Re: Re[2]: [ATM] Question about "Null-testing"

["Jeff Baldwin" <bald@olypen.com>]

This is hard.  I've put the razor at an acute angle with the drift of the
star to allow it to cross through the razor slowly, and it still is very
tough to capture visually.  Adjusting the razor to the right focus is also a
trial and error eternal game.  A controlled autocollimation test in the shop
is not only easier to handle, but allows double reflection for increasing
error detection
JBald




> > Why do atms resist this wonderful test, which is so easy to do (tape a
> > razor
> > blade across the opening of the eyepiece draw tube?). Does anyone have
>
> 'Wonderful' test???  Not for me - I tried it more than a couple of times.
The
> problem is that seeing and the EVERY SO SLIGHTEST jitter make it
impossible to
> use.  At most one gets an impression of the surface.  Now, if you are
willing
> to take several seconds digital image, then that's different.  I think
there's
> great room here for practical innovation.  BTW, the razor knife edge so
close
> to your eye is a safety issue.
>
> Mel Bartels

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