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CPC1100 Question

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#1 jloweva

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Posted 13 November 2013 - 10:11 PM

Can anyone with a CPC 1100 tell me the distance between the end of the tube and the base at zenith? I have a large diagonal and a turret and am trying to figure out what the clearance tolerance would be. So I need the distance without any diagonal, visual back or focal reducer inserted.
Thanks!

#2 brianb11213

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Posted 14 November 2013 - 04:14 AM

It's hard to measure accurately but with my CPC1100, the clearance between the LSCT threads (everything removed from the back end of the scope, including the large SCT to standard SCT thread adapter & the azimuth clamping knob is approximately 7.8 inches.

In practice you will almost certainly find that the balance of the tube about the altitude axis is far more of an issue than the rear end fork clearance. My scope is STILL tail heavy with everything removed from the back end. You WILL need a counterweight system!

#3 rg55

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Posted 14 November 2013 - 08:50 AM

If I may ask a tangential question of you both...

My next scope would be a C11, but I'm not sure which model is best. My use would be almost entirely lunar/planetary AP. Is the CPC up to this, or should I look for something GEM-mounted?

#4 WesC

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Posted 14 November 2013 - 01:41 PM

AP will be a lot easier with a GEM...

#5 PowellAstro

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Posted 14 November 2013 - 02:07 PM

The Alt/Az scope will be lighter and easier to setup. No counter weight needed to offset the tube weight. The Alt/Az will do fine for solar system imaging of the planets and can even work great for DSO with the right camera gear.

#6 brianb11213

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Posted 14 November 2013 - 02:13 PM

My use would be almost entirely lunar/planetary AP. Is the CPC up to this, or should I look for something GEM-mounted?

In practice I find that, for planetary imaging, the thermal characteristics of the C11 tube are far more of a limitation than the altaz mount. But the inherent field rotation does make mosaicing of the moon difficult.

The CPC mount is a compromise (as is just about everything else on the market). It isn't steady enough for long exposure work but it's fine for planetary imaging or visual observing. Far superior to the Meade LX90 mount, just about equal to the LX200 which is considerably heavier. There is not much doubt in my mind that a good GEM is more convenient once it is set up & aligned but the CPC mount is more practical if you have limited time & no permanent observatory.

HTH.

#7 Sorny

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Posted 14 November 2013 - 03:15 PM

Can anyone with a CPC 1100 tell me the distance between the end of the tube and the base at zenith? I have a large diagonal and a turret and am trying to figure out what the clearance tolerance would be. So I need the distance without any diagonal, visual back or focal reducer inserted.
Thanks!


Clearance behind is not a problem. As an earlier reply suggested, it's nearly 8 inches. Balance, however, is going to be a huge issue unless you've got a counterweight setup.

A CPC1100 is so back heavy without anything on the back, I ordered a full starizona counterweight set (top & bottom) even before adding my power x switch diagonal and binoviewers. Putting a turret loaded with eyepieces on the back will make it quite interesting if you loosen the altitude clutch... and not in a good way.

#8 MitchAlsup

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Posted 14 November 2013 - 09:01 PM

My next scope would be a C11, but I'm not sure which model is best. My use would be almost entirely lunar/planetary AP. Is the CPC up to this, or should I look for something GEM-mounted?


CPC is up to this is you go through the effort to replace the RS balls with real steel ball <bearings>. When used on a wedge, the RA bearings take a heavy load and the plastic originals are not quite up to the job.

#9 azure1961p

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Posted 14 November 2013 - 11:36 PM

If I can use my alt az Nexstar 6SE as an example - its more than adequate for lunar and planetary. A GEM technically is better but not in anyway meaningful for what you are doing and as stated set up is quick and clean with an alt az. Doing a lunar mosaic is another issue altogether and could be a deal breaker if its meaningful to you to do that. Straightforward vid runs on the planets and moon though - I think the alt-az would be perfect.

Pete

#10 RossSackett

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Posted 15 November 2013 - 08:46 AM

I regularly use my CPC 1100 for lunar and planetary imaging. For the moon I keep the capture to 2-4 minutes, which will stack to a nice un-rotated image. I mosaic in Photoshop, which automatically rotates frames when it fits them--field rotation need make no difference at all in mosaicking.

I love the alt-az because it is soooo easy to set up and align to the sky.






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