video frame rate?

[alocky (Andrew lockwood)]

Hi all, I'm about to take the plunge and buy a ccd for solar, lunar and planetary imaging. I'm looking for the best compromise to use on an 80mm Lunt for the sun, a 4"f15 for the moon, and a 25"f5 for planets. The Imaging Source 1/2" chip (DBK41) version seems to be about right for all three applications, and with the right juggling of barlows gives me about a half arc second per pixel on the big scope to 0.7 on the solar scope.

Question is, the bigger chip has a lower frame rate than the smaller chip - how much difference is that likely to make in practice?

thanks in advance,
Andrew.

[renormalised (Carl)]

For solar...not all that much, but for planetary work, the difference in frame rate can mean the difference between a nice steady image and one that's plagued with distortion and looking out of focus. If you're going to be doing planetary work (barlowed scope) to make sure you're not getting bad shots, the faster the frame rate the better. Remember, upping the FL/FR with the barlow is also going to magnify the effects of any seeing/transparency defects as well as distortion caused by tube currents and such. If you want to minimise those, the faster frame rate of the smaller chip will help to "freeze" those moments of good viewing, plus give you all those extra frames/subs to play around within any given length of time.

Most of the guys here tend to use the DBK/DMK41 for solar work and a DMK21 for planetary and lunar work.

[alocky (Andrew lockwood)]

Thanks for putting it so clearly - I guess the best compromise would be the smaller chip and a bit more work stitching it together on the solar pics.
cheers,
Andrew.

Originally Posted by renormalised

For solar...not all that much, but for planetary work, the difference in frame rate can mean the difference between a nice steady image and one that's plagued with distortion and looking out of focus. If you're going to be doing planetary work (barlowed scope) to make sure you're not getting bad shots, the faster the frame rate the better. Remember, upping the FL/FR with the barlow is also going to magnify the effects of any seeing/transparency defects as well as distortion caused by tube currents and such. If you want to minimise those, the faster frame rate of the smaller chip will help to "freeze" those moments of good viewing, plus give you all those extra frames/subs to play around within any given length of time.

Most of the guys here tend to use the DBK/DMK41 for solar work and a DMK21 for planetary and lunar work.