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Faulty exposure -- light leak somewhere



 
 
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  #1  
Old October 18th 10, 05:01 PM posted to rec.photo.equipment.large-format
Lawrence Akutagawa
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Posts: 145
Default Faulty exposure -- light leak somewhere


"Cheesehead" wrote in message
...
I'll add a link to a result later, but right now I think a description
will suffice.
I went out Sat. a.m. to do some early a.m. shooting.
After I developed the negs, I saw some right-angle lines.
The center of each of two negs was identically darker than the outside
portion.
*By "center" I mean roughly the middle 1/3, horizontally, and
vertically from the top down about 2/3 of the height.
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . . . . . . . . . .

I used two different lenses, each on its own respective lens board
(135 Xenotar and 210 Caltar)
I've used the camera before and not had this problem. It is a Speed
Graphic, circa 1950.

The obvious question is to find the cultprit.
My first though was the seal around the film holder
Next thought is the back edge of the bellows.
Any other ideas?


In a darkened room, place a very small flashlight (turned on) in your camera
on the tripod with the bellows extended, the lens closed, and the film
holder inserted.


  #2  
Old October 22nd 10, 05:29 AM posted to rec.photo.equipment.large-format
Richard Knoppow
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Posts: 751
Default Faulty exposure -- light leak somewhere


"Cheesehead" wrote in message
...
On Oct 18, 12:01 pm, "Lawrence Akutagawa"

wrote:
"Cheesehead" wrote in message

...

I'll add a link to a result later, but right now I think
a description
will suffice.
I went out Sat. a.m. to do some early a.m. shooting.
After I developed the negs, I saw some right-angle
lines.
The center of each of two negs was identically darker
than the outside
portion.
*By "center" I mean roughly the middle 1/3,
horizontally, and
vertically from the top down about 2/3 of the height.
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . . . . . . . . . .


I used two different lenses, each on its own respective
lens board
(135 Xenotar and 210 Caltar)
I've used the camera before and not had this problem. It
is a Speed
Graphic, circa 1950.


The obvious question is to find the cultprit.
My first though was the seal around the film holder
Next thought is the back edge of the bellows.
Any other ideas?


In a darkened room, place a very small flashlight (turned
on) in your camera
on the tripod with the bellows extended, the lens closed,
and the film
holder inserted.


Good idea. And easier as it gets darker earlier each day.
:-)

There are a couple of ways of looking for light leaks.
First is the above, put a flashlight or lamp that won't get
too hot in the camera and examine the bellows with them
extended fully. However what you describe does not sound
like fogging from pin holes. Also, all Speed Graphics made
since about 1938 have synthetic bellows that seem to last
forever and not develop leaks.
To check the holder and back of the camera remove the
lens board place a holder with white paper in place of the
film in the camera and remove shine a strong light around
the periphery of the holder and camera back. Do this with
the dark slide in place and removed. There should be no
light leak visible when looking into the camera through the
front.
Light leaks can be very hard to find.
Are you sure the darker areas are due to being light
struck and not to uneven development?


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



  #3  
Old October 24th 10, 09:30 PM posted to rec.photo.equipment.large-format
David Nebenzahl
external usenet poster
 
Posts: 1,353
Default Faulty exposure -- light leak somewhere

On 10/24/2010 4:22 AM Cheesehead spake thus:

It looks like next week I will have time to check it out via various
methods. The negs were developed in a jobo tank that was rotated on
it wheel base. The lines on the two negs are in the same place. If it
were processing, if the tank were not rotated, then the lines would
be offset based on the relative neg position in the liquid.


You say there are "lines" on the negative, but it's not clear exactly
what exactly these are. Are they sharp, distinct lines? Fuzzy but
visible lines? If lines, are they lighter (less dense) or darker (more
dense)? Or are they *areas* of different density with a more or less
distinct edge?

More description here might help us to diagnose the problem. Or you
could scan the negs and post the results somewhere online.


--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)
  #4  
Old November 1st 10, 05:04 PM posted to rec.photo.equipment.large-format
Lawrence Akutagawa
external usenet poster
 
Posts: 145
Default Faulty exposure -- light leak somewhere


"Cheesehead" wrote in message
...
On Oct 18, 12:01 pm, "Lawrence Akutagawa"
wrote:
"Cheesehead" wrote in message

...

I'll add a link to a result later, but right now I think a description
will suffice.
I went out Sat. a.m. to do some early a.m. shooting.
After I developed the negs, I saw some right-angle lines.
The center of each of two negs was identically darker than the outside
portion.
*By "center" I mean roughly the middle 1/3, horizontally, and
vertically from the top down about 2/3 of the height.
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . . . . . . . . . .


I used two different lenses, each on its own respective lens board
(135 Xenotar and 210 Caltar)
I've used the camera before and not had this problem. It is a Speed
Graphic, circa 1950.


The obvious question is to find the cultprit.
My first though was the seal around the film holder
Next thought is the back edge of the bellows.
Any other ideas?


In a darkened room, place a very small flashlight (turned on) in your
camera
on the tripod with the bellows extended, the lens closed, and the film
holder inserted.


Good idea. And easier as it gets darker earlier each day. :-)

******

Soooo...any findings yet?


  #5  
Old November 14th 10, 05:09 PM posted to rec.photo.equipment.large-format
Lawrence Akutagawa
external usenet poster
 
Posts: 145
Default Faulty exposure -- light leak somewhere


"Lawrence Akutagawa" wrote in message
...

"Cheesehead" wrote in message
...
I'll add a link to a result later, but right now I think a description
will suffice.
I went out Sat. a.m. to do some early a.m. shooting.
After I developed the negs, I saw some right-angle lines.
The center of each of two negs was identically darker than the outside
portion.
*By "center" I mean roughly the middle 1/3, horizontally, and
vertically from the top down about 2/3 of the height.
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . . . . . . . . . .

I used two different lenses, each on its own respective lens board
(135 Xenotar and 210 Caltar)
I've used the camera before and not had this problem. It is a Speed
Graphic, circa 1950.

The obvious question is to find the cultprit.
My first though was the seal around the film holder
Next thought is the back edge of the bellows.
Any other ideas?


In a darkened room, place a very small flashlight (turned on) in your
camera on the tripod with the bellows extended, the lens closed, and the
film holder inserted.

Soooo...any findings yet?




  #6  
Old November 16th 10, 12:33 AM posted to rec.photo.equipment.large-format
Lawrence Akutagawa
external usenet poster
 
Posts: 145
Default Faulty exposure -- light leak somewhere


"Cheesehead" wrote in message
...
On Nov 14, 11:09 am, "Lawrence Akutagawa"
wrote:
"Lawrence Akutagawa" wrote in message

...



"Cheesehead" wrote in message
...
I'll add a link to a result later, but right now I think a description
will suffice.
I went out Sat. a.m. to do some early a.m. shooting.
After I developed the negs, I saw some right-angle lines.
The center of each of two negs was identically darker than the outside
portion.
*By "center" I mean roughly the middle 1/3, horizontally, and
vertically from the top down about 2/3 of the height.
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . x x x x . . . .
. . . . . . . . . . . . .


I used two different lenses, each on its own respective lens board
(135 Xenotar and 210 Caltar)
I've used the camera before and not had this problem. It is a Speed
Graphic, circa 1950.


The obvious question is to find the cultprit.
My first though was the seal around the film holder
Next thought is the back edge of the bellows.
Any other ideas?


In a darkened room, place a very small flashlight (turned on) in your
camera on the tripod with the bellows extended, the lens closed, and the
film holder inserted.


Soooo...any findings yet?


Yes. It appears that in all likelihood it was my processing.
It seems that I apparently did not fill the tank full and set it still
for some seconds at a time.
This seems to be the case because the lines on the images are
staggered a bit,
somewhat like their position in my Jobo tank.

******
Glad to hear that you seem to have found the source of your problem.


 




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