Author Topic: Another M27  (Read 4280 times)

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MarkS

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Re: Another M27
« Reply #30 on: Jul 21, 2008, 23:20:29 »
Last night, although the conditions were windy and the moon was 2 days after full, I managed to get 2 hours of data from the modified Canon 350D.

So below, we have in order:
1)  Unmodified Canon 300D   -  Ambient temp 19C and still.
2)     Modified Canon 300D   -  Ambient temp 16C and windy
3)     Modified Canon 350D   -  Ambient temp 16C and windy

All are taken with the Celestron C11 with F6.3 focal reducer on EQ6 mount with guiding.
All are 24 x 5min
All are scaled by 2/3 and then cropped.
The Canon 350D image is slightly larger because it is 8 Mpixels instead of 6 Mpixels. 

[Edit] All were taken from Sidcup using an Astronomik CLS filter.

The 350D image does show a bit more detail in the very faint areas but the improvement is marginal.  The 350D colours are a bit more bland but I could have done a bit more processing to match them better.




« Last Edit: Jul 22, 2008, 08:19:53 by MarkS »

JohnP

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Re: Another M27
« Reply #31 on: Jul 22, 2008, 07:29:50 »
Excellent comparison Mark - I actualy prefer the modified 350D image - I like the colour (slight more greeny (less blue))....

It'll be interesting to see what you get with this from a dark site.

John

RobertM

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Re: Another M27
« Reply #32 on: Jul 22, 2008, 09:10:40 »
I have to agree with you John, the colours are more what I would expect.  The 350d image has more stars - is it really more sensitive or is it the post processing that's made them different ?

MarkS

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Re: Another M27
« Reply #33 on: Jul 22, 2008, 10:10:09 »

The difference is not in the 350D's sensitivity but in the massively reduced dark current and read noise.  This allowed me to increase the gain when processing the 350D to bring out more detail.

I'll do a further test where I perform identical processing on each - that could be quite interesting ...

MarkS

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Re: Another M27
« Reply #34 on: Jul 23, 2008, 00:27:32 »
Here we are - identical processing on each - the subs are just stacked with no range compression applied. 
No RGB balancing has been done, so the colour balance is just how it came off the CCD.
Each image is 24 x 5min at ISO 800 using a CLS filter.
They are 2x2 binned in software and cropped.

Left to right:
Canon 300D unmodified
Canon 300D modified
Canon 350D modified

« Last Edit: Jul 23, 2008, 06:23:04 by MarkS »

RobertM

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Re: Another M27
« Reply #35 on: Jul 23, 2008, 11:54:46 »
That's interesting, the 300d does very well but I think the colour balance in the 350d is much better for the OIII emission line.  Ha doesn't really seem much different other than for the image scale.

Rocket Pooch

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Re: Another M27
« Reply #36 on: Jul 26, 2008, 09:08:26 »
I like the 300D image, best because the colours look right, only my opinion though.

Anyway, are you going to try the AMP off mod or cooling?

Chris


P.S. Does anyone want to use my 6 inch F5 at DSC, I have a specific image I'm after so I might not use it until later this year.