Robert_T
13-12-2005, 11:40 PM
Hi All, well I've had the C9.25 OTA (with XLT coatings) for nearly a month now, long enough to get a feel for the OTA and it's potential and thought it worth jotting down some early, highly subjective, impressions in no particular order and with very little rigour :P.
Introductory comments
While I've had many different scopes over more than 25 yrs of interest this is the first SCT I've ever owned. The lure for me (as I see for Rumples and others) was the purported high quality and plantetary imaging potential of the 9.25 among the ranks of other SCTs. So far I haven't been dissapointed, in fact I've been pleasantly surprised. :) Having become accustomed to Takahashi quality of my Mewlon DK cassegrain I was pleased to find the C9.25 to have a robust feel (even moreso than the Tak in some respects - for eg the close fitting metal corrector cover vs the vinyl shower cap style cover of the Tak) and a similar level of fit and finish. It looks good, it feels good and it exudes solidity and quality! I've yet to fully explore the optical performance and capabilities, but a few glimpses under rare good seeing promise many good things to come!
Out of the Box
The OTA was despatched to Brisbane via Aust Post from Andrews Communication in Sydney - it was well packed and arrived in pristine condition. Accessories included the fitted dovetail plate, a 24mm plossl, 1.25in diagonal, 30mm finder scope, The Sky intro planetarium software and 1.25in visual back.
I quickly set the OTA up on my pier mounted EQ5 and breathed a sigh of relief that this mounting seemed to handle the weight effortlessly and with damping less than 2 sec (on the 2in tripod legged LXD75 damping is even better). Most of the vibration rests with the orange aluminium dovetail plate which might have to be replaced one day, but it's really a minor niggle for now. With some trepidation I gazed down the OTA at the primary from a couple of meters distance superimposing the secondary on it's shadow and was very relieved to see nice concentric shadow rings emanating out from the secondary to the primary edge indicating close to perfect collimation! :)
Having already become a "bobs knobs" collimation junkie I had got the knobs before the OTA and so fitted these and easily tweaked the collimation back to near perfect alignment before taking the new beasty outside.
Under the big black (or more correctly, light polluted grey blue)
My immediate thought looking at the "toy-like" 30mm finder scope was "this will have to go". But on using it I found it bright, clear and easy to align with easy to see cross-hairs. Sure if I were a deep sky junkie it wouldn't do, but for my planetary passions it's actually not too bad at all :P.
A big plus is that the collimation of this C9.25 is easier than with the Tak - I don't know exactly why, but the knobs turn easier and the movement of the secondary is consequently smoother and collimation more "controllable".
The focusser is smooth and only produces a small amount of mirror image shift - perhaps a little more than my Mewlon, but it's very good in this regard. At 640 x480 on the Neximage chip with a 2.5 x powermate it only jogs around 1/4 to 1/3rd of the chip breadth when reversing focus.
I made up a DIY dewshield from black laminate (see below) which was fiddly to fit and does get in the way of my collimating addiction. The first couple of nights I had the scope out were dry so I ditched the dewshield and could tweak away at will. Unfortunately I've since discovered dew of such an attitude that it looked at my feeble dewshield and laughed in contempt :lol:
Damn that dew - anyway, I quickly ordered an Astrozap combined dewshield and dewzapper and a Kendrick controller (more on those when they arrive) in the hope of beating the dew blues.
Some light
Ok so I've only really had three good nights of viewing, and I can't say I've achieved perfect collimation or had a cracker night's seeing, but as I hinted at earlier I'm impressed with the views. Star images in good seeing are fine very similar to that I get through 1/20th wave optics of the Mewlon. Images are noticably BRIGHTER. And when it come to Mars I've had glimpses of detail (such as the finer bits of Solis Lacus) that I simply haven't been able to see visually with any of my other scopes - this I attributed mainly to the slightly larger aperture that makes finer resolution possible, the specific primary<>secondary Fratio combination that makes secondary collimation easier, and optical quality that if not exactly tak quality is really not that far from it either. The images I've obtained on Mars with only a small amount of familiarisation are (I feel) as good as those obtained with the Tak Mewlon 210 when Mars was at equivalent size before opposition.
In sum
It stacks up well and can hold it's head high in any company. Worth noting too that at ~$2400-2500 AU it represents excellent value for money compared with many other alternatives. All in all I'm very happy with the C9.25 and am looking forward to being able to use it under conditions that will show off it's full potential. Thanks for reading!
Introductory comments
While I've had many different scopes over more than 25 yrs of interest this is the first SCT I've ever owned. The lure for me (as I see for Rumples and others) was the purported high quality and plantetary imaging potential of the 9.25 among the ranks of other SCTs. So far I haven't been dissapointed, in fact I've been pleasantly surprised. :) Having become accustomed to Takahashi quality of my Mewlon DK cassegrain I was pleased to find the C9.25 to have a robust feel (even moreso than the Tak in some respects - for eg the close fitting metal corrector cover vs the vinyl shower cap style cover of the Tak) and a similar level of fit and finish. It looks good, it feels good and it exudes solidity and quality! I've yet to fully explore the optical performance and capabilities, but a few glimpses under rare good seeing promise many good things to come!
Out of the Box
The OTA was despatched to Brisbane via Aust Post from Andrews Communication in Sydney - it was well packed and arrived in pristine condition. Accessories included the fitted dovetail plate, a 24mm plossl, 1.25in diagonal, 30mm finder scope, The Sky intro planetarium software and 1.25in visual back.
I quickly set the OTA up on my pier mounted EQ5 and breathed a sigh of relief that this mounting seemed to handle the weight effortlessly and with damping less than 2 sec (on the 2in tripod legged LXD75 damping is even better). Most of the vibration rests with the orange aluminium dovetail plate which might have to be replaced one day, but it's really a minor niggle for now. With some trepidation I gazed down the OTA at the primary from a couple of meters distance superimposing the secondary on it's shadow and was very relieved to see nice concentric shadow rings emanating out from the secondary to the primary edge indicating close to perfect collimation! :)
Having already become a "bobs knobs" collimation junkie I had got the knobs before the OTA and so fitted these and easily tweaked the collimation back to near perfect alignment before taking the new beasty outside.
Under the big black (or more correctly, light polluted grey blue)
My immediate thought looking at the "toy-like" 30mm finder scope was "this will have to go". But on using it I found it bright, clear and easy to align with easy to see cross-hairs. Sure if I were a deep sky junkie it wouldn't do, but for my planetary passions it's actually not too bad at all :P.
A big plus is that the collimation of this C9.25 is easier than with the Tak - I don't know exactly why, but the knobs turn easier and the movement of the secondary is consequently smoother and collimation more "controllable".
The focusser is smooth and only produces a small amount of mirror image shift - perhaps a little more than my Mewlon, but it's very good in this regard. At 640 x480 on the Neximage chip with a 2.5 x powermate it only jogs around 1/4 to 1/3rd of the chip breadth when reversing focus.
I made up a DIY dewshield from black laminate (see below) which was fiddly to fit and does get in the way of my collimating addiction. The first couple of nights I had the scope out were dry so I ditched the dewshield and could tweak away at will. Unfortunately I've since discovered dew of such an attitude that it looked at my feeble dewshield and laughed in contempt :lol:
Damn that dew - anyway, I quickly ordered an Astrozap combined dewshield and dewzapper and a Kendrick controller (more on those when they arrive) in the hope of beating the dew blues.
Some light
Ok so I've only really had three good nights of viewing, and I can't say I've achieved perfect collimation or had a cracker night's seeing, but as I hinted at earlier I'm impressed with the views. Star images in good seeing are fine very similar to that I get through 1/20th wave optics of the Mewlon. Images are noticably BRIGHTER. And when it come to Mars I've had glimpses of detail (such as the finer bits of Solis Lacus) that I simply haven't been able to see visually with any of my other scopes - this I attributed mainly to the slightly larger aperture that makes finer resolution possible, the specific primary<>secondary Fratio combination that makes secondary collimation easier, and optical quality that if not exactly tak quality is really not that far from it either. The images I've obtained on Mars with only a small amount of familiarisation are (I feel) as good as those obtained with the Tak Mewlon 210 when Mars was at equivalent size before opposition.
In sum
It stacks up well and can hold it's head high in any company. Worth noting too that at ~$2400-2500 AU it represents excellent value for money compared with many other alternatives. All in all I'm very happy with the C9.25 and am looking forward to being able to use it under conditions that will show off it's full potential. Thanks for reading!