pmrid
10-09-2009, 09:50 AM
I'm having a 'focuser' episode.
First it was the GSO RC. Despite being hyped as the ideal scope for imagers, the focuser (a GSO Crayford-style with 10:1) was so poor that it could not take the weight of any decent sort of camera without slumping out of focus and collimation. So in order to make the RC fir for imaging, it is necessary (on the original models at least) to spend several hundred dollars more on a focuser that an imager can actually use. Let's not talk about the need to also fpock the baffle tube for much the same reason. So about A$500 and one Feather Touch later, the scope is now approaching the original hype.
Then, having sorted that out, I turn to the Newtonian on the pier beside the RC. Having recently bought a Celestron Radial Guider (A.K.A. Off-Axis Guider) that pinches about 50mm of back-focus, I decided to mount the brand spanking new Low-Profile focuser I had bought on spec some months back. Once installed, it became apparent that it was even more unstable than the one on the RC. Opening up the beast, it was apparent that the plastic track in which the axis of the focuser runs was missing. So I scavenged the one out of the 'full-length' focuser (also GSO) I had just removed. And here was that sense of dejaa vu all over again. Even with the missing bits installed, the thing could not be made to rack in and out with the weight of a DSLR on it, if you tightened the tensioninig nut enough to take out the slop. And if you applied the brakeing tension nut, the focuser tube was thrown waaay out of alignment entirely.
I am not as forgiving of the RC as others in parallel threads seem to be. If a scope is hyped as the imager's dream machine but needs another 25% of its cost price spent on a replacement this or that, I count that as a gross deficit. Now, at great expense to the management, I have compensated for the deficiencies (over-hype perhaps) of the RC but am I really going to have to go down that same road to deal with the inadequacies of the GSO focuser on my GSO Newtonian. If, as I suspect, the answer is 'yes', may I ask others whjrether there is an optio n not quite so hurtful to the budget. How do WO focusers stand up, for example, in their ability to take the weight of imaging gear?
Any recommendations?
Peter
First it was the GSO RC. Despite being hyped as the ideal scope for imagers, the focuser (a GSO Crayford-style with 10:1) was so poor that it could not take the weight of any decent sort of camera without slumping out of focus and collimation. So in order to make the RC fir for imaging, it is necessary (on the original models at least) to spend several hundred dollars more on a focuser that an imager can actually use. Let's not talk about the need to also fpock the baffle tube for much the same reason. So about A$500 and one Feather Touch later, the scope is now approaching the original hype.
Then, having sorted that out, I turn to the Newtonian on the pier beside the RC. Having recently bought a Celestron Radial Guider (A.K.A. Off-Axis Guider) that pinches about 50mm of back-focus, I decided to mount the brand spanking new Low-Profile focuser I had bought on spec some months back. Once installed, it became apparent that it was even more unstable than the one on the RC. Opening up the beast, it was apparent that the plastic track in which the axis of the focuser runs was missing. So I scavenged the one out of the 'full-length' focuser (also GSO) I had just removed. And here was that sense of dejaa vu all over again. Even with the missing bits installed, the thing could not be made to rack in and out with the weight of a DSLR on it, if you tightened the tensioninig nut enough to take out the slop. And if you applied the brakeing tension nut, the focuser tube was thrown waaay out of alignment entirely.
I am not as forgiving of the RC as others in parallel threads seem to be. If a scope is hyped as the imager's dream machine but needs another 25% of its cost price spent on a replacement this or that, I count that as a gross deficit. Now, at great expense to the management, I have compensated for the deficiencies (over-hype perhaps) of the RC but am I really going to have to go down that same road to deal with the inadequacies of the GSO focuser on my GSO Newtonian. If, as I suspect, the answer is 'yes', may I ask others whjrether there is an optio n not quite so hurtful to the budget. How do WO focusers stand up, for example, in their ability to take the weight of imaging gear?
Any recommendations?
Peter