Why stack?

[jammo]

Hi everyone,

This might sound like a silly question but i`ve just started taking images of the Milky way with my DSLR and just a tripod and i was just wondering how more detail is brought out by stacking say 10 photos of which is essentially the same shot just rotated slightly?

[brantuk]

Stacking rotates them all back into alignment - it's "stack and align" software. As a simple example - a small cloud or a moment of poor transaprency over part of the shoot will cause some data to be lost on those particular frames - but it will still be on others. Stacking and aligning brings all the data back into place

[Jessun]

Hi jammo,

Simple answer: usually a tremendous ammount! Try something like DSS and it's a joy to see an image 'grow', but it depends on your sky and camera setting I would think. The better the sky the less need to stack... but with a tripod you're limited to shortish exposures so even for a wide field image I'd imagine it's a great benefit to stack!

Good luck

/Jessun

[jammo]

Cheers guys, i`ll have to try it out, i`ve seen some wide angle millky way shots processed with DSS and they look awesome, even with my 10mm wide angle 30 seconds is about the maximum exposure time i`m happy with:)

many thanks

[Beyond_Vision]

Here's a stacked image of mine taken in several panes which were an hour of 5 minute exposures each. It does make a great deal of difference. These images though were taken with a tracking mount so field rotation wasn't an issue. It is difficult to align the seperate panes when using a 10mm wide angle lens due to the distortion. A 20mm lens would make it a bit easier to mosiac.

The stacking process will improve the signal to noise ratio of your image and allow you to stretch the data more easily.

Regards

Kevin

[jammo]

Wow Kevin that is impressive

It gives me something to aspire to, you`ve compiled an amazing image there

[ismangil]

Hi,

I'm also starting on widefield astrophotography.

I've seen many tutorials on stacking DSO subs, is there anything specific or different for widefield subs?

-- Perry Ismangil

[Beyond_Vision]

Hi,

I'm also starting on widefield astrophotography.

I've seen many tutorials on stacking DSO subs, is there anything specific or different for widefield subs?

-- Perry Ismangil

When using a wide angle lens if you have any rotation between images it can be difficult to stack. You may need to apply a set amount of lens correction (available in Photoshop etc) to each sub prior to stacking. Stopping down the lens will also reduce the amount of distortion.

If you have any scenery in the image it will smear when stacked. You can however composite an image of the foreground with a stacked image of the sky.

Other than that the principles should be the same as DSO's

Regards

Kevin

[ismangil]

Thanks Kevin, that's clear!

-- Perry Ismangil