Picture breaks up when photgrapher uses flash???

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digexpressions

Active member
I shot an Indian ceremony recently and came about a problem I've not seen in my several months using the HMC150. The photographer had set up several strobes around the very dark room in which the ceremony was taking place. It seems like during some of his stronger flashes the picture of both my HMC 150s would break up. Some of the other flashes, this did not happen. I'm a little confused. I thought I was safe from flash problems since I wasn't going to get rolling shutter with a CCD camera. Any ideas on why this is happening?

Here's a clip to show what I'm talking about:
http://www.vimeo.com/10220795
 
I think that might be your computer not playing back properly or your refresh rate being too slow on your monitor. It looks fine to me.
 
It's definitely on the original footage and not the encoding. And it only happens during a flash. Here are some pics:

Here's the shot before the flash
Image12.jpg


Here's the shot during the flash
Image13.jpg


Here's the shot right after the flash
Image14.jpg


Here's one from my other camera. As you can see, there is a strobe directly behind me.
There were 5 or 6 of these around the perimeter of the room. Do you think it has anything
to do with the radio transmition or actual power of the flash? I'm puzzled.
Image11.jpg
 
Oh my, looks like the compression is acting up... I predict that the flash frame (almost totally white) fools the encoder into thinking it can get away with a low quantizer, and then it holds this for the next frame...
 
Oh, I thought your original post was referring to only half the frame showing the flash as is the case with a CMOS chip. I did see the compression error, I thought it was the compression you used when uploading to Vimeo.
I have had this camera since it was released and I have never seen that happen before.

What bit rate were you shooting in? Do you see the error when you play back the footage in camera?
 
I remember some people have had that happen in the past... with strobes and such. I'm not sure if it was a card or camera issue... sorry to hear about that.
 
This was shot in PH mode 720/60p. Never had this happen to me before either. Gain was at 6dB, manual iris, and (I think) the shutter was at 1/60. Didn't look at all the footage in camera, so I'm not sure what it looked like. But when I play the raw file it has these gliches. Any advice on how to prevent this from happening again? Do you think shutter speed had anything do do with it? It may have been on Auto.
 
Someone else had the same problem in a club, it seems the strobes made the camera kick down the variable bit rate on the encoder, not sure if there is there was ever a fix.
 
I think that the strobes are simply too strong. It definitely looks like a VBR issue because of the white frame caused by the flash.
 
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I think the problem in the club might have been different, as the strobe was firing continuously for bursts which would be pretty tough on the compression. In this case just one flash sets it off. Haven's had this problem myself despite lots of flashes, think it must be something to do with the power of the flash as some have said.
 
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