Shutter speed/lighting Hz

[Wayne Avanson]

I got asked to film a Big Band gig on saturday night and it was my first time out since the firmware upgrade. I set things up as Jon mentioned a few threads ago, - Shutter at 60 aperture and something decent for the light level and a reasonable ISO setting too.

While setting up I noticed the picture was flickering at shutter speed of 60 but went away at 50. Do I have it right that that is because the lights at 50Hz clash with the shutter speed here in PAL land? And that I should stick to shutter 50 from now on?

I shot the gig at 50 by the way, and no problems, just wanted clarification here guys,

Cheers

Avey

[Jon Fairhurst]

Yeah, in 50 Hz land, shooting 1/50 in artificial light is the way to go. Outdoors, you can shoot at any shutter you want. I'm glad you didn't stick with 1/60... "But Jon said..."

I hope the footage (bytage?) turned out great!

[Richard Hunter]

The problem is that the frame rate is out of sync with the lighting power. Slower shutter speeds help, but I'm surprised that 1/50s removed all flicker because the frame rate is still 30fps and the power line frequency is still 50Hz. Still, if it worked then that's great.

Richard

[Peter Berg]

sorry if this is a dumb question... but what use is the PAL/NTSC setting on the camera, when the only option is to shoot at 30fps? (and also forgive me if this is the wrong thread to post this - just been bugging me for a while...) I'm in PAL land.
thanks

[Wayne Avanson]

Thanks for your helps guys.

And you know, I always do what Jon says… Apparently, he's the boss of me.

[Nigel Barker]

Originally Posted by Peter Berg

sorry if this is a dumb question... but what use is the PAL/NTSC setting on the camera, when the only option is to shoot at 30fps? (and also forgive me if this is the wrong thread to post this - just been bugging me for a while...) I'm in PAL land.
thanks

The PAL/NTSC setting is output only e.g. connecting the camera to a TV. It has no effect on recording.

[Nigel Barker]

Originally Posted by Richard Hunter

The problem is that the frame rate is out of sync with the lighting power. Slower shutter speeds help, but I'm surprised that 1/50s removed all flicker because the frame rate is still 30fps and the power line frequency is still 50Hz. Still, if it worked then that's great.

Richard

As I understand it doesn't matter what the frame rate is as it is the shutter speed that matters. 1/50, 1/100 or 1/30 are OK in PAL land but any other shutter speed indoors should be avoided.

There area couple of clips on Vimeo that demonstrate this nicely.

EOS 5D mark II manual shutter test with 50Hz lights on Vimeo
5Dmk2 tests with 50Hz lights part 2 on Vimeo

[Wayne Avanson]

Thanks Nigel, these were well handy clips

[Richard Hunter]

Originally Posted by Nigel Barker

As I understand it doesn't matter what the frame rate is as it is the shutter speed that matters. 1/50, 1/100 or 1/30 are OK in PAL land but any other shutter speed indoors should be avoided.

There area couple of clips on Vimeo that demonstrate this nicely.

EOS 5D mark II manual shutter test with 50Hz lights on Vimeo
5Dmk2 tests with 50Hz lights part 2 on Vimeo

Hi Nigel. Obviously the frame rate matters because this is only an issue with 24 and 30 fps in PAL countries (or 25 fps cameras in NTSC countries). 25 fps in PAL countries is fine (although certain lights do show colour shifting with faster shutter speeds).

The worst type of lighting I have seen for causing this problem is the fluorescent lights you commonly get in shop windows. These even cause problems when shooting street scenes in the daytime. It would be good to see a test done with these lights using different shutter speeds to see if 1/50s works ok.

Richard

[Dan Uneken]

Hi folks!

We've shot our first day of a feature with three MKii's and have made the mistake of filming some of it under fluorescent lights. The scenes are rather difficult to re-shoot (kids), so: does anyone know of a software solution to remove the flicker from the footage?

Thanks!

Dan.

1st AD and a lot besides on ¡Primaria!
¡PRIMARIA!

[Mark Hahn]

Originally Posted by Richard Hunter

Hi Nigel. Obviously the frame rate matters because this is only an issue with 24 and 30 fps in PAL countries (or 25 fps cameras in NTSC countries). 25 fps in PAL countries is fine (although certain lights do show colour shifting with faster shutter speeds).

The worst type of lighting I have seen for causing this problem is the fluorescent lights you commonly get in shop windows. These even cause problems when shooting street scenes in the daytime. It would be good to see a test done with these lights using different shutter speeds to see if 1/50s works ok.

Richard

Florescents (and for that matter many other lights) flicker at 100 Hz in Pal countries and 120Hz in NTSC country. The flicker is double the line rate because the light brightens on both the positive and negative part of the sine wave.

If the FPS is an integer divider of the flicker rate the brightness will not flicker fast in the video, BUT, it will vary slowly over time because the frame rate doesn't exactly match the flicker rate and their sync will drift.

However, making the shutter speed an integer divider also works and it doesn't have the slowly varying problem. That is because the exposure time covers one part of the sine wave and as the phase of the two drift, the sum of the sine wave stays constant.

So use shutter time to fix flicker, not FPS.

Correction: I shouldn't have said integer divider. The values are 1/2, 1, 2, 3, etc. times the fast flicker rate.

[Jon Fairhurst]

Originally Posted by Wayne Avanson

And you know, I always do what Jon says… Apparently, he's the boss of me.

Wayne, I just now caught your post - and I'm still laughing!

Now, go out and make a great film.

Sincerely,

- Your Boss :)

[Richard Hunter]

Originally Posted by Mark Hahn

Florescents (and for that matter many other lights) flicker at 100 Hz in Pal countries and 120Hz in NTSC country. The flicker is double the line rate because the light brightens on both the positive and negative part of the sine wave.

If the FPS is an integer divider of the flicker rate the brightness will not flicker fast in the video, BUT, it will vary slowly over time because the frame rate doesn't exactly match the flicker rate and their sync will drift.

However, making the shutter speed an integer divider also works and it doesn't have the slowly varying problem. That is because the exposure time covers one part of the sine wave and as the phase of the two drift, the sum of the sine wave stays constant.

So use shutter time to fix flicker, not FPS.

Correction: I shouldn't have said integer divider. The values are 1/2, 1, 2, 3, etc. times the fast flicker rate.

Hi Mark. That makes sense, thanks for the explanation.

Richard

[Wayne Avanson]

Originally Posted by Jon Fairhurst

Wayne, I just now caught your post - and I'm still laughing!

Now, go out and make a great film.

Sincerely,

- Your Boss :)

OK Boss. Will do. I WAS going to make a rubbish one but now I guess I have to do what you say.

Actually. Just got back from Canada yesterday where we shot a nice music video on the 5D2. Looking at editing it over the next week or so. Will keep you all posted..Avey