Would you bin?

[Galaxyfaraway]

I can't decide whether I would be better off to bin in order to get more subs/lower the exposure times a little as UK's weather is a pain and you never know when clouds come rolling in. Also my views are not terribly open so that after about 6 or 8 narrowband exposures (if I am lucky) the targets disappear behind the trees.

In any case, my equipment (Atik 490EX and WO 81GT) currently give me 1.99" per pixel. If I binned 2x2 this would go up to close to 4". Is this under-sampling too much? I see some people image at 3.5" pp and produce stunning images.

I am enclosing some examples to get an idea of my skies.

Heart Nebula was imaged at bin 1x1 4x20mins (couldn't do more as target moved away).

Elephant's trunk imaged at bin 2x2 16x10mins.

There is much more noise in the Heart (because there were much less subs I presume). Overall I can't seem to notice resolution degradation in the Trunk and it seems to me that it might be a reasonable tradeoff to image at 2x2 and get much more subs in at 10 minutes than 1x1 at 20 mins.

Thoughts? Thanks, gfa

[Galaxyfaraway]

Heart nebula:

[cfpendock]

That is tricky for your situation.   I find the stars in the elephant a bit "blocky" when viewed at full size and when compared to the heart.  Personally, I would go for 1 x 1 binning for narrowband - I think that maybe 4" per pixel is pushing a bit too far, especially if you subsequently want to crop the image at all.  I agree that the weather can be a pain - but hopefully you would be able to eventually build on the total image time.  In any case, both are pretty good images considering the light pollution problems, and I particularly like the framing of the elephant.

Chris

[Scott]

Let me begin by saying I'd be happy with the elephant as is. That said, the stars in the heart are much tighter and at the end of the day aren't we all trying for the best we can possibly achieve? 

Anyway, from my spot here on the fence I'll say "your call"

[Galaxyfaraway]

Thanks very much.

I see what you mean about blockiness. For screen this might be ok but for a print out, perhaps not.

 

[ollypenrice]

I do lots of imaging at 3.5"PP but would love to have the option of having the same field with smaller pixels. I put up with 3.5 because the chip is huge, so the presented image is usually downsized, and we usually do mosaics anyway so it gets downsized still further. By this time the resolution is looking good relative to the target size so we're happy. But on a small chip with limited field you'll be wanting to show it at, or close to, full res and you'd propbably be happier unbinned. I agree with Scott. Your call.

Olly

[iksose7]

Am i right in saying it would be fine to bin even if under-sampling, when you are using LRGB? The RGB layer will be blurred and only provide colour to the L. So as long as the L exposures are 1x1 it shouldnt matter?

Callum

[MartinB]

14 minutes ago, iksose7 said:

Am i right in saying it would be fine to bin even if under-sampling, when you are using LRGB? The RGB layer will be blurred and only provide colour to the L. So as long as the L exposures are 1x1 it shouldnt matter?

Callum

The only problem, when genuinely undersampled is star bloat.  You can bet round this by taking some short unbinned stars subs but adding those in seemlessly can be a bit of a processing challenge.  Personally I feel that binning the colour data allows more time on the luminence which is the engine of the image.  For UK imagers this can be a compromise worth making.