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

["Bill Kelley" <flex@commspeed.net>]

Try it on a planetary image. This gives the equivalent of a bit of slit 
(pinhole) width.
Ronchi with stars- Planets with Foucault.  Jupiter is well positioned now 
for Foucault at the focuser.
Regards-  Bill Kelley


> 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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>
> 


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