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Suggestion for built-in crystal option in Bolex EBM/ESM/EL


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#1 Boris Belay

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Posted 16 November 2005 - 10:05 AM

Here's a simple idea I want to try out as soon as I get a chance -- it should be sound and easy, but if anybody (Clive Tobin ?) has anything to add/confirm/improve/take down, please let me know.
The EBM grip is necessary to strart/stop the camera but it is also supposed to house proprietary (cylindrical!) batteries that are now mostly dead or very expensive to replace. They also add weight to a hand-held system for not much power, even at full charge. So besides the cable to an external battery (minor annoyance in most cases), standard 12V. external battery packs are a big improvement.
Which leaves us with an empty cavity in the grip, whose connector handles all outboard connections to the camera, including an optional crystal unit. If we have an external battery pack, the crystal unit must then be piggy-backed to the battery (ok but still inconvenient with the Bolex External Battery Housing, harder with other set-ups).
I recently picked up a Tobin TXM 11 Crystal Unit (EBM/ESM/EL) and realized it's so tiny (thanks, Clive!) that it could easily fit in the battery compartment of the grip. Since all the connections are through the grip anyway (and it's easy to take it apart), I thought it would be a perfect idea to hard-wire one of these crystals in a grip to have a permanent built-in crystal camera rather than a dangling series of outboard bits and pieces.
All it involves is desoldering the crystal's plug and soldering the connections from the inside into the grip's main connector (where it would plug in anyways). The one question to work out (but it's a matter of personal preference) is what to do with the crystal unit's synch light. If one knows the camera to work well as is, perhaps the light is not so necessary. Otherwise a hole could be drilled in the back of the grip so the light is visible trough it. A better option would be to bring the light outside of the grip (a couple of soldered wires) and place it wherever it is convenient for the shooter. Ultimately, it could even be placed inside the view-finder, EL-style, but that's a lot more involved and makes the conversion more or less permanent.
One point : besides this last option, this modification only involves the hand-grip, which is detachable anyway. So one could even have one crystal grip and a spare regular one. Also, the modified grip could just as easily be brought back to its original state (besides the hole for the light, but that's not even a concern for the grip's function).
The only limitation is that the crystal unit is not easily removeable anymore, so not useable with the tripod base, for instance. Or another option could be worked out where a second connector is soldered inside the grip with enough wire to easily connect and disconnect the unit when needed, while still all fitting in the grip.
Obviously, the same modification works with the ESM outboard motor for Rex-4/5/SB/SBM. And that grip could be adapted for the EL too (with just the crystal connector changed, or both power and crystal through the grip).
Has anybody tried anything like this ? Any suggestions or good reasons why not even bothering with it ?
Also, which other crystal units, besides the Tobin TXM-11 would work, space-wise (short of dismantling them) ? The Bolex Unit is housed in a largish enclosure but perhaps there isn't that much in there once the two connectors are removed. Other brands ? Any other Tobins, now that the TXM-11 has been replaced ?
-B
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#2 Clive Tobin

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Posted 16 November 2005 - 07:56 PM

Here's a simple idea I want to try out as soon as I get a chance -- it should be sound and easy, but if anybody (Clive Tobin ?) has anything to add/confirm/improve/take down, please let me know.
The EBM grip is necessary to strart/stop the camera...


The TXM-11 was a cute little unit that normally works fine, however it does not have an actual out of sync light. I rather euphemistically called it a "status light" since it is on all the time and the way it does or doesn't blink tells you if it is out of sync.

The subsequent TXM-16 had a sync alarm but it tended to be very dim for some out of sync conditions.

The current TXM-24 is a board I would recommend if there is room. The board is 1.4 x 2.5 inches if that will fit in the available space. We can make it as a single speed unit for 23.976, 24 or 25 FPS or switchable from 24 to 25. It has a perfectly reliable and bright sync alarm. We can supply with the sync alarm LED not mounted on the board so you could remote it to elsewhere on the grip. There are 4 wires to connect, +, -, tachometer signal in and correction signal out. We could make some sort of deal for a qualified tech to buy the basic board without the case and cable. Price may depend on how much hand-holding we have to do...

You wouldn't need two grips in order to shoot at other speeds. Switching the camera out of the "sync" or "crys" switch position makes it ignore the correction signal from the crystal. So the sync alarm will be flashing wildly but this wouldn't hurt anything.
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#3 Boris Belay

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Posted 19 November 2005 - 09:21 AM

Thanks Clive. Sounds interesting and I'll look into the possibility of using this upgraded Crystal Unit. I'll start with my TXM-11, but if anyone else is interested in either sharing info on this or possibly my doing the mod for them, let me know.
And indeed, the non-modified spare grip is only useful as a safety back-up, since the crystal can stay plugged in while on non-synched speeds.
-Boris
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CineTape

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rebotnix Technologies

Broadcast Solutions Inc

Technodolly

Opal

Paralinx LLC

Visual Products

Willys Widgets

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Gamma Ray Digital Inc

Wooden Camera

Abel Cine

Media Blackout - Custom Cables and AKS

Aerial Filmworks

Rig Wheels Passport

Glidecam