Telescope Reviews: Re: Setting Circles

I can't speak for the mount itself, but in pictues, the circles look to be a decent size.

Now just becase I think the circles on the SP and GM8 are more than big and accurate enough for a 4" scope doesn't mean I personally would own one these days.

The problem is that for them to work, you have to not only accuratly polar align, but you also have to ensure that you have adjusted your OTA to your mount to eliminate cone error. If you fail to do this, pointing may not be accurate on both sides of the mount.

And there is also the issue of precession. You may also have to plan your observing in advance using a chart or astronomy program that is updated for precession. While this seems to be minor, things up there do move around.

And by the time you accuratly polar align, you could have a go-to mount up and running and have already done a few targets.

So, while I like the GM8 and SP mounts (and I would think the Orion mount would be similar) in terms of their fairly sized setting circles, the truth is that today, when you can get a used LXD55 for $250, and it comes with electronic drive in both axises, and has a computer that automatically adjusts for precession, and can be up and running in 3 minutes, and give you motor driven sweeping, and fairly precise pointing, and allows the swapping of OTAs witout having to worry about Cone error, and can get you a catalog description of an object you stumble on while just slewing around (Identify function), then I simply don't know why someone would WANT to manual circles today.

And to be fair, while I prefer the circles on the SP to those on the GP, even those on the GP and CG5 are good enough for most 4" refractors being sold today. Most 4" refractors being sold today can generate a 2 to 5 degree field, and when you relize that centering the pointer on a CG5 even in the middle of two fat index 10 minute marks is giving you .75 degree pointing then if you are BOUND and DETERMINED to keep it simple with a manual setting circles, then all of these mounts should deliver the goods.

But they are SUCH a pain in the rear!

I was only giving the OP what he asked for though.

Me? I went to DSCs when they first came out, and have never looked back. They were the single biggest revolutaion in mounts in 300 years. Using a mount without DSCs to me is an exercise in tedium.

But that is NOT because the circles are too small. It is because dealing with all of the adjustments and fiddling simply consume too much time. And you HAVE to do it to get accuracy. It is not optinal. And when people tell me that that manual circles don't work well, I know that it is because they didn't take the time and considerable effort needed to make them work correctly.

If the mount were on a permanant pier, that would be another story. There, even CG5 style manual circles can give outstanding results in a modern 4" refractor. But if you have to move it? Like wearing a "Kick Me" sign.

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Celestron C14, CGE (Big Al)
Astro-Physics 6" f/8 (Buffy)
Televue 101 (No name, but I call it my Widescreen HD Space TV)

The night sky is my mistress. She seduces me away from all other lovers.

Edited by Eddgie (07/04/09 06:37 PM)

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