Comment by waerhert
5 days ago
I switch between the cheap Byomic 76/700 newton and my Sigma 600mm lens (Canon EF but using an adapter to fit the Olympus body). I tried to get the DSLR looking into the newtonian but it was just too heavy, causing the plastic focuser to simply bend way off axis. I've since bought a dedicated astro camera (Neptune C II) which fits alright on the newtonian. I'm keeping the Byomic 76 only for visual observations now. Looking to buy a proper refractor of around 480mm. The Sigma 600 does alright with the DSLR but isn't very sharp, hard to focus and suffering from some coma. It's good enough to learn the ropes for now.
Yeah, in astro, the quality of the lens shows in much more disappointing ways that regular photography. Any softness from the lens can be part of the art in regular photography, but in astro is a lesser image.
Maybe I missed it, but where in Europe are you? Are the temps part of your softness issue? I'm in Texas, and during the summer when it's prime time for central part of the Milky Way the seeing is horrible from the extreme high temps and the disturbance it causes in the air.
I've been looking at getting a dedicated astro camera as well to reduce that weight as well as free up the camera body to go back to its primary mission of time lapse. I've already gone down the rabbit hole deep enough to have a secondary scope and camera to use as a guide scope to overcome any of the slight mis-alignments during polar alignment. The hole is deep and easy to fall into. Be careful when looking down that hole wondering how far you'd be willing to go as you'll be deeper than you expected before you realize you've left the edge.
> slight mis-alignments during polar alignment
For long enough observation there is no such thing as correct polar alignment on earth, thanks to atmospheric lensing. The density of the atmosphere shifts stars up with increasing amounts depending on how low they are.
If your mount can accurately track in dec, then using a more complete pointing model-- the accommodates this lensing along with the major mount orthogonality errors-- generally eliminates the need for a guide camera.
Yeah I didn't expect such a stark difference in image quality from the same lens when using it for day photography vs astrophotography. Just goes to show how incredible a proper astrograph is. I'm located in Belgium: high light pollution and very humid skies. The only targets worth bothering here are close to zenith. It's a fun rabbit hole to be in :)
At my home, it is so light polluted, I don't even bother with attempts at zenith objects. I joke about every hotel in town is a 5-star hotel because you can literally only see 5 stars at night. With a 4 hour drive, I can be in one of the darkest spots in the state. To get to the darkest, it would be at least 8 hours. Either way though, it's Texas, so the high temps play havoc on image quality.