[LargeFormat] Bad Kodak Lens

[Richard Knoppow]

----- Original Message ----- 
From: "philip lambert" <philip.lambert@ntlworld.com>
To: <largeformat@f32.net>
Sent: Sunday, March 14, 2004 2:58 PM
Subject: Re: [LargeFormat] Bad Kodak Lens


> > > finally encountered a bad one. This is a 101mm, f/4.5
lens
> > > for a Miniature Speed Graphic. The particular lens was
> > built
> > > in 1941. The problem is excessive spherical
aberration.
> >
> >   After some experimentation I find the problem
persists.
> > Its possible that the front and rear cell were mixed but
I
> > don't think so. Unfortunately, Kodak doesn't mark the
rear
> > cells with the lens serial number. I will try a couple
of
> > other things with this lens to see if it can be brought
up
> > to the performance I expect from Ektars. Very strange.
> >
> Do you mean the lens is back to front or that the
components have been
> reassembled in the wrong sequence?  How many glasses in an
Ektar?   PL
>
>
>
  This particular Ektar is a Tessar type. Kodak used Ektar
as a trade mark for its premium quality lenses rather than a
particular type of lens so there were Ektars of several
designs. I have other Ektars of this series, they are all
very sharp and free from aberrations. I don't know
specifically what is wrong with this lens. Partially
unscrewing the cells to increase their distance makes the
problem worse so it may be cell spacing. The front element
is removable. I've remvoved it in the past to clean the
inside surfaces in the front cell. I've done this with a
number of other Ektars and other lenses without out
upsetting the lens performance. I've just redone this about
four times with cleaning and very careful assembly with no
change. The spacing of the front element is very critical,
even a very slight change changes the focal length and
corrections. I don't think this is what happened.
  I think I payed $20 for this lens. There may have been a
reason. It came on a Miniature Speed Graphic lens board. The
date code indicates the lens was made in 1941, which is, I
think, the first or second year these lenses were made. I
have another, a 127mm, f/4.7, also uncoated, made in 1942,
which is one of the sharpest lenses I've ever used.
  Either this lens was defective from the factory or as I
suggested it may be cobbled together from a front and rear
element of different lenses. In any case, its been an
education and disappoiintment both.
  The original lens on the camera was a later Optar. The
camera was built in 1947 or 48 from its serial number. I've
found some Wollensak dogs in the past as well as a couple of
excellent lenses. This one was probabably in the latter
class before someone cleaned it with steel wool. I wrote
before that it was etched but when I looked at it today
realized it just scratched up. I've never scratched a lens
and don't understand how people can do this. In any case I
will be at the Buena Park show next week (or whenever it is)
looking for yet another lens for this camera.
  In the meanwhile I've learned a lot about the construction
of these little cameras and have some practical experience
with repairing Kalart rangefinders to pass along. I wanted
to have the camera completed before writing and posting all
that but may not wait.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com