D810A + FSQ106 + M8, 20, 21 and some dark(ish) skies.
On Monday I headed out into the wheatbelt with the D810, FSQ and the G11 to see what I could see. Low temperatures (-2C) certainly kept the noise levels down and I was also rewarded with a nice auroral display as I packed up in the morning.
I used ISO 6400, and although noise isn't an issue I wonder if I'd get more subtle contrast and detail if I'd used a slower ISO speed. Certainly, the subs were limited to 2 minutes by the sky. This is about an hour's worth (33 x 120s)
Processing in pixinisght - background subtraction, levels and curve, a mild unsharp mask and saturation boost.
Astrobin link is here
comments, constructive criticism, withering critique, all welcome!
cheers,
Andrew.
Wow that's a colourful field. Looks like the D810A is letting in a nice balance of H-alpha to other colours, though I suspect it's comparable in colour balance to the 60Da, but with a much better sensor.
Wow that's a colourful field. Looks like the D810A is letting in a nice balance of H-alpha to other colours, though I suspect it's comparable in colour balance to the 60Da, but with a much better sensor.
What was the focal ratio?
Cheers,
Cam
Cheers Cam. The FSQ is f5. I also took an image of the SMC with the 0.75 focal reducer on - I'll post that later.
Ripper image Andrew. I really like it. Gorgeous colours and the star field is divine.
As far as ISO6400 goes. Marianne Oleund who is an engineer and knows a lot about Nikon cameras said there was no gain from going above ISO1600 as its digital gain after that not native ISO. So theoretically that means you would get the best efficiency from the sensor imaging at ISO1600 and boosting in post processing rather than ISO6400 which will lower your dynamic range from the sensor. It also reduces well depth. Perhaps the 810a is different but I doubt Nikon would reprogram their analogue to digital converter for an offshoot model. Anyway that is the theory. You'd have to do 2 images one at 6400 and one at 1600 and process each to know for sure.
I did image long exposure at ISO100 for an hour with the D800e and it seemed to protect stars and colours really well versus say much shorter and high ISO.
My only criticism of sorts is envy Fantastic shot.
Ha ha - thanks :-)
Quote:
Originally Posted by Paul Haese
Looks great to me Andrew. Great colour saturation and nice detail.
Cheers Paul - it's always hard to know when it's overcooked, but this is a such a spectacular field it's hard to mess it up. I'm finding it more fiddly to get the colour balance right with a DSLR than doing LRGB with a CCD.
Quote:
Originally Posted by gregbradley
Ripper image Andrew. I really like it. Gorgeous colours and the star field is divine.
As far as ISO6400 goes. Marianne Oleund who is an engineer and knows a lot about Nikon cameras said there was no gain from going above ISO1600 as its digital gain after that not native ISO. So theoretically that means you would get the best efficiency from the sensor imaging at ISO1600 and boosting in post processing rather than ISO6400 which will lower your dynamic range from the sensor. It also reduces well depth. Perhaps the 810a is different but I doubt Nikon would reprogram their analogue to digital converter for an offshoot model. Anyway that is the theory. You'd have to do 2 images one at 6400 and one at 1600 and process each to know for sure.
I did image long exposure at ISO100 for an hour with the D800e and it seemed to protect stars and colours really well versus say much shorter and high ISO.
Greg.
Thanks for that info Greg -I'd settled on 1600 as a compromise with the D800, so I'll do some more experimentation with this one. The relatively low noise of this thing made me greedy!
I sent Alex Cherny a whole pile of flats at different iso numbers so hopefully he'll do the hard work for me and tell me what to use.
However, the big image that I see on Astrobin has terrible artifacts, like the image is warped in places, which is a bit distracting..?
Mike
Thanks Mike - although I'm not 100% sure I know what you mean by artefacts? There's definitely some oversmoothing that is most visible around the edges of the dark nebula, which I will blame on using too high a NR setting in camera, but I'm not sure which areas look warped. That's where the virtual world falls down - all you have to do is point and I'd be able to see what you mean!
Thanks Mike - although I'm not 100% sure I know what you mean by artefacts? There's definitely some oversmoothing that is most visible around the edges of the dark nebula, which I will blame on using too high a NR setting in camera, but I'm not sure which areas look warped. That's where the virtual world falls down - all you have to do is point and I'd be able to see what you mean!
Well that's funny...I looked at your image three times tonight (I usually look at images several times over a little while before commenting) and each time saw what looked like warping/large scale jpeg compression ...but now I just looked again and its gone ....you are right, this virtual world can be crazy the image looks good now.
Well that's funny...I looked at your image three times tonight (I usually look at images several times over a little while before commenting) and each time saw what looked like warping/large scale jpeg compression ...but now I just looked again and its gone ....you are right, this virtual world can be crazy the image looks good now.
Impressive FoV Andrew. Quite a busy scene overall. I like what you've presented, but not sure of the colour. Looks like you've sucked all the green out of the highlights. Raising the green channel white point using levels resolves the matter. Still a great image. Well done.
Impressive FoV Andrew. Quite a busy scene overall. I like what you've presented, but not sure of the colour. Looks like you've sucked all the green out of the highlights. Raising the green channel white point using levels resolves the matter. Still a great image. Well done.
That explains the redness to the star fields that was bugging me. I think it was an overenthusiastic application of the SCNR tool in PI.
I've since reprocessed it using drizzle integration which has worked extremely well, and have wound the colours back a smidgen. http://www.astrobin.com/189475/B/
This is an 85Mb image that should print nicely at a very large scale.
Quote:
Originally Posted by Retrograde
Lovely image Andrew. Nice to see someone doing such great work with a DSLR.
Cheers! Having the extra H-alpha response makes it a lot easier though.
Quote:
Originally Posted by ghsmith45
Really great image Andrew. Lots of interesting stuff. It's nice to put into perspective the many objects that are often imaged singly.
Geoff
Thanks Geoff - it's a pretty busy part of the sky!
Quote:
Originally Posted by Slawomir
I really like your image Andrew, well done!
Cheers Slawomir! This one's destined for the wall, so the next challenge will be getting good reproduction at the print end.
Nice work Andrew! With the Astrobin version, the blacks could probably be clipped a little more and the image could benefit from a slight saturation boost (at least from how it looks on my monitor / taste), but otherwise well processed. Good to see the D810A performs well.
Nice work Andrew! With the Astrobin version, the blacks could probably be clipped a little more and the image could benefit from a slight saturation boost (at least from how it looks on my monitor / taste), but otherwise well processed. Good to see the D810A performs well.
Cheers Troy - the saturation one's always a bit of taste, and I'm starting to prefer the '70s' look to the highly saturated version. Easily changed though. I've deliberately set the black point where it is for printing, I find that having anything coming out of an 8 bit histogram below 20 is going to be clipped on the printer anyway.
Quote:
Originally Posted by Camelopardalis
Nothing constructive from me (I'm not worthy!), but that's pretty awesome Andrew
I still appreciate the positive feedback - thanks! And nobody is unworthy
Quote:
Originally Posted by Rex
That's a stunner Andrew. Love the deep colour and the golden stars are beautiful.
Thanks Rex, this one is destined for the pool room!
Fantastic shot.
...but now I just looked again and its gone 
the image looks good now.
