Oh my God, I opened the back with the film not rewound!!

Well, actually I have not done this in a while but have at least a few times in my 38 years of shooting film. Of course our immediate inclination if we do this is to quickly slam the back door shut again, but do we really need to be so fast? I mean, light travels at 186,000 miles a SECOND. Once that door is opened and the film exposed to light, even though it's spooled up the take-up end, it's been exposed. Perhaps some of the interior of the roll can be salvaged but does slamming the door shut REALLY fast make any difference to perhaps let's say, cursing yourself for a few seconds and then casually closing the camera door again?

Reason I ask is on a film blog I follow the author was sharing how he did this due to a film not being attached to the end spool correctly, and more than a few posts in reply to him talked about how they did it in the past and would then quick as lighting would close the door again. I commented: 'These comments about quickly slamming the door shut are funny. Light travels at 186,000 miles per second. Once the door was opened all the light that was going to hit any of that film has done so, no matter how fast you close the film door!" The author replied: "That would be true, Richard, if the film was laid out flat. When it's tightly coiled around the take up spool then longer exposure to light is more likely to lead to increased fogging." He seems to be implying that light penetrates in those extra few seconds, and I'm not sure I agree. What do you think? Do we really need to quickly slam a camera door shut or would closing it casually, but perhaps in some haste, make any difference?

Here's my take. Think of the tightly wound film as you would an aperture. I.E. light travels to the inner windings at the speed of light, but relatively little light gets through. The longer you leave the door open, the more light (i.e. light for a longer period of time) hits that film.

It's at least plausible.

Maybe some light hangs around a bit before speeding up to the usual speed?

I would think, with 120 film, take up roll is usually fairly tightly wound and there's paper backing. So maybe it will take quite a while to fog up the inner part?

mgb74 said:

Here's my take. Think of the tightly wound film as you would an aperture. I.E. light travels to the inner windings at the speed of light, but relatively little light gets through. The longer you leave the door open, the more light (i.e. light for a longer period of time) hits that film.

It's at least plausible.

Click to expand...

I agree but how much in 1 second vs. 3-4 seconds? I'd say not a noticeable difference at all.

tkamiya said:

Maybe some light hangs around a bit before speeding up to the usual speed?

I would think, with 120 film, take up roll is usually fairly tightly wound and there's paper backing. So maybe it will take quite a while to fog up the inner part?

Click to expand...

Sorry, should have been more specific. This pertains to 35mm which we're supposed to respool before we remove from the camera. Not 120 which we remove and tape up on the take up spool anyway.

It's human nature p.s. Richard, you have some excellent photos on your Flickr River.

Richard Sintchak (rich815) said:

I agree but how much in 1 second vs. 3-4 seconds? I'd say not a noticeable difference at all.

Click to expand...

How much? I would have to guess 3-4 times as much.

Noticeable? I suppose that would depend on the speed of the film and how tightly wound.

To go back to your initial question: "Do we really need to quickly slam a camera door shut or would closing it casually, but perhaps in some haste, make any difference?" My guess is that closing the film will be just as safe - or just as ruined - by closing casually but quickly as opposed to slamming it shut. Not to mention the risk of damage by slamming it shut.

Dont feel bad I pulled the darkslide on one of my filmholders that was pretending to be empty.....it wasn't.

Your most recent shots are ruined at the speed of light...

But the first shots coiled tightly against the inside of the take-up spool are protected by layer upon layer of film which by nature of its base density and anti-halation coating, will hold back the light enough that it takes more time to expose and fog to the point of total loss. The sprockets will be most impacted because they give light a free path in... But the faster you close the back, the less damage is done.

Take 2 rolls of junker film. Run through each with the lens cap on (ie, no images). On roll #1, nonchalantly open the door, fiddle with it, then relaxingly close it back up. On roll #2, do the same but as quick as you can. Develop both rolls together, and see if there is a difference.

I've done this a few times, and usually the only negs that are ruined are the ones that were exposed across the film plane when I opened the back. Keeping the back open longer also increases the risk you'll move the camera up, down, or to one side, which will change the angle of direct light and may ruin more of the roll.

W/ 120 film, you may ruin more than a few negs, at least on the edges.

Like momus, this has happened to me a few times and when it has the only frames ruined were the ones across the film plane -- the rest of the roll has always turned out just fine. So perhaps slamming the film door does have its benefits.

Richard Sintchak (rich815) said:

I mean, light travels at 186,000 miles a SECOND.

Click to expand...

The speed of light doesn't come into play. Exposure equals intensity times time. The longer you leave the door open, the greater the exposure. The more exposure the film receives, the more likely the light is to fog the film at the center of the coiled film.

Richard Sintchak (rich815) said:

I agree but how much in 1 second vs. 3-4 seconds? I'd say not a noticeable difference at all.

Click to expand...

The difference between 1 and 4 seconds is two stops.

Like others said fogging is exposure and degree of exposure is a function of time and intensity. Nothing you can do about the intensity but it makes sense to minimize the time.


Sent from my iPhone via Tapatalk using 100% recycled electrons. Because I care.

So bottomline is I am wrong. 1 second open vs say 4 seconds open will very likely increase the likelihood of fogging significantly, eh?

I don't think you're necessarily wrong Richard. As others said, it is just human nature to slam the back closed ASAP, so that makes sense to do. The only maxim I know is that this only happens on the negs you really wanted to print! The throw aways will be fine, but any good shot will undoubtedly be the one that gets ruined. Why is that? I haven't a clue, but it sure seems to go that way.

Just make a filter pack from those film windings and measure the filter-density from that you can do a rough calculation on the exposure to your film.

I've only had that happen after a pro shop's "repair"/replacement of the rewind spindle (I've since fixed it right myself). I close it as fast as I can (without slamming) for the above mentioned reason that the longer it's open, the more exposure it can get.

Interestingly, I don't think I've ever lost an entire frame - it always seemed to be the left and right half of two frames that are ruined, right over the film gate - even though more film than that was flat across the back and exposed to light. I think the body helps protect the film; for example, the back itself is hinged on the take-up spool side, and it's shadow probably helped shield that part. Fortunately, I've not lost anything important, and the half-frames that survived give me a good idea of what was there.