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Idea for 2-perf that doesn't involve modifying pulldown


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#1 Zachary Vex

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Posted 11 December 2006 - 02:00 AM

Okay, call me crazy, but I've got an Eyemo and I'd like to shoot Techniscope-style images, but none of the transfer facilities in my town (Minneapolis) have the ability to do 2-perf (except scanning, which I don't want to pay for.) So being the imaginative nutjob that I am, I've come up with a scheme which I think might work...

First, I have a machine shop fabricate a modified gate so that only the upper (or lower) half of the image is exposed on the film, protecting the other half from being exposed at all. The film is run through the camera from beginning to end. The camera is stopped before end of the roll and turret is moved out of the way, exposing one of the frames to the open air, where the film loader pokes a pin through the center of the exposed half-frame. This marks the film so that it isn't accidentally re-inserted in such a manner as to expose over the original shots!

Next, the camera is run out in the change bag and the loader flips the rolls over a-la regular 8mm, to expose the other half of the film. The film is drawn off the new supply reel until the pinhole is felt with the fingertips, which is carefully placed behind the protective part of the gate as the sprocket holes are locked onto the pull-down claws.

Finally, the other "half" of the film is exposed, and during the tele-cine process, the image is sized and letter-boxed to suit as the film is run through the transfer twice, once for the first half, once for the second!

Anyone see any flaws in my reasoning, or have any suggestions?
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#2 Zachary Vex

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Posted 11 December 2006 - 03:50 AM

Just to be clear, I've applied for a patent on this approach. 8^)

I think it will help indie filmmakers make the best use of their film/process/scan money! Nothing like increasing depth-of-field and close focus while using easily-obtained spherical lenses, cutting film/process/scan costs in half, and getting all the way to 2.33 wide all at once! Imagine modifying your 35mm movie camera for about $500 with a simple screw-in gate that takes advantage of the new low-grain stocks and all of the lenses you have available in town, plus lets you use your local telecine people to take care of transfers (once forward, then again!)

BTW, it's called CineVex [tm]. 8^P At least that's the working title. heh.
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#3 Nick Mulder

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Posted 11 December 2006 - 04:45 AM

how are you going to move the optical centre of the lens ?

especially with wides it would be noticeable ...

why not mask the tops and bottoms to the 2-perf aspect ?
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#4 Zachary Vex

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Posted 11 December 2006 - 05:20 AM

how are you going to move the optical centre of the lens ?

especially with wides it would be noticeable ...

why not mask the tops and bottoms to the 2-perf aspect ?


good idea. i've just re-written my patent application. thanks! z

Edited by Zachary Vex, 11 December 2006 - 05:21 AM.

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#5 Stephen Williams

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Posted 11 December 2006 - 05:44 AM

Hi,

Nothing new about that. I believe that was trick was used in India! No optical blow up either just modify the projector, not sure what happened with sound!

Stephen

Okay, call me crazy, but I've got an Eyemo and I'd like to shoot Techniscope-style images, but none of the transfer facilities in my town (Minneapolis) have the ability to do 2-perf (except scanning, which I don't want to pay for.) So being the imaginative nutjob that I am, I've come up with a scheme which I think might work...

First, I have a machine shop fabricate a modified gate so that only the upper (or lower) half of the image is exposed on the film, protecting the other half from being exposed at all. The film is run through the camera from beginning to end. The camera is stopped before end of the roll and turret is moved out of the way, exposing one of the frames to the open air, where the film loader pokes a pin through the center of the exposed half-frame. This marks the film so that it isn't accidentally re-inserted in such a manner as to expose over the original shots!

Next, the camera is run out in the change bag and the loader flips the rolls over a-la regular 8mm, to expose the other half of the film. The film is drawn off the new supply reel until the pinhole is felt with the fingertips, which is carefully placed behind the protective part of the gate as the sprocket holes are locked onto the pull-down claws.

Finally, the other "half" of the film is exposed, and during the tele-cine process, the image is sized and letter-boxed to suit as the film is run through the transfer twice, once for the first half, once for the second!

Anyone see any flaws in my reasoning, or have any suggestions?


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#6 Nate Downes

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Posted 11 December 2006 - 06:49 AM

how do you mark so as to make sure that you don't accidentally double-expose a roll, or even worse, half-double-expose? From my math, you have a 25% chance of getting it right on re-load.
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#7 Zachary Vex

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Posted 11 December 2006 - 08:01 AM

how do you mark so as to make sure that you don't accidentally double-expose a roll, or even worse, half-double-expose? From my math, you have a 25% chance of getting it right on re-load.


Repeating what I said above...

"The camera is stopped before end of the roll and turret is moved out of the way, exposing one of the frames to the open air, where the film loader pokes a pin through the center of the exposed half-frame. This marks the film so that it isn't accidentally re-inserted in such a manner as to expose over the original shots!"

"The film is drawn off the new supply reel until the pinhole is felt with the fingertips, which is carefully placed behind the protective part of the gate as the sprocket holes are locked onto the pull-down claws."
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#8 Chris Keth

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Posted 11 December 2006 - 09:41 AM

Not a terrible idea but as Nick mentioned above, how do you move the lens when you reload to shoot the other half-frames? It will be noticeable on wider lenses and will look like moving a view camera with a rise or fall movement applied.

Honestly, if you want to shoot 2-perf that much and are already modifying an inexpensive camera, why don't you just modify it properly, movement and all?
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#9 Stephen Williams

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Posted 11 December 2006 - 10:02 AM

Not a terrible idea but as Nick mentioned above, how do you move the lens when you reload to shoot the other half-frames? It will be noticeable on wider lenses and will look like moving a view camera with a rise or fall movement applied.


Hi,

I don't think they worried about that!

Stephen
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#10 Chris Keth

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Posted 11 December 2006 - 10:29 AM

Hi,

I don't think they worried about that!

Stephen


No, view cameras don't tend to move much ( :P ) but if you have ever applied a drastic rise or fall (and even though half the frame on 35mm is small, it is large when thought of in percentage of frames) and then panned or tilted, you know it's a strange look.
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#11 Zachary Vex

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Posted 11 December 2006 - 10:50 AM

When Nick Mulder first mentioned that problem, I immediately figured out how to solve it.

It's easy to change the setup to park the 2-perf window in the middle of the frame. This still leaves a 2-perf region unexposed.

As far as the idea of using 2-perf pulldown, there are zero transfer houses in Minneapolis that can handle that... however, they can all handle this idea, which is 4-perf pulldown but would have to be transferred twice on each piece of film, once forward and once reverse, just re-framing and re-centering in each direction. And to anyone else poo-pooing this idea, the conversion for any camera would only be in the hundreds of dollars (a new gate only) rather than the thousands required to convert to 2-perf pulldown.

The advantages are immediately apparent to anyone familiar with Technoscope 1:2.33... you can use spherical lenses, get full depth-of-field, pay half as much for 35mm film stock and development, convert a camera for a song, and gain 25% vertical resolution and 40% width over a Super 16mm frame. The only disadvantage over 2-perf pulldown (Technoscope) is that the film has to be marked and re-loaded carefully so as to not re-expose any frames, and the total run-time per roll is the same as standard 35mm cameras rather than double for 2-perf pulldown. Also, keep in mind that the negative cannot be conformed... it must be scanned for release prints, but that's really not a problem in 2006 if an indie company gets that far.
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#12 Paul Bruening

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Posted 11 December 2006 - 11:30 AM

Zachery,

I have to admit, this is a pretty darn good idea.
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#13 Hal Smith

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Posted 11 December 2006 - 11:39 AM

How do you know where you're at on the 2perf/4perf scheme of things if your film runs out? This would only work if you don't ever run your film out on a shot. Otherwise you might as well rewind the half exposed roll in a darkroom and start over from the marked head of the roll offset two perfs.

On balance though it is a heck of an idea!
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#14 Paul Bruening

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Posted 11 December 2006 - 12:00 PM

No sweat. When you load the first time, you hand turn the works until the claw pulls out. Then, you pull the lens, take a Sharpy and run the tip around the edge of the gate then mark a "1" in the rectangle. The next time you reload the same roll, you mark the adjacent frame with a different rectangle and put a "2" inside it. You have to jimmy the film around in the sprockets sometimes but you can reliably line up the second set of frames. Of course, if you don't have your head screwed on straight when you do this, you botch up a lot of work and may not know it until the dailies come back.

It is a riskier system than a 2 perf pull down due to the chance of misaligning the two tracks (for lack of a better term), but darn clever on the do-it-for-cheaper scale.
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#15 Zachary Vex

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Posted 11 December 2006 - 12:06 PM

If the film runs out you are not screwed... you simply don't expose it in the opposite direction. That one roll costs you normal 35mm film and processing instead of half.

I realized this morning that there's one more problem I didn't address... the fact that the perfs pull down from the bottom of the hole in one direction and the "top" of the hole in the other. That will cause the "center" of the frame to be offset when the film is flipped in the other direction... no problem, though. I can't set the gate exactly in the center vertically... it will have to be very slightly offset up or down to compensate for the perf size. Yes, this will introduce very mild distortion in the corners of the frame when shooting 1:2.33 with a very wide lens. Will anyone notice? Heck, I've suffered watching all sorts of visual distortions associated with anamorphic shooting and projection ever since I was a kid... I'm sure it won't be a problem at all.

BTW, for those of you worried about changing a roll in a change bag or tent, trying to feel the position of a frame that's been marked with a pinhole, there's a solution to this problem as well. This guy offers cassettes that allow you to load a camera in full daylight and then drop the film into place in the change bag once you're finished.

Posted Image

http://www.supervision2perf.com/

No sweat. When you load the first time, you hand turn the works until the claw pulls out. Then, you pull the lens, take a Sharpy and run the tip around the edge of the gate then mark a "1" in the rectangle. The next time you reload the same roll, you mark the adjacent frame with a different rectangle and put a "2" inside it...


Brilliant except for one thing... the frame you've marked "1" is at the original "head" of the roll. When you're ready to change direction, you're at the tail. Oh well!
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#16 Hal Smith

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Posted 11 December 2006 - 12:08 PM

No sweat. When you load the first time, you hand turn the works until the claw pulls out. Then, you pull the lens, take a Sharpy and run the tip around the edge of the gate then mark a "1" in the rectangle.

I guess that's a given then, you have to plan to rewind rolls if one ever runs out. IMHO it would be best to implement the system planning on rewinding all your rolls. Probably on a longer shoot always re-running rolls on the next day would make for smooth operations. I wonder what experienced AC's like Doug Hart would think of this idea - I'll email him and get his opinion. Bruce at Aranda would have some interesting input also.
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#17 Paul Bruening

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Posted 11 December 2006 - 12:11 PM

I wouldn't try to run the film in both directions for the reason you stated, Zach. The frame line in techniscope is thin to begin with. I don't think the perf holes will allow you to pull that off. I do think you can rewind the rolls and shoot them again. If you have a camera that can transport film in reverse, well, problems solved.

I wouldn't try to run the film in both directions for the reason you stated, Zach. The frame line in techniscope is thin to begin with. I don't think the perf holes will allow you to pull that off. I do think you can rewind the rolls and shoot them again. If you have a camera that can transport film in reverse, well, problems solved.

As well, let a shop that knows cine do the machinig. Bob and Mark at Fries or Bruce at Aranda Film Group are some that come to mind.
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#18 Zachary Vex

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Posted 11 December 2006 - 12:13 PM

Kodak keeps their perf holes cut to a very tight spec. I'm absolutely certain that offsetting the gate very slightly up or down will make every last fraction of a millimeter available for exposure in both directions!

Edited by Zachary Vex, 11 December 2006 - 12:14 PM.

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#19 Paul Bruening

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Posted 11 December 2006 - 12:15 PM

I look forward to hearing about your results. Please, keep us up to date.
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#20 Zachary Vex

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Posted 11 December 2006 - 01:22 PM

Hey Paul, your domain is expired.
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Gamma Ray Digital Inc

Wooden Camera

Ritter Battery

Aerial Filmworks

Technodolly