Rho Ophiuchi Nikon D750

[aljo2345]

Image of Rho Ophiuchi in Scorpius, Nikon D750, first attempt. :question:

[Stephane]

To me, that looks amazing, but I’m sure the more experienced photographers will be able to give some tips.

[JA]

Hi Alex,

It's a beautiful image and great that you've captured the lovely smooth nebulous gas around Rho , but the colours are somewhat suppressed and stars saturated, suggesting lowered dynamic range perhaps due to the use of too high an ISO and/or exposure duration. That would improve with perhaps lower ISO. What were you image settings, subs etc..

Is that image from Melbourne or Out of Town darker areas?

Best
JA

[aljo2345]

Hi JA

Thanks for that.

The image was taken at ISO 8000, which is pretty high.

The image was produced from stack of 90 30sec exposures, no flats, again using the Nikkor 24-120mm lens. I am also using the SW Star Adventurer for tracking. Thinking that I should perhaps raise exposure time and lower the ISO to 6400. Your thoughts?

Alex

[aljo2345]

... the image was taken in outer Melbourne in Sunbury.

[JA]

Hi Alex,

The D750, D600, D610 and the D8xx series all have wonderfully high dynamic range (approx 12 stops) and are up there compared with any of the full-frame DSLRs from any company, including even Nikon's new Z series mirrorless BSI sensored cameras, as you can see in the graph from Photons to Photos where the dynamic range is plotted as a function of ISO....
281524

At ISO 8000 your photographic dynamic range is about 5.6 stops, whereas at about ISO 1600, it's about 7.8 stops, which is 2.2 stops higher or put another way 2.2^2 = 4.84 times higher allowed brightness before clipping compared to ISO 8000.

Now why did I pick ISO 1600 ? Well I too have a D750 and D600 and know that I like to use it around ISO 800 for astro, BUT the real kicker is an WONDERFUL astroimage that I recall being taken on a Nikon D610 of Rho Ophiuchi, by one of our very own IIS photographers, Archioptic (Nathan) . Not only did he do a wonderful job :thumbsup:, but he definitely showed the way to what are a great set of settings on the Nikon and what these cameras are capable of colour wise. Here is a link to his image....
https://www.iceinspace.com.au/forum/attachment_browse.php?a=227448

His settings were ISO 2000 19 x90second exposures, other details here....
https://www.iceinspace.com.au/forum/showthread.php?t=166554&highlight=Nikon+D610+rho

In a darker environment like Sunbury and given the ISO-invariant nature of the sensor on these cameras, aside from the suggested ISO 1600 or 2000, I would even experiment with ISO800, but if you are concerned about tracking then perhaps 1600 to keep exposure duration on the lesser side, around 30 to 60s and see if OK tracking wise. Your current ISO 8000 image is quite clean, so you should be able to stretch considerably in postprocessing to bring out faint detail, without undue penalty, especially at the suggested lowered ISO.

Happy shooting.

Best
JA

[aljo2345]

Hi JA,

Thanks for all that information, it is very helpful!

I have to say that Nathan's image is simply jaw dropping :eyepop: and sets the bar pretty high.

I will give your suggested settings a try and post the results.

thanks again

Alex