# Request for advice: Nightsky Picture Stacking and PS techniques



## pedro (Apr 22, 2013)

Hi,

I do some nightphotography on my 5D3. It is still amateurish because one always can improve. 
After having seen this tutoring video

Curves and Levels - Easy 123 - Photoshop Astrophotography Tutorial

I am keen to do this myself. It is about curves and levels in Photoshop to enhance the data. My version is CS 2.

But there arise a few questions:

I downloaded deep sky stacker. stacked seven colour pictures: copies of the same photograph to give it a try.

This guy in the video starts with *a greyscaled* stacked picture. Others I've seen worked at RGB mode. 
How is he getting a greyscale type of stacked photographs as mine turned out to be colour? It never looked like his in the beginning. Here's my slightly enhanced original picture 



Z96A3724bMASTER by Peter Hauri, on Flickr
I guess it kinda deals with RGB channels. But I have no clue how to do it, even my curves and levels don't react the same way as his.

Is it a presetting in PS which he applied without mentioning it? 
How can I do it in CS 2?

Thanks for any technical help.

Just another question: at what ISOs are you taking nightsky photographs for stacking purposes?

I currently take them applying 600 rule at ISO 6400 to 12800, f/8 with a 16-35 USM II lens.

Cheers and thanks in advance, Peter


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## Thyg0d (Apr 22, 2013)

I can't help you with the stacking thing unfortunately 
but I gotta ask why use f/8? 
I use 2.8 on my 16-35 with the focus set to infinity.. 
That way you can keep your ISO down to a minimum and get less noise at
the same amount of time.. using the 600 rule... 
If you have a 30 Sec exposure using ISO 6400 @ f/8 you can go down to 
ISO 800 @ f/2.8 and still have a 30 sec exposure.. 
You'll still get the sharpness you need..


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## pedro (Apr 22, 2013)

Thank you so much. I was doing both : wide open and f/8. I will lower the ISOs next time and go wide open again. Still in the experimental phase with my new gear as well. I choose these settings due to the amount of environmental light as I was taking pictures around the house.

Cheers, Pedro


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## Quasimodo (Apr 22, 2013)

I thought for a while when first reading your post that he was using alpha channel adjustments. Having now seen the video it seems he has just gone and altered the view to grayscale. Click on Image - Mode - Grayscale (this is just a viewing mode while working on the file), and change it back when done with the adjustments. Working in a grayscale is much easier as it's easier to see the adjustments without being distracted by the colors and colorfringing and such. 

I have CS 6, but the same should apply. Also, be sure to shoot in Raw, as it gives you more flexibility in pulling on curves and levels afterwards.

Good luck.


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## Mr Bean (Apr 22, 2013)

I may not answer your question directly, but, a couple of ideas to try for night sky pics 

20 second exposure @ ISO 3,200
Zeiss 15mm @ f2.8 on a 5D3.
I wouldn't go beyond ISO 3,200 but with this lens, I could have gone a bit longer in the exposure.







Another way to create "star trails" is like this. 100 images @ ISO 200, 60 second f4 using a 35mm lens. Then "stack" them using a program called "startrails.exe"


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## ereka (Apr 22, 2013)

Quasimodo said:


> I have CS 6 ...Good luck.



When did CS6 become available???


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## pedro (Apr 22, 2013)

Quasimodo said:


> I thought for a while when first reading your post that he was using alpha channel adjustments. Having now seen the video it seems he has just gone and altered the view to grayscale. Click on Image - Mode - Grayscale (this is just a viewing mode while working on the file), and change it back when done with the adjustments. Working in a grayscale is much easier as it's easier to see the adjustments without being distracted by the colors and colorfringing and such.
> 
> 
> I have CS 6, but the same should apply. Also, be sure to shoot in Raw, as it gives you more flexibility in pulling on curves and levels afterwards.
> ...



Hi, thanks for your post. My problem is in CS2 if I have the color tiff on my PS desktop and click image-mode-grayscales, PS asks me: "Do you want to discard the color data?" And then as far as I can see it gets iretrievable afterwards...hmmm.

@MrBean: Thanks a lot! I will do so. Did several like that before, always like touch the limits ;- at least photography wise...

Cheers, Pedro


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## emag (Apr 22, 2013)

I don't dispute the simplicity of the '600 rule', but it is just that - simplistic. A more rigorous calculation can be made and set up in a spreadsheet to determine maximum recommended imaging times for each lens/camera combination you might use. A thorough explanation is at:

http://www.astrosurf.com/vdesnoux/virtualeq/virtualeq.htm


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## Quasimodo (Apr 22, 2013)

ereka said:


> Quasimodo said:
> 
> 
> > I have CS 6 ...Good luck.
> ...



Ehhh... It was released last summer/fall.


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## Quasimodo (Apr 22, 2013)

pedro said:


> Quasimodo said:
> 
> 
> > I thought for a while when first reading your post that he was using alpha channel adjustments. Having now seen the video it seems he has just gone and altered the view to grayscale. Click on Image - Mode - Grayscale (this is just a viewing mode while working on the file), and change it back when done with the adjustments. Working in a grayscale is much easier as it's easier to see the adjustments without being distracted by the colors and colorfringing and such.
> ...



Have to put the kids to bed, then I will check it out


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## Quasimodo (Apr 22, 2013)

pedro said:


> Quasimodo said:
> 
> 
> > I thought for a while when first reading your post that he was using alpha channel adjustments. Having now seen the video it seems he has just gone and altered the view to grayscale. Click on Image - Mode - Grayscale (this is just a viewing mode while working on the file), and change it back when done with the adjustments. Working in a grayscale is much easier as it's easier to see the adjustments without being distracted by the colors and colorfringing and such.
> ...



Hmmm.. Seems you are right. I have never used this, but gotten a grey picture when sharpening in alpha layers, so I thought it was retriveable. It probably is, I just don't know how to do it. There are however many people in this forum who are experts on photoshop. 

Below is a picture (actually eight taken with the 16-35 II, and stiched) I took some weeks ago in Shanghai. Below that is the same picture converted to grayscale, the one I was not able to revert.. I'd be interested in seeing how to solve this 

Good luck.


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## CarlTN (Apr 22, 2013)

Pedro, nice topic...I too am a night shooting enthusiast.

Mr. Bean, what hemisphere was that top photo of the Milky Way shot from? Those two "clouds" to the right side...I suspect they have a name...starting with "M"...never seen pics of them before. Also...Do you prefer the Zeiss 15mm over the 21mm?

Quasimodo, I love your Shanghai panorama! However, I don't care for the grayscale version at all. Did you ever do a print of either version, and if so, how large?


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## Quasimodo (Apr 22, 2013)

CarlTN said:


> Pedro, nice topic...I too am a night shooting enthusiast.
> 
> Mr. Bean, what hemisphere was that top photo of the Milky Way shot from? Those two "clouds" to the right side...I suspect they have a name...starting with "M"...never seen pics of them before. Also...Do you prefer the Zeiss 15mm over the 21mm?
> 
> Quasimodo, I love your Shanghai panorama! However, I don't care for the grayscale version at all. Did you ever do a print of either version, and if so, how large?



Thank you! The grayscale version was just to test for the OP here. I have not gotten the chance to print it yet. I also nelieve that I have a way to go in PP before doing so


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## CarlTN (Apr 22, 2013)

Quasi, no problem. I bet you could sell prints of it!


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## emag (Apr 22, 2013)

CarlTN said:


> Mr. Bean, what hemisphere was that top photo of the Milky Way shot from?



Yeah, I noticed that also and checked Mr. Bean's profile real quick - Melbourne. I had the pleasure of visiting Perth 30+ years ago, seeing Scorpius and the heart of the Milky Way overhead is something I'll never forget, back when I was in the navy and after a long cruise through dark skies on the Indian Ocean. I know you're a night sky fan Carl.....you should treat yourself to a southern hemisphere trip sometime. Milky Way, Coal Sack, Magellanic Clouds, Omega Centauri, all just spectacular. Check out the Southern Skies Star Party at Lake Titicaca.


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## preppyak (Apr 22, 2013)

Mr Bean said:


> Another way to create "star trails" is like this. 100 images @ ISO 200, 60 second f4 using a 35mm lens. Then "stack" them using a program called "startrails.exe"


Yep, and their are photoshop actions that do a similar thing...just googling Star Trails will get you to a dozen different things that do it well.


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## lilmsmaggie (Apr 22, 2013)

I didn't read this whole thread so I'll apologize in advance if someone already answered this.

A lot of astro-imagers use a dedicated monocrhrome CCD camera as opposed to a OSC or One-Shot color camera (DSLR or CCD). That would explain the monochrome image. Astro-Imaging requires a lot of post processing and monochrome image capture is preferred because its a truer image with all of the data as opposed to a OSC where there is software interpolation of the data in-camera.

If you want to capture more scientifically accurate image data, go with the monochrome. If you want to take portraits of beautiful objects, planets, nebulae -- a color camera can do an excellent job.

Color is more convenient. With the monochrome, you have to use separate RGB filters, and take three sets of images (one for each channel). Then combine them in software. Color is faster (only needs 1 set of images) which is important If the object moves in the sky. A planet may rotate in only 10 minutes. If it moves while you are still imaging, then the perspective is different. You cannot combine the images very well unless you're tracking.

My suggestion: Contact this guy (DugDog) of MyAstroImages.com via his YouTube channel and ask him how he captures his images, i.e. DSLR vs a dedicated CCD or webcam, or about that particular tutorial.

It's always best to get your answer from the source 8)




pedro said:


> This guy in the video starts with *a greyscaled* stacked picture. Others I've seen worked at RGB mode. How is he getting a greyscale type of stacked photographs as mine turned out to be colour? It never looked like his in the beginning.
> 
> Cheers and thanks in advance, Peter


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## Quasimodo (Apr 22, 2013)

CarlTN said:


> Quasi, no problem. I bet you could sell prints of it!



You are too kind


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## Mr Bean (Apr 22, 2013)

emag said:


> CarlTN said:
> 
> 
> > Mr. Bean, what hemisphere was that top photo of the Milky Way shot from?
> ...


Correct. I'm in a small town an hour+ drive north of Melbourne (Australia). Large and Small Magellanic Clouds are the 2 objects. The Southern Cross, Pointers and Coal Sack are roughly in the middle of the frame. The sky wasn't the clearest that night, but a test for the Zeiss 15mm I had picked up that day.



CarlTN said:


> Also...Do you prefer the Zeiss 15mm over the 21mm?


The 15mm as it gives that extra wide coverage. I've used the 21mm for similar types of pics. Both are excellent in sharpness. The 15mm has a hint of coma, wide open, in the extreme corners. Aside from the sharpness of the Zeiss, the infinity hard stop makes focusing sooooo much easier in the dark


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## cayenne (Apr 23, 2013)

pedro said:


> Hi,
> 
> I do some nightphotography on my 5D3. It is still amateurish because one always can improve.
> After having seen this tutoring video
> ...



What exactly is a stacked photograph? How do you take one? I didn't see that in the video...

Thanks,

cayenne


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## cayenne (Apr 23, 2013)

Thyg0d said:


> I can't help you with the stacking thing unfortunately
> but I gotta ask why use f/8?
> I use 2.8 on my 16-35 with the focus set to infinity..
> That way you can keep your ISO down to a minimum and get less noise at
> ...



What is the 600 rule?

Thanks,

C


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## Mr Bean (Apr 23, 2013)

cayenne said:


> Thyg0d said:
> 
> 
> > I can't help you with the stacking thing unfortunately
> ...


A rule of thumb method to calculate the maximum exposure time, for a particular focal length, before star trails become noticeable. It's simply 600 / focal length = exposure time (in seconds).

For a 50mm lens, 600/50 = 12 seconds.
For a 15mm lens, 600/15 = 40 seconds.

By keeping the exposure to those times or less, the stars appear as dots, not trails.


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## cayenne (Apr 24, 2013)

Mr Bean said:


> cayenne said:
> 
> 
> > Thyg0d said:
> ...



THANK YOU!!!

Wow...talk about a VERY informative post for a noob!!!!

Thank you very much!

C

ps. Do you have any insight into what stacking photos are? Is that similar to HDR photography?


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## Quasimodo (Apr 24, 2013)

Mr Bean said:


> cayenne said:
> 
> 
> > Thyg0d said:
> ...



Thank you  I did not know that, but it is very useful information.


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## Quasimodo (Apr 24, 2013)

cayenne said:


> Mr Bean said:
> 
> 
> > cayenne said:
> ...



There is many programs who can help you with stacking, and you use stacking for many things, which among them are stacking panoramas, HDR or focus stacking. There are great tutorials on this if you enter these names on youtube. I use Photoshop CS 6 for this, and Photoshop 5 before that and I think it works great. 

Example one Panorama picture (and you can see the result earlier in this post with my shot from Shanghai). I used a 5D II with a 16-35 II. I turned the camera to portrait mode (vertically, to get more sky) and shot eight pictures free hand. What I normally do is to make sure that the pictures overlap with about 25%. After getting them on the computer just go to photoshop - file - Automate - Photomerge and then choose the option that work best for your shot. 

Example two Focus Stacking. Although a lowres version of this picture, this picture is taken with the 17mm TS and is comprised of 28 pictures in one. 

Focus stacking can be especially useful in macropictures as DOF is very shallow. 

Good luck.


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## pedro (Apr 24, 2013)

Thanks everyone who engaged in replying to my questions. You helped me a good deal, folks! At CarlTN: enjoy! 
Cheers, Pedro


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## CarlTN (Apr 24, 2013)

And thank you again Pedro!



Mr Bean said:


> emag said:
> 
> 
> > CarlTN said:
> ...



Yes, I thought they were the Magellanic Clouds...they're beautiful! 

Coma wide open in the extreme corners of a 15mm lens, is still not too shabby! 

If you have an opinion, what do you think of the Tokina 16-28 f/2.8, compared with the Canon 16-35? (I know both would not compare to the Zeiss).


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## Mr Bean (Apr 26, 2013)

CarlTN said:


> And thank you again Pedro!
> 
> 
> 
> ...


Oops, sorry CarlTN, I meant to respond to your reply the other night.

I'll probably be burnt at the stake for saying this, but, I've never been a zoom fancier for astro work. Even some of the primes in Canon's wide angle / UWA brigade suffer around the edges from coma (the original 35mm f2 I have is one of those). Hence my search for the "perfect" UWA lens. And why I ended up with the Zeiss, happily I might add.

While I've read a great deal about "sharpness" of lenses over the past 6 months or so, the only real test was to hire a few and try them. Keeping exposures brief (less than 30 seconds) was enough to sort out the better ones, and quick


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## CarlTN (May 6, 2013)

Mr Bean, much obliged!


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