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clumsy_cool
01-07-2010, 12:09 PM
Hopefully this hasn't been covered already.

Is there a way to avoid flash photography flash bars when filming with the 7D?
I film a lot of fashion shows and flash photography is in almost every shot. I can only imagine how the camera performs with a strobe light.

Does changing the shutter speed affect the results? Any thoughts on how to avoid this issue?

I've been closely following the heated debates regarding the 7D and I can tell you that if there is no way around this issue...(which I don't think there is) I am definitely not selling my HVX.

Here's a frame from a video taken on NYE. The flash bars ruined ALL my footage.

http://ramifilms.com/flash.jpg

Filmed @ 60p

Barry_Green
01-07-2010, 12:13 PM
Is there a way to avoid flash photography flash bars when filming with the 7D?
No. It happens with ALL rolling-shutter CMOS cameras.


I film a lot of fashion shows and flash photography is in almost every shot. I can only imagine how the camera performs with a strobe light.
Yep, wrong camera for that job. And any CMOS camera will have the same problems. The HPX300 has a flash-band compensation function to minimize the effect.


Does changing the shutter speed affect the results?
No, not unless you use an extremely slow shutter speed like 1/4 or something. In general, for video- or film-looking footage, no, shutter isn't going to help.


Any thoughts on how to avoid this issue?
You can't avoid it unless you use a CCD camera. You can try to compensate for it in post by turning the partial flash-band frames all-white, but other than that... nope.

clumsy_cool
01-07-2010, 12:38 PM
OOoohhhh welll...Thanks Barry, that's what I thought.

I'm going to explore fixing it in post like you said. Maybe instead of turning the partial flash-band frames all-white I'll make just the subject white to mimic a real flash. I wonder how removing the frame completely would look.

Trial and error I guess... so far the 7D is a big error.

clumsy_cool
01-07-2010, 01:16 PM
Ok Here's a quick test for those of you who haven't seen flash bars first hand.

Here's a quick clip I took last night at a Jazz bar. I put the original footage first then removed the few frames that had flash bars.

http://ramifilms.com/flash.mov

Of course this would not work in this case because the lady is singing and removing frames would change the audio sync. Maybe it would work for a few quick shots if you absolutely need to save your footage... it still looks off though.

Barry_Green
01-07-2010, 02:23 PM
Without hearing how it sounds, yeah that looks a tiny bit stuttery but -- certainly not as distracting as the flash bars.

There may be software filters out there to automatically fix this too; this issue has been known about and talked about since the first CMOS cameras came out; I wrote about it in my article on CMOS imaging technology (http://www.dvxuser.com/V6/showthread.php?t=111003)back in September of 2007. Look around, there may be filters to fix this in your NLE of choice.

apardo
01-07-2010, 09:51 PM
I had exactly the same problem with the 5D, and had other problem as well:

Shooting at a Flat panel screen, i did fix it a little bit with the shutter, but it happens and then, the curious thing is that the light coming from the screen to the actors will do the same lines on their skins... :( je

apardo
01-07-2010, 09:53 PM
For the sync on the lady singing try to copy a frame and pasting it, so you have audio sync perfect.