How quickly will heat fog B&W film?

logan2z · Sep 3, 2023

I was recently photographing an event and had a lot of camera gear with me, so I had to leave one camera/lens in the car for several hours a day for two days. The outside temperature wasn't that hot (about 74 degrees), but the inside of my car was quite a bit hotter. The camera was stored inside a camera bag, outside of the direct sunlight. On the first day I left the bag on the floor of the passenger compartment and on the second day I put it in the trunk since it stays a bit cooler.

I just developed the roll of film that was in that camera and it looks like it has unusually low contrast. It's still drying so I haven't had a proper look at it on a light table yet, but it definitely doesn't look normal - denser overall and the contrast looks pretty low. The only thing I can think of is that the heat had an effect on the film since I processed it exactly the same way as I always do.

Could a 400 speed film like HP5 be heat fogged that quickly?

koraks · Sep 3, 2023

logan2z said:
Could a 400 speed film like HP5 be heat fogged that quickly?

No, not really.

Just wait until the film is dry and evaluate again, and then, if there's objectively a problem, consider the usual suspects of various modes of user error.

Agulliver · Sep 3, 2023

No. You'd have to keep the film in a seriously hot location for weeks/months.

Dali · Sep 3, 2023

Wasn't your film heavily expired?

logan2z · Sep 3, 2023

Dali said:
Wasn't your film heavily expired?

No, it was not expired.

George Collier · Sep 3, 2023

Did the sunlight ever fall directly on it, in the car?

Kino · Sep 3, 2023

Overall thin negatives would not be a symptom of heat fog.

High base + fog levels across the film, even in the margins, would most likely be the result in my experience.

MattKing · Sep 3, 2023

Kino said:
Overall thin negatives would not be a symptom of heat fog.

Agree.
Perhaps the heat affected the camera metering or shutter speed or aperture accuracy?

Sirius Glass · Sep 3, 2023

MattKing said:
Agree.
Perhaps the heat affected the camera metering or shutter speed or aperture accuracy?

Storing cameras and lenses in a hot car for long periods of time can mess up both.

logan2z · Sep 3, 2023

Sirius Glass said:
Storing cameras and lenses in a hot car for long periods of time can mess up both.

I know, it was unavoidable.

MattKing · Sep 3, 2023

Sirius Glass said:
Storing cameras and lenses in a hot car for long periods of time can mess up both.

It is really bad for pets and humans too!

logan2z · Sep 3, 2023

George Collier said:
Did the sunlight ever fall directly on it, in the car?

It very possibly did while the bag was in the passenger compartment. I moved it to the trunk after a few hours so it wasn't in direct sunlight then.

logan2z · Sep 3, 2023

MattKing said:
It is really bad for pets and humans too!

Not pets or humans were harmed as a result of my stupidity.

logan2z · Sep 3, 2023

MattKing said:
Agree.
Perhaps the heat affected the camera metering or shutter speed or aperture accuracy?

I don't use in-camera metering. And I don't think the shutter speed or aperture accuracy were the cause because there was a handful of photos I had shot on this roll before I left the camera in the car and those seem to be affected as well.

logan2z · Sep 3, 2023

Kino said:
Overall thin negatives would not be a symptom of heat fog.

High base + fog levels across the film, even in the margins, would most likely be the result in my experience.

I mentioned in my original post that the negatives appear more dense than I would expect, not thinner. All images seem to be affected similarly and I do see some signs of fogging in the rebate in a few spots.

The roll should be dry soon and I'll take it down and have a closer look.

Sirius Glass · Sep 3, 2023

logan2z said:
It very possibly did while the bag was in the passenger compartment. I moved it to the trunk after a few hours so it wasn't in direct sunlight then.

Even so the trunk and glove box get even hotter.

mshchem · Sep 3, 2023

Thus, the "greentrunk effect"

logan2z · Sep 3, 2023

Sirius Glass said:
Even so the trunk and glove box get even hotter.

The trunk in my car seemed cooler than the passenger compartment which is why I moved the camera bag there. But both were pretty hot.

Kino · Sep 3, 2023

logan2z said:
I mentioned in my original post that the negatives appear more dense than I would expect, not thinner. All images seem to be affected similarly and I do see some signs of fogging in the rebate in a few spots.

The roll should be dry soon and I'll take it down and have a closer look.

Sorry, my reading skills seem to be deteriorating as of late; I saw lower contrast and my brain shut down...

Have any solvents or oil treatment canisters in your trunk? Heat and certain chemicals could be a bad combo...

rcphoto · Sep 3, 2023

Unless you've bought your film directly from the factory, your film has already spent several days or longer in hot trucks on their way to the retailer. I wouldn't expect a couple extra hours would have any effect.

Agulliver · Sep 4, 2023

logan2z said:
The trunk in my car seemed cooler than the passenger compartment which is why I moved the camera bag there. But both were pretty hot.

I realise cars vary, but I've always found that the boot/trunk is cooler than the cabin as it has no windows. I cannot see how a few hours or even a few days in a hot car would do what OP describes. There's something else afoot.

Don_ih · Sep 4, 2023

Welllll .... Why doesn't someone do an actual test? I can cut a few inches of hp5 from a bulk roll and put it in my car for a few hours - it's going to be over 30 degrees this afternoon.

Frank53 · Sep 4, 2023

Don_ih said:
Welllll .... Why doesn't someone do an actual test? I can cut a few inches of hp5 from a bulk roll and put it in my car for a few hours - it's going to be over 30 degrees this afternoon.

I did the test, almost 50 years ago. Travelled mid summer from Europe overland to India and Nepal. Had about 50 rolls of Ektachrome 35mm and around 60 rolls black and white 120, Tri-x and Plus-x. The films stayed in van most of the time, or in non ac hotelrooms. After six months of travel, partly during the rainy season,
the films were developed and came out as expected: perfect!
we did not worry about such things in those days.

Don_ih · Sep 4, 2023

Frank53 said:
we did not worry about such things in those days

That's nice.

Anyway, that wasn't current hp5, so not exactly the same. And you had no control sample.

Frank53 · Sep 4, 2023

Don_ih said:
That's nice.

Anyway, that wasn't current hp5, so not exactly the same. And you had no control sample.

As I said, we did not worry about such things in those days.
but we can imagine, that the circumstances those films had to live under, were a lot worse than what OP describes.and if Ektachrome can do it, HP5+ can

How quickly will heat fog B&W film?

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