What is the proper name for bent edges of image?

[DavidOP]

The analog films do not produce a perfectly rectangular image. The edges are slightly bent, apparently to the way light projects through the aperture.

What is the proper name for it so that I can google and get more info?

How do you measure the size of this image? In the middle the distance will be longer than on the sides. Do you take the max, min, or average? This refers to the image on the film and not the way it is cut on paper.

 

[Josh66]

The shape of the image on film is defined by the shape of the mask. If it's not rectangular, it's only because the mask isn't rectangular.

Strong hi-lights can sometimes 'bleed' past the edges of the frames, but I don't think that is what you are talking about...

 

[timor]

Or, David, do you think of barrel and pincushion distortion ? Or diffraction ? When light bends on thin edge of small aperture iris ? In any case doesn't matter, lens projection is always circle, but on the film you have rectangular or square, but Josh said that.

 

[DavidOP]

maybe a sample will help

http://assassinationresearch.com/zfilm/z190.jpg

Notice all the sides are slightly bent. Since the horizontal size is longer, it is more visible. The distance from bottom to top is slightly longer in the middle when you compare to the leftmost side.

What is the name for this anomaly. If this is diffraction, then what is the name for this type?

 

[Light Guru]

The shape of the image on film is defined by the shape of the mask. If it's not rectangular, it's only because the mask isn't rectangular./QUOTE]

This is exactly right. Lenses don't create rectangular images they create circles. You are used to seeing rectangular images because that is the shape of the opening that would let light though to the film. If the edges are rounded its because that mask had rounded edges.

 

[Light Guru]

maybe a sample will help

http://assassinationresearch.com/zfilm/z190.jpg

Notice all the sides are slightly bent. Since the horizontal size is longer, it is more visible. The distance from bottom to top is slightly longer in the middle when you compare to the leftmost side.

What is the name for this anomaly. If this is diffraction, then what is the name for this type?

That peace of film is simply not being held flat hence the bulging in the edges.

 

[chris]

This is presumably a frame from the Zapruder film of the Kennedy assasination. It was taken on an 8mm movie camera, probably using 16mm film in a double 8 format where the film is run one way through the camera exposinfg down one side of teh film and then turned over and rerun through the other side to expose on the other half. The shape of the frame is entirely due to the shape of the film gate in the camera.

Judging by your post you seem to have a fixation with the Zapruder film; if you would explain what your interest is then maybe you would get a fuller discussion.

 

[timor]

maybe a sample will help

http://assassinationresearch.com/zfilm/z190.jpg

Notice all the sides are slightly bent. Since the horizontal size is longer, it is more visible. The distance from bottom to top is slightly longer in the middle when you compare to the leftmost side.

What is the name for this anomaly. If this is diffraction, then what is the name for this type?

Ha, film is bent and the picture is taken from on angle, look at the sprocket holes ! Possibly very short lens for taking this photo was used adding to the perspective distortion. OK, name for that effect is called: careless photography.