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I don't own a tracker or telescope so the only astrophotography I do is occasional milky way wide fields. Usually 20-30 images taken at wide angle and then aligned and stacked using Deep Sky Stacker.

I'm not very familiar with the drizzle algorithm and how it's best used/applied, so I'm curious to know if it would provide any benefit to images with my use case. I've been using it anyway but the resulting 168 megapixel images from even 2x drizzle really bloat file sizes and processing times, so I'm wondering if it's worth it to keep using it.

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  • \$\begingroup\$ Can you point us to a description of the "drizzle algorithm"? I've not heard of this before. \$\endgroup\$
    – user1118321
    Commented Aug 27, 2019 at 1:53
  • \$\begingroup\$ deepskystacker.free.fr/english/technical.htm#Drizzle \$\endgroup\$
    – jay.lee
    Commented Aug 27, 2019 at 2:59
  • \$\begingroup\$ Neat! Thanks for the link! They claim, "Drizzling is particularly good at enhancing the resolution so it is very useful when shooting small objects with a short focal length." So it sounds like it's useful for what you're doing. But I guess the proof is in the pictures. Are you happy with how they're turning out? \$\endgroup\$
    – user1118321
    Commented Aug 27, 2019 at 3:56
  • \$\begingroup\$ yeah, they look good. but i don't really have a way of quantifying if it's really extracting much more detail with the increased resolution \$\endgroup\$
    – jay.lee
    Commented Aug 28, 2019 at 4:23

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You can probably gain a little, but (as you've already seen) at the expense of considerably slower post-processing, and quite a bit of extra storage space.

Given that you're shooting with a fairly wide angle lens, if you want more detail you'd probably be better off using a longer lens, and stitching together a panorama instead.

I'd consider drizzle primarily when you're already using the longest lens you have (or at least the longest that's suitable--a lot of zooms work rather poorly for astrophotography), and you still want more detail. For example, here's a conventional stack of 10 frames (4 minutes apiece):

enter image description here

Here are the same 10 source frames, but combined with a 2x Drizzle:

enter image description here

I tried to get the contrast and such about the same, but I was adjusting by hand, so they don't match exactly (the color balance is particularly far off--sorry 'bout that).

Anyway, I do see more detail in the second than the first (e.g., the dust lanes are noticeably more visible in the second version (especially on the near side).

For what (little) it's worth, the tech specs on the shots: Sony A900 at ISO 160, 10 frames, 4 minutes apiece, 135/2.8 @ f/2.8, plus 3 dark frames (also 4 minutes apiece). And, of course, the target is M31, M32, and NGC 205.

Side note: looking at things, if you click them to view at full sized you'll see the JPEG conversion (especially on the second) shows some pretty obvious posterization. I'll see if I can fix that and update if I can.

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This is what Siril says about drizzle.

enter image description here

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