4 replies to this topic

[Surfer4329]

I’m currently imaging with an ASI2600MM and an 8” Orio. Astrograph (800mm FL) with a pixel ratio of 0.95” Per pixel. Kind of where I should be. However, I’m considering going to a Celestron EdgeHD 8” with the 0.7” focal reducer which will oversample my images at about 0.55” per pixel.

My main motivation for this is that I am hoping to be able to get further in on objects for printing my images. Fill more of my frame with data as opposed to cropping images and losing resolution. Am I wasting time and money to create images of the same quality?

I would say my seeing conditions are average or slightly above average when the winds are low and the humidity gets really low(which are the nights I image)

[KGoodwin]

I’ve found a benefit in resolution to sampling at a rate of 3-4x the seeing conditions. My CDK setup is 0.31”/pixel and provides significant increase in resolution beyond my refractor at 0.89”/pixel. My seeing conditions get as low as about 1” rarely, but are normally between 1.5” and 2.5”.

[SilverLitz]

My experience is consistent with Kyle's.  My Meteoblue measured seeing is typically 1.5" (0.7-2.5), and I see noticeable resolution improvements down to ~0.3"/px.  This includes both native and deconvolution methods.  My best resolving scope, SV152 (1216mm FL, TMB-LZOS lens), with my QHY268/600M cameras is natively ~ 0.64"/px.  This shows noticeably better details than my longer EdgeHD925 (2350mm).  I attribute the differences mainly due to build quality differences and the lack of central obstruction, as well as the SCT being more sensitive to seeing.

 

But the use of 2x Drizzle + BXT, resulting in ~0.32"/px scale, significantly improves the SV152 resolution.  Adding BXT to my CE925 output improves its resolution more dramatically, but still not quite to that of the SV152 (much closer than both without BXT).  Adding 2x drizzle to CE925 did not improve its resolution.

 

Instead of 2x drizzle, I also tried registering my SV152 files to a REF derived from the CE925's native 0.33"/px files.  The results were basically the same as using 2x drizzle; both these methods resulted in almost identical image scales.  Adding 2x drizzle to files that have this finer scale did not improve the result.

 

I have tried another tool, Seti Astro's SuperResolution.  Here again, my results seem to hit a minimum image scale wall.  SR noticeably improves my 2x drizzled AP110GTX (732mm FL) results, but makes no meaningful difference in my 2x drizzled SV152 (1216mm FL) results.

[KGoodwin]

My experience is consistent with Kyle's.  My Meteoblue measured seeing is typically 1.5" (0.7-2.5), and I see noticeable resolution improvements down to ~0.3"/px.  This includes both native and deconvolution methods.  My best resolving scope, SV152 (1216mm FL, TMB-LZOS lens), with my QHY268/600M cameras is natively ~ 0.64"/px.  This shows noticeably better details than my longer EdgeHD925 (2350mm).  I attribute the differences mainly due to build quality differences and the lack of central obstruction, as well as the SCT being more sensitive to seeing.

 

But the use of 2x Drizzle + BXT, resulting in ~0.32"/px scale, significantly improves the SV152 resolution.  Adding BXT to my CE925 output improves its resolution more dramatically, but still not quite to that of the SV152 (much closer than both without BXT).  Adding 2x drizzle to CE925 did not improve its resolution.

 

Instead of 2x drizzle, I also tried registering my SV152 files to a REF derived from the CE925's native 0.33"/px files.  The results were basically the same as using 2x drizzle; both these methods resulted in almost identical image scales.  Adding 2x drizzle to files that have this finer scale did not improve the result.

 

I have tried another tool, Seti Astro's SuperResolution.  Here again, my results seem to hit a minimum image scale wall.  SR noticeably improves my 2x drizzled AP110GTX (732mm FL) results, but makes no meaningful difference in my 2x drizzled SV152 (1216mm FL) results.

Just a note on seeing, MeteoBlue is typically optimistic about seeing.  I measure seeing directly via the CDK image results because the unguided tracking is functionally perfect, the aperture is large enough, and the image scale is oversampled enough to ensure that for the level of seeing I get at my site I can make a fairly firm judgement on actual local seeing that way.  I find it's usually about 0.5" worse than MeteoBlue indicates, which is probably a combination of "local seeing"/thermal effects and predicting seeing just being a very difficult problem.  It's possible (likely) that there exist nights (or short time periods) of exceptional seeing which are better than I can measure with this method.  My one neighbor does high resolution planetary imaging with a C14 and my other neighbor uses a 12" RC and we all compare notes on seeing sometimes, so it seems to be pretty accurate.

[andysea]

I’ve found a benefit in resolution to sampling at a rate of 3-4x the seeing conditions. My CDK setup is 0.31”/pixel and provides significant increase in resolution beyond my refractor at 0.89”/pixel. My seeing conditions get as low as about 1” rarely, but are normally between 1.5” and 2.5”.

That's my experience as well.