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Old 26-06-2012, 03:19 PM
gregbradley's Avatar
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gregbradley is offline
Join Date: Feb 2006
Location: Sydney
Posts: 15,516
STL11 will do well with 10 or 15 minute subs for most objects. For bright globs you go shorter like 3 minutes otherwise you burn out the bright core.

15 minutes is probably better if your tracking is up to it. But if you setup each night then 15 minutes is probably unrealistic. You'd get rounder stars with 10 minutes.

So whats ideal for the camera is not the only consideration. Round stars is your first milestone to achieve. You have to be able to get round stars almost every time with 10 minute subexposures otherwise you will have a lot of trouble getting bright enough images that you will be happy with.

You want to standardise this to some degree to minimise the number of darks you need.

For example 10 or 15 minutes at -20C should be a good achievable all year round subexposure for an STL11. I have been using 10 minutes for the last few years but now I tweaked my permanent setup a bit more 15 minutes is more common for me. 20 minutes for narrowband or even 30 minutes.

Now you only need a few darks in your library for all shots.

Say 10 minutes for LRGB and 20 minutes for Ha O111 and S11 all at -20C and then make sure your mount and autoguiding can provide that and tweak it until it does and you just completed step 1!

I used to run my STL at -30C in winter but in summer as I recall -20C was more practical. I think it does about 42C below ambient so
with summer temps of around 15C then -20C was achievable. I would go 90-95% power on cooling. Stronger cooling is better than warmer and the STL11 really sparkles at -35C on those really cold winter nights.

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