Quote:
Originally Posted by tilbrook@rbe.ne
That's good Ray! 
I'd have to say that's the most detailed 6302 I've seen, quite like the subtle colour.
Cheers,
Justin. |
thanks, that's very generous Justin! I would like to be able to get better colour, but that will have to wait on these skies clearing a bit and the moon moving on.
Quote:
Originally Posted by Lee
Ray - how do you get by (and get great results) with such short subs? especially with a 6nm Ha filter?
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Hi Lee
There are two major advantages to the ICX694:
1. it has 65%QE at Ha, which makes it more than twice as sensitive as many other CCDs - you can use under half the sub length (and total exposure time) for the same detected signal,
2. it has about half the read noise cf many other CCDs, so you can take 4 times as many subs for the same contribution of read noise to the SNR (read noise adds in quadrature).
ie, a single sub of 10 minutes with some alternative CCDs is roughly equivalent to 4 subs of 1 minute with the 694, if the aperture and pixel scale is the same for both.
In practice, on a bright nebula, I use pretty much the same settings as any other filter when imaging in Ha. Of course, short subs means that the tracking of an EQ6 is just about good enough (not perfect, but not too bad over 1 minute) and subs from periods of short term degraded seeing and wind gusting can be deleted to improve resolution. In windy conditions, have been able to image effectively with really short subs - the colour for the posted image was from 20 sec subs.
The icx694 really is quite a revolutionary CCD from a systems perspective.
regards ray