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Neil.Roehrborn

Jerky Fixture Movement

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I want to star by saying I love my fat frog. Now on to the question. I have noticed that the DMX output on my fat frog seems to be a bit jerky. I really have only noticed it with pan and tilt movements, usually slower moves. The fixtures will move in small increments of pan then tillt then pan etc.. till it reaches it's destination. I have the newest version of software but have noticed it with a few versions of software now. I have noticed this movement issue with all of our moving lighting including Cyber mode 2, Studio Spot 575, Studio Color 575, Intellabeam, Mac 600. Is there anything In the console that controls dmx output proccesing or is there something I can do to the fixtures? Thanks for your help!

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Check the outputs screen or the fixture outputs screen and see if the DMX outputs for the pan/tilt parameters for the fixtures looks jerky or smooth.

 

If the DMX outputs appear smooth on these screens, then it is probably something in the way the fixtures themselves are set up.

 

Do they have a movement speed or pan/tilt speed parameter ?

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-I checked out the dmx output. The fixtures are 16 bit. The coarse channels appear to be fading corectly (as best as I can tell from watching numbers on the screen). The fine channels seem to jump instead of moving smoothly. I tried capturing the fine channels at 0 (with an external dmx device) and then did the cross fade again. It made the problem worse as you might have expected. It almost seems like the fine channel is either not having enough calculations made to move the light smoothly or the calculations are incorrect, hence the light appears to move jerky. This would also explain why the symtom is not present with other parameters.

 

- The fixtures have an option for 8 bit control however I would prefer to not use this as the result would probably be worse than I have now.

 

- The fixtures do have an internal speed control. High end recomends it for smooth fades when using an 8 bit controller.

 

Thanks for all your help so far.

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Are you using software version 9.2? If so, do you have the Pan/Tilt inverted or swapped? I'm wondering if this is where the problem lies.

 

EDIT: I just tried some 99 minute fades with 16 bit fixtures on the Phantom Frog, with various combinations of Pan/Tilt invert and swap, and the numbers on the DMX output screen (course and fine) look good.

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As far as I know all pan/tilt calculations in the desk are done as 16-bit. The resultant values are then sent to the fixture as 8 or 16 bit depending on the fixture data personality.

 

Coarse and fine parameters are treated as a single 16 bit value which is then output on the two separate DMX channels.

 

If a 16 bit fixture is moving slowly you would expect the coarse channel values to be moving slowly, but the fine values will be changing very quickly between 0-255.

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I've had some problems like this too. Didn't bother me because the movement speed of the macs calculated a fine move for me, so I used that. I wasn't able to get a nice smooth move out of it, maybe something to test with an actual head in stead of the phantom.

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-Sofware version is 9.2 but like I said I have noticed it with previous versions as well when doing fades with memories.

 

-I had the tilt inverted but fliped it back to normal with no change

 

-I just did as Paul did and the numbers seem to roll smooth with that slow of a fade.

 

-As Ice said, I used to deal with Pan tilt moves with M-Speed before the super cool new software release. With the ability to fade on submasters that seems like a better way to control speed, because it's more easily editable. Worse comes to worse I'll just keep using M-Speed but I'd love it if there was a way to make things work smooth in the desk not the fixture.

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Hi all,

just a silly question. How old are your desks?

 

We had a problem with coemar heads a year ago. The movement was jerky like missing some bits.

After testing, changing DMX boards and analysing Keith found some chips which were a little bit out of specs. Probably it´s a simular problem?

 

 

Cheers

 

Sven

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I think ours is about... eeeh 2 years old, is that possible? Don't really know, but I'll try to find out.

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This does not sound like the problem that we were experienced with the the coemar fixtures. That was more of a twitch on the pan and tilt when stationary and or a large jump when it was being moved. It also had a jitter on the Gobo wheel and looks like it was jumping back and forwards between two of the gobos.

 

It would be useful if you could give me the desk serial numbers so that I can date them and see what hardware is fitted.

I will also have a little play with the mac 600 and 500 we have here and see if I can spot anything.

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Responses to your questions

 

-I am using proper DMX Cable with good solid connections. I was doing the tests as suggested above with a 10' cable from the console to the fixture.

 

-Console Serial # is 0073301 xxxxxxxx it is about 2-3 years old

 

Moderation: serial number removed.

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I'd like to second the jerky fixture movement. I see it on 16 bit fixtures with the desk. when I run those same fixtures with a hog, it's very smooth movement. When I run 8 bit fixtures with the desk, it's jerky again.

 

I suspect that whats happening is that the encoders seem to have an accelleration calculation built in so that if you move the encoder wheel fast, the fixtures move more quickly. (in other words, a 1/4 inch travel at very high speed on the encoder seems to move the fixture all the way from 0-0 to 255-255. This accelleration appears to be very very touchy.

 

This is a big disadvantage when doing focus every day...

 

 

Yes, I'm running version 9.2, yes I have good DMX cables.

 

 

John.

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my bad. I'm going to follow up my own post....

 

It's the 16 bit fixtures that I have problems with. The 8 bit fixtures are very smooth. (when I said, 8 bit jerky, I meant, 8 bit, NOT jerkey!)

 

I do have problems with the encoders on various frogs being not sensitive to very slow movement, and then going too fast when I go fast with them, so I attribute this movement issue to the algorithm for handeling 16 bit control channels.

 

And, maybe I'm responding to a different issue. What I see isn't really "jerkey" (where the fixture moves a bit, stops and then moves more, say as I crossfade from one position pallete to another...

 

what I see is that the fixture as I run it on the encoder wheels, doesn't move far enough when I move the wheel slowly, and then, boom, when I run the wheel just slightly more agressively, the fixture is at the end of the range for that parameter....

 

 

John.

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Any ideas on fixing this one? It doesn't seem to be solved yet. I didn't have much problems with until I really needed some smooth fades, and didn't have time to play with the movement speeds. Sorry guys but even movement made by the position effects generator is louzy.

 

I used: 4 macs 250 krypton; I set up a circle movement with no Y and 100% X. Set the speed to 2, and there they went! The movement was jerky (and ugly), nothing to work with. On the other hand (strangely) our Robe washes don't seem to have the same problems.

 

So that's why I thought it was one of the software bugs the Kryptons had. Went for an upgrade, and checked out movement at the same speed on a different controller (non-Frog); too bad it was super smooth. That only leaves one cause here, and that's the console. I'm going over to program some more stuff tonight, so I'll make sure to write down the serials codes and stuff.

 

Oh by the way; I checked out the fine channel manually (reading it out at the head) and that seemed to jump. I know that's rather normal because the "rate" told me the Frog sends about 20 DMX packages per second. But could that be the cause of this problem? I know the Kryptons movements are very, very well calculated, so maybe it moves 20 times a second causing this jerky movement?

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The four Kryptons that hang outa the back of my desk work fine, slow or fast. Have you set the internal speed of the unit to NORM.

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That makes no difference. The new software in the heads have improved moment qualities, so the weird things happening before are solved (the heads couldn't keep up with very fast moves).

 

I've looked up the serial number of the console:

007380101470005

 

And the tag says it's manufactured in November 2001, so that's a while ago.

 

I can't find an explanation for this problem; Robe's work perfectly, no jerky moves at all; but the Kryptons shake like duck (nothing to work with really). Martin doens't recognize my problem and because they work properly on another controller, or with a slow movement speed set up they're blaming wiring / console. The wiring is definitely not the cause of it, so that leaves the console I'm afraid.

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I was reading the release notes that come with the newest software for the kryptons, and it stated the problom with the frog range of desk was solved a few updates ago. All my martin gear works fine with the desk both before and after the new software uploads to the lamps. Try changing the internal speed of the mac's, apart from that :(

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Hi

 

We provided Martin with A Frog quiet a while back so they could test all their fixtures. I believe that they have solved all outstanding issues. Will see if I can contact them and find out more.

 

Anyone else having problems with Kryptons?

 

Graham

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I believe I found the cause of the problem. While our dealer assured us of the software being the latest version, I found out we're running a beta, and a official 1.4.3 was released on the Internet. So I'll go and update (again...) and hope all problems will be solved.

 

I'll keep you informed about this.

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I know that's also beta, but the version we're running is 1.3.4. I'm getting an update tomorrow, and I'm gonna take the console with me to check if it's fixed.

 

Oh by the way: we now own 2 Frogs... Rrrrribbit! :D

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