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Very First Picture

beginner CMOS EAA mount
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#1 Seaquel47

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Posted 21 September 2019 - 08:11 PM

So, I received my new mount this week and in two nights felt that I could operate it ok.  I also received an Atik Infinity camera from the CN classifieds and just had to see if I could get some pictures.  After some trial and a lot of error I started to get a recognizable picture.  I thought I saved quite a bit of data but apparently I messed up and could only find this one afterwards.  I used the Infinity software with 4 second exposures and auto ranged the exposure with the medium setting.  I found the graph for FWHM and used it to focus with the best I could get varied around 3.5.  I adjusted the histogram to get what you see.  For some reason the trackpad mouse would jump around when I was in the histogram area and that made it difficult to grab a bar to make adjustments but it was steady anywhere else on the screen.  I wonder if this is a Windows 10 issue?  I am surprised at how bloated the bright stars are.  Is this normal or are there adjustments I should have made to improve that?  I will appreciate any suggestions on how to improve.

 

Thanks

 

 

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#2 OleCuss

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Posted 21 September 2019 - 11:05 PM

That's really not a bad image.  That said, you aren't happy with the bit of bloating.

 

I've never used the Infinity and you didn't exactly say which scope you were using but at a guess?

 

I'm betting you used the Tele Vue 85mm.  That's an ED-Doublet and I would expect that when used for AP you'd have some bloat due to IR not being brought into focus at the same focal plane as your other wavelengths.  This doesn't mean you cannot or did not get a good image but it just doesn't quite do what a great triplet with field flattener and all that would do.  The ED-Doublet also isn't as heavy and it isn't as expensive. . .

 

But that isn't really quite all. . .  Your camera has pixels which measure 6.45 microns.  Your Tele Vue 85 has a focal length of 600mm.  These are not necessarily bad numbers but together they may or may not be so good.

 

If one assumes you had fairly average "seeing" of 2 arc-seconds then by typical calculations your sampling should be at about 0.67-1 arc-seconds in order to have best detail and tight stars.  Given your pixel size and focal length your actual sampling is right around 2.2 arc-seconds which means you are under-sampled and cannot expect to capture all possible detail.  But this is often just not a big deal depending on your goals.

 

Not really knowing your software and camera very well I'm not sure about another potential issue.  Your Full Well is about 24K but your ADC is apparently 16-bit which (as a non-guru) just seems a bit out of proportion.  And you have a fairly noisy sensor.  You add in the fact that I don't know what your gain was or what your actual bit-depth would be at that gain - you could be over-saturating and your software could actually be handling some of that for you.

 

Net effect is that I can't tell for sure why the stars are a bit bloated in this case but you could potentially clear things up a bit by using an IR filter, shortening your sub-exposures to avoid saturating.

 

And if you used the camera with the 8" SCT?  Since the corrector plate is only doing weak refraction you likely needn't worry about an IR filter.  When using even a 0.63x reducer at 2 arc-second seeing you would be only mildly under-sampled.

 

But then, going with the 8" SCT would mean that your FOV would be narrower even if it fixed a few problems.  A little bloating may be worth it in order to get the wider FOV which comes with the shorter focal length?

 

If you are using the SCT already then things get a little more interesting.



#3 elpajare

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Posted 22 September 2019 - 02:24 AM

As I see in the screenshot you put you have not stacked any images.

 

If it's true, you're missing a good opportunity to improve your result.

 

UV / IR filter: In practice, its use is usually good for reducing size and halos on the stars


Edited by elpajare, 22 September 2019 - 02:26 AM.

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#4 Seaquel47

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Posted 22 September 2019 - 04:26 AM

Thanks for the comments.  Good call on using the TeleVue.   I forgot to mention that I used the TV-85 with the TV 0.8 reducer/flattener for the shoot.  I remember reading about using an IR filter but I don’t have one yet.  Looks like I have another shopping opportunity.  I did stack during the session but my lack of understanding of the software resulted in only saving 3 individual pictures.  I tried several runs with exposures between 4 and 7 seconds and up to 45 frames stacked.  I wish I had saved the entire session because during the live event I couldn’t see much difference during the stacking.  Thanks for bringing up under/over sampling.  I’m going to revisit that to see if I can determine what I actually did.  As I recall slight undersampling is somewhat better than oversampling. 



#5 OleCuss

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Posted 22 September 2019 - 05:19 AM

It's difficult to say whether under- or over-sampling is better/worse.  It sort of depends on your priorities and your equipment.

 

If you have a low-noise camera then over-sampling has very little penalty.  If you have a rather noisy camera then the noise penalty to over-sampling can be a significant problem.

 

Under-sampling can mean less detail.  So if your goal is lots of detail under-sampling may carry a significant penalty.  But if your mount is not tracking well, or your optics are not great, or your atmospheric conditions are bad then under-sampling may just be no big deal.

 

But if you were using the 0.8x reducer then your under-sampling is a bit worse than I was figuring.  My calculation that your sampling was at 2.2 arc-seconds per pixel was based on a focal length of 600mm and your effective focal length was actually 480mm so your actual sampling was at 2.77 arc-seconds per pixel.  But again, if your image meets your priorities then things are fine no matter what your sampling might be.



#6 GaryShaw

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Posted 22 September 2019 - 10:01 AM

Thanks for the comments.  Good call on using the TeleVue.   I forgot to mention that I used the TV-85 with the TV 0.8 reducer/flattener for the shoot.  I remember reading about using an IR filter but I don’t have one yet.  Looks like I have another shopping opportunity.  I did stack during the session but my lack of understanding of the software resulted in only saving 3 individual pictures.  I tried several runs with exposures between 4 and 7 seconds and up to 45 frames stacked.  I wish I had saved the entire session because during the live event I couldn’t see much difference during the stacking.  Thanks for bringing up under/over sampling.  I’m going to revisit that to see if I can determine what I actually did.  As I recall slight undersampling is somewhat better than oversampling. 

Hi Seaquel

You might want to look into using Sharpcap for EAA viewing and image capture. There’s a bit of a learning curve for sure but once you’ve climbed up part of the curve, things start coming together. There are free versions as well as the pro version that costs 15/year I believe. The pro version is worth it for the added functionality. There’s a manual and down loads at the end of this link. There’s also a quick start manual by one of the CN members, just search for it in CN.  Also an active Sharpcap Forum if needed.

 

https://www.sharpcap...pro/sharpcappro

 

Lots of Sharpcap guru’s in this sub forum so take advantage of them and enjoy the ride.

good luck 

Gary



#7 Seaquel47

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Posted 22 September 2019 - 11:07 AM

Thanks Gary, my plan is to use Sharpcap Pro but apparently this camera is not supported directly but I believe there is an ASCOM driver for it.  I wanted to start with the Infinity software since it is written for this camera and to keep things simpler.  I have downloaded the CN member manual already but haven't started on the official Sharpcap manual.  Down the road my current thinking is to get an ASI 294 MC Pro camera but I need to get more experience first.



#8 Seaquel47

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Posted 22 September 2019 - 11:17 AM

OleCuss, thanks again for the reminder about sampling.  When I first did the image scale calculations I didn't have the reducer and I saw that the TV/Atik combo would be just somewhat under sampled.  Then I thought about the need for a flattener and forgot about how it increased the under sampling.  At least it should be useful when I get a smaller pixel camera.



#9 GaryShaw

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Posted 22 September 2019 - 12:15 PM

Thanks Gary, my plan is to use Sharpcap Pro but apparently this camera is not supported directly but I believe there is an ASCOM driver for it.  I wanted to start with the Infinity software since it is written for this camera and to keep things simpler.  I have downloaded the CN member manual already but haven't started on the official Sharpcap manual.  Down the road my current thinking is to get an ASI 294 MC Pro camera but I need to get more experience first.

So, that all makes total sense.

 

BTW, I got the 294 MC, the non-cooled version, based on a lot of opinions on CN relative to what you need for EAA. What I'm finding now is that the hot pixels, if they bother you, necessitate doing Dark Frame subtraction and that can be a bit of a bother if you're using a dew prevention system and have to take it off and on to do multiple darks over an evening when you might be changing exposure or gain settings. 

 

I'm less than a year into all this so I'm wandering a bit in the dark still. I'm not sure if the cooled version ($300 more) will avoid the hot pixels entirely but I understand that it offers other options for creating a Dark Frame 'library' as well as just controlling temperature more tightly. I think I'd be ahead of the game if I'd gotten the cooled version. Certainly, if you ever drift into full AP, you'd want the cooled camera.

 

 

Hope this makes sense or that some of the experts above will correct anything I misunderstood.

Gary



#10 OleCuss

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Posted 22 September 2019 - 01:07 PM

OleCuss, thanks again for the reminder about sampling.  When I first did the image scale calculations I didn't have the reducer and I saw that the TV/Atik combo would be just somewhat under sampled.  Then I thought about the need for a flattener and forgot about how it increased the under sampling.  At least it should be useful when I get a smaller pixel camera.

As an old guy I think you may be a bit hard on your image.  Yeah, OK, it may not win APOD tomorrow but for me that has never been a goal.  I can remember back to when (IIRC) an image not all that different from yours might make it into one of the astronomy magazines.

 

You got a good image which, if one wants to be persnickety has some issues.  It's good enough if you are enjoying it.  And if you want to compete with the best you typically have to have great skies, lots of aperture, superb optics, and get hours and hours of sub-exposures which may take you hours to days of post-processing in order to produce that spectacular image which NASA wishes they could acquire.

 

Personally, I'm just not all that interested in competing.  I don't have the budget, the time, or sufficient interest.  Kudos to those who do, I'm greatly impressed!

 

Define what you want to do and be happy when you achieve that.  If you enjoy what you are getting then you don't need anything more/different.

 

We have a tendency to push people more and more to achieve the ultimate in excellence in terms of SNR, resolution, etc.  The better goal is enjoyment.

 

You can become a slave to the equipment and hobby rather than having the hobby serve you.

 

If you enjoy it, it's good.


Edited by OleCuss, 22 September 2019 - 01:08 PM.

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#11 Seaquel47

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Posted 22 September 2019 - 01:23 PM

So, that all makes total sense.

 

BTW, I got the 294 MC, the non-cooled version, based on a lot of opinions on CN relative to what you need for EAA. What I'm finding now is that the hot pixels, if they bother you, necessitate doing Dark Frame subtraction and that can be a bit of a bother if you're using a dew prevention system and have to take it off and on to do multiple darks over an evening when you might be changing exposure or gain settings. 

 

I'm less than a year into all this so I'm wandering a bit in the dark still. I'm not sure if the cooled version ($300 more) will avoid the hot pixels entirely but I understand that it offers other options for creating a Dark Frame 'library' as well as just controlling temperature more tightly. I think I'd be ahead of the game if I'd gotten the cooled version. Certainly, if you ever drift into full AP, you'd want the cooled camera.

 

 

Hope this makes sense or that some of the experts above will correct anything I misunderstood.

Gary

Like you, I have also been reading the various opinions regarding cooled/uncooled.  Observing down here in south Florida in the summer it can be quite warm even late at night and I suspect that can result in more hot pixels.  It seems to me that the more expensive cooled version removes some of the problems involved and as you say, simplifies the dark frame library.

 

I really appreciate all of the advice, it does make sense.  The forums are a wealth of good information.



#12 elpajare

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Posted 22 September 2019 - 01:59 PM

I liked Olecuss's comment: APOD vs EAA

 

Many people have forgotten that the EAA was not born to win any prize, it is just a way to enjoy impossible things (almost) with an eyepiece and our eye.

Expensive and sophisticated equipment is not really necessary.


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#13 GaryShaw

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Posted 22 September 2019 - 04:01 PM

I liked Olecuss's comment: APOD vs EAA

 

Many people have forgotten that the EAA was not born to win any prize, it is just a way to enjoy impossible things (almost) with an eyepiece and our eye.

Expensive and sophisticated equipment is not really necessary.

Agree totally but it’s hard sometimes not trying to preserve what you see onscreen to look at later or share with friends and family. It amazes me how even the modest images we capture in EAA can inspire awe in friends and especially their kids. I’d like nothing better than feeling that my humble images might inspire someone to pursue a science career or at least help create a life long interest in science and the natural world around us. 

 

I keep reminding myself - it’s not about imaging - it’s about ‘seeing’ ... but then delving into it and learning about what we’ve seen. 


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#14 roelb

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Posted 22 September 2019 - 07:13 PM

quote:

<I found the graph for FWHM and used it to focus with the best I could get varied around 3.5>

unquote

 

I experienced it is better to use a Bathinov mask.


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#15 Matt Harmston

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Posted 24 September 2019 - 02:26 PM

Agree totally but it’s hard sometimes not trying to preserve what you see onscreen to look at later or share with friends and family. It amazes me how even the modest images we capture in EAA can inspire awe in friends and especially their kids. I’d like nothing better than feeling that my humble images might inspire someone to pursue a science career or at least help create a life long interest in science and the natural world around us. 

 

I keep reminding myself - it’s not about imaging - it’s about ‘seeing’ ... but then delving into it and learning about what we’ve seen. 

It is easy to rapidly run into paralysis by analysis, in that there are many important details to consider when trying to get the most out of our cameras. That said, with today's cameras, achieving a decent first image (and saving it) can be fairly straightforward for many camera makes and models.  That said, you can get as complex or remain as simplistic as you wish. This technology is amazing...what might have been in a magazine is now the beginner's first image (as Olecuss indicated). Advanced users are doing some amazing things...hardly imagery to which one must settle. 

 

Your skills will improve, and your interests will pull you in the direction of experimenting with functionality (and more equipment waytogo.gif ). But, in the end, you're on a journey full of "Holy cow!" moments, and will have something sweet to share with others.  Keep at it, and don't unnecessarily pressure yourself...enjoy that camera!


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#16 Seaquel47

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Posted 06 October 2019 - 09:00 PM

I had a chance to re-do my imaging of the Lagoon Nebula tonight.  The moon was far enough away to not wash out the sky but I did have some high, thin clouds around.  It was very windy and I had to limit the number of stacked images to reduce shake and tracking problems.  I used the TV-85 with the 0.8 reducer/flattener and I added a UV/IR cut filter as suggested by OleCuss.  I used an Atik Infinity camera with their Infinity software.  This picture resulted from 6 second exposures and 30 stacked images.  I can definitely see the reduction in star bloat due to the filter.  The color is more subtle.

 

 

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#17 OleCuss

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Posted 06 October 2019 - 09:22 PM

You have about 3 minutes of integration time.  You really should be quite happy with that image - pretty remarkable in context.


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