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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old May 1st, 2008, 01:58 PM   #1
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XH-A1 "Pulse" Weirdness...

Just wrapped a shoot using my A1 and Letus Extreme. I noticed on a few shots - mainly where fine lines and or high contrast looks are involved - I'm getting a very slight "pulse" or moire. I did notice it once or twice on location in the field monitor and would immediately change batteries on the Letus. But I'm not so sure it's a Letus issue.

I recall shooting something a month or so ago and my subject's glasses on his face did a similar thing - sans Letus.

It's not your typical moire though. It really "pulses" more.

Anyone have a similar issue? With or without a Letus attached? Should I get my camera serviced?

Any advice would be greatly appreciated. Thanks!
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Old May 1st, 2008, 03:24 PM   #2
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After further review it MAY BE the Letus adapter and not the camera. My other moire issue could be a coincidence.

Seems the entire image slightly studders and pulses - not just the fine line edges.

Could low batteries in the Letus cause this? I guess the ground glass not vibrating fast enough??
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Old May 1st, 2008, 03:40 PM   #3
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did you turn off your image stabilizer, if you were tripod mounted?...that can cause this effect, if i'm reading this right...
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Old May 1st, 2008, 04:15 PM   #4
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To the best of my knowledge it was turned off. This was the sixth shooting day of a 12 day shoot and we hadn't had any issues to that point (and I had it turned off on day one). It's possible it got clicked on though.
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Old May 1st, 2008, 05:41 PM   #5
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I had a same or similar problem and I thought it could have been was caused by operating in manual mode but with the M/AF switch set to AF. Could that be it? I haven't had time to check this theory out yet.
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Old May 1st, 2008, 06:52 PM   #6
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Quote:
Originally Posted by Blake Calhoun View Post
To the best of my knowledge it was turned off. This was the sixth shooting day of a 12 day shoot and we hadn't had any issues to that point (and I had it turned off on day one). It's possible it got clicked on though.
i had exactly that thing happen once -- image stabilizer that i thought was switched off, was on, and the anomaly didn't appear in the viewfinder, but the captured footage had a noticeable weird breathing.

but when i compressed it for output, the pulse seemed greatly reduced, mostly imperceptible to the point that i could get away with using it...far from an ideal solution, but no one else seemed to notice. i ultimately ditched most of that footage, because using it stuck in my craw.

but your hunch that it may be something in the adapter/lens relationship could be causing some sort of breathing anomaly, too...good luck figuring it out, it's always frustrating when these things hit you mid-stream...
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Old May 2nd, 2008, 07:27 AM   #7
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Also check for possible interactions with shutter speed. You can sometimes get a beat due to interactions between shutter speed, frame rate, and thing in the image or image path that move or vary periodically.

The classic examples of this are apparent white balance drift when using high shutter speed and discharge (e.g., fluorescent) lighting, and wheels turning backwards on moving vehicles in film. It can take other forms as well.
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Old May 4th, 2008, 04:15 PM   #8
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Thanks for the responses. I'm going to do a few tests to try and recreate the problem. Still baffling to us since shots in the same sequence (shot at the same time) don't have the anomaly. Seems mainly the wider shots using a 50mm lens. None of the tighter shots using 85mm have the problem...
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Old May 4th, 2008, 05:51 PM   #9
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are you shooting under fluorescent lighting?
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Old May 5th, 2008, 09:55 AM   #10
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No flos. It was a loft with big windows and lots of available sunlight. We did use a 1200w HMI Par with the available light. But the anomaly is not a flicker. It's an actual pulse in the footage. Like the whole image slightly shakes up and down. It's subtle on an LCD computer screen, but on an HD monitor it's quite noticeable. I'm narrowing it down to likely image stabilizer or auto focus accidentally being on (with Letus), bad batteries on Letus, or bad connection of 50mm lens on Letus. Must have something to do with vibration or ground glass and A1 functions...
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