[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: [ATM] Rodenstock Heligons
I have an XR-Heligon, and my questions were answered by a fellow at
Rodenstock.
Here's the thread:
From: "Dan Nagle" <dann@rodenstockoptics.com>
To: "Jay LeBlanc" <jaleblan@dakotacom.net>
Subject: Re: XR Heligon
Date: Sun, 31 Jan 1999 15:30:11 -0600
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook Express 4.72.3155.0
X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3155.0
Jay,
Actual BFL from rear mechanics is 3.2mm then there is a correction for a
2.3mm thick piece of glass with Index of refraction of 1.51045. If this
glass is not present then either subtract or add 30% to the 3.2mm distance
to get correct BFL. The lens only has a maximum coverage of 12.9mm diagonal
on the image side so it won't cover a 35mm film. Only upto a 2/3" CCD chip.
You may get some internal reflections for the visible range because this
lens was optimized for 550nm. However MTF should be acceptable because it is
40lp/mm @ 40% contrast wide open. Hope this is enough for you.
Dan
-----Original Message-----
From: Jay LeBlanc <jaleblan@dakotacom.net>
To: Dan Nagle <dann@rodenstockoptics.com>
Date: Sunday, January 31, 1999 4:22 PM
Subject: Re: XR Heligon
>At 02:41 PM 1/31/99 -0600, you wrote:
>>Your lens was designed for use with X-Ray image intensifier systems. The
>>term Bio-Medical stands for our division that makes medical lenses and
>>lenses for bio-medical (genome projects). These are 2 different designs.
>>Medical lenses typically work @ infinity only (i.e. collimating lenses)
have
>>very small field angles and very short back focal distances as opposed to
>>Bio-Medical that look at flourescing images @ 11:1 , 13:1, 7:1 @ f/1 .
>Hi Dan,
> Well, it appears this 50mm f/0.75 lens is of the medical type, it has a
>very short back focus, apparently around 0.4-0.5-in. With the design for
>infinite image conjugates, I might give it a try imaging some faint
>astronomical extended objects.
> Thanks for taking the time to fill me in, I bought it surplus a few
years
>ago and always wondered about it.
--
'70s Boston Photos
Visit my website at: <http://www.dakotacom.net/~jaleblan/index.html>
_______________________________________________
ATM mailing list http://www.atmlist.net/