Quote:
Originally Posted by rustigsmed
hi col,
i am pretty sure Richard M did a lot of testing on cooled vs uncooled dslrs.
a melbourne winter might help but i don't think it was too promising for uncooled dslrs past 2 or 3 minutes.
on a side note - if you have ever wondered what a 30 minute exposure of the helix looks like with a Ha filter on an uncooled dslr @25degs i have the answer here
https://www.flickr.com/photos/803366...blic/lightbox/ ... very difficult to see the noise!! haha |
May just have to max myself at the 120s mark.
That's a great shot considering the sheer lack of red that can get through.
Quote:
Originally Posted by rmuhlack
|
Thanks Richard, only quickly glanced at it so far but it looks to be an interesting read.
Quote:
Originally Posted by glend
Forget 5 minute subs, even with winter weather the internal heat built up by the camera processor, sensor and battery (yes it gets hot too) will give you a mess of noise.
I agree two minutes is about all you can manage before the noise threshold gets too high, and really a long cool down pause would help as well, otherwise you build heat on heat and the images get worse and worse. This is why we use cold finger cooled dslrs, so the sensor can be held at 0C or lower. A battery eliminator adaptor also helps.
You can test yourself, just find a way to read the EXIF header temperature info on each image file, this will show you the processor temperature (as no dslr actually has a sensor temp probe), and you can watch it climb as you shoot a sequence of long subs.
|
This is pretty much where my concern was. Haven't ever noticed a temperature in the EXIF data but I'll check it out.
Quote:
Originally Posted by alocky
I have plenty of examples using 10 minute subs on a D800 at 1600 ISO at 20 degrees plus that were fine after dark and bias calibration and stacking, and although the D810A is 'unmodified', it is considerably cleaner.
http://www.astrobin.com/24974/
Cheers,
Andrew. |
The D800 may be cleaner than the 700, not sure. I haven't been game to push mine over the 60s mark yet. Haven't shot darks either, so far I have used the mount PE as a kind of dithering and then with a lot of subs there is a decent regection. Should probably give darks a shot in the future
Quote:
Originally Posted by Camelopardalis
I've done the vast majority of my DSO imaging with both unmodded and modded DSLRs. My cooling mod was only a recent addition to survive the QLD summer...
Down in your neck of the woods I'd expect 5 minute subs with your camera at a suitable ISO to be very effective. The Sony sensors in Nikons usually fare better than those in Canons.
I'd suggest favouring f-stop over stars though...you can always crop  |
Crop... CROP...
In saying that on my next dark sky trip I want to do some 30s shots at F/1.8 on NGC 5128 to see if I can detect the jets after 30m. Anything outside of the very centre will NEED to be cropped!
