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[peetyg]

I was about to purchase the edge hd with cgem mount. But just saw celestron coming out with the cpc hd version on fork mount. I am a novice. My goals are ease of use, portability and eventualy astro photography. My understanding is that if I go to cpc version i will need a wedge to do AP. w
What are the pluses and minuses to each? Now I am confused which one to buy. Any help would be appreciated.

Thanks

Peety G

[patrickm]

Wedge = PITA!

My 2 cents.

[Chicago Astronomer - Astro Joe]

Peety,

The HD is supposed to be for better astroimaging, but I find that in Patrick's 9.25 HD SCT, that the images are sharper visually. Saturn is pretty neat in that scope.

About the wedge...

Some people love 'em...I don't.

It's another heavy piece of equipment to lug around. And usually at a remote site, the elevation needs to be changed, due to the uneveness of the ground on-site. With no polar scope, it's hit and miss. It's good at home where one leaves the mount and just pops the OTA on and off...or setting up at a known regular site.

But...

Since the cpc has GPS build in the mount, I don't see why you need a wedge. It's smart enough to know where it's at in just the alt-az mount and will slew as such...no?


About the fork...

Some have experienced sympathetic vibration...like a tuning fork - ruining astro pics - and many avoid the fork. It picks up wind disturbances and shakes/vibrates the whole damned thing. Also, I'm not sure how the cpc drives work, but find out if you can slew manually and not dependent on the motor drives to move the scope around. Those with Nexstar-type of scopes, cannot slew manually, and when the power runs out, so ends their session.

I would personally get the EQ mount....and less bulky.

[patrickm]

Joe is generally anti-GoTo, with some good reasons. The EdgeHD CGEM mount is moveable if you run out of power. I don't know a about the CPC, but presumably it has clutch knobs, too.

Weight: The CPC is heavier than the CGEM, which AIN'T LIGHT. Adding a wedge increases the weight. This fact alone is a mark against "ease of use." Of course, a heavier mount should bring enhanced stability. My CGEM is infinitely more stable than my little EQ mount on my NexStar. Stability good. You have to balance the two, and that's a personal decision. For me, the CPC would only work if I had my own little observatory or a wheeled platform at home that I could use. TO ME, it is beyond portable and the wedge only makes that worse.

Power: I have 2 Celestron PowerTanks, one of each size. I was always fine running my CGEM off of the smaller one, but it always took a full day's charge when I was finished. I wanted to be sure to have power for any all night session, so I sprung for the larger one last month. It adds a significant amount of weight, so again, that's a personal choice. It does come with AM/FM radio. Regardless, the only time power has ever been an issue is when I bent the adapter plug. Without me realizing, the cord had wrapped around the base and tightened. When I slewed, the weak point that gave was the adapter, which bent. End of session. Aside from that user error, I've never run out of power, at least since I stopped trying to use AA batteries as primary power in the NexStar.

Price: I think you'll pay more for the CPC.

Fork mounts: I've never used one, but they seem to be a love/hate kinda thing. The guy down at Conway observatory had a 20 year old Meade 8" on a fork, and he lives and dies with it, someday possibly literally. Unlike many EQ mounts, the fork allows for tracking over the zenith, but so does the CGEM. I do know that people that love forks, really love forks.

Again, I love my EdgeHD+CGEM combo, but I don't have a lot of experience with anything else but dobs and my little EQ mount. Come out whenever I decide to set up and check it out...maybe tonight. Still on the fence. But whenever, come see how the setup works.

[peetyg]

Thanks everybody for the help

Peety