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Tobin Crystal and Arri 2B tachometer speed


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#1 Gene Fojtik

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Posted 26 February 2009 - 01:29 AM

I just picked up a TXM-21Ab w/ milliframe controller for my 2B. I notice that the tachometer reads a frame slower than the actual crystal speed selected. My assumption, given the age of the camera, is that the tachometer is slightly off. Should I assume this deviance if I were to run the standard arri hand grip motors on it?

Also, does anyone know what the highest speed I could safely run the motor at with this camera?

Anything else I should be mindful of with this motor? Tips?

Thanks!
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#2 Hal Smith

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Posted 26 February 2009 - 04:43 PM

I just picked up a TXM-21Ab w/ milliframe controller for my 2B. I notice that the tachometer reads a frame slower than the actual crystal speed selected. My assumption, given the age of the camera, is that the tachometer is slightly off. Should I assume this deviance if I were to run the standard arri hand grip motors on it?

Also, does anyone know what the highest speed I could safely run the motor at with this camera?

Anything else I should be mindful of with this motor? Tips?

Thanks!


A healthy Arri IIB can be run up to 50fps. A not so healthy one may start to get a bit jittery by 30fps. There was a high speed version of the IIC that can go to 80fps and conceivably your IIB could have been retrofitted with HS parts. The giveaway would be four small adjustment screws with lock nuts on the back of the camera's pressure plate.

The TMC-55 can be internally jumpered to limit the maximum motor speed. For 39.999fps Clive's instructions say to move all three jumpers to the left, the next option is 79.999fps which is only good for a healthy HS.

I don't know any serious caveats with respect to the TXM-21Ab other than make certain you've got a good stout 24VDC power supply and the polarity is correct. For AC power use I use a commercial "brick" power supply rated at 7.5 amps which is probably twice what's required but it runs nice and cool with no need for a fan.

If you didn't get instructions they're on Clive's website, you may have to email Clive to get the current URL's. Clive has always been very gracious to me with help, even for equipment now obsolete with respect to current manufacture.
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#3 Gene Fojtik

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Posted 26 February 2009 - 06:52 PM

Thanks Hal.

I don't think I have the high speed. I included the pic of the one I have.

pressureplate.JPG

My battery set up is 4 x 6v 3.3ah Werker batteries run in a series.
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#4 Tim Carroll

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Posted 26 February 2009 - 07:33 PM

Gene,

Here is a pic of the ARRI IIC High Speed Gate, it is the one in the lower left hand corner, with green paint on the four screws that Hal was talking about.

Posted Image

The gate in the picture you posted is not the High Speed version.

Best,
-Tim
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#5 Gene Fojtik

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Posted 26 February 2009 - 07:54 PM

Thanks Tim.
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#6 Hal Smith

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Posted 26 February 2009 - 08:27 PM

Here is a pic of the ARRI IIC High Speed Gate, it is the one in the lower left hand corner, with green paint on the four screws that Hal was talking about.........

Tim,

Now that I've got a IIC, Where did the 1.85 GG with the shadowed area come from? I like! Is that an original Arri GG or what?
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#7 Tim Carroll

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Posted 26 February 2009 - 10:05 PM

Tim,

Now that I've got a IIC, Where did the 1.85 GG with the shadowed area come from? I like! Is that an original Arri GG or what?


Got it from ARRI in Blauvelt, we had to look long and hard for it, found it at ARRI in Canada, had them send it down to New York and got it from them. It's nice. It's the original one from the factory. Pretty hard to come by these days.

Best,
-Tim

PS: Just another reason for you to buy the camera package, an original 1.85 ground glass, along with the Cinematography Electronics crystal motor base, that runs off of 12 volts, not 24. And can run natively at 1 fps all the way up to 80 fps, in 1 fps increments, and can be attached to an intervolometer for doing those time lapses you are so fond of. ;)
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#8 Hal Smith

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Posted 27 February 2009 - 01:00 AM

Got it from ARRI in Blauvelt, we had to look long and hard for it, found it at ARRI in Canada, had them send it down to New York and got it from them. It's nice. It's the original one from the factory. Pretty hard to come by these days.
PS: Just another reason for you to buy the camera package, an original 1.85 ground glass, along with the Cinematography Electronics crystal motor base, that runs off of 12 volts, not 24. And can run natively at 1 fps all the way up to 80 fps, in 1 fps increments, and can be attached to an intervolometer for doing those time lapses you are so fond of. ;)


Let's see: Cost benefit analysis; Buy Tim's camera...need new wife. Cost of new wife? Priceless, meaning she might as well as not have a price tag, I won't be able to afford anything after current wife is done picking my bones. And after all, I'm somewhat fond of the present Mrs. Smith.
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#9 John Sprung

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Posted 27 February 2009 - 04:19 PM

Let's see: Cost benefit analysis;


For ground glass markings, you can do your own with an ordinary pencil. It just takes some very careful measuring, using a vernier caliper as a guide, and good magnification. Better yet, the pencil can be washed off and changed when you need to.




-- J.S.
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#10 Hal Smith

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Posted 27 February 2009 - 10:37 PM

For ground glass markings, you can do your own with an ordinary pencil. It just takes some very careful measuring, using a vernier caliper as a guide, and good magnification. Better yet, the pencil can be washed off and changed when you need to.

Agreed. I do like the original Arri 1.85 GG's grayed area above and below the 1.85 aspect window. I have a hunch it's a lot easier to visualize the 1.85 frame's composition value when anything outside of it is still visible but with reduced intensity.
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#11 Tim Carroll

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Posted 28 February 2009 - 05:40 AM

Agreed. I do like the original Arri 1.85 GG's grayed area above and below the 1.85 aspect window. I have a hunch it's a lot easier to visualize the 1.85 frame's composition value when anything outside of it is still visible but with reduced intensity.


It's kinda weird. I shot a number of tests with the camera this past fall, some 4:3 Academy and some 1.85, and I really didn't notice the difference when I was shooting. For some reason it was easy/natural framing 4:3 and easy/natural framing 1.85 with that ground glass. And it wasn't something I thought about until later when looking at some of the negs and examining the ones that were framed 4:3 and the ones framed 1.85 and trying to remember if I had done anything special when shooting each, and I realized I hadn't even thought about it.

Just random thoughts floating around in the gray matter. Regardless, it's a nice ground glass, and if you can find one, I'd pick it up.

Best,
-Tim
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#12 Hal Smith

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Posted 28 February 2009 - 08:55 AM

.......... For some reason it was easy/natural framing 4:3 and easy/natural framing 1.85 with that ground glass. And it wasn't something I thought about until later when looking at some of the negs and examining the ones that were framed 4:3 and the ones framed 1.85 and trying to remember if I had done anything special when shooting each, and I realized I hadn't even thought about it.


That's what I was expecting, the design of the GG is such that it's easy to "see" the frame without thinking about it.

I've got an email into Arri CSC asking if they can find me one and letting them know Arri Blauvet had at least one of them in the not too distant past. I think I'll also post in cml-ac and see if one of the pros there has one sitting in a box or otherwise knows of the location of one.
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#13 Tim Carroll

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Posted 28 February 2009 - 09:18 AM

That's what I was expecting, the design of the GG is such that it's easy to "see" the frame without thinking about it.

I've got an email into Arri CSC asking if they can find me one and letting them know Arri Blauvet had at least one of them in the not too distant past. I think I'll also post in cml-ac and see if one of the pros there has one sitting in a box or otherwise knows of the location of one.


Just to be clear Hal, Blauvelt did not have one. They were able to find me one at ARRI in Canada, this was in 2007, and Laura said it was probably the last new one in existence. Now there may be another one floating around somewhere, and there were lots of them made, so someone probably has one used they could sell you.

Best,
-Tim
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#14 Tim Carroll

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Posted 03 April 2009 - 02:53 PM

That's what I was expecting, the design of the GG is such that it's easy to "see" the frame without thinking about it.

I've got an email into Arri CSC asking if they can find me one and letting them know Arri Blauvet had at least one of them in the not too distant past. I think I'll also post in cml-ac and see if one of the pros there has one sitting in a box or otherwise knows of the location of one.


Look what just showed up on eBay from "ARRI Canada".

K2-32083-B ARRI Ground Glass (1.85)

Can't vouch for the seller, but they are calling themselves ARRI Canada, though they don't have any feedback yet. But if the part number they have listed is the part they are actually selling in the auction, according to my ARRI sources, that is the ground glass they sold me.

Best,
-Tim
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#15 Hal Smith

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Posted 03 April 2009 - 03:21 PM

Look what just showed up on eBay from "ARRI Canada".

K2-32083-B ARRI Ground Glass (1.85)

Can't vouch for the seller, but they are calling themselves ARRI Canada, though they don't have any feedback yet. But if the part number they have listed is the part they are actually selling in the auction, according to my ARRI sources, that is the ground glass they sold me.


Unfortunately it looks like there's going to be quite a feeding frenzy for this GG, it's at $75.00 after two bids...darnit!
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#16 Tim Carroll

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Posted 03 April 2009 - 04:36 PM

Unfortunately it looks like there's going to be quite a feeding frenzy for this GG, it's at $75.00 after two bids...darnit!


Did you get in one of the two bids?

Best,
-Tim
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