[LargeFormat] funky plasmat

[LNphoto]

On Sunday, October 12, 2003, at 07:03  PM, Richard Knoppow wrote:

>
> ----- Original Message -----
> From: "LNphoto" <LNphoto@twmi.rr.com>
> To: "f32" <largeformat@f32.net>
> Sent: Sunday, October 12, 2003 1:38 PM
> Subject: [LargeFormat] funky plasmat
>
>
>> Since the LS is slow I 'd thought I'd throw this out to
> whoever was out
>> there.
>>
>> I was bottom feeding on ebay when I came across this
>>
>> http://home.twmi.rr.com/lnphoto/plasmat.jpg
>>
>>
>> Now it came with a camera, which was worth the auction, so
> I'm not
>> expecting much from this lens
>>
>> but can anybody have a reasonable explanation why it looks
> like both
>> cells are attached to the front?
>> Does anybody have any references about Plasmats?
>>
>>  From searching post auctions I found (a much better) 9
> 7/8"  14 1/4"
>> set.   Well the back cell looks like it might say 14"
>>
>> but I can't make out the front.
>>
>> I fear that the front cell is no more than the rim, but
> can't see any
>> evidence of it.
>>
>> Les
>>
>>
>   I also find the photo puzzling. Its hard to read the
> printing on the "rims". One looks like it may say Ross on
> it. Ross built lenses under license from Zeiss so its
> possible they built them for Meyer also
>   The Plasmat was derived from the Dagor by air spacing the
> inner elements. This gives the designer an additional
> surface and a "bending" to work with. The Dagor has an
> inherent problem with excessive zonal spherical aberration,
> this is the cause of the familiar focus shift. By air
> spacing the inner lens its possible to greatly reduce the
> zonal. The Plasmat is also capable of very low astigmatism.
> I don't know the quality of the original Plasmats but the
> generic type has become the standard for most modern large
> format camera lenses, copy lenses, and nearly all enlarging
> lenses. It was not too popular at the time of its invention
> because the additional surfaces increse the flare so the
> type had to await the availability of good anti-reflection
> coating for its virtues to be recognized and applied.
>   Hugo Meyer sold Plasmats in sets but the mountings were
> conventional. I can't make sense of the double looking rim
> either.
>   The Plasmat was designed by Paul Rudolph, the inventor of
> the Tessar, Protar, and other lenses. Kingslake says he lost
> his fortune because of WW-1 and had to come out of
> retirement. He prefered to work for a smaller company than
> Zeiss so joined Meyer. He designed the Plasmat and some
> other related lenses for them. From what Kinglslake says
> some of these designs may not have been too good. The name
> Plasmat suggests a "plastic" image, that is one with some
> softness, so, while the Plasmat type is capable of extremely
> good correction its possible that Rudolph's design did not
> achieve this potential.
>   We will be awaiting with 'bated breath to learn what this
> actually turns out to be.
>
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@ix.netcom.com
>

Yep I agree!

Les