Quote:
Originally Posted by Mickoid
That's the best detail I've seen on Mars in this forum of recent weeks, so you've done really well. You picked a difficult time to make it your first go. Scientist's prediction on the NASA website think the dust storm may last for months! So much for it's closest approach to earth in 15 yrs. We're getting some of the best views of an orange blob you'll ever see.  |
I was trying to pull as much detail from the images as possible to see what the new setup is capable of; to try and get a feel for the 'limits', I guess. To be fair, I never looked at the great red blob through the eyepiece, so I haven't exactly been working towards an image that was true to what was there on the night - all I saw was black and white!
85% of the visible detail was in the red channel, maybe 15% in the green. Apart from the poles, the blue channel was featureless - which brings me to an interesting question.
Mars is red, right? But the red channel needed another two thirds as long to expose correctly when compared to green (I guess the camera's greater response in the green spectrum helps here) but then BLUE? Exposures were ten times longer than the green channel! wow. Not sure if that's normal or not. I guess the chip is less sensitive in that area, plus the object itself itsn't reflecting as much light in the blue region of the spectrum, but wow!
I did grey card tests the other day with these filters and the results were not what I expected either, but I'm going to repeat them before I say what happened just in case I got something wrong.
Now I'm wondering if I should vary the exposure of the other channels at all. I'm trying to get the best SNR per channel, but with the lucky imaging thing, you lose the advantage of short shutter speeds. If I was shooting OSC, I would have one exposure for all three colours in the bayer matrix, wouldn't I? But then I wonder what happens to blue data that is ten times darker than the green channel in post processing. It must be harder for the algorithms to work on dark data. Sure you can just shoot it with more gain for same shutter speed, but it's the same thing really, isn't it?
So which is it? Is it shutter speed or noise that wins? or can you do like with Deep Sky stuff and shoot Luminance? That could give an even brighter (faster, therefore sharper) image and let the RGB channels be relatively noisy?
Sorry, rambling now.
Cheers