Posts Made By: Brett Wylie

I'm trying to get in touch with Dave Rowe about his Slevogt camera..i.e. concentric schmidt cassegrain..posting this here because he does astrofilm work instead of ccd..I want to build a telescope similar to his. Anyone having contact information for me please post in the "lost contact" section and I'll pick it up there. Thanks

The "experts", writing in articles and on the net, and the telescope manufacturers themselves, tell us to collimate using a slightly defocused star..the two diffraction rings scenario. This is difficult and thus in my opinion, absolute crap! Even so, most people hardly bother to go this far, collimating instead while looking at the 'big donut'at low power and are happy with "just about or good enough" collimation. With miserable results.
Don't collimate on a star at all! Why not? Well at 500-600x what do you see?..even with relative steady air the defocused highly magnified star will still be wobbling and the diffraction rings will be wiggling all over hell and back...how accurate a measurement can you do with this scenario??
Instead, try this...thread on a straight thru visual back adapter..don't use the diagonal..center Jupiter in the field of view..now you have a rock solid steady object to look at!..big difference..it's also bright and easy to see, large in the field of view...start at about 300x..look at the limb of Jupiter, usually one side will have a halo. That halo is a secondary image of the planet caused by miscollimation, & if your seeing that, your NOT getting NEAR the view your instrument is capable of, your not getting the most out of your SC telescope...go to the front of the scope and tweak the screws until that halo disappears..completely..now kick it, the magnification up, to 600x..say 4.6 mm eyepiece 2xbarlow combo...very very fine movements/changes now..1/15th turn..when your finished there should be no evidence whatsoever of limb halo, you should be looking at a solid planetary edge, while checking at high power all the way around the planet!..and I will guarantee you your eyes aren't going to believe the difference..when it's right on...WOW..POP..all those fine details you thought were impossible to get, with an SC, are going to suddenly be there.

I want to build a 16" concentric schmidt cassegrain. I've called and emailed a few people about doing so. No reply. Anyone have information they could share on such a project, it would be much appreciated.

I want to install digital setting circles/optical encoders on an older Parallax GEM which I'm fitting with new Byers gears/worms @ 11 15/16". I need some feedback on the various packaged systems out there..or single item suppliers unpackaged (homebrew). I don't need goto..just better accuracy then mechanical setting circles.

Anyone know of a product available?

I've heard that Celestron sells a unit such as this, but can't find it anywhere. Anyone using such a thing out there, and if so, the quality and a review of the improvement it gives to a fast scopes views would be appreciated.

I own and use a fast Newtonian, an 8" f3.5 primary mirror, with a large secondary for imaging purposes and a smaller secondary for visual use. These are mounted on a three vane spider. The views are "rich field" fantastic, but with the inherent coma present in all fast Newts. I've posted messages asking for imformation about using a field flattner..and I know about the TV Paracor, visual and imaging correctors. I'm looking for something simpler, fewer lens elements, and cheaper..but with good results. A ccd cameras' chip is small but I would still like to correct and optimize the field of view using my ccd camera with this system. Any suggestions?
I would like to duplicate this "rich field" Newt using a 16"to 18"primary..but optimize it for ccd use, with the camera placed at prime. I like to keep my feet on the ground and I don't have room for a stepladder (and big scope) in my roll off roof observatory anyway.
Any users out there of similar instruments with any suggestions? thanks, BW

Anyone with experience using or owning these telescopes please comment on same.

I have an older Parallax GEM, w/Byers 11 15/16" gear/worm set to be installed. I want to install encoders for better pointing and an interface that will transmit autoguiding commands from SBIG's cameras (2000xm) to the scope. It currently has a VE digitrack drive controller. I'm posting it here instead of "telescope making" to get input from SBIG users that are autoguiding using older telescopes. What's the best system out there for converting an older control system like this to ccd autoguiding..thanks.