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[OM] Re: Stray Big Foot spotted! Lay your snares

Subject: [OM] Re: Stray Big Foot spotted! Lay your snares
From: usher99@xxxxxxx
Date: Sun, 08 Jun 2008 19:05:22 -0400
Yep,

More precisely speaking the apparent construction quality is superb.  
The hood is a texturized aluminum , flat black with a nice voigtlander 
logo on it.  It is mounted like a lens replete with  an allignment red 
dot.  The extra material for a rectangular hood would seemingly be 
trivial. Thanks for the hood cap idea. Can't say I've seen too many 
tulip hoods on a prime, but that may just be my selective lens 
interests.  If a design compromise led to a bit a of tendency to flare, 
why not go all the way?  I have no clue, but will ask my one contact at 
Cosina:

 Keiji Kato
Cosina Company Ltd.,
11-5-1410, Tomihisacho
Shinjuku-ku, 162-0067
Tokyo, Japan


He was kind enough to send me the MTF data from their lab (before the 
reviews I linked to before were available) and amazingly went to a 
downtown Tokyo shop to retrieve a rare OM mount lens that I had 
tentatively located after my inquiry to a Malaysian dealer.   I'll ask 
Stephen Gandy at Cameraquest if any hood caps are around.  I vividly 
recall his one word response inquiring on the chance of any more new CV 
125mm macros in OM mount becoming available --"NONE"

I had read a history of C-V and their more recent design philosophy 
about 6 mos ago.  They apparently used computer aided design to build a 
"near optimized lens" then empirically try and cut back some elements 
to keep the cost from going through the roof.  I was surprised by the 
amount of reliance on an Edisonian approach.  Perhaps the square hood 
was arrived at in a similar fashion or was a design flaw.  A friend 
worked for IIRC Lockeed Martin a few years back and was on an 
engineering team for the Martian lander.  Signal sent to the lander in 
wrong units---crash. Much bigger oops.

Mike









Yes, a nice design detail. No reason it couldn't also be done with a

rectangular 3:2 hood.

> The squarish format should be more effective than an equivalent sized 
round

> hood

Yes, but less effective than a 3:2, rectangular hood.



Take another look at the link you provided. Down near the bottom, he 
has

some examples and a discussion of effectiveness. I think you will be

able to see that a square hood on a 3:2 format allows stray light in at

the top and bottom, landscape mode.



One elegant solution would be if you can obtain another hood cap, and

cut out a 3:2 opening the full width of the cap. It would be like the

capped tulip in the examples. You need a spare cap anyway, why not find

two at once?


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