PDA

View Full Version : Stacking Woes


Jeff
6th of October 2008 (Mon), 15:23
I finally tried to stack some images and fell flat on my face.

I shot 11 - 1 min images of Andromeda through a Sigma 70-200mm at 200mm f/2.8 piggybacked on top of my telescope. I also shot 4 dark images at the same time - same ISO, Exp, & temp.

I downloaded Deep Sky Stacker, loaded the darks as darks and the lights as lights. I clicked on "stack checked pictures" (all were checked) and below is what I got.

A few questions.
Is there a light:dark ratio that I should be going for? It's not 1:1 is it?
Did I miss a step in DSS?
Do I need to do something after they're stacked?
Finally, I can't open the resulting tiff file in Photoshop but I can't change the output file type either.

Johnny9s
6th of October 2008 (Mon), 17:41
That is how most of my images look after stacking. I always have to post process my photos to get the final results.

What happens when you try to open the file? Which version of photoshop are you using? Make sure that you are trying to open the .tif file.

le_R
9th of October 2008 (Thu), 01:53
I think you miss the flat frame step. The flat frame is a special shoot with a white or grey plan (a sheet of paper for example) in front of you scope. Use a white uniforme light to illuminate this sheet. this will help you to correct the vignetting and make your result more uniform.

And dont forget to adjuts contrast, color, saturation levels in your favorite post processing software.

Nortelbert
11th of October 2008 (Sat), 01:01
Here's a quick edit of what you can do with your picture... in Lightroom

Jeff
11th of October 2008 (Sat), 07:02
Thanks guys. I'm still looking around for a "dummy's guide" to stacking. You know, step by step instructions on what to do.

Steve M
15th of October 2008 (Wed), 10:35
Jeff: You might want to check this site..lots of info on amateur astronomy in general, and when you start to dig, there are lots of links to different sites.

http://www.weasner.com/etx/menu.html

Adamora
19th of October 2008 (Sun), 06:07
My god...i would love to try this.

bowtie`
2nd of November 2008 (Sun), 00:38
So jseivert, did you ever figure out how to open the TIFF's? I just downloaded DSS and have the same problem. I do not have anything that can open the stacks after they are done.

Jeff
3rd of November 2008 (Mon), 08:16
Nope. I tried Canon's Digital Photo Pro & ZoomBrowser EX, Adobe Lightroom 2, Photoshop 7.

I kinda lost interest a couple of weeks ago but I've saved all the raw files for another go. I think I'll try registax too.

Are you near Patoka Lake? I went to an annual star party there with a buddy of mine from Bloomington. Nice area.

Adrena1in
3rd of November 2008 (Mon), 10:09
Google Picasa (FREE Download) can open TIFFs I think. I have Adobe Photoshop Elements at home and that's what I tend to use.

Nightop
11th of November 2008 (Tue), 17:37
Google GIMP. Most of the features of Photoshop but it's open source and free. Downside is that currently it is only 8 bit vs. photoshop 16 or 32.

Adrena1in
12th of November 2008 (Wed), 08:08
Google GIMP.
I just tried that, and after some searching I finally found a download, but when I tried it run it it said the file was corrupt, so I gave up.

I want something like that old chestnut, Paint Shop Pro. That was always free and quite good for doing basic picture editing. Can't find that either.

Nightop
12th of November 2008 (Wed), 11:06
Hmmm, when I put GIMP in the result I was looking for was the top returned result.

Since it appears that your problem might be with the output of DSS rather than editing software once you have the stack (as I see you tried to open it in Photoshop), you might want to try Nebulosity by Stark Labs (http://www.stark-labs.com/). I find it easy to use, however I think the trial version limits you to JPG output with hash marks.

I don't know the process steps in DSS but most programs have the same basic work flow.

1. Darks
a. Stack the darks using a fixed stack (no alignment)
2. Flats
a. Again stack the flats using a fixed stack.
3. Bias
a. Same thing here
4. Pre-processing.
a. Here you choose your darks, flats, and bias frames and apply them to each of your light frames. Most programs will know the math to do this, if DSS does not I think Flats and Bias are divided and Darks are subtracted from the lights. However, you may also need to subtract darks from flats and divide bias from darks.
5. If you are working in RAW format at this point you need to color reconstruct your lights
6. Align and Stack, saving the resulting file in the format of choice (TIFF).

A lot of the newer stacking programs have Hot Pixel removal that can be used in place of Darks. With this you make a map of the bad pixels from your dark frame stack and then apply it to your light frames in the pre-processing step instead of using a dark frame there.

Adamora
12th of November 2008 (Wed), 11:42
I just tried that, and after some searching I finally found a download, but when I tried it run it it said the file was corrupt, so I gave up.

I want something like that old chestnut, Paint Shop Pro. That was always free and quite good for doing basic picture editing. Can't find that either.

Well! i have that old program on a Cd but damn if i could only remember where it is.