IFN, M81, M82 with Sony A7S

[MarkS]

So here's my first light with Sony A7S on the Tak Epsilon 180ED.  I tried to be adventurous and probably should never have started on this target.  The subs I took at Cairds were wrecked by the IDAS light pollution filter I was using - the filter was actually was not necessary and it reduced the S/N ratio of my subs.  So I threw those away and this is 4 hours of data taken in 90sec subs over 2 nights this week Mon/Wed 18/20 May.  SQM reading was 20.8 which really isn't dark enough to do justice to the Integrated Flux Nebula.

Gradients were a nightmare to remove (I haven't properly succeeded) and I think I may have a light leak or maybe amp glow along the top edge - left of centre.



Larger version here:
http://www.markshelley.co.uk/Astronomy/2015/ifn20150518.jpg

Mark

[Carole]

That certainly is an amazing camera.

Carole

[ApophisAstros]

"My God, it's full of stars!"

rog

[JohnP]

Mark that does look pretty amazing for 90 sec subs - I'd be interested in seeing the full size image & also a single full size sub (warts and all)... if poss.

Thks,  John

[Fay]

Well what can I say, superb

In my purse got £20 and saving....................................

Thing is it seems you have to be able to handle certain problems, and if it is difficult for Mark, not a lot of hope for someone like me

[Mike]

Wow look at that. Absolutely stunning. If that's what you can produce with that kit under what you consider to be less than ideal conditions then I can't wait to see what you are going to produce when we get the cold weather and dark skies back.

[RobertM]

That looks lovely Mark.  I agree about the filter, they should only be used where necessary.

I can imagine the trouble this was, I remember my attempt from kelling taking ages to process out the gradients as well.  The light leak is a serious annoyance, I got over mine (temporarily) by wrapping the camera connection loosely in bacofoil.

Robert

[The Thing]

RIP Canon!

What a superb image. And only you would be picky about it Mark (and maybe Robert).

[Kenny]

Agree. Absolutely fantastic.

[MarkS]

Mark that does look pretty amazing for 90 sec subs - I'd be interested in seeing the full size image & also a single full size sub (warts and all)... if poss.

I don't have a full size one - I did a 2x2 binning during processing to control the noise.

Here's a dropbox link to a single sub:  https://www.dropbox.com/s/dg7ybabowcz226m/DSC00040.ARW?dl=0

90 second subs for this camera on the Tak is nothing - I could have gone much shorter with no loss of data.  Consider these stats from a single 90sec sub at 8C ambient temperature:

Skyglow noise:  23e
Thermal noise: 2e
Read noise 1.4e

I could easily get away with 30sec subs and the skyglow (even at my darkish sight) would still be the dominant noise source.

[Fay]

I forgot it was taken with a 2.8 Tak!

[MarkS]

Yes it was taken with the Tak but the camera does makes a huge difference.  I have tried in the past to get the IFN with the Canon but the IFN was always fainter than the horrendous infamous Canon banding noise and impossible to extract successfully.  This Sony A7S has no banding noise at ISO 2000 and above though it does have in the normal sensor read mode used for ISOs 1600 and below.  Absence of banding noise makes a huge difference in ease of processing.

Mark