Quote:
Originally Posted by TechnoViking
I guessed this would be the case, I have written down a few settings, the hardest part is trying to find out if its my image settings or if its my post processing. From my understanding, if you have enough data you should not need to mess with the image in paintshop too much.
The image i took of NGC253 was 20 x 2 minute subs, see this is what im a little confused by, I have been told the more data the better, but at what point does it become too much data? is there such thing as too many shots? Is 20 x 2 minute subs good? or is 10 x 4 minute subs better?  |
Basically more is better. Nebula are surprisingly dim, you would need 10's of hours to get a visible image if them without stretching the stacked images first in most cases. What I look for is enough histogram 'volume' to the left to show some width on the luminance scale so I know there are plenty of photons to start with. Usually only about 10% or a bit less.
I do a first levels stretch which then shows me if there is an image hiding in the blackness. If it stays black then go get more photons. You'll need a bucket, a light bucket
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I then do another stretch if necessary to get enough image to see some
grey levels and a bit of colour hopefully and then work in the curves section to get it to a usable point using Photoshop 2.
Rolf ( Skyviking) has done images with 120 hours of exposure.
My M42 attempts have been a minimum of 45 mins, it is quite bright but could easily take another hour or two of exposure.
Same for Eta Carina NGC 3372 or more even. This is at ISO 1600 but I'm shifting down to either ISO 800 or even 400 to reduce noise effects so my exposures are going to double at least.
If you pm me your email address I can send my spread sheet through so you can see what I am currently logging. It is still a work in progress and in some cases the info is almost irrelevant, barograph readings for example and humidity but long term they become important when you are trying to beat ambient temp problems and dewing on lenses\mirrors.
Important ones to you at present are # of frames @ ISO xxx and duration xxx secs but also recording the aperture and f# of the scope + barlow or filter. Camera type, settings, software used for capture. Guide scope\hardware\software settings. The list goes on.
I'm bad at logging details but having it at my fingertips with a set format has already made a difference to how I work in the OB. And I don't forget things at power up time.
Process is stack it, save it, stretch it to a useful level then work on copies of it. I've gone back to some of my older images and reworked them in the light of new skills and knowledge. It just takes time and patience. Notes help
PM me if you want a copy.
p.s. NGC 253 ( Sculptor ) needs a couple of hours at least, it's dimmer than most nebula and hs low surface luminance.
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