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#1 Deepak Bajracharya

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Posted 29 July 2011 - 05:46 AM

Namaste,



Please notice that the picture has a noticiable vertical movement. It was shot with highspeed of 75 fps. However, the shots taken with 48 fps, 50 fps, 60 fps have never such issue.

Please help me trace out the problem regarding this issue. Whether it is on the camera or magazine or any other things else.

With best regards,
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#2 Dom Jaeger

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Posted 30 July 2011 - 08:28 AM

Hi Deepak,

First off, I'm not very familiar with Aatons, but I work on other cameras, so maybe I can help a little. Otherwise, if someone who knows Aatons better chimes in, listen to them.

If your other high speed footage was OK you can probably rule out things like unstable camera support, camera vibration or transfer issues.

To properly work out what's going on I think you should shoot a double exposure steady test, at various frame rates and with each mag. If you're unsure of any part of the procedure let me know and I'll describe it (or at least the version I find works best). Just make sure the camera is firmly supported on a solid floor when you shoot the test.

You haven't said what camera you're using, but as far as I know 75fps is the top speed of XTRplus and above 16mm Aaton models, so you're testing the camera and mags to their limit. Any wear in the movement, or out of tolerance pressure plates or clutches in the mags, or even just dirt build-up in the gate, will affect vertical steadiness at high speed more than normal speed, at least in the cameras I work on. But once you've shot a steady test you'll know for sure if it's the camera, a mag, or something external.
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#3 Deepak Bajracharya

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Posted 30 July 2011 - 09:56 PM

Thank you very much Dom for your thorough insigtful reply.

The camera is the XTR plus.This same thing was seen on final print so not the transfer issue. The camera was on solid support and I didnot notice any camera vibration during the shooting. However, the picture is fine upto the speed of 60fps.

Please describe the double exposure steady test procedure. I suspect the problem is with one of the magazine.

Thanks in advance.

With best regards,
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#4 Dom Jaeger

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Posted 31 July 2011 - 04:53 AM

Ok - basically you shoot a grid pattern test chart, then you rewind the film, offset or twist the chart slightly, and shoot it again. On the first pass you shoot at all the frame rates you want to check, maybe 24, 50, 60 and 75. You only need to get 5 or 10 seconds at each frame rate. Make sure you label the chart with the mag number and each frame rate. On the second pass, with the chart tilted and the labels removed, you shoot that same length all at 24fps. Repeat the procedure for each mag. You only need to process the film, viewing the projected neg is fine.

What you'll get is a double exposure with 2 grid patterns, offset so you can check if there is any movement between them. Don't worry about the whole image steadiness, that is unimportant (and related to the projector), what you're looking for is any change between the 2 grids. When a camera is steady the 2 grids will not move relative to each other.
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#5 Deepak Bajracharya

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Posted 10 August 2011 - 01:05 AM

Thank you very much Dom.

I checked with the footages shot on highspeed and the found out that the problem lies within one of the magazine. Rest is fine with the camera and the other magazine.

Think that magazine needs the servicing.

With best regards,
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#6 Dom Jaeger

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Posted 10 August 2011 - 09:06 AM

No worries Deepak, glad to hear you worked it out.

Thanks for posting your findings, often people never report back and you're left wondering what happened..

Namaste :)
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Glidecam