Metrogon

I bought an 8x10 camera mainly for its shutter and it came with a 6"
Metrogon. Boy, is this lens impressively SIMPLE! And not very sharp, but
then it has no diaphram aperture so I'm judging it wide-open and it's fixed
upon Infinity.

Now I am curious - can I change the lens spacing so that it performs better
at distances shorter than Infinity, or would it make no difference to the
better?

"Lorem Ipsum" wrote in message
...

I bought an 8x10 camera mainly for its shutter and it came
with a 6" Metrogon. Boy, is this lens impressively
SIMPLE! And not very sharp, but then it has no diaphram
aperture so I'm judging it wide-open and it's fixed upon
Infinity.

Now I am curious - can I change the lens spacing so that
it performs better at distances shorter than Infinity, or
would it make no difference to the better?

Do you really mean Metrogon or is it a Goerz Hypergon?
The line about its being really simple is why I ask. The
Bausch & Lomb Metrogon is a very wide angle lens for photo
mapping. There are a couple of variations but most of them
are five element lenses, not so simple. Metrogons are very
sharp and well corrected especially for geometric
distortion.
The Goerz Hypergon is a very early double meniscus lens
with an exceptionally wide angle of coverage of around 135
degrees! The Hypergon has a flat field and has low
astigmatism and coma but is not corrected for spherical
aberration nor is it achromatized. It must be stopped down
to around f/36 for decent sharpness but is quite respectably
sharp at small stops. The Hypergon, if that is what you
have, originally came with a light equalizer mounted in
front. This looks like a little air driven propeller. Its
supposed to be used for half the exposure, falling away for
the other half.
The Metrogon and Hypergon are related because both are
double meniscus types. Both have very great fall off of
illumination, actually greater than the cos^4 theta rule and
both require some sort of equalizer. In the Metrogon it
takes the form of a center filter usually combined with a
yellow or red filter.
The Hypergon design dates from 1900. It was invented by
Emile von Hoegh who also invented the Dagor and Celor
lenses. Goerz catalogues show the Hypergon as late as the
late 1920's, maybe even later. Again, at around f/36 ro f/45
it should be pretty sharp.
Element spacing is critical. These lenses were never
supplied in shutters because the spacing is too small. If
you have a Hypergon and its in a shutter its probably
mis-spaced.
The B&L Metrogon was designed by Wilbur Rayton and dates
from 1942. An older lens of this type is the Zeiss Topogon
of Robert Richter. The Metrogon has better correction due to
an additional element.

Metrogon USP 2,325,275
Topogon USP 2,031,792
Hypergon USP 706,650


--
---
Richard Knoppow
Los Angeles, CA, USA

"Richard Knoppow" wrote in message
ink.net...

Do you really mean Metrogon or is it a Goerz Hypergon?

Oh Richard, I wish it were a Hypergon. I just read-up on them and wow, would
that be a find!

[...] There are a couple of variations but most of them are five element
lenses, not so simple.

My poor expression. Perhaps Elegant would have been a better word: near
symetrical (front,back) surfaces.

The Metrogon and Hypergon are related because both are double meniscus
types. Both have very great fall off of illumination, actually greater
than the cos^4 theta rule and both require some sort of equalizer. In the
Metrogon it takes the form of a center filter usually combined with a
yellow or red filter.

Yes, this one came with a two filters. One is red and uses a 'star' in a
material that is mirror-like on one side, but translucent from the other and
the yellow filter is the traditional center-gradient type.

Do the filters attempt to correct color focusing issues (with B&W,
obviously) as well as to filter for blue, haze?

In article ,
Lorem Ipsum wrote:

Yes, this one came with a two filters. One is red and uses a 'star' in a
material that is mirror-like on one side, but translucent from the other and
the yellow filter is the traditional center-gradient type.

The "mirror-like" one is a neutral density filter made by depositing
metallic silver on glass. If I understand you correctly, it's combined
with a red color filter? So you have two center filters, one red and
one yellow. I suppose for most purposes you'd use the yellow one, though
it would be nice to have a non-colored center gradient filter -- it will
be hard to find one that's properly matched to your lens, I suspect in
fact impossible.

These lenses were used for aerial mapping. I suspect they're not well
corrected for blue at all, since the film they would have been used with
was sensitive well into the infrared which means they required color
correction there as well.

I was unaware that spacing on Metrogons was so tight that they wouldn't
work well in shutters. I've seen several Metrogons and the very similar
Goerz Rectagon in shutters, but they've generally had coverage issues.
Does this one cover all the way out to the edge? Is it sharp there?

--
Thor Lancelot Simon

"The inconsistency is startling, though admittedly, if consistency is to be
abandoned or transcended, there is no problem." - Noam Chomsky

"Thor Lancelot Simon" wrote in message
...

I was unaware that spacing on Metrogons was so tight that they wouldn't
work well in shutters.

Hello, Thor. I misread that part at first as well. Richard was speaking of
the Hypergon and shutters - none had shutters because of the close spacing.
A superficial look at the lens gives the impression that it is a hollow
marble.

The Metrogons can have shutters between lens cells. Here is one:
http://elearning.winona.edu/staff_o/jjs/shutter.jpg What is not shown is
how very thin the thing really is. This particular mechanism came from a
peculiar research 8x10 camera that used only conventional 8x10 film holders
instead of the typical 9.5" roll film. The (not visible) end of the shutter
mechanism had a coat of cement painted over that when removed said
"ballistic pinhole shutter", possibly for an earlier project.

(I am currently testing the shutter to find the voltages that might control
shutter speed. The solenoid is very interesting - it uses a set of
ball-bearings to resist/control shutter actuation so that speed across the
aperture is even, rather than slow at first, then fast towards the end of
its stroke.) I digress.

Yes, it covers 8x10 nicely without movements. I'd love to see a late style
Biogon made to fit 8x10. Spendy thing, that would be.

"Lorem Ipsum" wrote in message
...
"Richard Knoppow" wrote in
message
ink.net...

Do you really mean Metrogon or is it a Goerz Hypergon?

Oh Richard, I wish it were a Hypergon. I just read-up on
them and wow, would that be a find!

[...] There are a couple of variations but most of them
are five element lenses, not so simple.

My poor expression. Perhaps Elegant would have been a
better word: near symetrical (front,back) surfaces.

The Metrogon and Hypergon are related because both are
double meniscus types. Both have very great fall off of
illumination, actually greater than the cos^4 theta rule
and both require some sort of equalizer. In the Metrogon
it takes the form of a center filter usually combined
with a yellow or red filter.

Yes, this one came with a two filters. One is red and uses
a 'star' in a material that is mirror-like on one side,
but translucent from the other and the yellow filter is
the traditional center-gradient type.

Do the filters attempt to correct color focusing issues
(with B&W, obviously) as well as to filter for blue, haze?


The Metrogon is pretty well corrected for color, the
filters are haze cutters, remember, this lens was intended
for aerial mapping work.
It should be a sharp lens, if not there may be an error
in the cell spacing. The only prescription I have for a
Metrogon is the one in the patent, its at least worth
checking.
Any US patent can be gotten from the United States Patent
and Trademark Office web site at:
http://www.uspto.gov Those issued before 1975 are available
only as TIFF images and need a plug in viewer. IMO the best
of the freeware ones is Alternatiff available at
http://www.alternatiff.com There are versions for both
Internet Explorer and Firefox/Mozilla/Netscape. I don't
think there is a Mac version. Downloaded files can be viewed
and printed using the built-in FAX-image viewer in Windows.
Unfortunately, one can not do searches for other than
patent numbers for patents issued before 1975.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Thor Lancelot Simon" wrote in message
...
In article ,
Lorem Ipsum wrote:

Yes, this one came with a two filters. One is red and uses
a 'star' in a
material that is mirror-like on one side, but translucent
from the other and
the yellow filter is the traditional center-gradient type.

The "mirror-like" one is a neutral density filter made by
depositing
metallic silver on glass. If I understand you correctly,
it's combined
with a red color filter? So you have two center filters,
one red and
one yellow. I suppose for most purposes you'd use the
yellow one, though
it would be nice to have a non-colored center gradient
filter -- it will
be hard to find one that's properly matched to your lens,
I suspect in
fact impossible.

These lenses were used for aerial mapping. I suspect
they're not well
corrected for blue at all, since the film they would have
been used with
was sensitive well into the infrared which means they
required color
correction there as well.

I was unaware that spacing on Metrogons was so tight that
they wouldn't
work well in shutters. I've seen several Metrogons and
the very similar
Goerz Rectagon in shutters, but they've generally had
coverage issues.
Does this one cover all the way out to the edge? Is it
sharp there?

--
Thor Lancelot Simon


I may be wrong about the shutters. I think I've also seen
Metrogons in shutters now that you remind me.
They should be sharp to the edges although, as you know,
the resolution of lenses decreases as you move from the
center due to diffraction at the stop. There is also a
difference between radial and tangential resolution for the
same reason.
Unfortunately, the prescription information on most
lenses does not include the complete dispersion properties
of the glass so analysis of the chromatic correction must be
based on a best guess as to what glass might have been used.
While aerial lenses are usually used with blue cutting
filters, or for IR with a suitable filter, I would assume
automatically that they are poorly corrected for visual
blue. Blue bluring can come from both poor lonitudinal
chromatic correction and from spherochromatism, i.e.,
variation of correction for spherical aberration with color.
I don't have a Metrogon so I can't comment directly on its
corrections other than computer analysis of the patent data
shows it to be very well corrected for all the common
aberrations.
Probably the most important aberration for this type of
lens is geometrical distortion. As the name implies the lens
was used for metrology so has to present an geometrically
accurate image.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Richard Knoppow" wrote:
[...]
I don't have a Metrogon so I can't comment directly on its corrections
other than [...]

Well, for heaven's sake, let me send you one! Seriously. Reply to
*john/utat/stafford.net/

(Sorry for the obscure address. You know how to parse it. Exchange "/utat/"
for @ and drop the askerisk, etc....)

"Richard Knoppow" wrote

I may be wrong about the shutters. I think I've also seen
Metrogons in shutters now that you remind me.

http://www.skgrimes.com/lensmount/metrogon/

A metrogon must have had a shutter in its original aerial
camera mount. It looks like the front and rear elements
bolted to the shutter. I imagine the shutter was some
electric jobby with a control box and mysterious cables,
the whole lot running on 400Hz 48V(?) power.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
To reply, remove spaces: n o lindan at ix . netcom . com
Fstop timer - http://www.nolindan.com/da/fstop/index.htm

"Nicholas O. Lindan" wrote:

A metrogon must have had a shutter in its original aerial
camera mount. It looks like the front and rear elements
bolted to the shutter. I imagine the shutter was some
electric jobby with a control box and mysterious cables,
the whole lot running on 400Hz 48V(?) power.

Close, Nicholas. The front and rear elements are fastened to a body in which
the shutter slides in between the front and rear elements, and can be
removed the same way without disturbing the lens elements. The shutter runs
on variable voltage from 18V to 24V. Brief higher voltage won't hurt it.
Lower won't activate it. See my other posts on how the solenoid regulates
shutter speed.

See a shutter he http://elearning.winona.edu/staff_o/jjs/shutter.jpg