Stacking deep sky objects.

[ve2cjw]

When you want a picture of a deep sky object like Orion, you normaly have to expose for a long time with a guided telescope. A simpler way is to take many pictures and stack them to add the information from each picture and get a much brighter one. How should I do this in Affinity? I need to add all the pictures to simulate a longer exposure. This is not HDR or focus stacking, just adding data. Thanks.

[Yasir]

You need to use Affinity Photo, not Affinity Designer for this task,

I know you mentioned it's not a stacking focus question, but for what you are asking, you would achieve those results with stacking in Affinity Photo. I just did that a couple of weeks ago with flames, I took 200 shots of flames burning in a fires place, my camera was on the tripod, and I got good results.

In case you did not see a tutorial on stacking, here is one, it's simple and to the point.

 

- Video Tube for YouTube - iPhone/iPad

I hope this helped.

[ve2cjw]

Thanks, I'll look into it.

[Madame]

Here's the link 

 

http://http://www.youtube.com/watch?v=348zP-1wGpg

[R C-R]

There is one too many http prefixes in Madame's link. Try this link instead & the page should load.

 

EDIT: the forum seems a bit funky today about inserting URL links, which is why I had to use the indirect form.

[Madame]

Thanks. R C-R :)

[James Ritson]

The above link refers to focus merging/stacking - I think ve2cjw is instead referring to live stacking using operators.

 

ve2cjw - you can use File>New Stack and add your images. Photo will then align and place them into a live stack group. You can change the operator; you'll probably want Maximum (which does the same as setting Lighten to all images if you had them individually as layers).

 

See the Maximum Stacking video for a bit more information:

 

 

Once you've created the live stack, you can also ungroup the images using Arrange>Ungroup, then shift-click to select them all and change their blend mode. You should find Lighten achieves the same result as the Maximum operator, but you can experiment with other modes like Average.

 

I'm getting round to doing a "big stopper" effect tutorial and a light painting blending tutorial soon, which will use similar techniques to what you're after here. Hope that helps!

[strikele]

Most people doing deep sky astrophotography use a separate program to align and stack their images before taking them into a program such as Affinity for processing. One of the most common is Deep Sky Stacker (for Windows) which is free and will align the images (to correct for earth's rotation), rate the images and then let you choose which ones you want to stack. If you are on the Windows platform, this would be, I think, a much easier way to accomplish the task.

[ve2cjw]

Thanks James and Strikele. I found a stacking mode that adds all the exposures together and that's what I need but I'll also try the maximum mode. As to Deep Sky Stacker, I have used it a few times but never got interesting results. Most of the time it rejects 90% of my photos. I am a member of the Deep Sky Stacker Yahoo group. My Pentax K3 does have a mode to do stacking but it would have to track the subject. I prefer to take many pictures and use software to add them. This can be done in Photoshop but I don't use that software.

[ve2cjw]

I just had an idea. The concept of Deep Sky objects is taking a picture of a very dim subject in a supposedly black environment. I'm going to put my camera on a tripod and take a few very underexposed pictures of a barely lit subject on a black background. Then, I'll stack them using the different modes in Affinity untill I get a good exposure. I think this should give me an idea of which stacking mode is the best for that kind of subject. Any comments?

[strikele]

It is too bad that Deep Sky stacker has not worked for you; I do not know why it should reject so many images. I used it quite a few years ago, and did not run into that situation.

 

The rule of thumb for a properly exposed deep sky image is to have the back-of-camera histogram hump separated from the left side, and about 1/4 to 1/3 of the way to the right-hand side.  I have taken images, that I managed to successfully process, where the hump was about 1/2 of the way to the right, largely because of sky glow in my suburban location. Regardless of what software you use to align and stack, you will still need to stretch the combined image using a series of curves to bring out the object from the background. 

 

Good luck in your endeavours.