Re: brand new to this stuff, need starting advice

Khalid Baheyeldin

I can speak a bit about the CG5, since I had one for some time.

It was GOTO with the iOptron GotoNova 8400 kit.
That kit was supposed to have PEC, but it never worked for me.

Even without PEC, I was able to do unguided exposures of 45 seconds @ 1280 mm focal length (C8 with 0.63X reducer). Occasionally I would be able to do 60 seconds, or 90 seconds, depending on where the worm gear was. When it was changing directions in its sine wave curve it would change the least.

If you want sample pictures I took, I can point you to them.

One of the reasons I am exploring OnStep is to get PEC working. But things changed and I came across a Vixen GPDX with Vixen's Sky Sensor 2000 PC, and its PEC does work and I am able to do 120 seconds unguided. But that is due to more precision by Vixen in their gears. Will still build and OnStep, but it is less urgent. The parts are ordered (from prebuilt parts, since like you, I don't want to do deep electronics soldering stuff).

You said you will be using wide field. So the focal length will be less than 1280mm. Perhaps 600 mm or 400 mm, or even less. That means you can do more exposures than 45 seconds. Perhaps 60, 90 or 120 seconds.

Your camera is also a factor. Find out the sensor's data, and go here

And you will be able to know how many arc/seconds per pixel you will have. The more arc seconds you cram in a pixel, the longer the exposures you can take, and the more you can away with imprecise gears/pulleys.

OnStep's PEC should help, but it is not the be-all-end-all solution because of secondary non-periodic error in the gears/pulleys between the motor and the worm gear. Unless you connect the motor directly to the worm gear, like Howard and other Losmandy G11 owners do.

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