Film camera question
 

I see a lot of developed film and contact sheets at my school and every once
in a while I see a roll of negatives or a contact sheet that has a thin band
of lighter tone (darker on the negatives) at the bottom of most negative
frames, as if all the frames got a little overexposure only along one edge.
Usually it's the bottom of the negative frame, and the lighter band is soft
edged and only about1 or 2 mm thick. The surrounding negative is normal and
doesn't look fogged.
Could this be caused by the shutter curtains slowing down a little at the
end of the travel distance thus giving that part of the film a tiny bit more
light? I can't determine if these defects correspong to the direction of
travel of the camera's shutter curtain, but if it was caused by an
inconsistent shutter curtain speed it should show up along the edge where
the shutter curtain ends at.
Can anyone advise on what couyld be causing this negative defect?
Thanks for any advice.

Film camera question
 

Luis Ortega spake thus:

I see a lot of developed film and contact sheets at my school and every once
in a while I see a roll of negatives or a contact sheet that has a thin band
of lighter tone (darker on the negatives) at the bottom of most negative
frames, as if all the frames got a little overexposure only along one edge.
Usually it's the bottom of the negative frame, and the lighter band is soft
edged and only about1 or 2 mm thick. The surrounding negative is normal and
doesn't look fogged.

Could this be caused by the shutter curtains slowing down a little at the
end of the travel distance thus giving that part of the film a tiny bit more
light?

Probably not, since most focal-plane shutters travel horizontally across
the frame. A few use vertical-travel curtains.

I can't determine if these defects correspong to the direction of
travel of the camera's shutter curtain, but if it was caused by an
inconsistent shutter curtain speed it should show up along the edge where
the shutter curtain ends at.

Questions: does the dark band on the negatives extend over the frames?
In other words, is it continuous across the strip of film, or is it only
inside the frames? If continuous, it might be a light leak.

If the bottoms of the frames are all evenly darker (on the negatives)
but the darkness is confined to the frames, then it may be a localized
overdevelopment issue, where the very bottom (or top) of the film is
getting more development. (Assuming normal rollfilm tank development.)

More information, please.


--
I hope that in a few years it [Wikipedia] will be so bloated that it
will simply disintegrate, because I can't stand the thought that this
thing might someday actually be used as a serious reference source.
Because in its current form, it's not to be taken seriously at all.

- Horst Prillinger (see
http://homepage.univie.ac.at/horst.p...06/000623.html)

Film camera question
 

"Luis Ortega" wrote

[edge of film] the bottom of most negative frames ... ~1mm lighter band
... looks fogged. [why?]

One cause is the edge of the film not getting developed
because it is up tight against the spiral in the processing
tank. The stripe is unfixed film, showing up light on the
contact sheet.

If the stripe is black on the negative then:

With 120/220 it is normal for some light to get to
the edge of the film. The fit of the film in the spool
is an ooch loose, leaving a gap between the spool ends and
the roll of the film - light gets in and gets to the
edge of the film.

If the film is really loose on the spool, Holga & Co.,
then the fogging can extend in quite a ways.

If this is a 35mm roll then it may be because of: a leak
in the cassette; film was bulk loaded and some light got
at the pancake of film in the loader; mechanical stress
of loading the film on the developing reel caused fogging.

And sometimes 'just because'.

Film camera question
 

Luis Ortega wrote:
I see a lot of developed film and contact sheets at my school and every once
in a while I see a roll of negatives or a contact sheet that has a thin band
of lighter tone (darker on the negatives) at the bottom of most negative
frames, as if all the frames got a little overexposure only along one edge.
Usually it's the bottom of the negative frame, and the lighter band is soft
edged and only about1 or 2 mm thick. The surrounding negative is normal and
doesn't look fogged.
Could this be caused by the shutter curtains slowing down a little at the
end of the travel distance thus giving that part of the film a tiny bit more
light? I can't determine if these defects correspong to the direction of
travel of the camera's shutter curtain, but if it was caused by an
inconsistent shutter curtain speed it should show up along the edge where
the shutter curtain ends at.
Can anyone advise on what couyld be causing this negative defect?
Thanks for any advice.

This could perhaps be as a result of the film wound onto the film
reels for development. Are the reels plastic or stainless? The light
band MAY be the result of the developer not reaching that part of the
film which is resting between the external band of concentric rings on
the spool. As to why this is not the case on the upper band, I don't
have a clue. I have not noted this on any of my B&W film processed by
me on stainless reels.

David N.

Film camera question
 

David Nebenzahl wrote:
Luis Ortega spake thus:

I see a lot of developed film and contact sheets at my school and
every once in a while I see a roll of negatives or a contact sheet
that has a thin band of lighter tone (darker on the negatives) at the
bottom of most negative frames, as if all the frames got a little
overexposure only along one edge. Usually it's the bottom of the
negative frame, and the lighter band is soft edged and only about1 or
2 mm thick. The surrounding negative is normal and doesn't look fogged.

Could this be caused by the shutter curtains slowing down a little at
the end of the travel distance thus giving that part of the film a
tiny bit more light?

Probably not, since most focal-plane shutters travel horizontally across
the frame.

Most modern camera manufacturers use a verticaly traveling metal focal
plane shutter in their SLR and DSLR cameras.
It is definitely a symptom of a sticking shutter.
Don't forget that the image is _inverted_ at the film plane and the
bottom of the scene is captured at the top of the film frame.
A dark stripe on along the top of the negative (which is the bottom of
the scene) is a symptom of a sticking shutter, it starts a bit slow
(over-exposing the top edge of the film) and then runs at the correct
speed across the rest of the frame.

A few use vertical-travel curtains.

Have a good look at any AF Nikon SLR, a Canon EOS SLR, or any of the AF
Pentax SLR camera bodies, they all have a verticaly traveling metal
focal plane shutter.
Even the Voigtlander rangefinder series have a verticaly traveling metal
shutter.
The only "modern" manufacturer to use a cloth focal plane shutter is
Leica and that is only in their rangefinder cameras; Leica SLR cameras
use a verticaly traveling metal shutter.

I can't determine if these defects correspong to the direction of
travel of the camera's shutter curtain, but if it was caused by an
inconsistent shutter curtain speed it should show up along the edge
where the shutter curtain ends at.

Questions: does the dark band on the negatives extend over the frames?
In other words, is it continuous across the strip of film, or is it only
inside the frames? If continuous, it might be a light leak.

It could also indicate that the shutter is sticking slightly partway
across the film gate, and over-exposing that area of the film.

Film camera question
 

Thanks to all. I need to check out the various suggestion offered. To
clarify, the defect is not an undevelopment effect caused by the rails of
the reels impeding the developer along the sprocket hole areas but
something that is happening only inside the negative frame itself. It is
very evident on a contact sheet when you can see all of the frames side by
side. Each contact frame appears a little whiter and more washed out along
one edge, usually the bottom edge but sometimes the side edge.
I work in a school and see dozens of cameras in the darkroom so I can't do a
lot more than try to follow it up as it happens, but I am curious as to why
this is happening.
Thanks to all.

"Luis Ortega" wrote in message
...
I see a lot of developed film and contact sheets at my school and every
once in a while I see a roll of negatives or a contact sheet that has a
thin band of lighter tone (darker on the negatives) at the bottom of most
negative frames, as if all the frames got a little overexposure only along
one edge. Usually it's the bottom of the negative frame, and the lighter
band is soft edged and only about1 or 2 mm thick. The surrounding negative
is normal and doesn't look fogged.
Could this be caused by the shutter curtains slowing down a little at the
end of the travel distance thus giving that part of the film a tiny bit
more light? I can't determine if these defects correspong to the direction
of travel of the camera's shutter curtain, but if it was caused by an
inconsistent shutter curtain speed it should show up along the edge where
the shutter curtain ends at.
Can anyone advise on what couyld be causing this negative defect?
Thanks for any advice.

Film camera question
 

Luis Ortega spake thus:

Thanks to all. I need to check out the various suggestion offered. To
clarify, the defect is not an undevelopment effect caused by the rails of
the reels impeding the developer along the sprocket hole areas but
something that is happening only inside the negative frame itself. It is
very evident on a contact sheet when you can see all of the frames side by
side. Each contact frame appears a little whiter and more washed out along
one edge, usually the bottom edge but sometimes the side edge.
I work in a school and see dozens of cameras in the darkroom so I can't do a
lot more than try to follow it up as it happens, but I am curious as to why
this is happening.
Thanks to all.

"Luis Ortega" wrote in message
...

I see a lot of developed film and contact sheets at my school and every
once in a while I see a roll of negatives or a contact sheet that has a
thin band of lighter tone (darker on the negatives) at the bottom of most
negative frames, as if all the frames got a little overexposure only along
one edge. Usually it's the bottom of the negative frame, and the lighter
band is soft edged and only about1 or 2 mm thick. The surrounding negative
is normal and doesn't look fogged.
Could this be caused by the shutter curtains slowing down a little at the
end of the travel distance thus giving that part of the film a tiny bit
more light? I can't determine if these defects correspong to the direction
of travel of the camera's shutter curtain, but if it was caused by an
inconsistent shutter curtain speed it should show up along the edge where
the shutter curtain ends at.
Can anyone advise on what couyld be causing this negative defect?
Thanks for any advice.

So it's gotta be an exposure issue, and not light leaks. Most likely
uneven exposure due to dragging shutter curtains, as others have
suggested. A trip to the repair shop for those cameras may be in order.

By the way, if the uneven exposure is along the bottom (long) edge of
the frame, the offending camera has vertically-traveling curtains; along
the short edge, horizontally-traveling ones. Might help to sort out
which camera took which pictures.


--
I hope that in a few years it [Wikipedia] will be so bloated that it
will simply disintegrate, because I can't stand the thought that this
thing might someday actually be used as a serious reference source.
Because in its current form, it's not to be taken seriously at all.

- Horst Prillinger (see
http://homepage.univie.ac.at/horst.p...06/000623.html)

Film camera question
 

"Luis Ortega" wrote

something that is happening only inside the negative frame itself.

If this is 35mm, something everyone seems to be assuming,
I'll toss my hat in with the sticky-vertical-shutter crowd.
Vertical shutters were used on Exa's and Exakta 500s -- if there is
one of these hanging around I'd bet money it's the one with the problem.

A light leak is the usual culprit but 35mm cameras as a rule don't
leak light into the mirror box. Is the film fogged or overexposed?

You should only see this in contact sheets from one camera and
one photographer unless the class shares common camera(s).

Probably a good idea to report the problem to the camera owner/
class instructor. The problem will only get worse with time and
the shutter may stop completely in cold weather.


--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics, Photonics, Informatics.
Remove blanks to reply: n o lindan at ix . netcom . com
f-Stop enlarging timers: http://www.nolindan.com/da/fstop/

Film camera question
 

Nicholas O. Lindan spake thus:

"Luis Ortega" wrote

something that is happening only inside the negative frame itself.

If this is 35mm, something everyone seems to be assuming,
I'll toss my hat in with the sticky-vertical-shutter crowd.
Vertical shutters were used on Exa's and Exakta 500s -- if there is
one of these hanging around I'd bet money it's the one with the problem.

Oh, come on, Nicholas: how likely do you think it is that students would
be using these antiquated cameras?

Besides, I have an Exa, and it does indeed have a vertical shutter, but
it's definitely not a focal plane shutter. It's one of the weirdest
shutters I've ever seen, and even if it malfunctioned would not leave
that kind of an artifact within the exposed frame.

A light leak is the usual culprit but 35mm cameras as a rule don't
leak light into the mirror box. Is the film fogged or overexposed?

Read his post; he said the effect was within the frame only, implying no
fogging outside the frame, therefore not a light leak problem.


--
I hope that in a few years it [Wikipedia] will be so bloated that it
will simply disintegrate, because I can't stand the thought that this
thing might someday actually be used as a serious reference source.
Because in its current form, it's not to be taken seriously at all.

- Horst Prillinger (see
http://homepage.univie.ac.at/horst.p...06/000623.html)

Film camera question
 

"Luis Ortega" wrote in message
...
Thanks to all. I need to check out the various suggestion
offered. To clarify, the defect is not an undevelopment
effect caused by the rails of the reels impeding the
developer along the sprocket hole areas but something
that is happening only inside the negative frame itself.
It is very evident on a contact sheet when you can see all
of the frames side by side. Each contact frame appears a
little whiter and more washed out along one edge, usually
the bottom edge but sometimes the side edge.
I work in a school and see dozens of cameras in the
darkroom so I can't do a lot more than try to follow it up
as it happens, but I am curious as to why this is
happening.
Thanks to all.

If the effect is inside the frame its obviously happening
in the camera. Since it seems to happen on different edges
in various pictures its not likely the shutter. It _might_
be an internal reflection of some sort. The way to find out
is to put a small piece of ground glass in the film gate,
open the shutter (T exposure) and shine a flashlight intot
the lens from different angles. Actually you may be able to
see a reflection just by eye. The cure is to paint whatever
is causing the reflection with flat black paint or some
other light absorptive material.
It is possible for a focal plane shutter to cause a band
of under or overexposure at one end of its travel but it
will consistently at the same place on each frame. It is
also possible for a focal plane shutter to cause spots or
steaks on frames if it has holes in it, but this sounds like
something that is not shutter related.
If the camera is an SLR check for light leaks from the
finder when the mirror is in the up position. Sometimes the
light seals in SLR's get old and don't work. Unless you eye
is pressed right against the finder some light can get in
and cause some form of fogging. I am suggesting this only
because your problem seems to be a little unusual and the
cause may be a bit unusual.


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