Re: [ATM] back to longer FL

["Jan van gastel" <jhm.vangastel@wanadoo.nl>]

Vladimir,

Your calculation is correct, but I can (and I did yesterday) correct the FL
until the spherometer points exactly at the line marking the zero, which is
the same position I nulled it on my other mirror. And then it will be well
within 1%.

Jan
http://home.wanadoo.nl/jhm.vangastel/Astronomy/



----- Original Message ----- 
From: "Vladimir Galogaza" <vladimir.galogaza@zg.htnet.hr>
To: "Jan van gastel" <jhm.vangastel@wanadoo.nl>
Cc: "ATM List" <atm@atmlist.net>
Sent: Wednesday, June 29, 2005 11:44 AM
Subject: Re: [ATM] back to longer FL


> Hi Jan,
>
> >I null my spherometer on my already finished mirror, so I think I can get
> >the FL's pretty close using the spherometer, in any case well within 1%.
>
>
> If your spherometer has base 90.8 mm, the mirror is 300 mm,  f/5 (F=1500
> mm),
> and if you can read  dial indicator to +/- 0.01 mm :
>
> Than error in focal length due to +/- 0.01 mm sagita error will be +/- 45
> mm.
> This is 3% of F, not quite   " well within 1%".
>
> Unless I made gross calculation error (which I am very used to ).
> Will somebody please check on this.
>
> Regards
> Vladimir
>
>
>
>
>
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