[ATM] {Spam?} Re: optimal thickness of Schmidt correctors

[don clement]

That would be Max Bray IIR using a pedal lap documented in  S&T during the '70s. 

 
    
I have only heard of one other person making a Schmidt plate on a turntable. I wish you the best. Please keep us informed.


Dave Rowe



-----Original Message-----
From: Dominic-Luc Webb <dlwebb at canit.se>
To: David Rowe <aplanatic at aol.com>
Cc: atm <atm at atmlist.net>
Sent: Sat, Jan 14, 2012 8:13 am
Subject: Re: {Spam?} Re: [ATM] optimal thickness of Schmidt correctors



Turntable.

Dominic


On Sat, 14 Jan 2012, David Rowe wrote:

> Hi Dominic-Luc,
>
>
> How are you planning to make the corrector?
>
>
> Dave Rowe
>
>
>
> -----Original Message-----
> From: Dominic-Luc Webb <dlwebb at canit.se>
> To: ATM Superheros <atm at atmlist.net>
> Sent: Fri, Jan 13, 2012 10:47 pm
> Subject: Re: [ATM] optimal thickness of Schmidt correctors
>
>
> On Fri, 13 Jan 2012, Richard F.L.R. Snashall wrote:
>
> >   On 1/13/2012 11:25 AM, Dominic-Luc Webb wrote:
> > >
> > > I have access to pretty good cocktail of numbers to brew
> > > some equations, but no experience with applying them
> > > intelligently to the present question.
> > >
> >
> > I'm sorry, I don't remember exactly where it was, but I recall reading
> > D/50 to D/40.
> >
>
> First, thanks for all this input! You guys are great!
>
> I recall something like this too and this is what the thickness
> actually is in the rare cases I could get info for a modern
> commercial scope. One solution some people have used is to
> scale down the original 48" Polamar Schmidt camera, but that
> breaks all the rules. The original corrector (replaced only
> recently for transmission reasons) is 53" diameter and 3/8"
> thick (D/141)! A scaled down 8" would only be 0.06" thick!
> There are other broken rules: it is plate glass! Minor
> deviation from common ATM practice: it was optimized for
> 435.8 nm. This has been known to me since many years and is
> how I first started my designs with 6 mm plate glass
> optimized in the higher UV. The 48" Palomar camera
> represents my starting point when I first started "dabbling"
> with this design.
>
> Source of 48" Schmidt info is R.G. Harrington PASP(64/381):271-281.
> 1952.
>
> I have PDF of this ref if anyone wants it.
>
> Main point is that something has changed over time and I am
> curious why. People seem to be using thicker glass than needed
> and at same time even the pros have used thin plate glass on the
> correctors for the largest, most impressive Schmidt cameras ever
> built.
>
> It seems there is no good reason, mechanical or optical, to not
> use 6 mm thickness even for a Schmidt corrector around 400 mm
> diameter, above which gets into the largest Schmidt cameras
> in the world.
>
> Dominic-Luc Webb
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
>
>
>



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