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rockstarbill
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Reged: 07/16/13

Loc: Snohomish, WA
Re:NexStar AP Graduates Images and Discussions new [Re: Tel]
      #6022273 - 08/13/13 06:15 AM

Thanks! I think of exposure and framing as core things you have to be good at!

I used it on its least agressive settings, as the higher ones killed stars and I wasnt ok with that. Killing stars isnt cool unless there is nebula in their wake, I say!

I capture with Nebulosity 3, process in Photoshop CS6 Extended.


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rockstarbill
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Reged: 07/16/13

Loc: Snohomish, WA
Re:NexStar AP Graduates Images and Discussions new [Re: rockstarbill]
      #6022289 - 08/13/13 06:37 AM Attachment (22 downloads)

I threw a few moments of PS on this...

Edited by rockstarbill (08/13/13 06:37 AM)


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Tel
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Reged: 03/31/06

Loc: Wallingford England
Re:NexStar AP Graduates Images and Discussions new [Re: rockstarbill]
      #6022339 - 08/13/13 07:33 AM

You're way ahead of me in your capture and processing kit : I merely work with Nebulosity 2 and P/Shop CS2. However, that's handy because I would think you can carry out any operation, (and indeed more), than my software can come up with.

Try perhaps testing the effect of using the "Auto Levels" followed by the "Auto Contrast" followed by the "Auto Colour" on this image of M13. It's something I usually do. It often makes for a good basis on which to work but not always, in which case any of the features it produces you don't like, can easily be deleted.

In this case it does seem to work, followed up by visiting "Shadow and Highlight" where, try moving the "Shadow" a little to the left.

Follow this up with a +11 on the "Contrast" and a -11 on the "Brightness", (using the "Brightness and Contrast" tool), and I think it produces a very acceptable image.

By the way, if you'd like me to pass on that "Dirty Trick" regarding gradient elimination, let me know.

Good imaging !

Best regards,
Tel


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rockstarbill
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Reged: 07/16/13

Loc: Snohomish, WA
Re:NexStar AP Graduates Images and Discussions new [Re: Tel]
      #6023357 - 08/13/13 04:18 PM

Thanks Tel! Feel free to pass on that trick.

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Tel
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Re:NexStar AP Graduates Images and Discussions new [Re: rockstarbill]
      #6023628 - 08/13/13 06:04 PM

Hi Rockstarbill,

You're most welcome. Forgive me though if I don't put the method together tonight as it's now just after 11:00pm here in the UK, and I need my beauty sleep; (more than most) !

So saying therefore, I'll put the details of that piece of imaging trickery together for you and despatch them in the morning.

Best regards,
Tel


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rockstarbill
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Reged: 07/16/13

Loc: Snohomish, WA
Re:NexStar AP Graduates Images and Discussions new [Re: Tel]
      #6023977 - 08/13/13 09:14 PM

Sounds great! Sleep well.

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Tel
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Re:NexStar AP Graduates Images and Discussions new [Re: rockstarbill]
      #6024471 - 08/14/13 04:33 AM Attachment (19 downloads)

Thanks, yes, I did, not bad at all !

So; this is one, "Dirty Tricks" method which, in some cases, (but not all), is effective in reducing light gradients within images. The theory is that it creates an even reduction in the varying brightness of the background light while retaining the brightness and detail of the targeted object.

1) Go to the "Layer" feature and duplicate the layer.

2) Go to the "Select" feature and select, "Colour Range".

3) Use the left hand "eye dropper", (black point), pick an area on your image which you wish to darken and click on it.

Note that you will need to experiment in all cases with the "Fuzziness" slider to get the best results. In the artificially brightened example of your M13, designed to show the amount of vignetting present, (see attached), I used a setting of 165.

4) Go to the "Layer" feature and "Layer Mask". Select "Reveal Selection". A white mask will appear alongside the duplicate layer.

5) Hold down the "Alt" key on your keyboard and click on the white mask. Your on screen image will now produce a reverse image, (i.e. what was light will become dark and vise-versa).

6) Go to the "Filters" feature and select "Blur" followed by "Gaussian Blur". Set this to a high pixel rate of about 20 using the slider.

7) Click on the duplicate layer image, (next to the white mask).

8) Go to the "Layer" feature and click on "New Adjustment Layer. Select "Curves".

9) Using "Curves", drag the curve downwards. it will dim the background without significantly dimming the object of the image itself.

10) Note the effects you produce and, if necessary, use some of the other "tools" contained in the "New Adjustment Layer". When you are satisfied with the result of mask adjustment, "Flatten" the image and continue processing under the "Image" feature as required.

This method, as you can appreciate is a artificial means of replicating "Flats" where none have been taken or those that have, are ineffective.

The attached image is an enhancement of your original just to show the degree of vignetting present at the onset.

This method was first passed to me by our mutual CN colleague "Uggbits" in 2011, to whom all credit and thanks are due and who, I'm sure, would allow me to share it with others here.

Hoping you find it as useful as I have done,

Best regards,
Tel


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rockstarbill
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Reged: 07/16/13

Loc: Snohomish, WA
Re:NexStar AP Graduates Images and Discussions new [Re: Tel]
      #6024479 - 08/14/13 04:47 AM

Thanks Tel. I will give this a go on my stack.

I little insider info... The diagonal lines you see in this image are artifacts from the lines Nebulosity puts in images when you are operating in demo mode. I bought the license, but those nasty things still existed after pre-processing.

Lesson: Tel is a Jedi.
Lesson 2: Dont take awesome images in Nebulosity demo mode. You will cry at the end!


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Tel
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Reged: 03/31/06

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Re:NexStar AP Graduates Images and Discussions new [Re: rockstarbill]
      #6024490 - 08/14/13 05:11 AM

Ah yes: Now I look (very) closely at the above image, I see those diagonal lines with which I too was familiar when first trying the Nebulosity demo software but I've never come across them since I obtained the full version !

I must look into that, although, so saying, obviously in my not noticing them at all, shows them, at least in my case, to be innocuous.

Perhaps drop Craig Stark an email ?

As to Jedi's, I think this one's broken his light-sabre : at least my wife seems to think so !

Best regards,
Tel


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Tel
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Re:NexStar AP Graduates Images and Discussions new [Re: Tel]
      #6024587 - 08/14/13 07:55 AM

Quote:

Hi Rockerbill,

As to taking Flats, it looks as if you've tried the "Usual".

Leave it with me: I'll see what I can come up with.

Best regards,
Tel




Hi Bill,

I've subsequently been looking around for alternative methods of taking "Flats" and one idea apparently is to use your laptop placed close to the corrector plate with a white screen as might be achieved by using a blank text editor page. You can additionally use a "T" shirt cover for greater light diffusion if you wish.

With the LT screen in place, adjust the camera exposure to give an off-white to greyish image on the Nebulosity software and then without touching focus from that which has served to capture the "Lights", shoot a few "Flats": 10-20 should suffice.

There is also, seemingly, no need to match the exposure time used to capture the "Lights": 0.5 - 2 seconds will apparently do.

Perhaps try it ? I give no guarantees because only having just come across this idea myself, I too have yet to try it. I does seem to present another possibility though.

Best regards,
Tel


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rockstarbill
sage


Reged: 07/16/13

Loc: Snohomish, WA
Re:NexStar AP Graduates Images and Discussions new [Re: Tel]
      #6031694 - 08/17/13 08:26 PM

Thanks Tel!

I have had some cloudy weather (of course... right after I get my autoguider working!) so I have not been able to try this out yet. I have heard about the "Notepad" method, but I dont have anything tall enough to hold the laptop in place (and I do not have the steadiest of hands..)


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Tel
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Reged: 03/31/06

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Re:NexStar AP Graduates Images and Discussions [Re: rockstarbill]
      #6032250 - 08/18/13 04:17 AM

Hi Bill,

You don't need to raise a laptop or note-pad to the OTA in order to take your "flats". Merely put the LT or note-pad on, for example, a table close to your set-up and then bring the OTA's corrector plate into relatively close contact.

Think about it: One of the ways advocated is to take "flats" before an evening's imaging; pointing the OTA at the twilight sky: i.e. with no exact fix on the object you intend to image. Thus it's irrelevant where the "flats" are taken.

What is important is the position of the camera. Having taken the "flats", (dust motes and all !), the camera must be left in exactly the same position in the 'scope for the final image to relate to the series of "flats" you've taken.

By the way: if it's of interest, here's another article I've come across relating to the taking of "darks, flats and bias". It confirms what I've said but perhaps a little more eloquently and in more depth while also offering alternatives to LT/notepad use as "light boxes".

http://ccdastrophotography.com/article.php?id=2

Hoping this helps you a little further,

Best regards,
Tel


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Tel
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Re:NexStar AP Graduates Images and Discussions [Re: Tel]
      #6038295 - 08/21/13 12:44 PM Attachment (16 downloads)

Back to some practical imaging after almost six weeks due to a combination of short nights and old age but it was nice to find that all within my dome was still in full working order !

So, to continue with my early attempts at colour imaging according to the Hubble palette procedure of combining monochrome sub-frames resulting from Hydrogen Alpha and Oxygen lll filtration, I thought M27, the Dumbbell nebula, to be well placed last night.

The result obtained, is rather a "dirty" image, to which no accompanying "darks or flats" were taken and on which, one or two dust motes were equally noticeable at the start of processing.

10 X 5 minute subs in both Ha and Olll served as red and green channels respectively, while a copy of the Olll stacked subs doubled as the blue channel (normally covered by Sulphur 2 but I don't yet possess this filter).

Limited pretty well to emission nebulae, there is one major advantage to imaging in this way: the full moon might as well not exist as far as this narrow band filter technique is concerned !

Capture 'scope: 4" (102mm)/f/5.9 achromatic refractor.
Guide 'scope : Nexstar 8i at f/6.3.

Mount: Skywatcher HEQ5 Pro.

Capture camera: Atik 314L
Guide camera: Meade DSI Mk.1

Capture software: Nebulosity 2.
Guide software: PHD.

Processed in both Nebulosity 2 and P/Shop CS2.

Thank you kindly for looking.

Best regards,
Tel

Edited by Tel (08/21/13 02:52 PM)


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Tel
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Re:NexStar AP Graduates Images and Discussions [Re: Tel]
      #6039641 - 08/22/13 06:44 AM Attachment (13 downloads)

Still working on the processing: I think this version has brought out a little more detail within the nebula.

Best regards,
Tel


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Peter9
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Re:NexStar AP Graduates Images and Discussions [Re: Tel]
      #6039648 - 08/22/13 06:53 AM

The nebula certainly shows more detail and the colours are also much softer in the second image, making it look more (here's that word again) natural, to my eyes at least.
With the blending of the colours, M27 does not look "stuck on" as it tends to do in your first attempt.

Not knowing a thing about processing images and the like, I hope I've been constructive in my comments Tel.

Thanks for posting.

Regards. Peter.


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Tel
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Re:NexStar AP Graduates Images and Discussions [Re: Peter9]
      #6039670 - 08/22/13 07:37 AM

Many thanks, Peter, for your kind and indeed very constructive comments.
I certainly think the second image is superior to the first but, d'you know, you can almost go on processing forever and a day and still not be satisfied !

One other positive note: I managed to identify and thus clear that dust mote or smudge, (whatever it was) from the optical train without any trouble, so next time out........

Many thanks once again for your appreciation,
Best regards,
Tel


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hopskipson
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Reged: 06/24/10

Loc: Queens, New Yawk, Light pollut...
Re:NexStar AP Graduates Images and Discussions [Re: Peter9]
      #6039674 - 08/22/13 07:41 AM

Great work Tel, I was afraid to comment on your first attempt, but your second one is much more "natural" looking. Natural meaning what I've seen processed by others. The first one looks almost "cartoonish" for lack of a better word. I hope you are not offended. Your use of the palette is progressing nicely .

I'm still working out the bugs on my imaging woes in the city. Since I tried Ha and obtained a red noise riddled image, I'm going to try a light pollution filter to see if I can obtain subs longer than 20 sec.


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haytor
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Reged: 11/29/07

Loc: Smethwick near Birmingham UK.
Re:NexStar AP Graduates Images and Discussions [Re: hopskipson]
      #6039690 - 08/22/13 07:59 AM

Totally agree, second image is much better Tel.nice work, and good to see you getting out there again.

best regards,

Tom.


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Greyhaven
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Re:NexStar AP Graduates Images and Discussions [Re: Tel]
      #6039764 - 08/22/13 09:15 AM

Great work Tel. Thanks for sharing your work with us.
I agree with the others that the second image is easier (more natural) on the eye.I don't use any filters when imaging so I have no experience with the amount of red you've capture in the first image, in the second you've eliminated a great deal of red and accentuated the green nebulosity surrounding the image softening the edge and gave the nebula a more " natural" transition area. The internal structure of the nebula in the first image is what I would call grainy compared to the more processed second I guess in an attempt to make adjustments to my own images I'm trying to understand the road you travel processing your images. Is the softness of the second image's green areas a result of a blur filter? Is the removal of the harsh reds of the first image bringing out the less aggressive greens in the image? I know, those that can, do, and those that can't just hang around and ask dumb questions.
Thanks for your willingness to share.
Be Well
Grey


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rockstarbill
sage


Reged: 07/16/13

Loc: Snohomish, WA
Re:NexStar AP Graduates Images and Discussions [Re: Greyhaven]
      #6040955 - 08/22/13 10:58 PM Attachment (8 downloads)

Here is a shot I took last night of the Ring Nebula. This was 16 subs of 2 minutes each, with my DSLR and scope at f/6.3. Next time I get open space I will be trying this same target (and M13) with Hyperstar to compare the two.

I will edit this post once I get the pre-processed stack and my final processed full res version uploaded to SkyDrive.

Note: You will see the AWFUL glow I had to deal with in processing. I didnt have flats either so I just experimented with Carboni's tools and Gradient Xterminator in PS6x.

Stacked Image: https://skydrive.live.com/redir?resid=9BD07ECBFEA191DA!1953&authkey=!AHSR...

My processed version: https://skydrive.live.com/redir?resid=9BD07ECBFEA191DA!1954&authkey=!AHgk...

Feel free to play with the stacked and non-processed version all you want! It will not hurt my feelings at all, and if you turn something else better out of it, please share with the class.

Take care and enjoy! Clear skies to all.

-Bill

Edited by rockstarbill (08/23/13 12:00 AM)


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