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Jupiter and Mars 14th August


neil phillips

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With the 300p last year I was using an APM coma correcting barlow operating at about 2.8x (with my QHY462c) and this year I’ve got a Tevelue 2x barlow and with the ADC between it and the camera (ASI485mc) it will operate at about 3x.

Like Neil I tend to oversample, but I’m not too fussed about the sampling really as long as it’s in the ballpark. On the list of ‘things that will ruin your images’ the exact sampling is way down the list in my opinion. 


Actually whilst we’re on the subject, one benefit of using greater barlow power than is strictly necessary is that you get a larger diffraction limited field size and so a bit more tolerance to collimation error. With a long imaging train and a newt with thin flexible tube wall that is not to be sniffed at. 
 

Edit: just thought I’d add this link to a tweet with a Jupiter image, captured with a C14 at F/25 with 2.9um pixels. It’s massively over sampled but has that ruined the image?  Could the image have been better if sampled more sensibly? Possibly. But my point is that oversampling won’t ruin your images, but bad seeing will, thermal issues will and focus error will.

 

Edited by CraigT82
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5 hours ago, CraigT82 said:

With the 300p last year I was using an APM coma correcting barlow operating at about 2.8x (with my QHY462c) and this year I’ve got a Tevelue 2x barlow and with the ADC between it and the camera (ASI485mc) it will operate at about 3x.

Like Neil I tend to oversample, but I’m not too fussed about the sampling really as long as it’s in the ballpark. On the list of ‘things that will ruin your images’ the exact sampling is way down the list in my opinion. 


Actually whilst we’re on the subject, one benefit of using greater barlow power than is strictly necessary is that you get a larger diffraction limited field size and so a bit more tolerance to collimation error. With a long imaging train and a newt with thin flexible tube wall that is not to be sniffed at. 
 

Edit: just thought I’d add this link to a tweet with a Jupiter image, captured with a C14 at F/25 with 2.9um pixels. It’s massively over sampled but has that ruined the image?  Could the image have been better if sampled more sensibly? Possibly. But my point is that oversampling won’t ruin your images, but bad seeing will, thermal issues will and focus error will.

 

And I will add under sampling. Your images may not live up to there potential. Some good points from Craig. 

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