Light Leak? Red Window? Dot on End of Film?

[Russell W. Barnes]

Not sure whether to post this here or in 'Film and Developing'.

When I've shot Fomapan or Rollei Retro 400 I've noticed that on the end of the film past the last shot, there's a black (fully exposed) dot about 10mm diameter on the neg. I've never seen it on Ilford or Kodak films and hitherto have assumed it to be a feature of the film, like the frame numbers on the rebates.

I've just shot a roll of Fomapan 400 Action through my Franka-Solida III and the black dot appears to have excessive light 'bleed-over', which has encroached onto the last frame edge. I also notice that one or two shots were fogged slightly at either the top edge or bottom edge of the shot, so somewhat inconsistent.

I admit to winding on in bright sunlight with the film number visible through the red window (little metal shutter open) and wondered if the sun would affect the film through this? I also observe that the red window in my Franka seems lighter than the red windows in my Baldixes, where it is very hard to read the numbers on Kodak and Ilford film compared to same film in my Franka.

Fomapan and Rollei numbers are easy to read, of course. Would sunlight through the red window be the cause of this fogging and the bleedover on the dot? I removed the film in a dark bag as I've had 'fat-film' issues with Fomapan in the past but ironically, not this time.
--

KInd Regds,

R.

 

[David Hughes]

Dufay thought that in the 1930's and so they put a little self adhesive metallic cover in with rolls of 120 Dufaycolor.



Regards, David

 

[Kai-san]

When I read this I suddenly remembered that some 120 films have a round hole, about 5 mm, punched through the backing paper at one point. I have never reflected on the purpose of this hole, I guess I just assumed that all films had the same. I will be processing both Fomapan, Rollei and Kodak 120 film in the next few weeks, I will check where the location of this hole is and if all of these brands have it.

 

[Russell W. Barnes]

Here's a pic of what I mean. This is the end of the roll, and normally it's a neat black dot. But not this time...

My Balda-Mess Baldix is great because I only need to look at the ruby window once then the film-counter takes over. And I get a 'bonus' 13th frame!

 

[Russell W. Barnes]

I've just shone an LED torch through the 'red' window of my Franka and it was ORANGE! The Baldix is red. My own view is that with the Franka, the mask for the red window is inside the camera, and so the plastic has faded, being exposed constantly to UV from the sun.

The red window on the Baldix is covered externally when not in use, and is so protected against harmful colur-degrading solar radiation. Bad design on the part of Franka! Tsk...

 

[petronius]

The Rollei Superpan has such a black dot at the end of the roll. It looks factory made to me though I don´t know why.

 

[css9450]

The Shanghai GP3 film has the hole too... And the dot on the negatives.

 

[Bill Clark]

Just a guess, could it be a mark the machine detects and uses to determine the end of each 120 roll during manufacturing?

With Ilford and Kodak I find there is some extra film after #12 and thought maybe I should try for 13 on a 120 roll!

 

[Russell W. Barnes]

When I read this I suddenly remembered that some 120 films have a round hole, about 5 mm, punched through the backing paper at one point...

Well... Every day is a learning day! I salvaged the backing paper and here's the end of it. Never noticed this before! It is pretty obvious that the light leaking onto my 12th shot (centre numbering) comes from that passing through this hole and bleeding out as I wind the film off with the red window unshuttered.


It is also obvious by the circular and regular bleed-out pattern that the 'ruby' (orange) window is where the light is getting in.

 

[Russell W. Barnes]

Well, you know what my next question is going to be...


Where can I obtain a deeper red ruby plastic to stick over the existing orange plastic or replace it? I lifted the pressure plate out and the springs on each end are strong but there are no other seals to prevent light seeping around the edge of the plate when the red window cover is open.



Might it be worth sticking some black light-seal foam strips in there?

 

[sepiareverb]

I’d color over the existing window with a red sharpie.

I have a black gaff tape flap over the red window on an old box brownie I shoot from time to time. I lift it up to wind, and try to keep it shaded while doing so.

 

[Russell W. Barnes]

I’d color over the existing window with a red sharpie.

Sounds like a plan. Somewhere, at work, we used to have sheets of green and red gelatin filter for indicator lamps (dead or alive) and I'll try to find some red, cut it to size, and glue it in place.

But I have a red sharpie somewhere so that's a good start. Thanks.

 

[Perry_B]

I would be cautious about inking in your red window. With panchromatic film, the film would be exposed through that hole in the backing paper, even through a red window. The only way to avoid light leaking through the hole and causing the black dot would be to completely block the window while winding past it. Intact film backing paper should block any light coming through the window, even if the red glass/plastic is degraded (although light could still bounce around inside the camera, I suppose).

 

[rangefinderlove123]

I've a similar problem with foma 400 used with rolleiflex in 120. The dot comes in the middle of the frame every time

 

[sepiareverb]

Sounds like a plan. Somewhere, at work, we used to have sheets of green and red gelatin filter for indicator lamps (dead or alive) and I'll try to find some red, cut it to size, and glue it in place.

But I have a red sharpie somewhere so that's a good start. Thanks.

An additional layer of red or some ND over either the existing red and or some new red would certainly take care of it. I have a few full sheets of ND if you'd like a chunk pm me.

 

[Russell W. Barnes]

I would be cautious about inking in your red window.

Too late!

ith panchromatic film, the film would be exposed through that hole in the backing paper, even through a red window. The only way to avoid light leaking through the hole and causing the black dot would be to completely block the window while winding past it.

I'm not too fussed about the black dot, as it only appears after the last frame, likely with me winding the film off with the red window open. It appears on my Baldixes and is neat and well defined. But on the Franka there is a distinct bleed-over which encroached onto the last frame shot (frame 12) so I had to do something to mitigate against stray light.

Intact film backing paper should block any light coming through the window, even if the red glass/plastic is degraded (although light could still bounce around inside the camera, I suppose).

I think that has been happening on some shots, as described in my original post. The pressure plate is matte black both sides but I may stick some 35mm SLR type light-sealing foam behind, between it and the camera back and see if that makes a difference.

 

[Huss]

Well, you know what my next question is going to be...


Where can I obtain a deeper red ruby plastic to stick over the existing orange plastic or replace it?

I have some I can send to you if you PM me your address.

 

[Kai-san]

Just a guess, could it be a mark the machine detects and uses to determine the end of each 120 roll during manufacturing?

With Ilford and Kodak I find there is some extra film after #12 and thought maybe I should try for 13 on a 120 roll!

It is possible to get 13 frames (6X6) on a 120 roll, depending on the camera. With my Pentacon Six I get 13 frames on all films if I expose frame zero. You cannot do it on a Hasselblad because the frame spacing is larger. Doing it on a folder or box with a red window will probably be quite tricky.

 

[Russell W. Barnes]

It is possible to get 13 frames (6X6) on a 120 roll...

I sometimes get 13 frames on my Mess-Baldix, as it has an auto counter and once you've set the first frame in the red window, you can close it. It's a cleverly-designed little camera and takes into account how the thickness of the roll varies as the film advances.

But some film must be thicker than others as there're've been times when I've had a minor overlap.

 

[Pioneer]

I place black electricians tape across the exposed windows on my 120 folder cameras. I fold a tab at one side to lift it when I am advancing film. Lasts quite a while and is very inexpensive to replace.


It is probably overkill but I know that I don't have light leaks from that source.