Help with stacking

Wanted to put the technique to the test but I lost the article about it

There are three kind of stacking so far as I know.
- Focus
- averaging
- exposure

Focus is not the one I want.
Averaging is easy and not a problem.
Exposure is the one I'm lost with at the moment, the idea is that you capture a small amount of light with every frame and then merge them together to get the right exposure.

So lets say you need a 30 second exposure, instead of that you should be able to make 6 photos of 5 seconds and stack those to 30 second.

I had a site about it but lost it, can someone please help me.

I have been wondering about the same Stefan, so I will join in with this question

This is HDR. You can merge your exposures with any intervals you want in Photomatix and probably other programs as well.

HDR means High Dynamic Range and I'm not trying to expend the dynamic range of the photos I'm trying to stack the "light output value" of several photos together without discrimination of what's light or dark to synthesize a longer exposure.

Have been searching and found this link Will try the program but would like to do everything in photoshop to be honest.

Some Astro-photographers can surely help me

Stefan, it's a technique used in astro-photography. They take lots of long exposures then stack them together.

Just added that to my Last comment Peter
That's where it comes from indeed but I lost how they did it

link

You should find something useful here.

How about Deep Sky Stacker?

EDIT: This has DCRAW incorporated into it and supports K-7 files.

Would this work with say, 20 copies of the same image?

What's the difference between 20 x 1 image and 1 x 20 images?

Thank you very much for the links but huh?

What I mean is, does one have to take 20 or so separate images, then stack them, or can you take 20 copies of one image, and stack them and get a similar result?

Hi Stefan, I had a program for focus stacking mainly for closeup, you could take 5-10 photos at different focus depths and when combined the whole object was in focus from back to front, hope that helps.

Jack.

@Peter.
I think you can use multiple copies but it would have the same effect as pulling hard on the exposure so the effect isn't so great.
When you have multiple seperate photos the noise of all of them would be different so if you stack those that would be average out and that's why I believe you can end with a good long exposure photos make out of shorter exposures.


@Jack
Thank you but like said not what I'm looking for

Understood Stefan. The focus stacking software Jack mentioned is probably CombineZM.

Correct Peter