Hyades

[Scooot]

Taken on 25/11/17, my first image with my Takuma 135mm lens with the lens wide open at f2.5 on the star adventurer. It’s about fifty 30 seconds and 20 1 minute exposures at iso 1600. Quite pleased with how the lens performed but probably needed some shorter exposures for better colour in the brighter stars. I love looking at the Hyades in bins so thought I’d try and capture it. Any suggestions gratefully received.  

[xtreemchaos]

great shots Richard, I do 45 sec at iso 800 with it stopped down three clicks with my 135/35, it shows nice colour then. charl.

[Scooot]

Thanks Charl, that’s good to know.  

[Radman40]

Nice image. Excuse my ignorance but why is it that colour is lost on longer exposures? I remember doing wide field images years ago using film and the colours were always bright and vibrant. 

[Scooot]

47 minutes ago, Radman40 said:

Nice image. Excuse my ignorance but why is it that colour is lost on longer exposures? I remember doing wide field images years ago using film and the colours were always bright and vibrant. 

Thanks @Radman40. I think the core of Aldebaran in particular might be over exposed or over saturated. I might be wrong though , but I found that even though I masked them whilst stretching and this helped, they still seemed to “blow out” too much. Maybe more experienced processors could do better with them  I don’t have any experience of film in such circumstances so i’d be interested in that as well. 

[coatesg]

15 hours ago, Radman40 said:

Nice image. Excuse my ignorance but why is it that colour is lost on longer exposures? I remember doing wide field images years ago using film and the colours were always bright and vibrant. 

Film doesn't saturate in quite the same way (or as quickly) as digital sensors - it's a non-linear recording medium, especially with long exposures of faint objects, and that lack of "blowing out" (and the gentle graduation you get when film does) helps retain colour.

[Radman40]

Thanks for this explanation. So I guess that means we have two 

choices. Either less light and coloured stars or more light (fainter stars) and less colour? Is that correct.

[Scooot]

17 minutes ago, Radman40 said:

Thanks for this explanation. So I guess that means we have two 

choices. Either less light and coloured stars or more light (fainter stars) and less colour? Is that correct.

I think you can combine exposures in processing to get the best of both worlds. One of the many things I’m yet to master  

[Radman40]

Ditto! My favourite quote from Star Trek applies here: "time is the fire in which we we all burn"

[coatesg]

3 hours ago, Scooot said:

I think you can combine exposures in processing to get the best of both worlds. One of the many things I’m yet to master  

Yeah - several ways to do it. Either keep the subs short and stack lots of them, or do a combination in post processing. If the stars aren't actually saturated in the raw data then it's a processing problem in doing them doing so!

[Scooot]

7 minutes ago, coatesg said:

Yeah - several ways to do it. Either keep the subs short and stack lots of them, or do a combination in post processing. If the stars aren't actually saturated in the raw data then it's a processing problem in doing them doing so!

I’m going to try using HDR composition in PixInsight with say three different exposures. If I’ve understood it correctly I should combine them whilst still linear, but after calibration, so it should be interesting.  

I like your blog btw  

[coatesg]

Good luck - HDR is one way to skin the cat. I do struggle with star control myself... It's not easy :-/