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Does 16mm run at exactly 36'/min?


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#1 Michael Collier

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Posted 08 January 2010 - 09:28 PM

I am working out the final details on my controller, and one sticking point that I haven't been able to 100% verify is the speed at which film runs through a camera.

I have always used 36' per minute as a rule, and I am sure its pretty close to that figure, but since my board will hold an odometer that counts up to 6.5 million feet, and because my warranty will be based in part on total film run, I need an accurate figure of the exact speed film runs through the camera.

So my question is has anyone heard of a more accurate figure than 36'/min?

(my calculation of feet passed for the counter works like this: 36'/min = 1440 frames @ 24fps. the motor has a 5:2 ratio in feedback pulses:frame. so every 3600 pulses = 1 min = 36', so 1' = 100 pulses. If its not exactly 36' then it might be 101 pulses or 100.0456 etc. Just want to be accurate)

Thanks
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#2 John Brawley

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Posted 09 January 2010 - 12:20 AM

I am working out the final details on my controller, and one sticking point that I haven't been able to 100% verify is the speed at which film runs through a camera.

I have always used 36' per minute as a rule, and I am sure its pretty close to that figure, but since my board will hold an odometer that counts up to 6.5 million feet, and because my warranty will be based in part on total film run, I need an accurate figure of the exact speed film runs through the camera.

So my question is has anyone heard of a more accurate figure than 36'/min?

(my calculation of feet passed for the counter works like this: 36'/min = 1440 frames @ 24fps. the motor has a 5:2 ratio in feedback pulses:frame. so every 3600 pulses = 1 min = 36', so 1' = 100 pulses. If its not exactly 36' then it might be 101 pulses or 100.0456 etc. Just want to be accurate)

Thanks


Does it not depend on your frame rate ?

Aren't you better counting frames ? There are 40 frames per foot.

jb
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#3 John Sprung

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Posted 09 January 2010 - 03:25 AM

You want to go by the frame rate. The negative pitch is indeed something less than 0.3000", IIRC it's 0.2996" or 0.2994". But that doesn't matter. Sync goes by frames and sprocket holes. Using 36 ft/min will get you the right answer.





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#4 Charles MacDonald

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Posted 09 January 2010 - 11:03 PM

You want to go by the frame rate. The negative pitch is indeed something less than 0.3000", IIRC it's 0.2996" or 0.2994".

0.2994 according to the Kodak Spec sheet
And If that is important to your application, the film does tend to shrink with age.
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#5 Michael Collier

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Posted 11 January 2010 - 04:17 PM

John, yes I am counting frames, (actually feedback pulses, which are 1/25 of a frame) but I wanted to get an exact measurement of how many interrupts to count per foot, so I started with what I had commonly held to be accurate: 36'/min. Thanks JS and Charles, going off those figures it would seem that film runs at 35.928'/sec. 36'/min is accurate enough for the mag film counter, but for the odometer I will have to adjust my values to make sure the figure is accurate over a 6.5 million feet pull. Its more like every 100.2004 interrupts/foot.
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#6 Tom Jensen

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Posted 11 January 2010 - 05:16 PM

Aren't you spending a lot of time and effort on a camera that is obsolete? Who really uses a CP-16? People can't unload their SR's fast enough. They drop in value daily, it seems.
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#7 Michael Collier

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Posted 11 January 2010 - 06:33 PM

Aren't you spending a lot of time and effort on a camera that is obsolete? Who really uses a CP-16? People can't unload their SR's fast enough. They drop in value daily, it seems.


Finally! somebody calls me on it. That is in my head a lot as I work, but keep in mind, this is just a side project. its cold and dark outside, there is litterally sun only until about 4 these days. Work is slow, so I got time to kill. And the economics are right for me. I don't have to sell very many of these boards to make it worth my time.

Plus its a two part effort, one is to gain credibility for the next time I want to design a new product so I can get financiers so I can hire engineers (so I don't have to design all the hardware and code and debug everything myself) and so I can get a little bit of cash to patent my game changing idea. Full worldwide patents aren't cheap. But I need a patent to even get to the stage where I start looking at how much it would cost to develop the next invention into a viable product.

but as far as my personal time, looking at very very conservative estimates on how many I can hope to sell, I should do alright, at least enough to make it worth my time, along with setting up other opportunities.

You mention SR3s and their dwindling market, that is the whole point, is to capitalize on a dwindling market that is shifting to the lower end/hobbiest with less cash to burn, where I can be more competitive. SR3s still sell north of 10-15K depending on accessories. Modifying a CP-16 which might cost $1000 on ebay with a $1245 upgrade results in a camera that has almost every feature the SR has (minus pin registration, which on a well maintained CP isn't an issue). Instead of spending 300 a day on a rental, you can spend under 2500 for a camera you own.

I have already gotten requests from people who have very low budget film projects in the works, and want to use my system to keep costs down, while sticking to a 16mm origination. film schools that just want to teach the basics of film can keep their cameras running, and bring it more in line with features that are available only in higher end cameras. Trust me when I say I have done lots of thinking on this subject, and it is a limited niche market, but one where I can make some money in.


(also, I spend only about 10-15 hours a week on the project. Max I have done 20 in a week, but that is rare.)

But thank god you called me out, I have been waiting for anybody to play devils advocate.
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#8 Tom Jensen

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Posted 11 January 2010 - 07:25 PM

I'm the perfect devil's advocate. Whenever a new camera came out, there was always someone who came up with something that (a) the builders neglected to add or (B) that was cheaper than the factory offered. What comes to mind is batteries, matted box, follow focus units, rain covers, barneys, crystal motors. There was always a market for that. There is a market for that but then it becomes saturated and sales slow. If you are into inventing, which you obviously are, watch where the rental houses spend their money. They are the first to figure it out before anybody else and they are the ones that get the business. They dumped the CP-16 a long time ago. The rare house that carries the CP-16 does so because they are paid for and they are a niche business. Video has completely changed the 16mm market and is changing the 35mm dramatically. When 16mm was in its' heyday, it was the work horse of the industry. Commercials were shot in 16mm, documentaries were shot in 16mm, industrials were all shot on 16 and even some home movies were shot on 16. Arriflex was really instrumental in changing the face of 35 because it gave Panavision a stark wake up call. Here was a 35mm camera that could go anywhere, it was "light" and you could shoot in all types of conditions. The SR pretty much made most 16mm film cameras obsolete. In the 80's, 99.97635% of all music videos were shot on SR's, Some were shot in 35mm but most were shot on SR's. Then once video reared it's head, it put a dent in 16mm like no other. There was no need to shoot 16 for most things like some commercials, infomercials, etc. Now it has taken over all aspects of film. Who would have thought that you could shoot a movie on digital. A director of photography or cinematographer was something that was reserved for someone to who shot film. Now everybody with a video camera is a DP/Cinematographer and some have never even shot a framer of film. OK, I digress but my point is that the CP-16 is at the opposite end of the spectrum. I would look to see what can compliment or accent what's being built today. It too will be obsolete some day but at least you can ride the gravy train if you can come up with something viable and usable today. I hope you sell a ton because I like to see others do well. But, I have seen lots of ideas sputter to a halt because of the lack of demand.
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#9 Michael Collier

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Posted 11 January 2010 - 07:42 PM

well I think we have different ideas of success/failure. You say you hope I sell a ton. I hope I sell 100. maybe 150 (maybe 15-25 pounds of gear in the end...no where near a ton). There are aprox 1000 CPs still being serviced at least every other year. market penetration probably won't exceed 20%. 200 sold is a smashing success. 100 sold at least gets me to the next invention.

This one is mostly a project of time. The features are achieved in the software, not hardware, so I can add more features by spending more time, not by cutting my profit margins. Also its customized to the type of person that would be using this camera. Its optimized for short ends and limited funds. Its a niche, which if nothing else, I will make a few grand off of, get to the next invention (that will be more aimed at the general market, not a niche segment like this product) and get to shoot a few thousand feet of film for free.

That last bit alone almost makes it worth it. Through the generous support of dozens of people and companies (including Kodak) I will get to try out the new V3 stocks, get some fashion photography on my reel (which at this point has none) and set me up to develop a product that I guarantee you won't find to be so limited in its potential.

But you did recognize one true thing, most after market crystal motors are saturated. That's why tobin got out of the game, (I infer of course, not directly quoting him) but CPs never had an after market crystal sync. Nor could one be easily adapted to the camera. Add in the fragile nature of two of the hybrid circuits included on the board that is no longer manufactured. It was when my board fried, in talking with the camera tech who told me there is no solution for a fried board. He would replace my board with a board from another camera, for almost as much as my upgrade costs. so its a small niche that I am filling by designing a board with as much functionality as I can, to make the CP sexy again, and give it features only found in used cameras more than 5 times the value of a CP.
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