skies, mount etc for the ease of taking images without getting into a tech discussion. This book has concepts well beyond a beginner. Peter, even you said you don't understand the processes in PS. This explains how to do them. You can certainly choose to avoid PS. This book is showing what procedures many of the top imagers are using to make their images look like they do. If that's what you want, then the book will help you. If you already know everything don't waste your money. This is a very difficult hobby to learn. This is a good resource. In talking about how much post processing is the key, I had a friend who sent me an image he shot a few years back yesterday. He had reworked the image from what he knows now compared to then. He was able to take the same data and went from an image that wasn't very good to an image that looked great using the same data. I'll use Warren Keller as a good example. I've had data I was ready to give up on. I couldn't get it to look right for anything. He could take the same data and make a great image. Why, he's a 100 times better than I in bringing out what's there because of his superior post processing skills.
This book highlights many of the post processing skills the top imagers use to make their images win APODS. Folks can sit in their chairs and criticize, but until they're producing APODS, it's all hot air to me.


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jgraham
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6089475 - 09/19/13 07:38 AM

Focal ratio aside...

I bought the Kindle edition and like hytham mentioned I don't see anything really new here, but it is nice to see so much pulled together into a single volume. It is a good read and a nice resource for ideas and things to try.

+1


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broca
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Re: "Lessons from the Masters"...first impressions new [Re: jgraham]
      #6089506 - 09/19/13 08:15 AM

Kids have it good these days. Back in my day I had to do countless web searches, spending hours gobbling up bandwidth, to find topics discussed in this book. I lost my job, my kids do not know me and my wife left me...
I highly recommend this book, I enjoyed reading chapter one and brushing up on the technical aspect, but I'm not going to get hung up in the f-ratio section (after all this is the first of hopefully many editions). There are a thousand ways to skin this cat and I, for one, appreciate these well known astrophotographers offering up their chapters and how they go about their workflow. I would recommend this book to anyone who has already connected their camera to the scope and has a good foundation and is looking for that first (or subsequent) AH HA!! moment.
All good books are open to criticism and discussion.


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vpcirc
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Reged: 12/09/09

Loc: Merced CA
Re: "Lessons from the Masters"...first impressions new [Re: broca]
      #6089537 - 09/19/13 08:47 AM

Oh no don't bring up cats, alf likes to eat them!

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6089660 - 09/19/13 10:18 AM

I just want to point out that I never bash this book (except for focal ratio myth). I said if you are a heavy PS user, this is the book to buy and read. I had to return the book for a refund because it won't help PixInisght users (except for one chapter written by Rogelio but it described very few PI tools and there are lots of fantastic PI tools).

Peter


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pfile
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Reged: 06/14/09

Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6089779 - 09/19/13 11:35 AM

fair enough, my short skim thru the "look inside" was misleading. there's a lot of PS in this book. but i don't think it's entirely useless, at least for me. i know zilcho about planetary imaging and there's some stuff in there on that topic. plus just seeing how others process images is useful regardless of the software involved.

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HunterofPhotons
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Reged: 04/26/08

Loc: Rhode Island, USA
Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6089783 - 09/19/13 11:38 AM

Quote:

..... I don't believe Stan's focal ratio myth was ever checked or approved by the professionals.....
Peter




Look in any physics book.
The rate of photons collected from any object is solely dependent on aperture, not focal ratio.
It's actually quite simple.

dan k.


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vpcirc
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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6089845 - 09/19/13 12:20 PM

An easy to understand explanation from Celestron
The focal ratio is the ratio of the focal length of the telescope to its aperture. It’s calculated by dividing the focal length by the aperture (both must be in the same units). For example, a telescope with a 2032mm focal length and an aperture of 8" (203.2mm) has a focal ratio of 10 (2032/203.2 = 10) or f/10.

It’s variously abbreviated as f-stop, f/stop f-ratio, f/ratio, f-number, f/number, f/no., etc.

Smaller f-numbers will give brighter photographic images and the option to use shorter exposures. An f/4 system requires only ¼ the exposure time of an f/8 system. Thus, small focal ratio lenses or scopes are called “fast” and larger f/numbers are called “slow”. Fast focal ratios of telescopes are f/3.5 to f/6, medium are f/7 to f/11, and slow are f/12 and longer.

Whether a telescope is used visually or photographically, the brightness of stars (point sources) is a function only of telescope aperture - the larger the aperture, the brighter the images. Extended objects will always appear brighter at lower magnifications. The main advantage of having a fast focal ratio with a visual telescope is that it will deliver a wider field of view than slower f-numbers.


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6089900 - 09/19/13 12:50 PM

Would you actually suggest to others to throw away their small aperture and "fast" (e.g. F/4) APO and replace it with large aperture and "slow" (e.g. F/10) scope so that large aperture/slow scope would actually reduce exposure time? Isn't that what Stan Moore pretty much is suggesting?

If I am missing the point, please explain.

If you would like me to stop discussing about focal ratio myth, I will be happy to stop. But the focal ratio myth is part of the book. I do not want to start the war about this and end up locking this thread.

Peter


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hytham
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6090402 - 09/19/13 05:55 PM

Peter, as a newbie (me) one of the best things I have *discovered* is the use of multiple tools to improve upon the images. There is no one tool to rule them all at this time and having the skill set to call upon the proper tool for a specific job will show an increase in, for a lack of a better term, *better* processing.

I'm so bloody new to PS (heck imaging in general) that this book is a great centralized reference to work on that particular skill.

My advice, give it a shot. It's $35 and compared to your financial *investment* into this hobby it is peanuts. Heck, the cost of photoshop is nearly the same as one of my 50mm square filters.

Now onto f-ratio. The f-ratio does not affect the rate at which photons are collected, but affects the concentration of those photons on to the area of the CCD. The decrease in f-ratio (F10 to F5) ultimately affects the angle of incidence thereby affecting the concentration of photons onto a smaller area of the CCD allowing for an increase in SNR. As we increase our f-ratio (F5 to F10), the constant rate of photons does not change (it's that simple), but what changes is the area which the photons are now spread across is much larger leading to a decrease in signal to noise ratio. Less photons per photodiode keeping us very close to that noise threshold.

The rate of photons is based on aperture, and concentration of photons is based on the angle of incidence to the surface area of the CCD.

Peter, a more appropriate test would have been to compare two imaging systems with the same aperture, different focal lengths and matching scale. I'm willing to bet the difference would not be as different as you think.

A good test would be to compare the Veloce RH 200 against my FSQ. Both produce similar image scales (with my KAF 16803 it is 3.1"/pixel vs. 3.5"/pixel) but with wildly different apertures.

My very humble .02.


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HunterofPhotons
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6090437 - 09/19/13 06:09 PM

Peter,
The take-away from any discussion of this is that for scopes of equal aperture the number of object photons captured per rate of time is equal.
It's a law of physics. <g>
For scopes of equal aperture but differing focal ratios, the scope with the lower focal ratio is capturing a larger field of view and therefore more photons of a larger field, but it is still capturing the same amount of photons of individual objects.
The confusion about this 'myth' comes from two places.
The first is that us old folks are locked into the paradigm of old-time cameras where a lower focal ratio meant more light into the camera. What is forgotten sometimes is that this was accompanied by an increased aperture by a changing iris.
What we are talking about in Stan's 'myth' is scopes of equal apertures.
The second area of confusion is that we are talking about object photons, not total photons. This was clearly stated by Stan, but many people seem to pass over this.
What you get with a lower focal ratio is a wider field of view and a decreased resolution of your chosen object.
What you get with a higher focal ratio is increased resolution and a narrower field of view.
Let's say you want to image The Ring Nebula. With a lower focal ratio you will capture the nebula in a smaller size with a large surrounding star field. With a larger focal ratio you will capture a larger image of the The Ring, but less of the surrounding star field.
For equal apertures you will have captured the same number of photons. They are just distributed over differing numbers of pixels. If you shrink the longer focal ratio image to the same size of the lower focal ratio image it will be the same.
The one caveat in this shrinkage is the contribution of read noise. Since the longer focal ratio image is distributed over more pixels than the shorter focal ratio image, read noise could become a contributing factor. If, however, you are taking sky-limited images, (which I hope you are), then this is not a significant factor.
What most imagers do is to frame their objects by focal ratio and expose appropriately. In other words, if you want to image The Veil Nebula, then go for the wide field of view with a lower focal ratio (or do a mosaic with the long focal ratio).
If you want to do a finely resolved image of The Ring Nebula and skip the surrounding star field, then, by all means go for the longer focal length.
Each focal length has its advantages, you just have to tailor them to the object of interest.

dan k.


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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6090515 - 09/19/13 07:03 PM

Very well put and explained!!! I think where people get confused is short focal length seems easier, but because all the tracking and guiding errors are hidden. The longer the focal length and image scale, the more apparent your problems are, including post processing. I think of it kind of like TV, if they do a close up of a face you can see every blemish there. If the shot is at a moderate distance, you wouldn't even notice!

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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6090521 - 09/19/13 07:07 PM

Generally speaking, all I am saying is if the goal in astronomy is to image deep sky objects that usually require long exposures due to low light from target objects is to aim for lower focal ratio whether the focal length is short or long. It pretty much guarantees to capture decent images at reasonable exposure times.

I know it's difficult to own one telescope and one camera to work with all objects since different objects have different sizes (e.g. one size fits all). That's not easily possible. Not every one has money or resources to own several telescopes of different focal lengths at reasonably low focal ratios and several cameras of different pixel sizes to better match to the optics. I understand all that.

It's possible that Stan's write up is poorly written that can cause people to mis-interpret his writings. It's very important for every one to understand otherwise people could end up buying the wrong telescope and equipment because of mis-understanding of other people's write up or articles. For example, Stan's comparison of two images may be mis-leading since it does not say whether both images are equally or unequally stretched. It also does not say if same camera was used. It does not even say what the object is. The object could have been bright enough for the signal to be well above camera's read noise for large focal ratio and stretch the image enough to match the low focal ratio image (less stretched). If Stan did that, then that may invalidate the test. I feel Stan's article has lots of holes that needs to be filled. In other words, Stan's article is lacking details.

Dan, your write up is excellent and better than what Stan explained. I pretty much already knew what you said. I was having a hard time deciphering Stan's write up.

Peter


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pfile
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6090531 - 09/19/13 07:14 PM

not to cast aspersions at the masters but that piece by stan is not very well written. i think that contributes to the confusion.

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Re: "Lessons from the Masters"...first impressions new [Re: pfile]
      #6090591 - 09/19/13 08:18 PM

Tony Hallis would tell you PixInsight is a waste of money because there's nothing it can do that he can't do in photoshop. Does that invalid what he's teaching because you don't agree? Or does he have a different approach to accomplishing what he wants? A great example might be the content aware healing brush in photoshop. I can't find anything as easy and quick to correct flaws in PI. When it comes to explaining things, it's sometimes easier for some to understand when it's explained one way, to others they may not get what's being said at all. Golf lessons are a great example, I can get what teacher says, but not the other even though both are trying to get me to correct my swing plane.
I agree with you Peter, one of the biggest mistakes new imagers make is to start out with an SCT at F10. They get frustrated really quick. I doubt many of them are reading Stan's write up though.


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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6090605 - 09/19/13 08:34 PM

Quote:

The confusion about this 'myth' comes from two places.
The first is that us old folks are locked into the paradigm of old-time cameras where a lower focal ratio meant more light into the camera. What is forgotten sometimes is that this was accompanied by an increased aperture by a changing iris.



You are making wrong assumption what others think. Honestly, you are the one who looks confused. You fell victim to his misinformation campaign. When it comes to imaging speed, focal ratio and pixel size rule.


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Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6090805 - 09/19/13 10:50 PM

Got my copy today and given my schedule, will take some time to read. Given the discussions here already, I'm sure there will be a number of critics and proponents. The F ratio 'myth' has been pretty well run to ground in these forums and I don't expect much to change. What I do hope is the PS techniques will improve my slowly evolving processing skills. BTW, for those in the Salt Lake area, Tyler Allred is scheduled to speak at the SLAS November meeting...

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Ken Crawford
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Re: "Lessons from the Masters"...first impressions new [Re: BlueGrass]
      #6090812 - 09/19/13 10:55 PM

Can't have too many processing tools in the tool Box! The problem is that powerful tools like PS - PI - Stack - ect can be used with the precision of a surgeons knife or a blacksmith's hammer! Depends on the touch!

Just don't have the touch of a blacksmith


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Re: "Lessons from the Masters"...first impressions new [Re: BlueGrass]
      #6090819 - 09/19/13 10:59 PM

Alf, the mars rover data shows no life currently on Mars. Since you're typically in outer space in your travels, is the rover misreporting information on the chemical composition and life on Mars?

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6090832 - 09/19/13 11:12 PM

As much as I have disagreed with Alph 98% of the time in the past, I am afraid he is correct. Focal ratio will always determine the image speed, film or CCD. That part will never change since the invention of camera.

Peter


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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6090860 - 09/19/13 11:29 PM

Peter, everything has a cost in imaging, faster speed has a cost as well. The key is finding the right balance. You can take wonderful images at F4, but you can take even better ones at F10 if the aperture is the same. It's just harder and takes longer, but in the end the F10 image will show greater detail and resolution. RCOS doesn't make an OTA at F5 for reason.

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6090924 - 09/20/13 12:26 AM

You said it yourself, "it takes longer" at F/10 than F/4 regardless of aperture (that's what you appear to be implying). That's the whole point of shorter focal ratio is to take shorter exposure times so we can capture the images quicker and take more DSOs in shortest possible time. Who wants to image 100 hours of the same object before imaging another 100 hours of another object. I don't think focal ratio have any effect of details.

F/10 (or any other focal ratio) does not necessarily mean it will show greater details. I think you meant longer focal length (higher resolution) then it would show greater details but not focal ratio. I think you are missing the point about differences between focal ratio (image speed) and focal length (resolution).

In the case of your examples, you can take not only wonderful images at F/4 but also in great details if the focal length is longer which will require larger aperture. You will get similar details in 10" F/4 as in 4" at F/10 because both scopes have same focal length but exposure times with 10" F/4 will be shorter not because of larger aperture but also shorter focal ratio. Maintaining same short focal ratio while increasing focal length just happens to increase aperture. It's very simple math.

In your previous post, everything you talk about is focal ratio but not focal length. You seem to imply that fast speed (short focal ratio) automatically means short focal length. That's not necessarily true because you can have short focal ratio and long focal length by increasing aperture size. But don't let aperture size determine image speed.

RCOS or any other Cassegrain-like scopes at F/5 or shorter would not be practical because the secondary mirror will be too big and reduce contrast. That's one of the reasons why Cassegrain-like scopes have slow focal ratio is to have higher contrast.

Pixel size can also determine image speed. There is a cost. Larger pixel size can help reduce exposure times but at the expense of under sampling (stars would be more square). That's the another subject I don't wish to discuss in this thread.

Peter


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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6091039 - 09/20/13 02:43 AM

Let's not forget about matching a CCD chip to the scope. That is as important as all the other factors. Good coverage and proper f/l and f/r to get the desired image pixel scale will give good results.
Blueman


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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6091058 - 09/20/13 03:37 AM

I'm due to receive a copy for magazine review and am greatly looking forward to it. When the Editor sent me the latest list of review titles it was the first on the list and I replied to his email without even reading the rest!
I did wonder how the Ps/PI thing would play out in the book.
Olly


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vpcirc
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Re: "Lessons from the Masters"...first impressions new [Re: ollypenrice]
      #6091087 - 09/20/13 04:31 AM

That's where you're wrong Peter. Because your image scale changes how much of what you see changes. If I hold an eye chart up for you at 10 feet which line can you read? If I now move to 20 feet which line can you read? Scale definitely effects resolution and detail. I'm not confused about the difference between ratio and speed for a second. Ratio only effects scale and therefore detail you can see. Faster = smaller scale and less detail.

"An f/5 system can photograph a nebula or other faint extended deep space object in one-fourth the time of an f/10 system, but the image will be only one-half as large. Point sources, such as stars, are recorded based on the aperture, however, rather than the focal ratio – so that the larger the aperture, the fainter the star you can see or photograph, no matter what the focal ratio" Astronomics

Again, I'm saying the "magnification" is what allows you to see more detail and resolution of the image in a slower system. I do agree with you in that the imager traveling to setup is unlikely to be able to gather enough data without lots of effort. That's why I setup a concrete pier in my back yard and went to automated imaging. I got sick of trying to stay up all night. Now of course I took it a step further, and I realize not everyone has these options available to them.


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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6091593 - 09/20/13 11:54 AM

Quote:

Ratio only effects scale and therefore detail you can see. Faster = smaller scale and less detail.




Mike,
Focal length and pixel size effect image scale. Focal ratio has nothing to do with scale. It only determines imaging speed. If there were no diffraction then aperture wouldn't matter much. In the olden days, astronomers and physicists were assuming that aperture did not matter at all! Only the discovery of light diffraction changed that thinking.


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HunterofPhotons
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6091612 - 09/20/13 12:04 PM

Quote:

.....That's the whole point of shorter focal ratio is to take shorter exposure times so we can capture the images quicker and take more DSOs in shortest possible time.....
Peter




Peter,
The rate of object photons captured by a telescope is solely dependent upon its aperture.
It has nothing to do with its focal ratio.
If you don't understand these principles of physics, then I can understand your befuddlement.

dan k.


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6091646 - 09/20/13 12:18 PM

Hi Dan,

I am currently using Google to look for information you are providing and I can't yet find them. If you know where I can find them, can you provide the links to web sites?

Thanks,
Peter

PS: Don't include links to Stan Moore's article.

Edited by Peter in Reno (09/20/13 12:27 PM)


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6091653 - 09/20/13 12:20 PM

Quote:

Quote:

Ratio only effects scale and therefore detail you can see. Faster = smaller scale and less detail.




Mike,
Focal length and pixel size effect image scale. Focal ratio has nothing to do with scale. It only determines imaging speed. If there were no diffraction then aperture wouldn't matter much. In the olden days, astronomers and physicists were assuming that aperture did not matter at all! Only the discovery of light diffraction changed that thinking.




Once again, I am afraid Alph is correct.

Image scale = (206.3 * pixel size) / focal length

Where is the focal ratio in the formula?

Peter


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korborh
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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6091670 - 09/20/13 12:30 PM

Quote:

Quote:

.....That's the whole point of shorter focal ratio is to take shorter exposure times so we can capture the images quicker and take more DSOs in shortest possible time.....
Peter




Peter,
The rate of object photons captured by a telescope is solely dependent upon its aperture.
It has nothing to do with its focal ratio.
If you don't understand these principles of physics, then I can understand your befuddlement.

dan k.




This whole "object photons" and "myth "wording used by Stan has caused much confusion on this very basic of optical concepts i.e. f/ratio.

As Alph says, f/ratio has nothing to do with resolution or image scale. You can get any resolution or image scale with any f/ratio.

F/ratio only says about the steepness of the cone of light which translates into SNR per linear dimension on the detector.

Having Stan's myth write-up in this book really undermines its credibility.


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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6091692 - 09/20/13 12:39 PM

Quote:


Peter,
The rate of object photons captured by a telescope is solely dependent upon its aperture.
It has nothing to do with its focal ratio.
If you don't understand these principles of physics, then I can understand your befuddlement.

dan k.




Dan, imagine adding a very long focal extender with very small pixels. Object photons will be spread out across many pixels. Signal to noise in each pixel will be small. At full resolution the image will look very noisy as each pixel may have captured only a few photons.

If you downsample the noisy image significantly in software you may recover an acceptable image, assuming that read noise was not a significant factor in the original. This downsampling is equivalent to decreasing f/ratio.

So to get a reasonably noise free image you either need a fast system, big pixels or a significant software downsampling.

Note however that faster f/ratio and big pixels is not always a good thing as both will increase the amount of sky background photons captured by each pixel. This increase may swamp the few photons from a dim star whose airy disc fits entirely within one pixel. So fast systems and big pixels are not necessarily a good way to capture dim stars.

Regards,
Mike

Edited by mikeschuster (09/20/13 12:42 PM)


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: mikeschuster]
      #6091745 - 09/20/13 12:58 PM

So far I found this link written by Steve Cannistra who is one of the authors in this book:

http://www.starrywonders.com/fratio.html

I let you be the judge and decide what you think.

Peter


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hytham
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Re: "Lessons from the Masters"...first impressions new [Re: korborh]
      #6091761 - 09/20/13 01:06 PM

I just don't understand the confusion people have between f-ratio and aperture. Increasing the aperture increases the amount of light gathering capabilities. Lowering the f-ratio allows for a higher concentration of light on a smaller surface because we have affected the angle of incidence (or steepness of the light cone) to the CCD (this is where you see vignetting).

Both work in conjunction to lead to a brighter image in a shorter amount of time. A 106mm scope running at F3 is not going to collect the same amount of light as a 200mm scope running at F3. If you say it does, prove it.

I hope nobody is arguing that f-ratio alone is enough. Then there are a lot of people that have been ripped off over the years by purchasing large aperture systems.

I really don't understand the confusion here.


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Re: "Lessons from the Masters"...first impressions new [Re: hytham]
      #6091786 - 09/20/13 01:16 PM

Quote:

A 106mm scope running at F3 is not going to collect the same amount of light as a 200mm scope running at F3.




Both scopes at f/3 will capture the same amount of light per pixel. That is the utility of f/ratio - in just one simple number to give SNR per linear dimension. Use this number for this purpose and nothing more.


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Re: "Lessons from the Masters"...first impressions new [Re: mikeschuster]
      #6091793 - 09/20/13 01:20 PM

Higher focal ratios=higher magnification and smaller field of view. Lower focal ratios= Wider field of view and less magnification. The reason a lower focal ratio images faster is because more light is being concentrated. That comes at the cost of resolution and magnification. Yes you can effect some of this based on the size of the chip and the pixel size, but if all things are equal, aperture and camera, the results are as stated above. If you don't want to believe that than by all means ignore it. There are tons of google searches that will tell you the same thing.

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: hytham]
      #6091798 - 09/20/13 01:22 PM

I too have been confused about larger aperture leads to larger light gathering power but does it really mean shorter exposure times regardless of focal ratio?

This just crossed my mind and please correct me if I'm wrong. Take a flashlight and a piece of paper. Make a pinhole at the center of paper and place the paper on flashlight. The light through the pinhole does not appear to be bright. Now as you make the hole bigger, light will appear to be brighter but is it really brighter on a camera? The brightness of flashlight is always the same. The hole in the paper is the aperture. Is this analogy accurate?

Interesting link about light gathering power:

http://starizona.com/acb/basics/observing_theory.aspx

Peter

Edited by Peter in Reno (09/20/13 01:36 PM)


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HunterofPhotons
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6091911 - 09/20/13 02:26 PM

Quote:

So far I found this link written by Steve Cannistra who is one of the authors in this book:

http://www.starrywonders.com/fratio.html

I let you be the judge and decide what you think.

Peter




He's talking about what happens for an individual pixel.
This has nothing to do with 'The F-Ratio Myth'.
Once again, let me repeat, the number of photons collected from an object is only dependent upon aperture.
Physicists are pretty sure this is true. <g>
Take two scopes of equal aperture, one f/10, the other f/5.
Whatever encompassing object they look at, they are capturing the exact same number of object photons. The only difference is that the f/5 scope is putting them in a smaller area.
Of course when you have a smaller area for the same amount of photons they will collect at a faster rate at the pixel level, but they are collecting the total number of object photons at the exact same rate.
Once again let me reiterate, Stan is talking about object photons, the total number of photons from an object.
All he has done is restate a law of physics and given it a provocative title.

dan k.


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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6091937 - 09/20/13 02:44 PM

Quote:

He's talking about what happens for an individual pixel.



That's all what it matters.


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vpcirc
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Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6092044 - 09/20/13 04:04 PM

Peter you are fond of focal reducers. Take an image with it on and without it, compare the two, and see what happens to the image.

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6092060 - 09/20/13 04:11 PM

I did. Take a look at my earlier posts. I uploaded sample images taken with F/10 and F/6.3 in RAW and FIT files for everyone to look at. The ADU values in F/6.3 image was more than doubled than at F/10 using same 10 minute exposures and same aperture size. This is pure emperical data. This proves that focal ratio matters. Please take a look at them.

The message # is 6089331.

Peter


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6092061 - 09/20/13 04:14 PM

Hi Dan,

Ok, I think I am getting the message from you. I already knew that same amount of photons (or light, signal or whatever) are hitting the detector for same aperture. I got confused with the term "object photons". I mis-interpreted the meaning of it. If you are saying what Stan Moore is saying, that's fine.

I am not really interested in object photons. This does not help me or others much to determine exposure times. I am interested in equipment that will allow me to expose in the shortest possible time for focal length (or image scale) I want. Obviously start with the shortest focal ratio for a focal length (or image scale) I want at the price (larger aperture size = higher cost) I can afford. I am not sure object photons should be part of the equation for purchasing telescope equipment. Don't everyone want to expose DSOs at the shortest possible times to maximize imaging as many DSOs as possible?

I still do not like the way Stan Moore writes. It needs to be revised or re-written to include more or accurate details to avoid confusion. I feel it's lacking details. Or change the title of the article because there's no myths about focal ratio.

Peter


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vpcirc
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6092085 - 09/20/13 04:35 PM

Quote:

I did. Take a look at my earlier posts. I uploaded sample images taken with F/10 and F/6.3 in RAW and FIT files for everyone to look at. The ADU values in F/6.3 image was more than doubled than at F/10 using same 10 minute exposures and same aperture size. This is pure emperical data. This proves that focal ratio matters. Please take a look at them.

The message # is 6089331.

Peter




Of Course, you're concentrating the light at the lower focal ratio, but your image is smaller and shows less detail You can try to make it look the same by enlarging it, but it's not the same period. There is trade off for a faster f-ratio, that's not going to change no matter how much you want it to. That being said, I'm not in anyway suggesting you're wrong for wanting to image faster. My only points are you sacrifice scale and detail, but that beats fighting imaging at a high F-ratio when you have to travel, setup, etc.


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vpcirc
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6092090 - 09/20/13 04:39 PM

Quote:

Hi Dan,

Ok, I think I am getting the message from you. I already knew that same amount of photons (or light, signal or whatever) are hitting the detector for same aperture. I got confused with the term "object photons". I mis-interpreted the meaning of it. If you are saying what Stan Moore is saying, that's fine.

I am not really interested in object photons. This does not help me or others much to determine exposure times. I am interested in equipment that will allow me to expose in the shortest possible time for focal length (or image scale) I want. Obviously start with the shortest focal ratio for a focal length (or image scale) I want at the price (larger aperture size = higher cost) I can afford. I am not sure object photons should be part of the equation for purchasing telescope equipment. Don't everyone want to expose DSOs at the shortest possible times to maximize imaging as many DSOs as possible?

I still do not like the way Stan Moore writes. It needs to be revised or re-written to include more or accurate details to avoid confusion. I feel it's lacking details. Or change the title of the article because there's no myths about focal ratio.

Peter




No
And if that's what you want get a Newtonian (cheapest per inch of aperture or go with fastar.


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6092180 - 09/20/13 05:35 PM

Mike,

The biggest confusion about Stan Moore's article was that most people including myself thought he was talking about that same exposure times can be used for same aperture at different focal ratios is true. What Dan was saying that Stan meant amount of object photons are the same for same aperture regardless of focal ratio. I agree with that. That's where the biggest confusion comes in. Most people thought Stan meant amount of light per pixel remains the same for same aperture size at different focal ratios and that's false but I don't believe that's what Stan meant. (If there is a hint Stan meant it, I don't want to talk about it). Like I said before, Stan needs to re-write the article or hire someone to make it more clear.

You mentioned many times about advantages and disadvantages of focal ratio. I know all about that and let's forget all about that. Now about choosing the right telescope to meet my or other people'e requirement. In my case, first I want a refractor, I am not interested in reflector of any types (Newt, SCT, etc.) of scopes anymore. Next, I wanted a scope at 1000mm focal length because I felt it was a good compromise for many different sizes of DSOs. Next was to determine the lowest focal ratio. Remember that focal ratio has NOTHING to do with image scale, only imaging speed so I wanted to lowest possible focal ratio which will also determine aperture size. As we know that larger aperture the higher the cost. Once focal ratio/aperture size is determined at the price I can afford, then I finally find the scope I want. These requirements allow me to get the proper image scale and details of DSOs I want. Picking a CCD camera is a whole different ball game but this discusion is about focal ratio.

Dan, please let me know if I made any mistakes in my first paragraph.

Peter


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vpcirc
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6092231 - 09/20/13 06:00 PM

Focal Ratio has everything to do with image scale. Faster = smaller, wide field. Slower = Larger, and less FOV given the same aperture. The lower the focal ratio, the lower focal length for a given aperture. A 16" at F/5 drops to 2000MM, the same as an 8 in at F10. That's a huge difference in what you see.

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6092259 - 09/20/13 06:22 PM

Image scale = (206.3 * pixel size) / focal length

Where is the focal ratio in the formula? The math does not lie.

2000mm focal length of different apertures and focal ratios is the SAME image scale. Just because focal ratios are different for same focal length does not change image scale. Focal length determines image scale, not focal ratio. Aperture changes details and resolution.

When I set my requirement to 1000mm focal length before anything else, determining focal ratio from then on will NOT change image scale, only changes imaging speed and aperture size.

You said for a given aperture, changing focal ratio changes image scale. You are correct because focal length also changes.

In other words, for a given focal length, changing focal ratio does not affect image scale because focal length remains the same, only aperture changes.

Peter

Edited by Peter in Reno (09/20/13 07:15 PM)


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vpcirc
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6092379 - 09/20/13 07:41 PM

That's true the bottom line is focal length will determine image scale. The difference is aperture for light gathering. Every March and April I have nothing to image because at 1200 mm most galaxies are far to small at that focal length. 1000 is great for widefield and since you can't image all the time you'll be happy. I'd much rather be at 2500+ so I could capture great detail I currently can't, but that means a bigger mount and lots of money for an OTA. I guess I'll be happy at 1200

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6092398 - 09/20/13 07:54 PM

Finally we are in agreement. I hope others are as well. If not, please feel free to comment.

I have been researching quite a bit lately about light gathering power. I find the term "LGP" somewhat misleading. My research shows that for a given focal ratio (never changes), larger aperture (also increases focal length and image scale) will not reduce exposure times BUT will resolve better like splitting double stars and show greater details in DSOs like you said. It's kind of like reading a book in poor light condition and show lack of details and then brighten the light to show more details or resolve better. Does that make sense?

Peter


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Aircrftr
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6092570 - 09/20/13 10:02 PM

WOW... This is just like the "Throttle controls altitude and elevator controls airspeed" argument.

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: Aircrftr]
      #6092586 - 09/20/13 10:14 PM

Are you referring to my light gathering power analogy? If so, can you think of a better analogy?

Peter


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Aircrftr
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6092868 - 09/21/13 05:05 AM

No, I was referring to the whole discussion. I can understand the benefits of both sides of the discussion. At the risk of getting involved, my take on it is this.
If you want to take a wide field exposure, then you are taking a large area of the sky and concentrating it on a "relatively" fewer pixels. Naturally those pixels get more of the photons per unit of time. That is your "fast focal ratio/short focal length" experience. If you want to "zoom" in on a smaller portion of that same piece of sky then you have to magnify it. If you kept the same aperture, then you have taken the photons from that smaller piece of sky and spread them over a larger portion of the chip. Same number of photons gathered for that portion of the sky, but now they are spread out over more pixels. That amounts to less photons per pixel per unit of time. How to get that same number of photons per pixel per unit of time? Use more aperture to gather more photons to put on each of those pixels.
Telescopes come in a wide variety of apertures, focal lengths and ratios. CCD cameras come with a different variety of pixel size and chip sizes. Use the combination of equipment to best suit what it is you are going for. More resolution by putting small patches of sky on large areas of the CCD chip. Less resolution by putting large areas of the sky on that same area of the CCD chip. Use pixel size to control under or over sampling of the image in arc seconds of the sky per pixel. Gather more photons per arc second of sky by increasing the aperture.
As Forest Gump would say; "That's about all I got to say about thaaat".


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: Aircrftr]
      #6093066 - 09/21/13 09:46 AM

That's pretty well said. No such a thing as one size fits all for one telescope and one camera for all objects in the sky. If you want to own only one telescope and one camera, you have to find a compromise.

Peter


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HunterofPhotons
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6093322 - 09/21/13 12:19 PM

Quote:

...I am not really interested in object photons. This does not help me or others much to determine exposure times. I am interested in equipment that will allow me to expose in the shortest possible time for focal length (or image scale) I want. Obviously start with the shortest focal ratio for a focal length (or image scale) I want at the price (larger aperture size = higher cost) I can afford. I am not sure object photons should be part of the equation for purchasing telescope equipment. Don't everyone want to expose DSOs at the shortest possible times to maximize imaging as many DSOs as possible?....

Peter




I don't understand your disdain for object photons.
If, as you say, that "Don't [sic] everyone want to expose DSOs at the shortest possible times to maximize imaging as many DSOs as possible?...." then I believe that you still misunderstand the concepts involved.
Let's take out the two telescopes I mentioned before, ones of equal aperture, but of differing focal lengths, f/5 and f/10.
Pick a DSO that fits within the field of view of both scopes.
Are we in agreement that for whatever total exposure time we take for this DSO that the same number of object photons will have been captured by each scope/camera? (I hope so. <g>)
Since we are following good imaging practices during these exposures, we will be taking sky-limited subexposures of appropriate lengths.
Since the field of view for the f/5 instrument is wider it will be collecting photons from outside the field of view of the f/10 scope. More photons falling on the same sensor means that the pixel wells will be filling up faster and the subexposure times will be shorter. This shorter subexposure time for the f/5 instrument does not translate to getting an image of your chosen object any faster. Shrink the f/10 image down to the same size as the f/5 and it will be of equal brightness.
Aperture alone determines object brightness.
If you want to decrease the time it takes to capture an object, increase the aperture.
Focal ratio will determine your field of view, how you frame an object, but it will not capture object photons any faster than an equal-sized instrument.
In practical terms, if you want to capture The Veil Nebula, The Andromeda Galaxy, or some equally large object in one shot, then grab that low f-ratio scope or put on a focal reducer. Your aperture will determine what total time you need to spend on that object.
If you can lay your hands on something like a 300mm Riccardi-Honders at f/3.8 then you've got an instrument that will pull in lots of large object photons fast.
If you want to go for a smaller target like The Ring Nebula and you don't want it to be some hardly recognizable blob in a large star field, then pull out a scope with a long focal length. It will give you the resolution you need. Your subexposures will be longer than for a scope of lower focal ratio, but you are still gathering the same number of total photons.

dan k.


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vpcirc
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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6093884 - 09/21/13 05:57 PM

I found a great explanation that most of us can understand.
Given a telescope of some specified aperture, it will collect and focus all the light that falls onto the objective. Whether that is an f/5 system or an f/10 system, is of course irrelevant. The light from a star will be focused onto the sensor. The size of that star will change depending on the focal ratio, but only because the focal length has changed. Two telescopes of the same focal length with different focal ratios would product the same size star. The telescope with the larger aperture would result in more light from the star falling on the sensor.

What does change with a faster focal ratio is the field of view. Light that would have missed the sensor with a slower focal ratio (longer focal length), will strike the sensor and get recorded by the faster focal ratio (shorter focal length). So, more total light is recorded on any given sensor (because of the larger field of view), but the number of photons striking the sensor from a star in the middle of the FOV will be identical, independent of focal ratio. Only the aperture matters (assuming similar glass, lens coatings and a million other variables).

Telescope focal ratio is different than a camera lens with an aperture stop. When you stop down a lens, you are blocking some of the light that entered the optical system from reaching the sensor. Stopping down a lens reduces the brightness of the recorded image and increases the depth of field (by rejecting light that would otherwise be out of focus).


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ollypenrice
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6094488 - 09/22/13 03:24 AM

Personally I think that the F ratio myth is itself a myth because I've never met anybody who believed that using a faster, shorter focal length optic would really give them the same quality image at the same scale in less time. Surely nobody really thinks it would?

When I explain this to our guests I refuse to be drawn into comparing two systems of different focal length. If you compare fast and slow but ONLY of identical focal length you cannot go wrong and a simple drawing shows that a doubling of aperture is a quadrupling of light.

Then comes pixels size!!

Olly


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jerryyyyy
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Re: "Lessons from the Masters"...first impressions new [Re: pfile]
      #6094772 - 09/22/13 10:19 AM

I guess I'll get the Kindle edition as I could use something to read, but a look at the excerpts on Amazon suggest it will be of limited use to people who use PixInsight like me.

I have had a very steep learning curve now almost 1 year into CCD imaging and if I had to do everything in CS5 I would be way behind where I am now. I have a lot of experience with CS5 and everything just takes so much longer and so much is automated in PI.

Also given one has say X numbers of hours to read/week on Astrophotography my hours are going into better understanding of the PI procedures, which seem to be written by pros with a deep understanding of things like noise reduction... read the background on TGVDenois for example (this is rocket science and I have show it to people in my lab who do neuroimaging and they use the same procedures not Photoshop... see also Craig Stark).

All that being said, I'll get the kindle edition and read it... if I get something out of it I am happy and at least it has stimulated discussion here.

BTW, i agree with Peter in Reno on f-ratios and my next scope is going to have a fast fast and faster system... I still have my original C8 and have done the FR experiments suggested by Peter. Craig Stark had a lot to say on this.

Anyway, enuf said and I guess I'll plunk down my $.

Edited by jerryyyyy (09/22/13 10:21 AM)


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elbee
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Re: "Lessons from the Masters"...first impressions new [Re: jerryyyyy]
      #6095071 - 09/22/13 01:29 PM

i desperately wanted to stay out of this thread, but i can't help myself any longer :-)

1. i think stan moore is brilliant and i hugely appreciate what he has done for the astrophotography community and i respect his writings -- even if they are not always easy to understand (there, i said it.. i'm a stan fan-boy :-)

2. the f-ratio myth. "the myth" is that for a given EQUAL aperture, an f/5 scope will capture the data 4x faster than an f/10 scope. they are collecting data at the same rate (determined solely by aperture). in terrestrial photography, changing from f/10 to f/5 -- with FOCAL LENGTH constant -- you ARE changing the aperture - DIAMETER - by a factor of 2. light gathering is purely a function of AREA. so if you change the diameter by 2x the area has changed by 4x and thus photographers say i can shoot at f/5 in 1/4 the time i can shoot at f/10. that is physics -- the aperture (area) went up by a factor of 4 in his camera (focal length stayed the same) and you can reduce the exposure time by 1/4.

3. changing the f/ratio on your telescope does not change the area, it changes the FOCAL LENGTH (linearly). but manufacturers liked to advertise "image in 1/4 the time with f/5 vs. f/10" -- THAT is the myth. you won't image 4x faster. the f/5 will reduce imaging time because of the change in image scale (focal length) but it won't be a factor of 4

4. changing focal length changed your image scale (linearly). no more data entered the scope -- for a given object. but what did enter was reduced into fewer pixels (assume you didn't change cameras). more signal per pixel was collected but it is a linear compression, not quadratic (like the f/ratio myth wants you to believe)

5. if you scale up the image of the object you captured at f/5 to the same scale as the object you captured at f/10 (double it) there will be less detail since you compressed the info into fewer pixels to start with due to focal length change.

- pick the focal length and chip size to capture the FOV you want.

- pick the camera pixel size to match your focal length and seeing conditions to provide your best arcsec/px resolution

- and then buy the biggest aperture scope you can afford (at the focal length you decided you "need")

- then take pictures that are sky limited.

measure your f/ratio if you want to (focal length divided by aperture) but it should have little to do with why you decided to buy that scope. and don't ever believe the marketing "myth" that an f/5 scope will capture data 4x faster than f/10. it's marketing written by someone who had no understanding WHY in terrestrial photography shooting at f/5 IS 4x faster than shooting at f/10. same rules don't apply to fixed aperture telescopes.

there i stepped in it... forgive me.


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Aircrftr
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Re: "Lessons from the Masters"...first impressions new [Re: elbee]
      #6095189 - 09/22/13 02:52 PM

Elbee;

I'm Hearin what your sayin.....picking up what your laying down... Smellin what your steppin in!

Edited by Aircrftr (09/22/13 02:54 PM)


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ollypenrice
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Re: "Lessons from the Masters"...first impressions new [Re: elbee]
      #6095195 - 09/22/13 02:57 PM

Sorry, I can make neither head not tail of how this forum's qupte/reply system works but that is because I'm a dim Englishman living in France. What do you expect? But I want to respond to this quotation, which is not correct.

'What does change with a faster focal ratio is the field of view.'

The FOV does not change with the F ratio, it changes with the focal length. All of this hot air arises from the muddling of variables, F ratio and focal length.

All of this pointlessly acrimonious debate can be ended if we apply one simple rule. Compare ONLY images taken at the same focal length. If you do this you are comparing the same picture with the same picture, which strikes me as screamingly reasonable. If you compare one picture with a different picture (one taken at a different FL) you will fall into the mire. Once in the mire you'll be tempted to sling mud in all directions, so I'd advise NOT falling into the mire. (English humour, broad smile.)

Olly


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elbee
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Re: "Lessons from the Masters"...first impressions new [Re: ollypenrice]
      #6095217 - 09/22/13 03:15 PM

you replied to my message because as you say, the reply/threading of these messages can easily be confused. :-)

as you probably know, it was not me that said 'What does change with a faster focal ratio is the field of view.' and you are correct in clarifying focal LENGTH changes field of view. however, it is not wrong to say focal ratio will change field of view in the context of constant aperture (since focal length must be changing in that case)

having lived in the UK for 5.5 yrs, i do enjoy those English expressions :-)


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: elbee]
      #6095300 - 09/22/13 04:08 PM

OK, I get the "concept" of object photons. This is going to be my last post in this thread because it's going in an endless loop about focal ratio myth.

I agree with both Dan's and Lee's explanation about Stan Moore's article. Both of their write ups should merge with Stan's article because his article is lacking details and information.

Now for practical purposes. Consider the following:

Scope 1: 20" F/5 (2540mm F/L/) and camera (12.31 uM pixels) so that the image scale is 1"/pixel
Scope 2: 100mm F/5 (500mm F/L) and camera (2.42 uM pixels) so that the image scale is also 1"/pixel

The camera part is theory and may not exist for the above setups, so forget about which camera is available. Let's assume both will have same FOV (yes, CCD size would be huge for 20" scope) and same target DSO.

What would be the exposure times for both setup? Would the exposure times be the same or different? If I had to answer, the exposure time would be the same because focal ratio is the same even though the focal lengths and apertures are quite different. The 20" scope will result better quality image (more details) thanks to larger aperture.

The following what Lee said is pretty much what I said earlier (I left out the camera and image scale but that's what I meant):

Quote:

- pick the focal length and chip size to capture the FOV you want.

- pick the camera pixel size to match your focal length and seeing conditions to provide your best arcsec/px resolution

- and then buy the biggest aperture scope you can afford (at the focal length you decided you "need")

- then take pictures that are sky limited.




The slight difference between Lee and mine is I said to find the lowest focal ratio for a given focal length which naturally increases aperture size so it's the same thing but different perspective.


Now, the following is my perception:

The amount of object photons striking the CCD dectector may affect the exposure time but it's the focal ratio that makes the final determination for exposure times regardless of aperture. It's been like that since the invention of camera. Aperture determines resolution (quality of image). Once again, this assumes you don't modify the images to get the image scale or FOV you want. For a given focal ratio, increasing aperture increases focal length (changes image scale if same camera is used) which results exposure time unchanged.

Summary:

Aperture = resolution (quality of image)
Focal length = image scale
Focal ratio = image speed (exposure time)


So the end result is I believe we are talking about pretty much the same thing but different perception.


Good bye.

Peter


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mikeschuster
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6095440 - 09/22/13 05:30 PM

Peter,
I like to use a spreadsheet listing Aperture, Focal length and Pixel size of various setups. The speed column is A * P / F. A rule of thumb that ignores things like QE and secondary obstruction. By this scope 1 appears faster.
Mike


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: mikeschuster]
      #6095482 - 09/22/13 05:55 PM

Mike,

You are correct. Remember Alph's statement said that only focal ratio and pixel size affects image speed and he is correct like you are. I didn't think pixel size would be so significant. Focal ratio is part of the formula because both aperture and focal length are included. Thanks for providing the formula.

So if you use same pixel size for both scopes, then image speed is the same but changes image scale.

I guess to make our lives easier, follow Lee's rule for choosing scope and camera which is pretty much what I did.

Quote:

- pick the focal length and chip size to capture the FOV you want.

- pick the camera pixel size to match your focal length and seeing conditions to provide your best arcsec/px resolution

- and then buy the biggest aperture scope you can afford (at the focal length you decided you "need")

- then take pictures that are sky limited.




This has been a very educational thread.

Peter


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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6095523 - 09/22/13 06:20 PM

frankly, i care more about chip size and focal length than i do about image scale. sometimes you accept reduced image scale and get under-sampled images because you want a large FOV -- without creating a mosaic. i don't mind over sampling unless the seeing is terrible which just enhances the "mush collection" (tech speak :-). i want the biggest aperture only to increase resolution and photon collection -- the result may be reduced f/ratio, but f/ratio is never "my choice", it's my consequence.

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: elbee]
      #6095533 - 09/22/13 06:26 PM

Hi Lee,

That sounds like a very good strategy. You have to play with all the numbers to find the best compromise for the money to meet your requirement.

Peter


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Re: "Lessons from the Masters"...first impressions new [Re: elbee]
      #6095534 - 09/22/13 06:27 PM

Lee, image scale is good. Speed is also $ * S, dollars times image scale. Small image scale means either pricy or slow.
Mike


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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: mikeschuster]
      #6095911 - 09/22/13 10:23 PM

Mike,

If you know where I can find information about the formula you provided, please let us know.

Speed = Aperture * Pixel Size / Focal Length

I am sure this is a simplified formula because QE is excluded.

Thanks,
Peter


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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6095966 - 09/22/13 11:03 PM

Quote:

Mike,

If you know where I can find information about the formula you provided, please let us know.

Speed = Aperture * Pixel Size / Focal Length

I am sure this is a simplified formula because QE is excluded.

Thanks,
Peter




I have given that formula first time few years ago on CN in a slightly different format. It seems almost a lost cause to keep reminding the formula to the CN members. It is valid only for extended objects. Here I go again

SNR is proportional to aperture_diameter * image_scale * sqrt(QE)
Or
SNR is proportional to (pixel_size/focal_ratio) * sqrt(QE)
Or
Exposure time is proportional to focal_ratio^2/(pixel_area * QE)

Hope this helps


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Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6096072 - 09/23/13 12:04 AM

Peter,

The Cannistra link you posted has something similar in equation 3. Alph's formulas are also the same thing.

For a bright target, photon noise sets the pixel signal-to-noise ratio SNR, where S is the number of photons detected by a pixel:

SNR = sqrt(S)

S scales with Aperture squared. Doubling aperture increases detected photons per pixel by four.

S scales with Pixel size squared. Doubling Pixel size increases detected photons per pixel by four.

S scales inversely with Focal length squared. Doubling Focal length decreases detected photons per pixel by four.

So pixel SNR scales with sqrt(A^2 * P^2 / F^2) = A * P / F.

Mike

Edited by mikeschuster (09/23/13 12:07 AM)


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jerryyyyy
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Re: "Lessons from the Masters"...first impressions new [Re: mikeschuster]
      #6096138 - 09/23/13 01:16 AM

Quote:

Peter,

The Cannistra link you posted has something similar in equation 3. Alph's formulas are also the same thing.

For a bright target, photon noise sets the pixel signal-to-noise ratio SNR, where S is the number of photons detected by a pixel:

SNR = sqrt(S)

S scales with Aperture squared. Doubling aperture increases detected photons per pixel by four.

S scales with Pixel size squared. Doubling Pixel size increases detected photons per pixel by four.

S scales inversely with Focal length squared. Doubling Focal length decreases detected photons per pixel by four.

So pixel SNR scales with sqrt(A^2 * P^2 / F^2) = A * P / F.

Mike




Not being an expert, but reading this carefully, does it imply that halfing the focal length, all else being equal, increases the number of photons detected by 4?


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Re: "Lessons from the Masters"...first impressions new [Re: jerryyyyy]
      #6096152 - 09/23/13 01:32 AM

Halving focal length concentrates photons that previously were hitting four pixels into a single pixel. So yes, PER PIXEL detected photons increases by 4. And as a result PIXEL SNR goes up by a factor of 2.

Some argue PIXEL SNR is irrelevant for imaging. That is fine with me.

I like to look at small patches of pixels in my images to see how noisy they look. For this purpose per pixel SNR is appropriate for me.

If on the other hand you are doing photometry where you add up pixel patches to form a single measurement, then per pixel SNR is less relevant. I think Aperture and Time rule here.

Also, for spectroscopy I suppose getting as much light as possible through the slit is most important. Again Aperture and Time rule, focal length is not so important. But grating dispersion and pixel size are relevant, as you need pixel SNR and sufficient sampling to resolve spectral lines and avoid aliasing.

Mike

Edited by mikeschuster (09/23/13 02:09 AM)


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Re: "Lessons from the Masters"...first impressions new [Re: mikeschuster]
      #6096192 - 09/23/13 02:27 AM

Quote:

If on the other hand you are doing photometry where you add up pixel patches to form a single measurement, then per pixel SNR is less relevant. I think Aperture and Time rule here.



As I said earlier these formulas apply only to extended objects. Don't even think to apply them to stars. SNR per pixel is ALWAYS relevant. For point sources, the focal ratio is irrelevant (FWHM does not depend on the focal ratio) and SNR (per pixel) is mainly determined by the aperture, the angular size of the seeing disc (FWHM), and the image scale.

Quote:

Also, for spectroscopy I suppose getting as much light as possible through the slit is most important. Again Aperture and Time rule, focal length is not so important.




For a slit spectrograph, the focal length is absolutely critical. The longer focal length the larger the linear size of the star image is and as a result of it less light passes through the slit.


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Re: "Lessons from the Masters"...first impressions new [Re: Alph]
      #6096510 - 09/23/13 09:59 AM

Thank you Alph, very helpful for me.

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Peter in Reno
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Re: "Lessons from the Masters"...first impressions new [Re: mikeschuster]
      #6096522 - 09/23/13 10:09 AM

Thanks Alph and Mike.

Thanks everyone else for your patience responding to my posts. I now understand.

Peter


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jerryyyyy
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Re: "Lessons from the Masters"...first impressions new [Re: Peter in Reno]
      #6096689 - 09/23/13 11:57 AM

I think I understand too. You only get these complex ideas clear through discussion.

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hfjacinto
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Re: "Lessons from the Masters"...first impressions new [Re: vpcirc]
      #6096886 - 09/23/13 01:54 PM

Ok I ordered it. I always wanted to know how Alan Friedman does his solar images, considering I have most of the same equipment I hope to do something close.

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Re: "Lessons from the Masters"...first impressions new [Re: hfjacinto]
      #6098377 - 09/24/13 12:19 PM

Quote:

..... I always wanted to know how Alan Friedman does his solar images...




Are you aware of the following?
Alan was a recipient of one the awards in the Royal Museums Greenwich's Astronomy Photographer of the Year contest.
A film crew came to his house and made this video.
It's a 'Pros from Dover' effort. <g>

dan k.


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hfjacinto
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Re: "Lessons from the Masters"...first impressions new [Re: HunterofPhotons]
      #6098815 - 09/24/13 04:28 PM

Thanks for the video, I knew he won, but after looking at the video, he has better equipment No AP mounts here.

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Re: "Lessons from the Masters"...first impressions new [Re: hfjacinto]
      #6108959 - 09/30/13 09:52 AM

I ordered the book and started reading. I read Alan Friedman's chapter on solar imaging, read the chapter on increasing color and started reading Tony Hallas' chapter on dealing with noise. Have to say its a great book, but its really tailored to PhotoShop and CS5 at that, so if you don't use PS, maybe not the best book for you.

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