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Canon EOS Crop Sensor for HD
APS-C sensor cameras including the 80D, 70D, 7D Mk. II, 7D, EOS M and Rebel models for HD video recording.


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Old December 3rd, 2009, 12:44 AM   #1
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shooting at high shutter speeds

Do you guys notice any dark horizontal banding when shooting video at high shutter speeds? is that normal? never noticed it before... kinda worried that my cam is sick.

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Old December 3rd, 2009, 07:44 AM   #2
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$100 says you shot that indoors?

Looks like your shutter is out of phase with the indoor lighting. The same thing will cause flicker on other cameras.
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Old December 3rd, 2009, 08:40 AM   #3
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Fluorescent lighting?
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Old December 3rd, 2009, 09:04 AM   #4
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Yes, out of synch with the lighting. I saw this last weekend shooting with a Sony Z7 at 24p 1/48 on a stage lit with del lights working at 60hz.
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Old December 3rd, 2009, 11:08 AM   #5
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If you're shooting video at 24 fps, your shutter speed needs to be at 1/50. You don't use shutter speed to control exposure in video as you do with still photography--that's what ND filters are for. If you go too high or too low with the speed, you will get weirdness. With the 7D it's fairly easy to change shutter speed accidentally, so you need to always be checking to be sure you're at 1/50. I there was a shutter lock as there is on the XH A1.
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Old December 3rd, 2009, 12:30 PM   #6
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Quote:
Originally Posted by Bill Pryor View Post
If you're shooting video at 24 fps, your shutter speed needs to be at 1/50.
NOT if you're under magnetic HMIs or fluos! If you shoot 1/50 in those cases, you're going to get problems. (speaking NTSC here). In those cases you have to use 1/60 and must not use 1/50.
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Old December 3rd, 2009, 12:30 PM   #7
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This will happen on all rolling-shutter CMOS cameras. It has to do with how the sweep of the rolling shutter interacts with the way ballasted light sources (fluorescent, HMI, sodium vapor, etc) work.

The answer is simple: do NOT shoot with any shutter speed other than 1/60 (NTSC) or 1/50 (PAL) when shooting under those types of lights. Most definitely you don't want to shoot 1/50 in NTSC under magnetic HMI or fluorescent lights, as it'll cause waves of fluttering ripples happening in your footage.

There is no such thing as an "HMI-safe" frame rate when it comes to CMOS. But there are HMI-safe shutter speeds, and those would be (in NTSC) 1/60, 1/40, and 1/30. In PAL, they're 1/50 and 1/25. You may also be able to get away with 1/120 (NTSC) and 1/100 (PAL).

This issue affects the older/magnetic-ballast lights, but not the high-frequency electronic ballasts.

If you want to know whether you are going to have the problem or not, quickly pop over to 1/500 and point at the lights. If you see bands like your picture shows, then yeah, you've got magnetic ballasts and you will have to stick to the 1/60 - 1/40 - 1/30 (or, PAL, 1/50 - 1/25) shutter speeds.
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Old December 3rd, 2009, 01:34 PM   #8
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Yeah, I normally keep it on 1/50 but I wanted to do slow mo on 720p.

I was trying to do slow mo and 1/50 at 60p loses all the detail of a rapid movement to motion blur so I cranked the shutter in an effort to reduce the unwanted blur.

Specifically it was a test of a strawberry dropping in water. The frames need to be crisp.

I need a light source that'll allow me to crank up the shutter (indoors) to reduce blur.

I'm surprised that I see noticeable banding in a tungsten lit room through ALL the fast shutter speeds.

I guess that until I can find a good light source that'll allow me to ramp up the shutter speed, I will have to do my high-speed stuff outdoors.

Glad that my camera isn't sick. Thanks for the help!

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Old December 3rd, 2009, 04:51 PM   #9
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I've been shooting at 1/50 under fluorescents with no trouble. All the HMIs I use are always electronic ballast, so I don't know if that's an issue or not. When shooting film I've had no problem under fluorescents either, both lighting with them (Caselights) and having office overheads on sometimes. Just finished a shoot today, in fact, where I couldn't turn the overheads off.
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Old December 4th, 2009, 12:22 PM   #10
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I had excatly same thing a couple of days ago and freaked me out until I figured out that I was shooting under fluorescent lighting and I changed my shutter speed to shoot stills and forgot to put it back on 60 for video.

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Old December 4th, 2009, 01:22 PM   #11
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Quote:
Originally Posted by Bill Pryor View Post
I've been shooting at 1/50 under fluorescents with no trouble.
High-frequency fluos won't cause a problem. Same with HMIs. It's the normal magnetic ballasts that cause the issue. Your CaseLites are high-frequency electronic ballast.

It's a very real issue and something to be aware of. The flutter in 1/50 isn't as noticeable as the banding at 1/250, but it's there. Here's what it looks like on a Red One, but it will happen on any rolling-shutter CMOS camera.

I strongly advise anyone who's shooting under fluorescents to "test" them by setting the shutter to something really fast, like 1/250, and looking for big orange scrolling bars in the footage. If they're present, then you MUST shoot at 1/60 (or, in PAL territories, 1/50) to avoid the fluttering/scrolling bars. But, if you point at fluos at 1/250 and see no scrolling bars, then you have no problem with using 1/50th under those lights.
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Old December 4th, 2009, 04:33 PM   #12
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I did a fantastic slow mo test outdoors earlier today. I ramped up my shutter super fast and tracked some stuff... everything recorded crystal clear with almost zero blur - Just fantastic!

I notice that I still get the horizontal bars with high shutter in certain rooms in the house with tungsten temps but I'm not all together sure that they're actually tungsten bulbs.

Lesson learned: If you want to shoot a quick slow-mo with fast shutter (for cheap)... just got outside! :-)
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