Quote:
Originally Posted by alpal
OK - do you have any photos of the setup for such a large scope?
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funnily enough I have a JMI scope - it is still being offered by JMI - mine is an NGT12 - a 12.5" f/5 scope - it does not need a rotator as a horseshoe mount is an equatorial mount.
https://www.flickr.com/photos/johnka...57594183210993
The scope has 1/16 wave optics from OMI and is used for both planetary and deep sky imaging. The quality of the optics means that focusing is a snap and considering the f/5 ratio is has low coma, although I do use a Baader MKIII corrector for deep sky imaging.
Some photos taken with the scope here:
https://www.flickr.com/photos/johnka...57640517313374
https://www.flickr.com/photos/johnka...in/set-1162379
https://www.flickr.com/photos/johnka...9369/lightbox/
https://www.flickr.com/photos/johnka...3154/lightbox/
In my mind, deep sky imaging may in effect mean that as we are imaging at a smaller focal length we can get away with lower quality optical quality - a flat field is more important - that's why the low cost RC's in the market now are getting so popular. But, as the focal length increases like that needed for planetary, then so does the need for better optical quality.
The Mars and Saturn images (links above) were taken at an affective focal length of nearly 9 meters - so you do need good optics imaging at the focal length.
John K.