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Gundlach 5x7 Rapid Symmetrical W.A.
Gundlach 5x7 Rapid Symmetrical W.A.
Hello:
I just picked up a Gundlach 5x7 Rapid Symmetrical W.A. lens, roughly
8" f.l. (don't have it in my hands yet).
The Rapid/Symmetrical names sound like a Rapid Rectilinear type, then
I read that Gundlach had an extra element modification to the RR to
get around a patent, so is it possible it might be 6 element rather
than 4?
Then I read that some of the Gundlach lenses had disappointing
centration. 6 vs 4 elements might make this worse?
Finally, the seller said 'it ain't no Wide Angle'.
>From this vintage, did W.A. mean anything else, or was that a relative
term that doesn't amount to wide angle these days? (Some older wide
angles were really wide, so I'm confused).
Is it a dog, worse than a dog, or a dog that only knows one trick?
Thank you
Murray
Hello:
I just picked up a Gundlach 5x7 Rapid Symmetrical W.A. lens, roughly
8" f.l. (don't have it in my hands yet).
The Rapid/Symmetrical names sound like a Rapid Rectilinear type, then
I read that Gundlach had an extra element modification to the RR to
get around a patent, so is it possible it might be 6 element rather
than 4?
Then I read that some of the Gundlach lenses had disappointing
centration. 6 vs 4 elements might make this worse?
Finally, the seller said 'it ain't no Wide Angle'.
>From this vintage, did W.A. mean anything else, or was that a relative
term that doesn't amount to wide angle these days? (Some older wide
angles were really wide, so I'm confused).
Is it a dog, worse than a dog, or a dog that only knows one trick?
Thank you
Murray
Re: Gundlach 5x7 Rapid Symmetrical W.A.
On 10/20/2007 5:54 PM murrayatuptowngallery spake thus:
[snip]
> Is it a dog, worse than a dog, or a dog that only knows one trick?
Perhaps it's a lovable dog that needs a good home ...
On 10/20/2007 5:54 PM murrayatuptowngallery spake thus:
[snip]
> Is it a dog, worse than a dog, or a dog that only knows one trick?
Perhaps it's a lovable dog that needs a good home ...
Re: Gundlach 5x7 Rapid Symmetrical W.A.
"murrayatuptowngallery" <murrayatuptowngallery@yahoo . com >
wrote in message
news:1192928072.513964.302640@q5g2000prf.googlegroups . com ...
> Hello:
>
> I just picked up a Gundlach 5x7 Rapid Symmetrical W.A.
> lens, roughly
> 8" f.l. (don't have it in my hands yet).
>
> The Rapid/Symmetrical names sound like a Rapid Rectilinear
> type, then
> I read that Gundlach had an extra element modification to
> the RR to
> get around a patent, so is it possible it might be 6
> element rather
> than 4?
>
> Then I read that some of the Gundlach lenses had
> disappointing
> centration. 6 vs 4 elements might make this worse?
>
> Finally, the seller said 'it ain't no Wide Angle'.
>
>>From this vintage, did W.A. mean anything else, or was
>>that a relative
> term that doesn't amount to wide angle these days? (Some
> older wide
> angles were really wide, so I'm confused).
>
> Is it a dog, worse than a dog, or a dog that only knows
> one trick?
>
> Thank you
>
> Murray
>
What speed, certainly not f/1 :-)
I can't find a Rapid Symmetrical W.A. but a Wide Angle
Symmetrical is listed in a 1926 catalogue at f/16. No
schematic is given but its described as a "wide angle
rectilinear type" covering 85 degrees. The No.5 has a focal
length of 8 inches and is specified for 8x10 plates.
There were some wide angle rectilinear lenses made by
others. The problem with the Rapid-Rectilinear type is that
they are not corrected for astigmatism so must be stopped
down for good sharpness away from the center. Astigmatism in
a camera lens is a different aberration than astigmatism in
the eye. In a camera lens it means that each point of light
in the image has two points of focus where the point is
focused as a line. At one point the line is axial, at the
other it is tangential. In between these two locations the
point is focused as a round blur spot. The less the
astigmatism the sharper the point. Since the size of the
blur is affected by depth of field astigmatism tends to be
minimised as a lens is stopped down.
The lack of correction of astigmatism comes from the lack
of glass types with the necessary properties at the time the
R-R lens was designed (1866). Until the development of
Barium glasses by Schott ("Jena glass, about 1890),
correcting a lens for both astigmatism and color was not
possible.
Ernst Gundlach was a curious character, Rudolf Kingslake
has a short biography of him in his book on lens history (1)
but also wrote a more lengthy bio of him (2). Gundlach
designed several lenses where he added an extra element
essentially go get around some existing patent. His version
of the Rapid-Rectilinear, which he called the Rapid
Rectigraphic, had three cemented elements in each half but
two were essentially just one of the elements in the R-R
split into two. The same with the Radar lens, essentially a
Tessar with an added element which evidently does nothing.
Probably Gundlach's most famous lens does not have his name
on it. This is the famous, or notorious, Turner-Reich
convertible. This is essentially a Zeiss Convertible Protar
with the same sort of split element seen in the Rectigraphic
and Radar. This lens was sold with all sorts of claims for
its superiority but the reality is that its not up the
Protar at all.
The centering problems apply mostly to the T-R lens,
which has 5 cemented elements in each cell. Lack of good
centering will disturb the performance of any lens but I
think the inherent performance of the T-R is not so
wonderful to begin with. In general, the more cemented
surfaces the more critical centering becomes. The method of
centering cemented elements was changed sometime around
perhaps the late 1940s but I can't be sure of the date. The
original method was to center each lens on a centering
machine and grind the edges as accurately as possible. The
cementing was then done by clamping the edges. A later
method is to center the lenses on the centering machine
after cementing but before curing. After the entire assembly
is cemented and cured the edges of the assembly are ground
concentric and parallel. This results in more precise
centering.
The centering machine is essentially a highly accurate
(with minimum run out) rotating tube on which the element to
be centered is fastened with a gummy substance. A point of
light is projected onto the lens and its image viewed in a
small telescope. The lens is then moved around until both
reflections (from front and back surfaces) are stationary
and stationary with respect to each other. For general
centering of elements the lens is then clamped by another
tube from above and the edges carefully ground to be
concentric and parallel. The same method can be used for
getting two lenses exactly together except there are than
four images to watch.
I would like to know if your lens turns out to be
something different. I have some access to older lens info
so might be able to find out what it is if not the lens
described above.
1, _A History of the Photographic Lens_ Rudolf Kingslake,
(1989) San Diego, The Academic Press ISBN 0-12-408640-3
2, "Ernst Gundlach: Nineteenth Century Pioneer Optician"
Rudlof Kingslake, _History of Photography_ 2, 361, (1978)
--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix . net com . com
"murrayatuptowngallery" <murrayatuptowngallery@yahoo . com >
wrote in message
news:1192928072.513964.302640@q5g2000prf.googlegroups . com ...
> Hello:
>
> I just picked up a Gundlach 5x7 Rapid Symmetrical W.A.
> lens, roughly
> 8" f.l. (don't have it in my hands yet).
>
> The Rapid/Symmetrical names sound like a Rapid Rectilinear
> type, then
> I read that Gundlach had an extra element modification to
> the RR to
> get around a patent, so is it possible it might be 6
> element rather
> than 4?
>
> Then I read that some of the Gundlach lenses had
> disappointing
> centration. 6 vs 4 elements might make this worse?
>
> Finally, the seller said 'it ain't no Wide Angle'.
>
>>From this vintage, did W.A. mean anything else, or was
>>that a relative
> term that doesn't amount to wide angle these days? (Some
> older wide
> angles were really wide, so I'm confused).
>
> Is it a dog, worse than a dog, or a dog that only knows
> one trick?
>
> Thank you
>
> Murray
>
What speed, certainly not f/1 :-)
I can't find a Rapid Symmetrical W.A. but a Wide Angle
Symmetrical is listed in a 1926 catalogue at f/16. No
schematic is given but its described as a "wide angle
rectilinear type" covering 85 degrees. The No.5 has a focal
length of 8 inches and is specified for 8x10 plates.
There were some wide angle rectilinear lenses made by
others. The problem with the Rapid-Rectilinear type is that
they are not corrected for astigmatism so must be stopped
down for good sharpness away from the center. Astigmatism in
a camera lens is a different aberration than astigmatism in
the eye. In a camera lens it means that each point of light
in the image has two points of focus where the point is
focused as a line. At one point the line is axial, at the
other it is tangential. In between these two locations the
point is focused as a round blur spot. The less the
astigmatism the sharper the point. Since the size of the
blur is affected by depth of field astigmatism tends to be
minimised as a lens is stopped down.
The lack of correction of astigmatism comes from the lack
of glass types with the necessary properties at the time the
R-R lens was designed (1866). Until the development of
Barium glasses by Schott ("Jena glass, about 1890),
correcting a lens for both astigmatism and color was not
possible.
Ernst Gundlach was a curious character, Rudolf Kingslake
has a short biography of him in his book on lens history (1)
but also wrote a more lengthy bio of him (2). Gundlach
designed several lenses where he added an extra element
essentially go get around some existing patent. His version
of the Rapid-Rectilinear, which he called the Rapid
Rectigraphic, had three cemented elements in each half but
two were essentially just one of the elements in the R-R
split into two. The same with the Radar lens, essentially a
Tessar with an added element which evidently does nothing.
Probably Gundlach's most famous lens does not have his name
on it. This is the famous, or notorious, Turner-Reich
convertible. This is essentially a Zeiss Convertible Protar
with the same sort of split element seen in the Rectigraphic
and Radar. This lens was sold with all sorts of claims for
its superiority but the reality is that its not up the
Protar at all.
The centering problems apply mostly to the T-R lens,
which has 5 cemented elements in each cell. Lack of good
centering will disturb the performance of any lens but I
think the inherent performance of the T-R is not so
wonderful to begin with. In general, the more cemented
surfaces the more critical centering becomes. The method of
centering cemented elements was changed sometime around
perhaps the late 1940s but I can't be sure of the date. The
original method was to center each lens on a centering
machine and grind the edges as accurately as possible. The
cementing was then done by clamping the edges. A later
method is to center the lenses on the centering machine
after cementing but before curing. After the entire assembly
is cemented and cured the edges of the assembly are ground
concentric and parallel. This results in more precise
centering.
The centering machine is essentially a highly accurate
(with minimum run out) rotating tube on which the element to
be centered is fastened with a gummy substance. A point of
light is projected onto the lens and its image viewed in a
small telescope. The lens is then moved around until both
reflections (from front and back surfaces) are stationary
and stationary with respect to each other. For general
centering of elements the lens is then clamped by another
tube from above and the edges carefully ground to be
concentric and parallel. The same method can be used for
getting two lenses exactly together except there are than
four images to watch.
I would like to know if your lens turns out to be
something different. I have some access to older lens info
so might be able to find out what it is if not the lens
described above.
1, _A History of the Photographic Lens_ Rudolf Kingslake,
(1989) San Diego, The Academic Press ISBN 0-12-408640-3
2, "Ernst Gundlach: Nineteenth Century Pioneer Optician"
Rudlof Kingslake, _History of Photography_ 2, 361, (1978)
--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix . net com . com
Re: Gundlach 5x7 Rapid Symmetrical W.A.
I couldn't tell from the photo what the scales say, so when I get it
I'll learn more. It has one scale that looked like shutter speeds, one
that looked like maybe US stops and a third that said W.A.
As far as being a dog, it's a rescue on at that...shutter is boogered
up, iris missing or not working (wide open).
It's an opportunity, not a problem. I get to actually make Waterhouse
stops instead of just recommending them to others!
Hopefully it has some interesting quality, and is really as wide as
predicted. All my other RR's are Kodak 3A type, not fast, not wide.
I'll let you know, Richard.
Thanks, both.
I couldn't tell from the photo what the scales say, so when I get it
I'll learn more. It has one scale that looked like shutter speeds, one
that looked like maybe US stops and a third that said W.A.
As far as being a dog, it's a rescue on at that...shutter is boogered
up, iris missing or not working (wide open).
It's an opportunity, not a problem. I get to actually make Waterhouse
stops instead of just recommending them to others!
Hopefully it has some interesting quality, and is really as wide as
predicted. All my other RR's are Kodak 3A type, not fast, not wide.
I'll let you know, Richard.
Thanks, both.
Re: Gundlach 5x7 Rapid Symmetrical W.A.
"murrayatuptowngallery" <murrayatuptowngallery@yahoo . com >
wrote in message
news:1192932566.590417.283870@q3g2000prf.googlegroups . com ...
>I couldn't tell from the photo what the scales say, so when
>I get it
> I'll learn more. It has one scale that looked like shutter
> speeds, one
> that looked like maybe US stops and a third that said W.A.
>
> As far as being a dog, it's a rescue on at that...shutter
> is boogered
> up, iris missing or not working (wide open).
>
> It's an opportunity, not a problem. I get to actually make
> Waterhouse
> stops instead of just recommending them to others!
>
> Hopefully it has some interesting quality, and is really
> as wide as
> predicted. All my other RR's are Kodak 3A type, not fast,
> not wide.
>
> I'll let you know, Richard.
>
> Thanks, both.
>
Let me know what kind of shutter its in if you can tell.
That will also give a clue as to the age of the lens.
For some reason both Bausch & Lomb and Kodak continued
to mark Rapid Rectilinear lenses with US stops long after
the system went out of use. B&L built most of the Kodak R-R
lenses up to the early 1930's.
--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix . net com . com
"murrayatuptowngallery" <murrayatuptowngallery@yahoo . com >
wrote in message
news:1192932566.590417.283870@q3g2000prf.googlegroups . com ...
>I couldn't tell from the photo what the scales say, so when
>I get it
> I'll learn more. It has one scale that looked like shutter
> speeds, one
> that looked like maybe US stops and a third that said W.A.
>
> As far as being a dog, it's a rescue on at that...shutter
> is boogered
> up, iris missing or not working (wide open).
>
> It's an opportunity, not a problem. I get to actually make
> Waterhouse
> stops instead of just recommending them to others!
>
> Hopefully it has some interesting quality, and is really
> as wide as
> predicted. All my other RR's are Kodak 3A type, not fast,
> not wide.
>
> I'll let you know, Richard.
>
> Thanks, both.
>
Let me know what kind of shutter its in if you can tell.
That will also give a clue as to the age of the lens.
For some reason both Bausch & Lomb and Kodak continued
to mark Rapid Rectilinear lenses with US stops long after
the system went out of use. B&L built most of the Kodak R-R
lenses up to the early 1930's.
--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix . net com . com
Re: Gundlach 5x7 Rapid Symmetrical W.A.
It arrived today.
I learned it has a Waterhouse slot, 2 air cylinders and springs that
look as modern as any (I guess I never really thought about helical
tension springs looking the same).
Number (serial?) on the back, nothing identifying the shutter it yet.
f/stop scale marked 6.2 - 45, so it must be newer than US stop
style..but Waterhouse stops certainly SEEM older than 'real' f-
numbers.
The scale about the f-stop scale must tell something about the
Waterhouse stop required, otherwise I don't see a point to labeling
the lens body if the Waterhouse stops are individually marked and
spend more time external to the lens than part of it.
I'm easily impressed - little lenses that throw large images.
It arrived today.
I learned it has a Waterhouse slot, 2 air cylinders and springs that
look as modern as any (I guess I never really thought about helical
tension springs looking the same).
Number (serial?) on the back, nothing identifying the shutter it yet.
f/stop scale marked 6.2 - 45, so it must be newer than US stop
style..but Waterhouse stops certainly SEEM older than 'real' f-
numbers.
The scale about the f-stop scale must tell something about the
Waterhouse stop required, otherwise I don't see a point to labeling
the lens body if the Waterhouse stops are individually marked and
spend more time external to the lens than part of it.
I'm easily impressed - little lenses that throw large images.
Re: Gundlach 5x7 Rapid Symmetrical W.A.
"murrayatuptowngallery" <murrayatuptowngallery@yahoo . com >
wrote in message
news:1193118450.275682.327550@z24g2000prh.googlegroups . com ...
> It arrived today.
>
> I learned it has a Waterhouse slot, 2 air cylinders and
> springs that
> look as modern as any (I guess I never really thought
> about helical
> tension springs looking the same).
>
> Number (serial?) on the back, nothing identifying the
> shutter it yet.
>
> f/stop scale marked 6.2 - 45, so it must be newer than US
> stop
> style..but Waterhouse stops certainly SEEM older than
> 'real' f-
> numbers.
>
> The scale about the f-stop scale must tell something about
> the
> Waterhouse stop required, otherwise I don't see a point to
> labeling
> the lens body if the Waterhouse stops are individually
> marked and
> spend more time external to the lens than part of it.
>
> I'm easily impressed - little lenses that throw large
> images.
>
The shutter could be any of several. One of the
cylinders is the speed regulator, the other to trip the
shutter with an air hose. It should have a hose fitting on
the bottom.
If it has a stop scale it must once have had an iris
diaphragm. A slot may have been cut later for Waterhouse
stops. About the only lenses I know which have both an iris
and a slot are process lenses where the slot was used for
special stops for process work or for filters.
If this is a standard make shutter it may be possible to
fit the cells into a newer shutter made by the same company.
US stops are calibrated in terms of relative exposure
time but are otherwise arbitrary. US-16 is the same as f/16
so US-8 equals f/11, US-4 equals f/8, etc. The stop scale
could be for either system but, assuming the lens is some
variation of the R-R lens its likely to be US stops.
--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix . net com . com
"murrayatuptowngallery" <murrayatuptowngallery@yahoo . com >
wrote in message
news:1193118450.275682.327550@z24g2000prh.googlegroups . com ...
> It arrived today.
>
> I learned it has a Waterhouse slot, 2 air cylinders and
> springs that
> look as modern as any (I guess I never really thought
> about helical
> tension springs looking the same).
>
> Number (serial?) on the back, nothing identifying the
> shutter it yet.
>
> f/stop scale marked 6.2 - 45, so it must be newer than US
> stop
> style..but Waterhouse stops certainly SEEM older than
> 'real' f-
> numbers.
>
> The scale about the f-stop scale must tell something about
> the
> Waterhouse stop required, otherwise I don't see a point to
> labeling
> the lens body if the Waterhouse stops are individually
> marked and
> spend more time external to the lens than part of it.
>
> I'm easily impressed - little lenses that throw large
> images.
>
The shutter could be any of several. One of the
cylinders is the speed regulator, the other to trip the
shutter with an air hose. It should have a hose fitting on
the bottom.
If it has a stop scale it must once have had an iris
diaphragm. A slot may have been cut later for Waterhouse
stops. About the only lenses I know which have both an iris
and a slot are process lenses where the slot was used for
special stops for process work or for filters.
If this is a standard make shutter it may be possible to
fit the cells into a newer shutter made by the same company.
US stops are calibrated in terms of relative exposure
time but are otherwise arbitrary. US-16 is the same as f/16
so US-8 equals f/11, US-4 equals f/8, etc. The stop scale
could be for either system but, assuming the lens is some
variation of the R-R lens its likely to be US stops.
--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix . net com . com
Re: Gundlach 5x7 Rapid Symmetrical W.A.
Seems that the old shutter blades and iris diaphragm were removed. The
shutter lever release was still banging around at the top because it
was captive by virtue of a swaged in pin that prevented it's non-
destructive removal.
The slot at the bottom is apparently for the former stop-adjusting
lever. The one at the was for the shutter release.
Shutter speed was set by a rotating ring, still there, but nothing to
couple to.
The scales are still interesting. I was wrong about 6.2-45. It said
6.2 - 64 and sideways 45S across two scales. The second scale has a 1
2 3 4 5 crammed very close together above the roughly 22-64 postion of
the f-stop scale. the t-stop between 32 and 64 is '44'.
Lastly, the W.A. marking is way down by the 6.2 on the lower f-stop
scale.
I imagine someone would have said something already if W.A. meant
something else like Weston Aperture, but I don't think he went back
that far anyway.
Anyway, there's nothing there functional but the glass. I left the
other things on for cosmetics.
Oddly, I have never been able to recognize a 'weak reflection' on more
modern lenses. On these cells it is distinctly visible.
This made real question/realize whether cement existed yet, and the
yellowish ring around the lens outer perimeter I was trying to clean
off is probably delaminating cement. This is over about the outermost
1/8" and the entire lens diameter is roughly 1.25".
I degreased it which loosened all kinds of paint inside. I think I'll
seal off the light-leaking openings at the top, repaint the interior
dead/ultra flat black & try my hand at Waterhouse stops.
Of course no mounting flange - that's an unwritten rule...
It's a Murray-rig project from here on -
Seems that the old shutter blades and iris diaphragm were removed. The
shutter lever release was still banging around at the top because it
was captive by virtue of a swaged in pin that prevented it's non-
destructive removal.
The slot at the bottom is apparently for the former stop-adjusting
lever. The one at the was for the shutter release.
Shutter speed was set by a rotating ring, still there, but nothing to
couple to.
The scales are still interesting. I was wrong about 6.2-45. It said
6.2 - 64 and sideways 45S across two scales. The second scale has a 1
2 3 4 5 crammed very close together above the roughly 22-64 postion of
the f-stop scale. the t-stop between 32 and 64 is '44'.
Lastly, the W.A. marking is way down by the 6.2 on the lower f-stop
scale.
I imagine someone would have said something already if W.A. meant
something else like Weston Aperture, but I don't think he went back
that far anyway.
Anyway, there's nothing there functional but the glass. I left the
other things on for cosmetics.
Oddly, I have never been able to recognize a 'weak reflection' on more
modern lenses. On these cells it is distinctly visible.
This made real question/realize whether cement existed yet, and the
yellowish ring around the lens outer perimeter I was trying to clean
off is probably delaminating cement. This is over about the outermost
1/8" and the entire lens diameter is roughly 1.25".
I degreased it which loosened all kinds of paint inside. I think I'll
seal off the light-leaking openings at the top, repaint the interior
dead/ultra flat black & try my hand at Waterhouse stops.
Of course no mounting flange - that's an unwritten rule...
It's a Murray-rig project from here on -
Re: Gundlach 5x7 Rapid Symmetrical W.A.
"murrayatuptowngallery" <murrayatuptowngallery@yahoo . com >
wrote in message
news:1193211281.829633.228220@v29g2000prd.googlegroups . com ...
> Seems that the old shutter blades and iris diaphragm were
> removed. The
> shutter lever release was still banging around at the top
> because it
> was captive by virtue of a swaged in pin that prevented
> it's non-
> destructive removal.
>
> The slot at the bottom is apparently for the former
> stop-adjusting
> lever. The one at the was for the shutter release.
>
> Shutter speed was set by a rotating ring, still there, but
> nothing to
> couple to.
>
> The scales are still interesting. I was wrong about
> 6.2-45. It said
> 6.2 - 64 and sideways 45S across two scales. The second
> scale has a 1
> 2 3 4 5 crammed very close together above the roughly
> 22-64 postion of
> the f-stop scale. the t-stop between 32 and 64 is '44'.
>
> Lastly, the W.A. marking is way down by the 6.2 on the
> lower f-stop
> scale.
>
> I imagine someone would have said something already if
> W.A. meant
> something else like Weston Aperture, but I don't think he
> went back
> that far anyway.
>
> Anyway, there's nothing there functional but the glass. I
> left the
> other things on for cosmetics.
>
> Oddly, I have never been able to recognize a 'weak
> reflection' on more
> modern lenses. On these cells it is distinctly visible.
>
> This made real question/realize whether cement existed
> yet, and the
> yellowish ring around the lens outer perimeter I was
> trying to clean
> off is probably delaminating cement. This is over about
> the outermost
> 1/8" and the entire lens diameter is roughly 1.25".
>
> I degreased it which loosened all kinds of paint inside. I
> think I'll
> seal off the light-leaking openings at the top, repaint
> the interior
> dead/ultra flat black & try my hand at Waterhouse stops.
>
> Of course no mounting flange - that's an unwritten rule...
>
> It's a Murray-rig project from here on -
>
I have no idea what the extra markings on the stop plate
indicate. For US stops US-1 is f/4, which is the fastest
lens the British Royal Society thought would ever be needed!
Other speeds are the time of exposure in comparison with
US-1.
I don't know for certain when cemented elements were
first used but I am sure it predates the Rapid Rectilinear
of 1866. The cement used until about WW-2 and to some extent
afterward, is Canada Balsam. Beginning about the late 1930's
this was supplanted by various synthetic cements. The
synthetics were first used for aerial camera lenses which,
at high altitudes, are subjected to very low temperatures.
The low temperature will nearly intstantly crystalze a
Canada Balsam cement resulting in the layer becoming milk
white and making the lens useless.
The yellow or brown ring is from cement near the
periphery of the lens becoming oxidized. This is from air
leaking in at the edge. Eventually, the balsam will also dry
out and crystalize around the edge. If the right edge paint
was used this effect will not take place so there is great
variation in the condition of the cement in old lenses.
It would be interesting if the shutter had any clue as
to its manufacturer. Its possible Gundlach, or one of the
companies who used that name, also made shutters but it
could have been made by a number of other companies.
--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix . net com . com
"murrayatuptowngallery" <murrayatuptowngallery@yahoo . com >
wrote in message
news:1193211281.829633.228220@v29g2000prd.googlegroups . com ...
> Seems that the old shutter blades and iris diaphragm were
> removed. The
> shutter lever release was still banging around at the top
> because it
> was captive by virtue of a swaged in pin that prevented
> it's non-
> destructive removal.
>
> The slot at the bottom is apparently for the former
> stop-adjusting
> lever. The one at the was for the shutter release.
>
> Shutter speed was set by a rotating ring, still there, but
> nothing to
> couple to.
>
> The scales are still interesting. I was wrong about
> 6.2-45. It said
> 6.2 - 64 and sideways 45S across two scales. The second
> scale has a 1
> 2 3 4 5 crammed very close together above the roughly
> 22-64 postion of
> the f-stop scale. the t-stop between 32 and 64 is '44'.
>
> Lastly, the W.A. marking is way down by the 6.2 on the
> lower f-stop
> scale.
>
> I imagine someone would have said something already if
> W.A. meant
> something else like Weston Aperture, but I don't think he
> went back
> that far anyway.
>
> Anyway, there's nothing there functional but the glass. I
> left the
> other things on for cosmetics.
>
> Oddly, I have never been able to recognize a 'weak
> reflection' on more
> modern lenses. On these cells it is distinctly visible.
>
> This made real question/realize whether cement existed
> yet, and the
> yellowish ring around the lens outer perimeter I was
> trying to clean
> off is probably delaminating cement. This is over about
> the outermost
> 1/8" and the entire lens diameter is roughly 1.25".
>
> I degreased it which loosened all kinds of paint inside. I
> think I'll
> seal off the light-leaking openings at the top, repaint
> the interior
> dead/ultra flat black & try my hand at Waterhouse stops.
>
> Of course no mounting flange - that's an unwritten rule...
>
> It's a Murray-rig project from here on -
>
I have no idea what the extra markings on the stop plate
indicate. For US stops US-1 is f/4, which is the fastest
lens the British Royal Society thought would ever be needed!
Other speeds are the time of exposure in comparison with
US-1.
I don't know for certain when cemented elements were
first used but I am sure it predates the Rapid Rectilinear
of 1866. The cement used until about WW-2 and to some extent
afterward, is Canada Balsam. Beginning about the late 1930's
this was supplanted by various synthetic cements. The
synthetics were first used for aerial camera lenses which,
at high altitudes, are subjected to very low temperatures.
The low temperature will nearly intstantly crystalze a
Canada Balsam cement resulting in the layer becoming milk
white and making the lens useless.
The yellow or brown ring is from cement near the
periphery of the lens becoming oxidized. This is from air
leaking in at the edge. Eventually, the balsam will also dry
out and crystalize around the edge. If the right edge paint
was used this effect will not take place so there is great
variation in the condition of the cement in old lenses.
It would be interesting if the shutter had any clue as
to its manufacturer. Its possible Gundlach, or one of the
companies who used that name, also made shutters but it
could have been made by a number of other companies.
--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix . net com . com
Re: Gundlach 5x7 Rapid Symmetrical W.A.
No name on shutter, just lens cells.
I removed the remainder of the linkages inside and left external
things on for cosmetic appeal (air cylinders & a nickel plated plate
with arrow that I can't get of anyway).
I had a 2-45 mm opening iris from surplus shed (origin either Edmund
or Melles Griot). Made a sketch for 'truncated annular ring' spacer,
a ring the same thickness as the iris body, i.d. just larger than the
iris body and o.d. just smaller than the shutter body i.d. The iris
has a lever that moves 90 degrees. The ring will be 'truncated' by
cutting a segment about 120 degrees out of the perimeter to pass the
lever. It will be mounted upside down (from the iris scale) in the
shutter body because there is already some slotting from non-existent
levers which if extended a little further will allow passage of the
iris lever.
Iris has no stops and moves too easily. The moving part is accessible
and slightly recessed. I may shim that with some fluoropolymer tape
(self adhesive) to give some friction.
2 holes thru the spacer adapter to clear the 2 screws that hold the
two shutter body shells together will finish it.
I am debating glue or three set screws in the ring's perimeter. The
blades are offset from center so reversing the iris body in the
adapter would allow placing the 'stop' in whichever position relative
to either element is more 'correct'. I'm not sure how to determine
that anyway. I imagine centered would be for 1:1, and some offset away
for infinity, NO idea whether it should be fore or aft, so it may be
that 'closest to center' may be the 'least wrong' rather than best
position.
It is so simple it could be made on a wood lathe. I was going to try a
fly cutter hole saw in plywood, but that would defy Murray's Law. Or
define, I'm not sure...
If only a shutter were as easy and fit inside (not much room left).
Murray
No name on shutter, just lens cells.
I removed the remainder of the linkages inside and left external
things on for cosmetic appeal (air cylinders & a nickel plated plate
with arrow that I can't get of anyway).
I had a 2-45 mm opening iris from surplus shed (origin either Edmund
or Melles Griot). Made a sketch for 'truncated annular ring' spacer,
a ring the same thickness as the iris body, i.d. just larger than the
iris body and o.d. just smaller than the shutter body i.d. The iris
has a lever that moves 90 degrees. The ring will be 'truncated' by
cutting a segment about 120 degrees out of the perimeter to pass the
lever. It will be mounted upside down (from the iris scale) in the
shutter body because there is already some slotting from non-existent
levers which if extended a little further will allow passage of the
iris lever.
Iris has no stops and moves too easily. The moving part is accessible
and slightly recessed. I may shim that with some fluoropolymer tape
(self adhesive) to give some friction.
2 holes thru the spacer adapter to clear the 2 screws that hold the
two shutter body shells together will finish it.
I am debating glue or three set screws in the ring's perimeter. The
blades are offset from center so reversing the iris body in the
adapter would allow placing the 'stop' in whichever position relative
to either element is more 'correct'. I'm not sure how to determine
that anyway. I imagine centered would be for 1:1, and some offset away
for infinity, NO idea whether it should be fore or aft, so it may be
that 'closest to center' may be the 'least wrong' rather than best
position.
It is so simple it could be made on a wood lathe. I was going to try a
fly cutter hole saw in plywood, but that would defy Murray's Law. Or
define, I'm not sure...
If only a shutter were as easy and fit inside (not much room left).
Murray
Re: Gundlach 5x7 Rapid Symmetrical W.A.
New iris mechanism:
* w w w .f295.org/DIYforum/cgi-bin/forum/Blah.pl/Blah.pl?b-len/m-1194995957/
I have an idea for a shutter. I can make a blade that works in a half-
slot at the back end of the 'barrel' with external linkage.
New iris mechanism:
* w w w .f295.org/DIYforum/cgi-bin/forum/Blah.pl/Blah.pl?b-len/m-1194995957/
I have an idea for a shutter. I can make a blade that works in a half-
slot at the back end of the 'barrel' with external linkage.
Re: Gundlach 5x7 Rapid Symmetrical W.A.
The iris I put in was Surplus Shed's PM1002. My memory was wrong on
the size. This is the 1.5 mm - 27 mm iris.
Murray
The iris I put in was Surplus Shed's PM1002. My memory was wrong on
the size. This is the 1.5 mm - 27 mm iris.
Murray
