Hello everyone! After many months researching and pondering several options, I am about to press the “buy” button to purchase an iOptron CEM60. The only concern that I have with this mount is how to setup the Zero Point correctly. I’ve noticed this is a crucial step for the mount to accurately center objects in the camera view, but reading threads in several forums (Cloudy Nights included) it is also the thing that most first time users struggle with. I’ve noticed that there’s even people who never were able to nail this down successfully!! I’ve read the CEM 60 owners manual but I think the instructions on how to set the Zero point are quite vague. I’ve also read several threads about this issue but honestly the exchanges have confused me even more. Some people seem to use Polaris to setup the Zero point while others simply put the mount roughly pointing to the North, others seem to use levels... I’ve also watched Paul Chase’s tutorial, which is more clear but based on an EQ25. If any of you who own a CEM60 and have successfully setup your Zero point could share the steps you followed with me I will be more than grateful!!
I do the following.
Set the zero point by eye. For RA, you can go parallel with an obvious straight line. For DEC, you can align two screws.
Polar align very carefully with a PoleMaster. This is what's crucial, to get DEC tracking close (so autoguiding doesn't have to work very hard), and avoid field rotation during a subexposure. It's the one thing I can't do remotely.
"Sync to" a star near my target. Don't really care if the star is even in the field. Sometimes it is, sometimes not.
Take an image, platesolve (I use PlateSolve 2, computerized pattern recognition of the stars to say where you're pointed) to get exactly where I'm pointed at, correct the RA and DEC to the star. Take another image.
There it is. Center if necessary, hit enter to confirm the sync.
The mount is now clued in, further GOTOs work fine.
When I get to my target, I usually make some adjustments to frame the image. I wouldn't have wanted to center either object here.https://www.astrobin...8597/B/?nc=user
I do all this remotely from my desk in the house, shortly I'll be using Sequence Generator Pro, which automates the process of getting on target via platesolving. You feed SGP the coordinates, it images, platesolves, corrects.
Basically platesolving has pretty much made GOTO accuracy almost moot. Level is also almost moot, you just don't want the scope to tip over. <smile>
For people who have not yet platesolved, it's nearly trivial. Doesn't require the night to learn. Download and install PlateSolve2, and either of the 2 associated catalogs. Free. Fire up PS2, load any image (it eats jpg and fit), enter the approximate RA and DEC, and the approximate field of view. Hit solve. The speed with which it works depends on how good your approximations were, it has to know where to start looking.
Edited by bobzeq25, 27 March 2018 - 12:22 AM.