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Another M51

Started by MarkS, Apr 23, 2018, 01:09:54

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MarkS

M51, the Whirlpool Galaxy is one of my all time favourites.

This one was taken last week Thursday 19 April as part of an experiment with a new setup:  Sony A7S on Celestron C11 with Starizona 0.72x large format corrector.

This is 240x30sec at ISO 10000 i.e. 2 hours total exposure:



Large version, a crop at 100% scale is here:
http://www.markshelley.co.uk/Astronomy/2018/M51_C11_20180419.jpg

Mark

Carole

It's a beautiful image Mark, but why go back to the C11 with it's much slower focal ratio?  Is it because you wanted to get in "closer" to the Galaxy? 

Carole

JohnP

Very nice Mark - loads of detail in the full size - I'd be well haps with that experiment... ;-)

MarkS

Quote from: Carole
It's a beautiful image Mark, but why go back to the C11 with it's much slower focal ratio?  Is it because you wanted to get in "closer" to the Galaxy? 

Yes, it's all about focal length.  This will get me close into those small objects.  The read noise is so low on the Sony A7S that the slow F-ratio isn't a serious issue. 

Mark

Carole

Gotcha, makes sense now.

Carole

MarkS

#5
I've done a complete re-process, this time using the Bayer Drizzled version, for increased sharpness.  The previous version was also a bit too green.

So here's version 2:



Larger version:
http://www.markshelley.co.uk/Astronomy/2018/M51_C11_20180419_v3.jpg

Mark

JohnP

definitely less noise visible & colours do look better - nice one - John

Carole

Much prefer the new version, both the colour and smoothness.

Carole

The Thing

Very nice Mark love the knotty clumps.  I prefer the second version as well.

As 'tis the season of galaxies. I've got my ASI294 on my LX90 for doing galaxies and Jupiter at the moment :) Hopefully a go at a planetary or two as well.

Fay

Lovely M51 Mark. you seem happy with the Sony now. is it still difficult to process the subs, is it something you have to get to know how to do it?
It is healthier to be mutton dressed as lamb, than mutton dressed as mutton!

MarkS

Quote from: Fay
Lovely M51 Mark. you seem happy with the Sony now. is it still difficult to process the subs, is it something you have to get to know how to do it?

Thanks.  Processing the subs is not difficult.  It's just time consuming and occupies too much disk space - hundreds of subs for every image.

Mark

NoelC

An amazing image thanks Mark
The difference in texture between the two galaxies really comes out in your image.
Noel
Swapped telescopes for armchair.

Mac

Very nice,

all these images are screaming at me to get back outside an image........

Mac.