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Re: Focus steps on CD7
OK, I can do both. Take a large step run. Measure it once. And put in a
All should give useful information.
All I need is a clear night and a computer that has not yet died because it
is going click, click.
At 03:51 PM 2/10/00 GMT, you wrote:
>On Tue, 08 Feb 2000 20:08:40 -0600, you wrote:
>>Well, I do have a bunch of different ones for the RA drive and the other
>>places where I turn a shaft, but for linear motion, I use all the seme
>>devices. These have an internally threaded armature. The lead screw goes
>>through the motor. All have the same thread, and the drive is full
>>stepping. So they move 0.001" per step, no more, no less.
>On further thought, the results can be just about
>squared with the assumption that the entire coma
>comes from the outer reaches of the lens and the
>bright core is light that goes down the middle with
>a higher effective f number/lower aperture. It's still
>a bit tight; 2/3 of the light is in the core so there's
>a lot of middle and not much by way of outer reaches!
>The thing to try next dark night might be that
>cardboard stop that you were talking about rather
>than wasting time with calipers! The 1/3 coma
>suggests only covering 1/3 of the aperture.
>Andrew Bennett, Avondale Vineyard, Nova Scotia, Canada.