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Bolex H16 150fps and higher possible ?


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#1 Nick Mulder

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Posted 04 January 2006 - 01:17 AM

hmmm


is there anything to stop a bolex (spring wound) from going faster than 64fps if a suitable motor were attached to it ? (either/or the 1:1 or 8:1 shaft)

obviously less light getting to the film... and it would be nice to get it up to speed with a bit of ramp so as not to put too much torque on it nuts, wotnots and sprockets

but could it be a cheap 150fps+ camera ? it wouldn't be for scientific or sound sync purposes so sync would be judged by listening to the whine it made :lol:

I'm just afraid the action might rip itself or the film to bits :unsure:

cheers,

nick
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#2 Clive Tobin

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Posted 05 January 2006 - 10:22 PM

hmmm is there anything to stop a bolex (spring wound) from going faster than 64fps...


Yes, the governor. Which is always connected unless you take the camera apart to remove it.

After that, I don't know how fast it could stand.

I did hear once from an old Army photographer that they used to remove the governor from B&H Filmo 70 cameras, and then they would run 128 FPS more or less. (I don't know how long...)
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#3 Tim Carroll

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Posted 06 January 2006 - 01:12 AM

Yes, the governor. Which is always connected unless you take the camera apart to remove it.

After that, I don't know how fast it could stand.

I did hear once from an old Army photographer that they used to remove the governor from B&H Filmo 70 cameras, and then they would run 128 FPS more or less. (I don't know how long...)


Clive, from an engineering standpoint, don't you think that if you took the governor out of the camera that it would run very inconsistent? Wind the spring up and it starts spinning at 150 fps but quickly decelerates all the way down to about 10 fps as the spring winds down. Doesn't the governor work as a way to keep the spring force from dissipating all at once?

Tim
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#4 Nick Mulder

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Posted 06 January 2006 - 03:46 AM

Clive, from an engineering standpoint, don't you think that if you took the governor out of the camera that it would run very inconsistent? Wind the spring up and it starts spinning at 150 fps but quickly decelerates all the way down to about 10 fps as the spring winds down. Doesn't the governor work as a way to keep the spring force from dissipating all at once?

Tim



I dont know much about governers myself and would like to know the answer to this also but I was originally refering to using the camera in MOT mode with a DC motor driving it in a rudimentry closed loop type system (a tacho, some sort of reference sync generator and comparator) - with a mind of seeing how easy it would be to make my own crystal sync drive in the future, thought maybe I could go for gold and try some other lower and higher and waaaay higher sync speeds in it as well -

depends on the general motor characteristics at different RPM's and then what sort of effects the inards of bolex will have on the drive speed at different FPS's tho

There are myriad websites re. engineering and electronics but does anyone know any good links for learning the mechanics and electronics that are specific to cameras and crystal sync, motion control etc ??

Also what is the best source for bolex service guides ? ... i'm about to super 16 my rx4 and am feeling confident but am a bit scared to get into the gears, spring and wotnot that would be involved in this sort of governer removal - dont want to loose an eye ;)

thanks Clive for the reply - very helpful
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#5 Clive Tobin

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Posted 06 January 2006 - 07:11 PM

Clive, from an engineering standpoint, don't you think that if you took the governor out of the camera that it would run very inconsistent? Wind the spring up and it starts spinning at 150 fps but quickly decelerates all the way down to about 10 fps as the spring winds down. Doesn't the governor work as a way to keep the spring force from dissipating all at once? Tim


Yes, though I would guess it would drift from 128-150? down to maybe 60 as the spring wound down. There is a pair of cutout gears that stops the mechanism from turning, after a certain number of turns of the spring, before the point that the spring is totally flaccid. If you filed out the notches in the cutout gears, then it would pull a bit more film and gradually sink in speed all the way down to 0. Kind of like ramping in reverse.
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#6 Clive Tobin

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Posted 06 January 2006 - 07:29 PM

...There are myriad websites re. engineering and electronics but does anyone know any good links for learning the mechanics and electronics that are specific to cameras and crystal sync, motion control etc ??...


I am not aware of any for crystal sync. Motion control texts don't seem to cover this subcategory of speed control. Most crystal motor development seems to consist of buying your competitor's motor and copying... er, Reverse Engineering it.

Not to mention names, but some companies including one whose initials are Cinematography Electronics were so concerned about being copied that they would actually remove all the part numbers with sandpaper.
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#7 Sam Wells

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Posted 06 January 2006 - 08:22 PM

Not to mention names, but some companies including one whose initials are Cinematography Electronics were so concerned about being copied that they would actually remove all the part numbers with sandpaper.


25 letter initials ? What on earth could that stand for ? :D

Similar to whatsis name who made the Stellavox coating all his electronics in epoxy so as to discourage Kudleski from discovering he'd reversed engineered the Nagra, sort of.

Ironically Kudleski ended up manufacturing Stellavox recorders for a while when the Stellavox founder (forget his name) was too sick to run the company.

Factoid: Yul Brynner backed Stefan Kudelski's venture (Nagra). A friend of mine once borrowed Yul Brynner's personal axe. Delivered by limo B)
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#8 Nick Mulder

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Posted 20 May 2006 - 04:16 AM

I inadvertanly unconnected the governer today in an SB and didn't realise there was still a little pep in the spring - wowsa did it rocket off! lucky the claw was disconnected - I did however shear off a part of the switch/run linkage system - I will have to order a new 'odd lookin thingy plate thing' from bolex...

I may instead of removing the governer and experiencing the joy of breaking my bolex at the speed of sound just slightly modify the governer springs to see how far either way I can extend the speed ranges - 4fps could be just as interesting as 100fps...

I'll order another governer to go with my aforementioned doohicky plate thingy and wear safety glasses B)
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#9 Nick Mulder

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Posted 22 May 2006 - 06:22 AM

... well I got my new doohicky bit and the SB is all go again.

As for the governer idea, yes you can get your bolex to go super fast, but as has been mentioned earlier in this thread, the speeds fluctuate so much its not useful and another problem is that as there is no registration pin the claw provides so much momentum for the film that it wont stop once the claw retracts which means vertical ghosting. One way to remedy this would be to use more spring in the pressure plate but that leads to other issues and is just as much a dead end.

There is the possibility however of slowing the Bolex down by bending the governer springs and although I am yet to try it, you can easily get down to 5fps this way and still have up to the 64fps range at the top end.. I'll have to draw a pic or take a photo to explain how - will update once I've done it :lol:
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#10 Charles MacDonald

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Posted 22 May 2006 - 08:38 PM

but could it be a cheap 150fps+ camera ? it wouldn't be for scientific or sound sync purposes so sync would be judged by listening to the whine it made :lol:

I'm just afraid the action might rip itself or the film to bits :unsure:



Actually rather than risk making yourselfa fine swiss paperweight, why not prowl the surplus stores. The auto industry has apperently gone to digital imaging for crash tests, which is probaly the real reason we lost VNF. The High speed cameras use little tricks like a prism shutter so the film can be exposed without having to start and stop, or at least multi-perf claws so that the load of starting and stoping is spread out on many perfs.

THese things are not useable slowed down and so SHOULD be less than a bolex to start.
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#11 Nick Mulder

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Posted 23 May 2006 - 06:13 AM

Actually rather than risk making yourselfa fine swiss paperweight, why not prowl the surplus stores. The auto industry has apperently gone to digital imaging for crash tests, which is probaly the real reason we lost VNF. The High speed cameras use little tricks like a prism shutter so the film can be exposed without having to start and stop, or at least multi-perf claws so that the load of starting and stoping is spread out on many perfs.

THese things are not useable slowed down and so SHOULD be less than a bolex to start.



yep, I've seen some of the designs for high speed cams and they are much more suited to the job than a bolex - its just I have a few Bolex's and am interested in tinkering :D

(also it could be used handheld)
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#12 Mark Dunn

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Posted 23 May 2006 - 06:31 AM

Locams sometimes come up on ebay. They go to 500fps and have an intermittent movement and register pin, so they're much sharper than rotating prism types. They need double-perf film though, and don't have reflex viewing when running. But they were, and still are in some places, the bee's knees for medium-speed cine.

Here's one in England but the price is a bit high. Locams sometimes come up on ebay. They go to 500fps and have an intermittent movement and register pin, so they're much sharper than rotating prism types. They need double-perf film though, and don't have reflex viewing when running. But they were, and still are in some places, the bee's knees for medium-speed cine.

Here's one in England but the price is a bit high. http://cgi.ebay.co.u...1QQcmdZViewItem
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