Overall Rating: 10
Optics:9 Mount:10 Ease of Use:10 Value:10
Weight: 1 (Unreliable Vote)
Date: 04/03/2004 11:46:56 pm PDT
By: Anonymous (xxx.xxx.234.249)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=351399
> Stars focused through most of fov - extreme edges show coma but - hey - its an f/5 fast mirror.
The MN56 is not f/5, it's f/6. This reviewer repeats his "f/5" error several times in his report.
> The fast primary mirror makes pinpoint stars across entire fov through edges impossible - but with proper cool-down it's only apparent at very edges. They're not comets or anything gross - they just go out of focus as you near the edges. That's why I gave the optics only a 9 rating.
Sounds like field curvature and/or astigmatism/coma in his *eyepieces*. Maks are reknowned for wide _flat_ fields. The official specs of the MN56 include:
-- photographic field = 13.5 mm diameter;
-- spotdiameter at edge of photographic field = 11 micron.
This is superb sharpness at a considerable distance off-axis. It would have to fall apart completely, further off-axis, at a rate faster than coma becomes apparent in normal f/6 Newtonian paraboloids, to match the decription given by this reviewer. I doubt that could be the case, so I would suspect the eyepieces or collimation, rather than the telescope optics themselves.
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