I came across this link from someone who has imaged alongside Damian, his comments are very interesting and seem to agree with comments that I and others have been making about how to get good images:
What are your thoughts about gain? Obviously if you have a Lumenera or similar camera with fast frame rates and no data loss, you can take a lot more frames with high gain, and therefore have more frames to stack to eliminate it.
But for those of us on ToUcams, unless I can stack over 1000-1500 frames, high gain will be very grainy.
Well, you might accept a small amount of rotation blur in exchange for lower noise overall - the rotation blur will be partially hidden by the alignment pass in registax, and actually you can hide it completely with enough work (multiple passes, align on different regions each time, slice n dice to make a composite result).
It's just a question of how much effort you want to put in :-)
Also, for mars almost all of the detail is in the red channel, so there's not as much visible blurring as you might expect.
I tried something last night while waiting for the clouds to part (they didn't). I had mars videos from Ballarat for 2:01, 2:05 and 2:10, about 2400 frames of each colour in each of these runs. I loaded all the red frames into registax - i.e. about 8000 frames - and processed them all together.
The result is that I got to stack 2500 frames instead of the normal 800 or so, here is the result (red channel only). Not too much motion blur evident even though the capture spanned almost 13 minutes!
You can also write software to "undo" motion blur - this is something I might try one day. I'd love to record 30 minutes on Mars and be able to process almost all of it :-)
I also agree with the "don't be afraid of gain" comment from Ian, allegedly said by Damian. I've tried low gain to see if the lower noise is better but in practise the lower gain just makes it harder for the software processing to "lock" onto features.
Nowadays I'm not afraid of high gain and grainy individual frames - if you stack enough of them together then the problem sorts itself out :-)
Here's one of the raw frames from that Ballarat Monday night - look how noisy it is, mostly cause I had the camera working close to it's limit. Short exposures give sharper details.
p.s. don't forget that rotation blur depends on your image scale - if you're working with a smaller image then the rotation blurring is much less.
Yeah, I read that thread on UKastro imaging, a couple of weeks ago when it was first posted.
Had not occurred to me to use higher gain and faster shutter speed to get more out of the image. Everything depends on your setup and image scale. Maybe if this high cloud disappears I will try longer avi's with some new settings.
Quick question. When I alter the gain to zero, the image on the laptop dims off until the planet can't be seen! Do I then brighten the image & then start capturing?
Asi, don't use gain close to zero - crank it up until the image looks like it's close to saturated - ie the brightest parts of the image are almost, but not quite, at maximum brightness on the screen.
