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Old 23-10-2010, 04:07 PM
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gregbradley is online now
Join Date: Feb 2006
Location: Sydney
Posts: 15,935
I have 3 robofocus units, one on each of my refractors. I also have a FLI PDF digital focuser.

The FLI unit is very good but it takes up backfocus and needs adapters in the imaging train.

The Robofocus are good as they don't take up any room in the imaging train, don't require an extra adapter and are very accurate. I love them. Simple, easy to use.

I didn't get the temperature compensation going though. You have to callibrate the focuser with various temperatures so the software can form a scale of how much the focus shifts with different temps.

One minor bug with Robofocus is it uses RS232 ports instead of USB so its a bit old fashioned that way. Most laptops either don't have an RS232
port or only one.

You can get RS232 to USB adapters and software. I use one with my Planewave CDK17. That one worked. I bought another one for the Robofocus and it did not appear to work. So get a good one.

Oh and make sure you get a specific connector for the shaft of the Robofocus to your specific scopes focuser. The shaft diameters vary and if you get the standard shaft connector it will be too large causing a wobble in the focuser as it spins the shaft. This can lead to it being easier to focus on one side of the focal point than the other.

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