I just watched part 1 of Place of Execution, a PBS mystery. The plot (spoilered in case you want to see it in repeats):
It is northern Britain in early 1963. The stepfather of a teenage girl is suspected in her disappearance. Police find photos and apparently matching negatives in a hidden safe in the family house, showing the stepfather and the girl having sex. Stepfather, a skilled photographer, scoffs that both photos and negatives are fakes. The lead detective, who is said to be a skilled photographer himself, is shown looking at the negatives very closely with a magnifying glass.
My understanding was that the state of photography in 1963 was such that although a photo could be faked, negatives could not be in such a way as to withstand scrutiny. A faked negative would be obvious to any pro of the time. True?
Hell no. You could modify a picture and then photograph it to produce a new negative. I made high quality negatives from photographs whose negatives had been lost.
Depends upon how careful the pro was being. For instance if someone claimed the neg came from a particular camera, I would be looking at the exact framing of the neg, and comparing it with any other neg from that camera.
I would also be looking at the precise optical distortions in the picture, and comparing them with pictures taken with that camera and lens.
Both of these examinations could reveal whether the picture had been rephotographed, and certainly whether it had been taken with the camera claimed.
Other things to consider. What the film used was. Was the film consistent with the picture being taken? The picture’s charateristics will be a guide to the actual photographic parameters. Depth of field tells you the f-number. Any motion blur can help constrain the shutter speed. And the picture subject and conditions tell you about the light. Are these all consistent with the film used?
Reproduction film is different to normal film, and rephotographing a picture onto a new negative will change the contrast of the picture in a difficult to disguise manner. If the picture was rephotographed from a print it would be trivial to show that it was faked. It would have a dynamic range at least three stops less than a real neg. Not obvious if the neg is reprinted, but trivial in the extreme to find with a photodensitometer.
Nowdays a fairy simple set of tests using well known signal processing steps could reveal most of these issues quite quickly. Back then it would have been harder to be sure, but I would hope that a pro who was familiar with faking techniques would have a good idea what to look for.
Not so sure, under magnification event the best etching, brush strokes, as well as inclusions are unlikely to go unnoticed. Superposition changes texture or density, any blanking out is difficult to join perfectly. Maybe a very poor quality image would be difficult to detect, but I would have too see it to agree.
In the past I did a bit of retouching offset graphic negatives by hand, even under quite low magnification (5 to 15x) just about every modification was visible and those films were without gray intermediairy tones.
I doubt it possible, even discounting hand mistakes, to do anything significant to a picture without some sort of line or texture or shadow distortion, color is worse.
If you altered a picture then rephotographed it the depth of field and blur would remain the same. If you used the same camera and the same film, the negatives would look the same. Unless you had the original negative to compare it against, I don’t see how you could determine there is less dynamic range. I believe there is too much variation among original negatives to say whether or not it was rephotographed. I’ve printed photos from negatives that have just the faintest image to those that are very dark.
The guy could be looking at the negatives just to see if they are actually the same as the photographs.
Theoretically, one could fabricate a negative by simply painting with light exposure. But the intricacy required to create a real looking photograph is far too time consuming and the skill is so far beyond 99.9999999% of the artists out there.
The question I have for the OP: were the negatives actually faked in the plot? If not, then the detective was simply scrutinizing for the kinds of manipulation that would be easy to fake but hard to hide in a negative - like spliced heads. If he didn’t see anything to make him believe it was a fake, its hard to say how good the fake had to be.
My cousin did this with Civil War-era family photos for an art project. This was pre-Photoshop.
She photographed the old photos first so she could print multiple copies and physically cut them apart and paste new elements onto them.Then photographed those collage-like photographs. She ended up with freaky realistic looking and totally impossible photographs and corresponding negatives.
In the OP’s scene it sounds only as if the cops found photos and negatives that matched the images. I would assume that they hadn’t yet actually examined the negs are enlarged the images on the negs yet.
But for the general PBS plot: Faked negatives? I’m sure fakes could have been been made in 1963, that to the untrained, would look legit. But undetectable? That would be pushing it.
I, too, would agree with this. Done skillfully, with a razor sharp lens, a good print, and even lighting of that print, I think it would be difficult to tell, at least with just a loupe. There will be a minor degradation of the quality of the negative from the copying process. But, as you mention, it will be hard to tell without the original for comparison.
My only guess would be analyzing the grain might yield some forensic information that could help determine whether a print was an original or a copy. The original scene you’re photographing does not have grain. The print from that scene does have grain. Photographing that grainy print would yield grain on top of grain. If I had to guess, I’d think that looking at the grain under a microscope, or at least something more powerful than a photographer’s loupe, should be able to reveal that something is amiss.
edit: And, after seeing the above post, if you have the faked prints and the negs made from them, I believe the grain analysis should be enough to figure out that the negative is a photograph of a print, not the original scene.
We don’t know yet. Part 1 aired on Sunday; part 2 will air this coming Sunday.
It’s a murder whodunit, and it has been implied that the negatives might be faked; the prime suspect insists that they were. It’s even possible that the lead detective, a skilled photographer himself as I wrote, either chose to say nothing about any problems he noticed with the negatives in his determination to nail the prime suspect, or was - less likely - complicit in the actual faking of them. We’ll find out on Sunday, I hope.
I haven’t seen the movie, but I have read the book three or four times (and no, I’m not going to give anything away). The defense in the case presents no evidence that the photos in questions were faked. The attorney simply makes the suggestion during the trial as part of an all-out assault on the integrity of the lead investigating officer.
Yes. The point was that DOF can tell you what the f number was.
Finding fakes is about consistency checking. If the f number, required shuter speed and lighting don’t match the film speed of the film stock you have, there is an inconsistency. I most certainly did not say that the depth of field changed.
Indeed they would. But faking very likey does not have such access. This is another consistency check. Using whatever camera was suppoised to have been used originally as the rephotographing camera may well impose all sorts of very difficult constraints on the faker. Only if it was a high quality pro-level camera would things be easy. A simple point and shoot would make things very hard.
This is trivial. The negative will exhibit a charteristic truncation of the transfer function. There will be no information available outside the dynamic range imposed by the paper it was photographed from. Film has a dynamic range much wider then paper.
Exactly. You found information in the very thin areas and the very dense areas. Paper does not have this range of information, and if you printed, retouched, and rephotographed, you would lose all that information. The negative would be quite easily proven to have been so created. Not obvious with a loupe, but easy for a pro to demonstrate.
In modern times fakery, even good quality Photoshop fakery, is often easy to find with signal processing tricks. Even something as a simple as running an FFT over the image can find evidence of fakery that defeats the human eye to detect. Then again, a really high quality professional faker will now run though these tests and tweak the evidence away. But even a skilled Photoshop user is probably unaware of them.
True, but the film could have been pushed/pulled or unintentionally over- or under-developed. And it’s not like you have EXIF information to check f/stop and shutter speed. Sure, on a telephoto or normal lens it’s pretty easy to tell whether something was taken at f/5.6 or f/2.8. With a wide lens it’s more difficult, depending on where the point of focus is. For a nearby subject (within five feet or so), f/2.8 and f/5.6 would be easy to distinguish on anything but lenses 20mm or wider. For something focused farther away, it becomes rather difficult to make an accurate guess beyond a range of about two or three f-stops.
The easy answer for a whole range of the technical questions is to take the camera (or an identical one) to the point where the photos in question were supposed to have been taken and to retake the same scene, under much the same conditions, with the same film type. Thus a baseline can be established that will make a fake based upon retouched rephotographed pictures trivial to demonstrate.
The plot in question has the opposite problem. Showing that the photos are genuine. Showing the absence of obvious markers is always a bit less convincing.
Pushed or pulled film development can be detected without too much trouble. The grain structure tends to change in a well defined way. Also, the borders of the film - outside the exposed area will have a different density, and again can be easily measured. Talking to the film manufacturer would probably be needed, although again, knowing the film type, all the possible variations could be reproduced and measured, and thence compared to the negatives in question.
