Imaging with a Refractor

[prova]

Just a question for those who do image with any sort of Refractor, I'm just wondering what the sweet spot is as far a aperture?

eg. Skywatcher ED100 with a short-tube 80mm autoguider?

[RB (Andrew)]

Originally Posted by prova

Just a question for those who do image with any sort of Refractor, I'm just wondering what the sweet spot is as far a aperture?

eg. Skywatcher ED100 with a short-tube 80mm autoguider?

What do you mean 'sweet spot' ?
If your talking about a lens where the aperture can be adjusted that's different but at prime focus on a scope you can't adjust the aperture setting on the camera.

[prova]

more just thinking what size refractor, ED80/ED100 etc?

[Robert_T]

Hi - I think the sweet spot in terms of optimum refrcator size for imaging is determined primarily by your mount quality and guiding accuracy. For me with an LXD75 and all sorts of guiding woes I'm pushing it with at ED80. It would be pointless for me to have a five inch flurorite if all I can get is wobbly stars. If you got a perfectly polar aligned G11 the sweet spot is probably as big as you can afford. Regs, Rob

[prova]

in that case I may just use my current setup and get myself a Meade DSI as an autoguider and try my hardest to get Drift-alignment bang on!

[TrevorW]

For imaging some amazing photo's have been taken with 66mm APO telescopes, examples of these can been seen on Stellarvue, TMB, William Optics web sites. So with imaging sometimes it's not about size but the mount, guiding and tracking etc that counts as mentioned by Robert.

[Terry B]

Resolution is proportional to the diameter of the scope. Little scopes can give very good widefield images but aren't much chop for little objects as the resolution is not there for hight magnification. Depends on what you want to image.