Re: [ATM] LWT setup questions

[Bernard Maugoust <maugoust@free.fr>]

In message <200505201554.AA1603010718@mail.johnspics.com>, 
 "john sherman" <atm@mail.johnspics.com> wrote:

[snip]

> Did you try the method where you stack many layers of foil, and shove a
> well-sharpened needle partway into it? You must sharpen your needle
> yourself. When I look at a standard sewing needle with a 25mm eyepiece, it
> appears far from sharp. Until I discovered that, my pinholes were quite
> poor. 

Good info, thanks. There was also the issue of having to apply a correction
to the readings made, for which the precise size of the spot had to be known.
 
It sort of slowed down my enthusiasm for using the method to gather test
data :-(

The spot test you propose still has the virtue to show off astigmatism, even
though I hope I have taken all the recommended steps to avoid it when going
round the barrel...

Regards,

Bernard

-- 
Bernard Maugoust 3°59'E 44°28'N

_______________________________________________
ATM mailing list http://www.atmlist.net/