Mars through high cloud

[AbsolutelyN]

We had a constant stream of high cloud and haze last night but atmosphere seemed relatively steady so had a quick crack at mars despite. Quite surprised so much detail visible given the conditions. 250PDS with 3x barlow.

Edited October 31, 2020 by AbsolutelyN

[geoflewis]

Nice work and good comparison of the 178MM and 462MC, the mono being the clear winner here IMHO.

[AbsolutelyN]

2 minutes ago, geoflewis said:

Nice work and good comparison of the 178MM and 462MC, the mono being the clear winner here IMHO.

Thanks Geof. Yes the 178MM always seems to win out for me. I switched to the 462 mostly because shutter speeds were quite slow on the 178 (100fps for red, about 50 or less for blue) where as could get 325fps on the 462. Was interested to see how they compared. Image scale of the 178 helps and I find it easier to focus too.

[geoflewis]

2 hours ago, AbsolutelyN said:

Thanks Geof. Yes the 178MM always seems to win out for me. I switched to the 462 mostly because shutter speeds were quite slow on the 178 (100fps for red, about 50 or less for blue) where as could get 325fps on the 462. Was interested to see how they compared. Image scale of the 178 helps and I find it easier to focus too.

I had an interesting discussion with Anthony Wesley and Niall MacNeil, both of whom are excellent planetary imagers from Australia. They both propose that fast frame rate isn't everything, but needs to be matched with photon count per frame. Anthony typically images at around ~60-70 fps and Niall at around 75fps. Niall did a lot of testing recently with his ASI174MM / C14 combo and concluded that the trade off between photons per frame and fps saw the 174MM optimised at 13ms (76fps), so I have been following that recommendation with my ASI290MM / C14 and have been pleased with the results. I adjust the gain for each filter to maintain a consitent histogram with the exp fixed at 13ms for each. I only recently purchased the 290MM and was considering the 462MC, but opted to stay with mono, hence was very interested to see your comparison. Did you capture any IR with the 178?

Edited October 31, 2020 by geoflewis

[AbsolutelyN]

1 hour ago, geoflewis said:

I had an interesting discussion with Anthony Wesley and Niall MacNeil, both of whom are excellent planetary imagers from Australia. They both propose that fast frame rate isn't everything, but needs to be matched with photon count per frame. Anthony typically images at around ~60-70 fps and Niall at around 75fps. Niall did a lot of testing recently with his ASI174MM / C14 combo and concluded that the trade of between photons per frame and fps saw the 174MM optimised at 13ms (76fps), so I have been following that recommendation with my ASI290MM / C14 and have been pleased with the results. I adjust the gain for each filter to maintain a consitent histogram with the exp fixed at 13ms for each. I only recently purchased the 290MM and was considering the 462MC, but opted to stay with mono, hence was very interested to see your comparison. Did you capture any IR with the 178?

That's really interesting thanks. It's not the first time I've noticed the 178MM gets better results despite significantly lower frames per second. I usually adjust the exposure between filters with shutter speed, will try gain instead and experiment with those frames rates.  

I'm afraid I did not get any IR with the 178. However I do have one from a few days earlier - this was on the 25th.

178MM ZWO IR 850NM
Capture Area=344x350
Gain=342
Exposure=0.01425