Re: ATM 4" ronchi, day 4

["John D. Upton" <upton@austin.ibm.com>]

Peter,

     I read with interest your comments concerning using the Ronchi Test 
mostly inside the ROC.  For those of us who sometimes have trouble getting 
close enough to the grating to see everything well, I tend to agree that it 
is easier to see inside of the ROC.

     I have found, though, the test seems most sensitive outside the ROC 
between about 1 LA and 3 LA distance from the ROC.  Within that range, the 
subtle differences in figure are most apparent to me.  Does this match your 
experience also?  I find that the differences between good and bad figure 
are much harder to judge inside the ROC or far outside the ROC.  The most 
sensitive region seems to be outside the ROC with a fine grating placed 
such that 2 to 5 lines appear.

At 08:28 PM 10/12/00 +1000, you wrote:
> > It's too bad I can't get the camera to take pictures outside of ROC,
> > as they really seem to confirm I got rid of the TDE and that I am near
> > if not on the parabola.

... SNIP ...

>I find myself using the inner position far more than the outer one simply
>because spectacles make the inner position more amenable to all rays passing
>into the iris of my eye.
>
>Once used to interpreting Ronchi images inside of ROC,  I believe there is
>little to choose.  To me interpretation seems more instinctive inside ROC.

Sincerely,


John D. Upton
Georgetown, TX
<http://www.atm-workshop.com/>     "The ATM's Workshop" (new address)
<http://members.aol.com/RonWin20/> "Ronchi For Windows Home Page"