Different fog+base levels in HP5+, why?

[koraks]

I doubt it. That could be cosmic radiation fog from being high in the atmosphere. X-ray exposure wou;d have some sort of pattern or structure.

Your doubts are doubtful. CT machines do usually yield a constant level of base fog exactly as shown here. Also, cosmic radiation of a single flight (or even a dozen of flights) physically cannot yield this amount of fog.

 

[dcy]

Your doubts are doubtful. CT machines do usually yield a constant level of base fog exactly as shown here. Also, cosmic radiation of a single flight (or even a dozen of flights) physically cannot yield this amount of fog.

Exactly. If it was cosmic rays, then *everyone* travelling with film would see it and the issue would be well known, and the first comment in this thread would have been "Everyone has known since the 1950s that you can't fly with film".

 

[Agulliver]

I used to be of the understanding that CT scanning would leave wave patterns on film, because that is what the hold baggage CT scanners do and it's how I understand CT normally operates.

However, our own @koraks has shown examples of uniform fog on film from modern airport security cabin bag CT scanners. As has Lina Bessanova.

Everything we know about cosmic rays suggests there is precisely zero chance of them fogging film in the timeframe considered here. If that were the case, humans would be at significant risk. Cosmic rays are more an issue for film refrigerated for decades than a handful of flights - though it should be noted that airline pilots and astronauts do have to log their active hours to ensure they're not exposed to too much cosmic radiation.

 

[skahde]

A friend, who is running a commercial lab, and me did a test this spring, where I took one roll with me through the CT-scanned hand-luggage at Palma de Mallorca and put one in the checked luggage and left one at home. So in total we sacrificed three rolls of Portra 400 from the same, fresh batch. All three were exposed covering different natural scenes and test-charts and than developed and examinded in his lab. Both rolls which went on the plane were severly fogged with markedly increased density in unexposed areas, there were still pictures that could be rescued but colours were off and grain was heavy. It looked nothing like portra rather like some long expired stuff found on an attic. And I can assure anyone in doubt: No, this is not cosmic radiation. I have been flying with film for decades and until the advent of ct-scanners never have seen something like this crap. BTW: Palma de Mallorca refuses implicitly to hand-check. They switch to spanish if you ask in english and if you follow and insist to catalan.
So this is it for both of us: We are not going to fly with film for the time being.

 

[RalphLambrecht]

Definitely. You've got a case of CT fog.



That's the case with the regular/old fashioned x-ray inspection machines, which virtually never result in noticeable problems anyway. But CT scans result in significant amounts of overall fog, exactly what you're seeing on your film.

Especially when going through CT scans with your film, request a manual check! This is virtually always granted in Western countries.

and how does help when the film isstill in the camera?

 

[Agulliver]

A friend, who is running a commercial lab, and me did a test this spring, where I took one roll with me through the CT-scanned hand-luggage at Palma de Mallorca and put one in the checked luggage and left one at home. So in total we sacrificed three rolls of Portra 400 from the same, fresh batch. All three were exposed covering different natural scenes and test-charts and than developed and examinded in his lab. Both rolls which went on the plane were severly fogged with markedly increased density in unexposed areas, there were still pictures that could be rescued but colours were off and grain was heavy. It looked nothing like portra rather like some long expired stuff found on an attic. And I can assure anyone in doubt: No, this is not cosmic radiation. I have been flying with film for decades and until the advent of ct-scanners never have seen something like this crap. BTW: Palma de Mallorca refuses implicitly to hand-check. They switch to spanish if you ask in english and if you follow and insist to catalan.
So this is it for both of us: We are not going to fly with film for the time being.

Isn't Palma de Mallorca still using older traditional X-ray machines?

I've been flying with film for over 40 years now, and it's only the last few years that I've had any concerns about hand baggage scanners. Cosmic rays never caused any damage even on 11 hour flights to/from or journeys with three legs totalling 15 hours each way in the air. Think of the millions of people who flew with film before digital photography. I've flown with anything from 50ISO colour or B&W film to Delta 3200 which I pushed to 12800 and with movie film. Conventional x-rays and cosmic rays were never a concern. The new CT scanners are.

and how does help when the film isstill in the camera?

It doesn't help. It's going to be best to remove film from a camera, and if necessary make a note of how many exposures you took and reload it later.

What I tend to do these days is try to arrive early and then load up my cameras after security while I am awaiting the gate designation. If you're transiting through multiple airports then removing part shot rolls might be your best option.

 

[skahde]

Isn't Palma de Mallorca still using older traditional X-ray machines?

CTs were installed in November 2024. Guess why we ran the test this spring. I considered mailing the film to and from the location but it's taking chances in other areas: The post-office near to my hotel was closed on the friday before I left: What the flying fork, it was a normal working day. In that case it only hit me with respect to a few oldfashioned postcards I could send from home too, but if I was standing there with a box of exposed film it would have been a serious issue.

 

[Saganich]

I left some TriX in camera and sent it through the CT recently. The base fog was was high, like is sat in a draw for 20 years. The wave patterns is a result of x-ray inclination or the single particular angle of the x-ray to the film over some time period. CT takes on theoretically an infinite number of angles to generate a 3D image, bur actually uses 1000 to 3000 single projections during a single 360-degree rotation, or slice, which could be 1-10mm. So, regardless of the orientation of the film in your bag, it will receive a fairly uniform exposure that looks like bad fogging.

Often physicians will accidentally fly with their dosimeters and then we have to recreate and document the resulting radiation dose before removing it from their record. Generally we see 30-40 millirems per scan for carry-on plus 1-2 millirems from cross country flights. Of course this is an average across airport technology since the physicians don't know what scanner was used or if their dosimeter was in their luggage or carry on most of the time.

 

[BrianShaw]

Your doubts are doubtful. CT machines do usually yield a constant level of base fog exactly as shown here. Also, cosmic radiation of a single flight (or even a dozen of flights) physically cannot yield this amount of fog.

It might be worth notating that the NEWER CT machines being introduced/used for carryon baggage appear to be producing a constant level of base fog. The previous generation of CT used for checked baggage, indeed, were more patterned, as depicted in publications by US TSA, Kodak and others.

I once was a naysayer from repeating past experience in the present...