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2 1/2 perf


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#1 Michael Baltazar

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Posted 28 May 2005 - 09:50 PM

Hi,

Having read up on 2-perf - I'm interested in pursuing a 2 perf conversion for my camera, but I don't want to give up 1.85 entirely. Its a huge loss of quality to crop a 2 perf 2.39 frame to 1.85, so I'm interested in other solutions...

Here was my thought - Looking at a 35mm negative - would it be possible to have a gate that's say half a perf open on the top and bottom. So it would expose more like 2.5 perfs. Essentially maintain as little room possible between frames? This would get me closer to 1.85 and still be
at 2 perf motion. Anyone know what this final aspect ratio might be?

I realize it might be an issue in post-production - printing and telecine and scanning would have to account for this area - but i'm not worried about that at this stage... Just wondering if this modification is a workable solution when shooting.
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#2 Landon D. Parks

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Posted 29 May 2005 - 12:11 AM

Id it's half a perf open on each side, it becomes "3-Perf", which is already a format.

2 perf + 1/2 perf on bottom + 1/2 on top = 3 Perfs.

Aspect ratio in 3 perf is 1.78:1 (16:9) - HD TV Ratio.
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#3 David Mullen ASC

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Posted 29 May 2005 - 01:21 AM

If you want a 1.85 : 1 image, then 3-perf is much better because it is 1.78 : 1, just SLIGHTLY taller than the 1.85 frame, so when it gets transferred to 4-perf for projection, your 1.78 mask is just slightly outside the projector's 1.85 mask. It's better to be slightly oversized rather than possibly see part of the camera mask come onto the screen. Plus the trouble with a gate that is exactly 1.85 is that you have issues like the slightly hair in the gate coming into picture frame. A 1.78 gate like with 3-perf gives you some leeway.

Besides, as Landon said, a 1/2 perf more top & bottom makes 2-perf into 3-perf, and a 1/4-perf extra top & bottom means that with every frame, you are in a different relationship to the perfs. The first frameline will be 1/4 past the perf, the next halfway between the perfs, the next 3/4, etc.

Here is a drawing of a 1.85 frame inside a 1.78 frame -- you can see that there is hardly any waste:

Posted Image
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#4 Michael Baltazar

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Posted 29 May 2005 - 02:53 AM

I guess I wasn't being clear enough - I was thinking more of using the area between perfs, which looks equal to the area of 1 perforation. Adding half of that on the bottom and half of that on the top.

Correct me if I'm wrong, but image area of 2 perf is really the area of 2 perforations plus the area between them. The image area of 3 perf is 3 perforations plus 2 'in-between perf' areas.

I guess the semantics of this is confusing - so below is a pic illustrating my proposal.

I'm familiar with 3-perf but I'm wondering if this is a viable alternative to 3-perf. even if my proposed 2.5 perf isn't exactly 1.85, would it be close enough? i.e. 2.0:1 or less. Then having to crop only 10% off the sides as such.

perfs.gif
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#5 Stephen Williams

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Posted 29 May 2005 - 03:25 AM

I guess I wasn't being clear enough - I was thinking more of using the area between perfs, which looks equal to the area of 1 perforation.  Adding half of that on the bottom and half of that on the top. 

Correct me if I'm wrong, but image area of 2 perf is really the area of 2 perforations plus the area between them.  The image area of 3 perf is 3 perforations plus 2 'in-between perf' areas.

I guess the semantics of this is confusing - so below is a pic illustrating my proposal.

I'm familiar with 3-perf but I'm wondering if this is a viable alternative to 3-perf.  even if my proposed 2.5 perf isn't exactly 1.85, would it be close enough?  i.e. 2.0:1 or less.  Then having to crop only 10% off the sides as such.

perfs.gif

<{POST_SNAPBACK}>


Hi,

The frame line is always inbetween the 2 perfs, so what you call 2.5 perf is what I call 2 perf!

Stephen Williams DoP
Zurich

www.stephenw.com
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#6 Josh Hill

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Posted 29 May 2005 - 03:32 AM

Everyone remember this thread. Someone actually agreed with Landon. And it was David Mullen at that! :P
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#7 David Mullen ASC

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Posted 29 May 2005 - 03:37 AM

Yes, that's the 2-perf format he's labelled as "2.5 perf".

There are no gaps between the frames with 2-perf, 3-perf, or 4-perf. Full Aperture means that each frame touches the next with a very thin frameline between them. Of course, you can use smaller gates to expose less than the Full Aperture, but you are either pulling down 2-perf, 3-perf, 4-perf, etc.

There's a drawing of 2-perf here:
http://www.multivisi...u/moreinfo.html

A "2.5" perf format would require the top or bottom of a frame to split a perf but the other frameline to be between perfs.

You can see a diagram of 3-perf here:
http://www.aaton.com...lm/35/3perf.php
comparing the 3-perf Full Aperture 16x9 area to the same frame shape inside the 4-perf sound aperture area.

Bottom line, if you want 1.85 but do not want to waste negative 3-perf is the way to go.

Truth is that 2-perf Full Aperture is 2.66 : 1. Techniscope and Multivision 235 use the offset sound aperture width but Full (silent) Aperture height, more or less, so you waste a little even for 2.39 despite what Multivision says about it being "naturally 2.35".
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#8 Michael Baltazar

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Posted 29 May 2005 - 05:10 AM

Aha. Guess I had a misunderstanding of 2-perf and full aperture. Thanks, its all clear now.

Yes, that's the 2-perf format he's labelled as "2.5 perf".

There are no gaps between the frames with 2-perf, 3-perf, or 4-perf.  Full Aperture means that each frame touches the next with a very thin frameline between them. Of course, you can use smaller gates to expose less than the Full Aperture, but you are either pulling down 2-perf, 3-perf, 4-perf, etc.

There's a drawing of 2-perf here:
http://www.multivisi...u/moreinfo.html

A "2.5" perf format would require the top or bottom of a frame to split a perf but the other frameline to be between perfs.

You can see a diagram of 3-perf here:
http://www.aaton.com...lm/35/3perf.php
comparing the 3-perf Full Aperture 16x9 area to the same frame shape inside the 4-perf sound aperture area.

Bottom line, if you want 1.85 but do not want to waste negative 3-perf is the way to go.

Truth is that 2-perf Full Aperture is 2.66 : 1. Techniscope and Multivision 235 use the offset sound aperture width but Full (silent) Aperture height, more or less, so you waste a little even for 2.39 despite what Multivision says about it being "naturally 2.35".

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#9 Brad Grimmett

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Posted 29 May 2005 - 08:48 AM

Everyone remember this thread. Someone actually agreed with Landon. And it was David Mullen at that!  :P

<{POST_SNAPBACK}>

There's a first for everything.
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#10 David Mullen ASC

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Posted 29 May 2005 - 12:20 PM

"Full Aperture" just means the largest area possible, which the top & bottom touching the next frame, and the sides touching the perfs. You can obviously have a camera gate that exposes less than Full Aperture, or compose for some other area on Full Aperture. With the sound aperture formats (non-Super), the lens is centered for the offset frame, not centered for the Full Aperture frame.

Since 4-perf 35mm Full Aperture is 1.33 : 1, a 2-perf Full Aperture frame has to be 2.66 : 1, which is why 2-perf Techniscope & Multivision-235 just use the sound aperture width, with the lens centered for that, since they don't need 2.66.
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#11 Landon D. Parks

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Posted 29 May 2005 - 02:37 PM

Awsome dudes! :blink: :D
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#12 Landon D. Parks

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Posted 29 May 2005 - 08:35 PM

I don't even understand why you want to have a 2.5 perf design. If what you really want is 1.85:1, shoot 1.85:1 or maybe 3 perf and get 1.78:1 (As David said), Which is so close to 1.85:1 that you dont even have to crop hardly anything.

And if you think by shooting 2.5 pers you'll save money, maybe a bit on the film stocks, but in post is where it will catch up to you. 2.5 perf is not a projection format, nor is 2 perf. I'm sure there is some kind of process that is needed to convert 2.5 or 2 perfs to 4 - perf, which will run your budget up a considerable amount. In fact so much so that you could have shot 3-perf in the first place, which still requires a similare optical step or D.I!

If you really want to by-pass the whole optical step from 2m / 2.5 or 3 perfs to 4 perf, you have to shoot 4-perf format, like 1.85:1 or 2.39:1. There is of course other 4 perf formats.

I'm right ain't I?

Plus there is all kinds of problems you'll run into shooting 2.5 instead of 2, 3 or 4... NEw Formats are always trouble.

Edited by Landon D. Parks, 29 May 2005 - 08:42 PM.

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#13 Michael Baltazar

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Posted 29 May 2005 - 10:21 PM

I don't even understand why you want to have a 2.5 perf design. If what you really want is 1.85:1, shoot 1.85:1 or maybe 3 perf and get 1.78:1 (As David said), Which is so close to 1.85:1 that you dont even have to crop hardly anything.

And if you think by shooting 2.5 pers you'll save money, maybe a bit on the film stocks, but in post is where it will catch up to you. 2.5 perf is not a projection format, nor is 2 perf. I'm sure there is some kind of process that is needed to convert 2.5 or 2 perfs to 4 - perf, which will run your budget up a considerable amount. In fact so much so that you could have shot 3-perf in the first place, which still requires a similare optical step or D.I!

If you really want to by-pass the whole optical step from 2m / 2.5 or 3 perfs to 4 perf, you have to shoot 4-perf format, like 1.85:1 or 2.39:1. There is of course other 4 perf formats.

I'm right ain't I?

Plus there is all kinds of problems you'll run into shooting 2.5 instead of 2, 3 or 4... NEw Formats are always trouble.

<{POST_SNAPBACK}>


I'm well aware all the issues in post, thanks Landon. (I do know how to add too, by the way =)).

The attraction for me is yes, 50% savings on stock, but also the 16mm running times you get w/ 2-perf. 8+ minutes on a 400' load, almost 20 min on a 1000' load. Creatively it opens up a lot more doors with the ability to shoot longer takes. And you could probably finish a 35mm 2.35 feature with a 16mm budget.

I'm still up in the air on the issue i.e. weighing the options between converting to either 2-perf or 3-perf. Here's what I'm debating...

If I'm shooting 1.85 for tv - say for music videos, shorts, commercials... I don't think the loss of area is an issue since the newest stocks have such fine grain well enough for TV, even HDTV.. Usually I can't tell the difference between 35 and 16 on a TV res anyway.

I *might* be able to live with a 1.85 originating from 2-perf on an independent short or even feature. Its still twice the area of 16 I believe. In this case I could convince myself (or whoever I"m working for) its just as well to shoot 2.35 anyway.

The drawback comes if I'm using my camera as a B-cam on a shoot that's 1.85. Not having that 1.85 option here without a loss of quality renders my camera useless in this application. In this case having 3-perf would be a better compromise.

I guess I was hoping for a best of both worlds solution... I'll still keep debating about it but thanks for all the info everyone.
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#14 David Mullen ASC

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Posted 29 May 2005 - 11:39 PM

Well, splitting the difference between 2-perf and 3-perf is splitting hairs...

If you want quality compatibility with standard 1.85, I'd go with 3-perf over 2-perf. You still get a 25% savings in stock compared to 4-perf, plus 3-perf is a lot more supported in the rental and post houses. And you can always use it with other rented 3-perf cameras. And 3-perf 1.85 is actually a slightly bigger image than standard 4-perf 35mm 1.85.
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#15 Matt Pacini

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Posted 31 May 2005 - 01:59 PM

Are there any Panavision, Aaton, or newer Arri 2-perf cameras?
Or are they all older Arri's & russion conversions?
MP
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#16 David Mullen ASC

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Posted 31 May 2005 - 06:22 PM

Are there any Panavision, Aaton, or newer Arri 2-perf cameras?
Or are they all older Arri's & russion conversions?
MP

<{POST_SNAPBACK}>


Multivision converted some Moviecams to 2-perf (I don't know if it was a Super America or Compact.)

Otherwise, what you see predates the Panaflex and Arriflex because 2-perf Techniscope died just before these two cameras hit the market. It tends to be converted Mitchells, Arri-2C's, Eclair CM3's (Cameflex)... In fact, I believe these were the cameras used to shoot Lucas' two Techniscope features, "THX-1138" and "American Graffitti".
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#17 John Pytlak RIP

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Posted 31 May 2005 - 10:03 PM

About a decade ago, a 2-1/2 pulldown was proposed for 35mm release prints, as a cost saving measure. It was known as the "Compact Distribution Print".
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#18 Dominic Case

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Posted 01 June 2005 - 05:33 PM

About a decade ago, a 2-1/2 pulldown was proposed for 35mm release prints

Ah! Thank you John.

I opened this thread thinking that it would be about that proposed format. Then as I read on and no-one mentioned it I began to doubt my memory. So it's true! There WAS a proposal for a 2 1/2 perf print format.

I think it got laughed out of court at the time didn't it? I never understood it or saw the point of it - except that it fitted the 1.85:1 frame size most economically to use minimum print stock. Projector mechanics would have been a puzzle, surely.
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#19 John Holland

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Posted 22 November 2005 - 11:57 AM

tons of films were shot on 2 perf and they looked great. widescreen and no need to use anamorphics, hence, no costly lenses, less light needed and a shallower dop. using todays stocks with 2 perf will just make the frame look even better than they did before.

The main reason Techniscope looked so good in th 60s/70s was the dye transfer Technicolor Prints , dont have that anymore , so dont think it will look that good . john holland , london
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#20 Mitch Gross

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Posted 22 November 2005 - 12:03 PM

The main reason Techniscope looked so good in th 60s/70s was the dye transfer Technicolor Prints , dont have that anymore , so dont think it will look that good . john holland , london

True, but now we have DIs. If the result is a 35mm anamorphic print. then a DI from a 2-perf will look essentially the same as one from Super-35, all other things being equal.
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