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Old September 9th, 2005, 04:11 AM   #1
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Will a setting of 60 shutter on a PAL cam cause transfer problems?

Hi Everyone.

I'm about to shoot a short film on mini-DV with a good chance of getting transferred to film. I'm using a Panasonic AGDVC32E, which is the PAL version of the DVC30. I live in an NTSC country and am quite aware that in order to avoid those annoying flickering problems with fluorescent lights (lights run at 60Hz, camera is 50i) I have to adjust my shutter speed to 60.

My questions are:

1. Will a setting of 60 shutter on a 50i camera cause film transfer problems? I'm concerned with the deinterlacing and 24p conversion stages. The standard is 50i to 25p or 60i to 30p, then pulldown to 24p. I have no idea what will happen with 60 shutter on 50i or how it will affect the footage later on.

2. Will the same setting cause problems in converting to NTSC for DVD output?

3. Will a shutter speed of 60 on a 50i camera turn the interlaced footage to 60i (thus almost making my camera NTSC-compatible with higher resolution but wrong frame size)?

4. Lastly (and this is a bit off-topic), regarding deinterlacing: I don't understand why I get clearer horizontal/vertical lines with DVFilm Maker but get generally sharper images by simply using Vegas 6 on interpolate setting. Any thoughts on this?

Would greatly appreciate your replies.

Jerrold Tarog is offline   Reply With Quote
Old September 9th, 2005, 07:04 AM   #2
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Technically, shooting 50i with a shutter of 1/60 sec shouldn't create an issue for your conversion to 24p. I'm not even sure if PAL cameras can shoot 1/60 (however, they might have that synchro mode to match display timings).

PAL is always recorded at 50i regardless what the shutter is set to. The 24p conversion for interlaced PAL is: 50i -> 25p slowed to 24p. To create NTSC DVDs from your PAL source footage is: 50i -> 25p -> 24p -> 60i with 3:2 pulldown.

I think your real question is how the image is going to look because all film conversion sites and software recommend you either shoot 1/50 or 1/60 at all times. I don't want to get too technical here but most film look algorithms are based around certain motion characteristics and are better to emulate film if your recording device is treated like a film camera.

Motion picture film is typically shot at 24 fps with 180-degree shutter angle which is equivalent to 1/48 sec shutter. To emulate the typical film motion characteristics with an electronic device, you need to keep that 1:2 ratio. PAL records 25 frames per second (2 fields = 1 frame), so using 1/50 sec shutter emulates the motion of film. NTSC is 30 fps, so 1/60 is the optimum shutter speed.

When using higher shutter speeds, you are not increasing the frame rate (it stays constant) but what you are really doing is capturing less blur because you are capturing more images per second (but only 50 or 60 of them is recorded to tape). Example: Think about a photo camera shooting a moving bicycle wheel. A shutter of 1/60 has lots of blur while a shutter of 1/2000 will have no blur at all. If your camera has a max burst rate of 3 frames per second, it doesn't matter what speed your shutter is, the camera is only capturing 3 fps with either lots of blur or no blur.

So, shooting 1/60 sec with PAL is going to change your motion characteristics in that the resulting 24p won't have the blur/slur that we are used too. Your footage will look more stuttery.

I hope this helps and isn't too confusing.
Xander Christ is offline   Reply With Quote
Old September 9th, 2005, 07:05 AM   #3
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The shutter controls the internal shutter of the camera, no matter what you choose you'll get 50i output (presuming it doesn't have a progscan mode). So yep, change the shutter to 60 to match your countries electricity frequency, then export to the PC as normal.

For instance, I sometimes shoot on a shutter setting of 2500 or so to get strobic movements, but i'll still end up with the same spec footage as if i shot in 50.
James Connors is offline   Reply With Quote
Old September 9th, 2005, 07:11 AM   #4
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If you're serious about a film transfer then you would be wise to discuss this issue with the company that might do the job. Otherwise you may end up doing something you'll regret later....
Boyd Ostroff is offline   Reply With Quote
Old September 10th, 2005, 11:28 AM   #5
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thanks for the replies. much appreciated. looks like i have to decide if a stuttery look is more tolerable than flickering lights!

i guess i'll just do some tests and convert my footage all the way to 24p (but not transferred to film). if anyone out there has actually shot footage with a PAL camera with a 1/60 shutter speed and have gone through the entire 24p conversion, i'd love to hear from you.

still bothered about dvfilm vs vegas interpolation though. eenie meenie...
Jerrold Tarog is offline   Reply

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