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12 1/4 hours on M33, Ha LRGB


Tiny Small

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I revisited M33 over the last couple of nights whilst I was trying to sort some guiding issues out.

L: 57 x 300s 

R: 25 x 300s

G: 25 x 300s

B: 25 x 300s

Ha: 15 x 300s

All at 200 gain, offset of 65 and temp of -20 C with the ASI 178 MM-Cool and the Altair 60 EDF.

 

M33 HaLRGB small.jpg

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17 minutes ago, fwm891 said:

Nice data - I think you are clipping the background and loosing the outer arms slightly.  Try reducing the contrast and lifting the highlights a touch after reducing the contrast.

I think that that might be your monitor as it looks fine on mine and the histogram shows no clipping.

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2 hours ago, Tiny Small said:

As is mine, but more importantly, the histogram shows that it is not clipped.

I'm going to say that I think it is, though. Really only a tad. The histo doesn't tell you everything. Dennis (Roundycat on here, no longer active but much missed) discussed the way in which the histo can be deceptive. Alas I don't remember the details of his argument.)

It's a cracking image, a real winner. The tones are a bit chilly to my eye but that's only personal. Great stuff.

Olly

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22 hours ago, ollypenrice said:

The tones are a bit chilly to my eye but that's only personal. 

Olly

You're not the first person to mention that. A slightly warmer tone might improve it a bit. With regards to the histogram, the only way that I can see it being misleading is if the final image were composed of other images that had been only slightly clipped. If it was anything more than that, the histogram would show corrupted data. Having looked at the different layers used in this, none of them display clipped histograms. And I honestly can't see it. Maybe I should get my eyes checked? If one person says it's clipped, an argument can be made (and has been), but if others are saying the same thing, perhaps it's time to turn the gaze inwards.

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23 minutes ago, Tiny Small said:

You're not the first person to mention that. A slightly warmer tone might improve it a bit. With regards to the histogram, the only way that I can see it being misleading is if the final image were composed of other images that had been only slightly clipped. If it was anything more than that, the histogram would show corrupted data. Having looked at the different layers used in this, none of them display clipped histograms. And I honestly can't see it. Maybe I should get my eyes checked? If one person says it's clipped, an argument can be made (and has been), but if others are saying the same thing, perhaps it's time to turn the gaze inwards.

Funny old game but the image is good.

Olly

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2 hours ago, Tiny Small said:

....Having looked at the different layers used in this, none of them display clipped histograms. And I honestly can't see it. Maybe I should get my eyes checked? ...

You and me both, then. ?  I can't see anything wrong with this at all, let alone "clipping".  Yes, maybe the background looks a bit dark but the transition from the edges of the galaxy to the edges of the frame is smooth and the arms are well-defined.  I'd be well happy with this...

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Looks great.  Not to be a stick in the mud.....but I agree you have clipped the outer spiral arms just a smidgeon.  It may not be that the background is clipped (though I do think it is a bit).  It could be the outer regions were not lifted enough--maybe they were protected during stretching inadvertently?  It could be a million things.  Its a small thing.  if you really look for a while, you can just make out the furthest edges of the extensions (if they were a notch brighter would be perfect)

Rodd

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