Lunar Imaging - Scope Comparison

[Stratis]

So, I remember when first trying to figure out what scope to buy for astrophotography, the hardest part was understanding the real-world differences between the various scope options. There seemed to be strong arguments for almost every variety of scope (besides small Maks which are universally discarded for AP), and this made it extremely difficult for me, a practically-minded individual, to envisage the end result.

A year later and, with the exception of Newtonians, I have imaged through every kind of scope with varying degrees of success. I've found Maksutovs extremely challenging so have abandoned using them for the time being, but I have arranged this small selection of my lunar images that may help someone else trying to picture the real-world differences between scopes.

I am fortunate enough to be able to say my scopes are all superb optical examples that I wouldn't part with, so I hope these images are at least mostly representative of their class

              

This first image was my first ever astroimage, taken with an ST80 achromatic refractor and an SPC900NC webcam. Chromatic aberration is intrusive and obvious, even after processing in Registax. I've never managed to get an acceptable image out of an achromat, some have and I admire the effort, but this turned me off achros forever and inspired a move to the second imaging setup.

The second image is through an Ikharus/Ostara 102ED apochromat, captured by a Canon 6D DSLR. The difference made by the sharper optics is obvious, and the lack of colour is encouraging. It's worth pointing out that without a dual-speed focuser, this would have been a lot harder . The 102ED is still my favourite imaging setup at f/7, down to f/5.9 with a reducer for deep sky work, although I need to get autoguiding up and running to make the most of it.

              

The next two images sort of inspired this post.... one is captured by a Celeston C8 SCT (shrunk to half size for upload), the other was taken on the same night through the William Optics ZenithStar 66 SD.... without clicking on the photos, can you tell which was which from the thumbnail? It isn't easy for me, and they're my shots! Neither image has received any processing, just straight shots onto the 6D. 

Personally I was delighted by the performance of the tiny ZS66, particularly the obvious lack of CA on a scope which has the problematic 'Special Dispersion' label on its glass.... I can't see any reason to ever deprive myself of this tiny little travel scope.

The C8... I have to confess to some surprise that the greater image scale has not translated into better detail. Seeing was mediocre and the corrector was practically a pane of ice, but it would have been nice to get a few more craterlets out of the larger aperture . If anyone has solid advice on squeezing better detail out of medium-size SCTs, I'm all ears .

Hope this helps anyone looking into lunar imaging

~Paul

[sologuitarist61]

Well done Paul, these sort of comparisons are always useful!

[Luke]

Interesting post, Paul. It's surprising how much detail a small aperture scope can grab from the moon.

I think with the C8 the detail it can capture will depend more on the conditions. On iffy nights I don't bother with my 8 inch SCT, I stick to an ED80 or possibly ED120.