Catadioptric Lens

[Stub Mandrel]

I'm sitting here while my 500mm catadioptric lens and 450D happily click away at the 'M96 group'.

It's the first time I've used it for AP (and about the third time I've used it properly in about thirty years, I hate the doughnuts, but they are not an issue for astro).

My lens doesn't have a hugely great reputation, so I'm interested to see what results I get. It certainly gives a lovely compact, light setup. Focusing is VERY critical, but using a bahtinov mask I was able to get it pretty good.

Interestingly, unlike all my other lenses it allows you to go well past infinity so it needed no changes to work with the astro-modded camera.

I'm hoping it will give less CA and better star colour than my 400mm conventional telephoto.

 

How do these photographic lenses compare with entry-level SCT scopes? Is it effectively an f8 500mm scope or are they optimised for their different roles?