24-08-2013, 12:15 AM
hi David
I've pulled out my trusty American Cinematographer Manual for the first time in a long while (thanks!). Could you please direct me to a technical discussion of the foreground/background question? According to the depth of field chart before me, admittedly not exact to Zapruder's camera, I have a 25mm lens filming at f22 (bright sunny day) with a depth of field extending from several feet into infinity, suggesting to me that most everything within Z's frame should be in focus.
If I was step-printing the Z-film to convert 48fps footage to 16fps - then the formula you set in Example 1 would be my starting point. In fact, the printer itself could be automated to film this sequence.
But I would be concerned about the 4 sequential frame removal from Example 2, and at the very least I would want to shoot this and then have a look to be sure. This is part of the trial and error process which is a feature of optical printing. Imagine this happening numerous times - shooting a portion, then processing the footage, analyzing it, make adjustments if necessary, carry on... Point being, it is time consuming so I believe that if any work like this was done, then it could not have been completed on the Sunday. It is work that would have been extended beyond that time frame.
As a technician concerned with achieving a particular result - in this case converting a 48fps sequence into a 16fps (or 18) - I would be very concerned with "jumps", but not those contained in the body movements of people within the frame. Rather I would be concerned about time jumps and framing jumps that effects the image in total. So in Example 2, I would worry that the excise of 4 sequential frames might be too much to run past the eye smoothly. That is, the difference between frame 5 and frame 10 creates a problem that wouldn't be there if, say, it was frame 5 and frame 8 side by side. Hope I'm explaining it okay.
That said, a scenario of converting 48 to 16 (18) allows some degree of leeway that wouldn't be there if the conversion was, say, 48fps to 24fps.
In my scenario, the money quote is what Horne got from Brugioni, paraphrasing Ralph Pearse: the spring-wind mechanism of the camera results in a variable film speed. Inside this technical fact lies an alternate explanation for the quick body movements (Greer headsnap) which does not require film alteration.
Can we agree on frame rate, for discussion purposes, to represent the Z-camera's regular setting - 16fps (official camera setting) or 18fps (established average rate)?
I've pulled out my trusty American Cinematographer Manual for the first time in a long while (thanks!). Could you please direct me to a technical discussion of the foreground/background question? According to the depth of field chart before me, admittedly not exact to Zapruder's camera, I have a 25mm lens filming at f22 (bright sunny day) with a depth of field extending from several feet into infinity, suggesting to me that most everything within Z's frame should be in focus.
If I was step-printing the Z-film to convert 48fps footage to 16fps - then the formula you set in Example 1 would be my starting point. In fact, the printer itself could be automated to film this sequence.
But I would be concerned about the 4 sequential frame removal from Example 2, and at the very least I would want to shoot this and then have a look to be sure. This is part of the trial and error process which is a feature of optical printing. Imagine this happening numerous times - shooting a portion, then processing the footage, analyzing it, make adjustments if necessary, carry on... Point being, it is time consuming so I believe that if any work like this was done, then it could not have been completed on the Sunday. It is work that would have been extended beyond that time frame.
As a technician concerned with achieving a particular result - in this case converting a 48fps sequence into a 16fps (or 18) - I would be very concerned with "jumps", but not those contained in the body movements of people within the frame. Rather I would be concerned about time jumps and framing jumps that effects the image in total. So in Example 2, I would worry that the excise of 4 sequential frames might be too much to run past the eye smoothly. That is, the difference between frame 5 and frame 10 creates a problem that wouldn't be there if, say, it was frame 5 and frame 8 side by side. Hope I'm explaining it okay.
That said, a scenario of converting 48 to 16 (18) allows some degree of leeway that wouldn't be there if the conversion was, say, 48fps to 24fps.
In my scenario, the money quote is what Horne got from Brugioni, paraphrasing Ralph Pearse: the spring-wind mechanism of the camera results in a variable film speed. Inside this technical fact lies an alternate explanation for the quick body movements (Greer headsnap) which does not require film alteration.
Can we agree on frame rate, for discussion purposes, to represent the Z-camera's regular setting - 16fps (official camera setting) or 18fps (established average rate)?