Condensation on sheet film or lens?

[Pasto]

I've been working on a project of environmental portraits taken in cold rooms/wine cellars using TMY-2 in 4x5. On three occassions my negatives turned out having a "fogged" area near the center. Very difficult to see on the negative but it turns out clearly visible in the print or scan. This only ever happens when I'm using my Nikkor SW 75mm lens. However, this lens has taken many other pictures with no such problem.

The only explanation I could come up with is condensation on the film in the film holder or on the lens itself. My holders are always kept in ziplock bags just before taking the exposure. On all three occassions the weather was hot and humid outside. The inside of the celler is much cooler, and two of the cellers were air conditioned. I'm wondering if this is a problem others have encountered, and whether it is more likley to be condensation on the lens or on the film? Why would the condensation only occur near the center of the image, and does this distinguish between film and lens as the culprit?

I attached a picture showing the fogged area directly to the right of the subject.

[tkamiya]

Are you letting your equipment (lens and film included) acclimate to the environment before use? Condensation can happen anywhere and on any part of your setup. You may be looking at either-or-or_both type of situation.

[Leigh B]

Condensation occurs when a cold surface is introduced to a humid atmosphere. That's the opposite of the situation you described.

If your camera cooled curing the shoot then you took it outside, you might get condensation that would dissipated as the camera warmed up.

In any case it would not be in the light path when the exposure was made.

Is it always in the same place on the print? Could it have occurred in the darkroom during printing?

- Leigh

[Pasto]

Tkamiya it takes me about 30-40 minutes to set up my lights, compose, and meter so I just assumed that this was enough time for everything to acclimate. Yes, it's clearly on the negative so it has to be a problem with the lens or with the film. Leigh you're right that condensation occurs when a cold surface comes into contact with humid air. This situation may actually occur in the lens itself (i.e., on the internal elements). Hot air spaces in the lens could possibly condense onto an outer element that's been cooled quickly. So the condensation could be on one of the inside surfaces. Thanks to Ian for this suggestion. I'm not sure but I do need to take some precautions. I'm also womdering that if it is the lens, why it only happens with my Nikkor 75mm and never with my Super Angulon 90mm. Could my Nikkor be damaged such that the internal elements are not properly sealed from the outside environment?

[DREW WILEY]

The filmholders themselves need to be acclimated. If it's condensation on the film itself, there will
be tiny water droplet distortions in focus when viewing the image under a magnifier. If the fog is
somewhere on the lens, it will act more like soft-focus diffusion, blurring the image overall. Fog inside of a lens takes awhile to dissipate and will be apparent upon lens inspection. When any kind
of lens fog is present, it will naturally be difficult to focus, and you should be suspicious.

[George Collier]

I'm thinking that if it was in or on the lens (front element or otherwise), it wouldn't manifest on the negative as such a defined area, but might soften the image overall.
Also, you could remove the lens from the camera before shooting, and see it (by looking through it) if it is there. Maybe you should store your holders there overnight before the shoot, if you can.

[adash]

Are you sure you're not seeing flare because of the light, which is apparently to the left of the subject on this photo?
Condensation usually happens when a cold object is introduced in a warm humid environment.
In the film holder case I would assume it will start over from the edges and progress towards the center, since the edges are where the warm air would come in contact with the film first while still in the film holder.
If a lens is to get condensation, it would happen all over the exposed glass surface, so you're probably looking at a flare or internal reflection artifact.

[Pasto]

Thanks Adash. I have not considered that. However, flare would manifest itself more evenly across the picture rather than a relatively small spot??

[adash]

Thanks Adash. I have not considered that. However, flare would manifest itself more evenly across the picture rather than a relatively small spot??

Not really. Usually the filter thread acts like a small shade for light at that extreme angle, so if the front coating is bad or old (not that it ages, but coatings were not that good 50+ years ago), it would shine or flare in the spot where light shone on it. I have had such problems with Industar 50-2 and Helios 44M-4, that I believe were single coated, although made in 1980-ies. I guess you could imagine at what angle the flare would look like the one on the picture and how to test. BTW, flare is much more difficult to spot on ground glass than on film, so I believe that's why you didn't see it.

[adash]

BTW, I am not completely sure that is flare, but it's a direction to check on the particular lens.