Re: Horseman SW 612 & also 47mmXL

["Mitchell P. Warner" <indepth@xxxxxxxxxxxxxxxx>]

Joel,  

	If you'll take a metric ruler and measure your 612 horseman back you'll
may find that it is short of the supposed frame size .  I'd like to know.
I use a Calumet 612 roll film back in a folding wood field when the 617
doesn't fit the scene.  The Calument 612 doesn't cover the full frame
either.  

	So, do the roll film back manufactures build to fit the lenses, or the
lens manfactures build to fit the roll film backs?  Makes no difference!
It is what it is.  Expending angst over it,,,,, I don't have the time.
My solution was to buy lenses with the widest coverage circle combined with
angle of view that I could find.  That has been, almost always, the
Schneider XL lenses.  Expensive, heavy, huge filters, but they work.  Yes,
I get a lot of fall off on the edge of those lenses if I don't use the
center filter.  I suppose they 'could' make them better, such as 35mm
format wide-angle lenses are corrected, but they don't, aren't and there it
is!
	
	The center filter may have to be used at a specific distance. Imagine
holding a dime in between your thumb and index finger. Held close to your
eye it blocks all the sun. Held at a distance it does not.  The graduated
circle of decreasing neutral density probably does have to be a certain
distance from the lenst for optimum performance. That doesn't mean it won't
have an effect at different distances, but the effect may be 'rings' of
varying density showing up as circles near the center and showing only as
partial arcs as you near the edges.  Stacking the center filter on the
polarizer may have done it to you.  Let me know the results of experiments
please!, as I was about to convert a center filter for my 90mm SAXL to fit
a 72mmSAXL.  Save me some wasted effort, please!




At 04:03 PM 6/23/99 +0000, you wrote:
>Mitch,
>
>I was referring to the center filter, not the polarizer.  Allegedly the
center filter
>is designed to work at a set distance from the lens.  I do not know the
>optical/physics techincal  aspects so I am just passing on what has been
imparted to
>me by those who claim to know.  May or may not be valid.
>
>The Rodenstock brochure shows that the 45MM Apo-Grandagon is a few mm
short of
>covering the 112MM width on a Horseman 612.  Does this mean that the
center filter is
>incapable of making up for this optimistic design?  Does this mean that
Horseman
>should not offer the 612 without disclaimer?  Horseman also offer a 35MM
that has
>even less coverage!  I believe that Linhof uses the same lens on their
612.  Does
>this set up work for anybody?
>
>joel
>
>Mitchell P. Warner wrote:
>
>> Joel,
>>         I could understand the restriction on the distance a polarizer
is supposed
>> to be from the taking lens if it were a lens itself, but seeing as how
>> Polarizers are not lenses, but filters, I cannot see the justification.  I
>> have used a 95mm circular polarizer and a linear polarizer successfully on
>> every lens I own by employing step-down adapter rings. No problem. I have
>> never seen any scientifically based information on the distance a
>> polarizing filter is from the lens, other than referring to possible
>> vignetting.  If you have any information I'd be interested......
>>
>> Mitch Warner
>>
>> At 02:33 PM 6/23/99 +0000, you wrote:
>> >Don,
>> >I have been told by those in the know that polarizers should not be
mounted
>> >under the center filter, as they are designed to work at a specified
distance
>> >from the lens.  However, others have told me that they do this with
success.
>> >
>> >joel
>> >
>> >
>> >
>> >
>
>
>
>
>
At Your Service, 
                         Mitch Warner

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