Overall Rating: 9
Optics:10 Mount:6 Ease of Use:10 Value:10
Weight: 14 (Trustworthy Vote)
Date: 01/23/2003 08:30:46 pm PST
By: pjsviolin
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=88750

I think that the author of this review should take a course in logic, optics, and writing.
First, ALL Schmidt Cassegrain Telescopes have an aspheric corrector plate....NOT a lens in the classic sense. It is NOT an optical window. It corrects for the spherical aberration of the primary mirror, which is spherical.
Second, the primary mirror of all SCTs are spherical, have an F ratio of approximately 2, and use a curved secondary (I can't remember if it's spherical as well), in order to reach the ratio of F10. 
The primary CANNOT be a parabola. If it was the scope would be about two times longer than it is, with a secondary obstruction over 50% of the primary diameter.
NO modern cassegrains of ANY type or design uses a flat secondary....The optical tube would be longer than a newtonian with an F10 primary, and would be very short with and F2 primary, which by the way is the actual F ratio of an SCT primary mirror.
Yes, the C9.25 is a great scope...and deserves a 10...but it is not a different scope over any other SCTs. It's primary mirror is a bit longer in focal length than a standard SCT, about F2.4. Which lengthens the OPT tube, and allows a much higher quality primary mirror figure during manufacture.
One last note....occasionally the secondary mirror holder can loosen and shift during shipping. That is the cause of the corrector lens appearing to be "off to one side". This holder is easily repositioned, to achieve optimum optical mechanical alignment.
Otherwise, the first scope was probably a good one. I've owned 3 now, and they were all great performers.



>I just got my second 9.25 the first one had a few bugs. Optics were average and the alignment of mirror in tube in relation to the secondary was poor. never could get  dead on collimation and the front glass holding the secondary was over to one side to compensate for poor mirror alignment.  Planets looked great but beep sky and faint stars were a problem never could get critical focus so I exchanged for another one and got very lucky this one is much better .Owning two other scopes and haveing extensive knowledge in optics I would have to say the scope is at least 1/6 to 1/7 wave or better the first one was around 1/4 to 1/5 kinda of a lemon in my opinion but for the money they are great scopes. The mount is some what light and the tripod worse. So I completely took it down and got rid of the pancake syurp grease they use and adjusted all bearings and worm gears with very good teflon grease and filled the legs with sand also put rubber washers at the inside and outside of the tray to leg connections. The screw is long and the gap is to much also drill a hole in the middle of the triangle tray and put a bolt and nut through the center and tray holder which already has a nice 3/8 hole at the center WOW tightened things up nicely not perfect but major improvement .Now this Photon Busting 9.25 handles 500+ no problem and the focuser on mine is silky smoth with the teflon grease job can turn with one finger  and not wiggle the scope. Hope these tips will  help you photon busters out their. Feel free to email me for help and other tricks not listed. Thanks  By the way I heard rumor that the 9.25 was a parabloid mirror and not a spherical as all other cass scopes are. I beleave this is true the front corrector plate is just glass not a lens the secondary is a magnifiying curved type not flat.  I could be wrong but I don"t think so. UPDATE just spent 3hours collimating this scope and I feel this scope is closer to 1/7 wave instead of 1/6 wave as I posted after adjusting and tweeking at both sides of focus at 600x this thing is absolutly perfect on collimation and the  image just out of focus on both sides is identical and the closeing of focus back to critical focus is perfect with no spikes and no oblong star at very slight and I mean slight tweeking of focus knob. I have looked through some fine scopes of all types and I have never seen a scope go back to perfect focus with no spikeing or slight flare at the end just before critical focus. This is absolutly a keeper whish I could find another one this good I would buy it just to have one so well corrected whith no zones and stars that look like diamonds on black velvet. Not bragging just makeing a point that this is  one of those rare production units that is a gem on optics and no image shift at 600x. I wish Celestron could be this consistant with all there scopes but cost would be a major factor for quality control this tight.GREAT SCOPE I would like to compare to say a 10 or 11 inch and wouldn"t be suprised to win on a 10 and good run on a 11 if not better.