Olympus-OM
[Top] [All Lists]

[OM] Re: Telecentric Lens Ray Diagram

Subject: [OM] Re: Telecentric Lens Ray Diagram
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Thu, 12 Jul 2007 06:12:29 -0400
I rather think the design decision went the opposite direction.  You're 
an Oly engineering team charged with the development of this new digital 
thing and right now nothing exists; in particular, you don't even have 
any lenses for testing except a bag full of OM lenses.  So, the first 
thing you do is decide that the OM lenses set the diameter of the mount 
and you then decide how big the sensor can be to be telecentric within 
that range.  Then you design the MA-1 OM to 4/3 adapter so you can do 
all your initial optical testing on a new body design while new lenses 
are designed.  Makes sense to me.

Chuck Norcutt

Moose wrote:
> Jeff Keller wrote:
>> Bringing back an old subject ...
>>
>> This is the first time I've seen a ray diagram that sort of  shows why
>> the camera body might need to have a larger lens mount for a
>> telecentric lens for a __particular sensor size__.
>>
>> However since the sensor is smaller than a 35mm frame it doesn't
>> really imply that the four-thirds mount has to be as large as a 35mm
>> lens, The rearmost lens element is still smaller than the sensor.
>>
>> <http://www.four-thirds.org/en/about/benefit.html>
>>   
> So you are an engineer charged with designing a lens mount for not yet 
> extant lenses that are to be telecentric for a certain sensor size. 
> Maybe there are some lenses in the design stages, but you are designing 
> a new standard that will, with luck, support many future lenses, many 
> not designed by Oly. So you really know nothing except sensor size and 
> telecentric lenses coming along.
> 
> So what can you do but assume that, worst case, you need room for a lens 
> element with a clear diameter equal to the diagonal of the sensor, held 
> just clear of the movement arc of the mirror. So you take that diameter, 
> add for supporting structure, focus helicoid, etc. then add a little for 
> safety.
> 
> If you are any sort of thoughtful student of historical camera design, 
> you will be aware of the many advantages Canyon got with the extra large 
> diameter of the EF mount and will be generous with the "safety margin".
> 
> Also, the illustration you linked to is not of a fully telecentric lens. 
> The edge rays aren't perpendicular to the sensor plane. So the words and 
> the illustration are not in agreement. Think either existed in that form 
> when the lens mount was being designed?
> 
> Moose
> 
> ==============================================
> List usage info:     http://www.zuikoholic.com
> List nannies:        olympusadmin@xxxxxxxxxx
> ==============================================
> 
> 
> 

==============================================
List usage info:     http://www.zuikoholic.com
List nannies:        olympusadmin@xxxxxxxxxx
==============================================

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz