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C5+ on a NexStar 4GT/5i tripod/wedge

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#1 prozach


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Posted 19 May 2011 - 11:07 AM

I got lucky and purchased an excellent C5+ second hand several years back. I love it to death but have no tripod for the wedge.

I have been improvising with a friends surveying tripod and a couple C-Clamps. Not an ideal situation.

There are a couple tripods out in the classifieds that might work but I am really trying to keep the cost as close to 100 bucks as possible since WAF is a major concern.

Looking at the bolt pattern, it looks like the NexStar 4GT/5i tripod might work with the C5 tabletop wedge that I have, but that the 5i Wedge has an offset bolt pattern so I would not be able to mount the drive/fork of the C5 directly to the integrated wedge(so I can avoid dragging the C5 wedge with me).

My primary purposes are a travel/grab'n'go setup with some prime focus AP thrown in for fun. Nothing crazy like 5 hour exposures but 5-10 minutes or more as my drift aligning skills get better.

Poking around through the forums, it seems that many folks are using the C5 OTA on photographic tripods, however in my experience, this was a barely usable configuration for astronomy. Once you get a photographic tripod that is beefy enough, you might as well just get a telescope tripod given the amount of scratch you have you lay out...

Does anyone have any experience with this or other suggestions?

#2 Midnight Dan

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Posted 19 May 2011 - 12:39 PM

Hi prozach:

The mount you're referring to is not something you can expect to get 4-5 minutes out of. It's essentially an older version of the NexStar SLT mount as seen on this scope:

These mounts, like the SE series, have spur gears which have a lot of backlash. There are folks using these mounts for astrophotography (see Celestron Nexstar forum here on Cloudy Nights) but the exposures are limited to 15 to 30 seconds, and even then it can be frustrating - especially with a long focal length OTA like the C5 at 1250mm.

Part of the reason for the short exposures is the alt/az setup. But, even though a wedge will eliminate field rotation, it can't compensate for the sloppy gears. These mounts were never designed for AP. They can be used for it, but within limitations. 5 minute exposures are far beyond what you can expect.


#3 prozach


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Posted 19 May 2011 - 01:16 PM

Yeah, see I keep coming back to the same conclusion.

I have the C5 and a C8. The C8 is the old great polaris configuration from the mid 90's with an AC clock drive. My ideal goal is an Orion Atlas or Celestron C-GEM but I don't have 1500 bucks to spend right now.

5 minutes is probably out of the question, however I have had okay results at the one to two minute mark which is enough to keep me interested as I continue to learn.

Thanks for the feedback.

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