24P 30P concerns & questions

N

newsbykko

Active member
We are starting on our first HD documentary using two HVXs and 16Gb P2 cards.

Even thou both of use are very experienced news shooter Nether of us have much HD or 24P experience.

We have done several test shoots with the HVX and found it to be great, but the Progressive scan seems to bothersome.

The 24P/30P flicker always seems to be a problem even with slow shutter.

Our understanding is film cameras capture footage at 24 or 30 frames a second. But if this is the case why have we never seen the "strobing or flicker" associated with shooting in 24/30P with the HVX in older movies?

Even with old 50s 60s handheld footage there is no strobing or flicker? There pans are much faster then what can be done with the HVX at any shutter speed?

I talked to a shooter that shoots snowboard films and he has no strobing or flicker in his film footage?
I also asked an older friend that shot film back in the day. Neither seem to recognize the flicker or strobing.

We both understand the technical reason why there could be a flicker or strobing during sudden movements, but why does it not show even in slow movment? And why does it not show up in any film footage? Even during handheld shots?

Any links, advice or recommendations are appreciated.

Thanks Kris

www.KrisztianKOrban.com

www.NoOneEverWins.org
 
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I have seen strobing along with motion blur in many movie pans -- but I agree with you that there are many pans on film that look so much smoother than some of the pans I end up with on HD video. I swear that I've seen shots on film that seem like they would strobe much more using HD video.

I don't really know if there is a magic formula that can make us all say "Oh yeah, that explains it" but I do have a few ideas that may be food for thought.

First - I seem to get great results in 720pn and I wonder if the fact that 720p is a progressive DVCPro HD format (unlike 1080) and that the native mode truly supports the progressive format by not even wrapping the data into an interlaced NTSC data stream, has anything to do with eliminating the appearance of strobing to any degree. I realize that technically the advanced pulldown and proper processing of the NTSC video results in truly progressive video but I catch myself wondering if there is any possibility that NTSC has any effect on the end footage. At the very least you should be aware that improper processing involving the pulldown removal or adding will usually make strobing much more apparant.

Second - consider that most of the film footage that people view on TV is telecined and also remember that the viewing monitor or TV that you use may have an impact on how your video looks when it is displayed. Whether you're filling in the pulldown in your NLE by rendering to NTSC, or letting the DVD player add the pulldown, or you are watching in HD at the original framerate on your computer monitor ... those things will have an impact on how the footage looks.

I think the only way you'll see true 24 fps display involving movies is in the theater on projected screens where they still use projectors and film. It seems to me that strobing and motion blur are more apparent in theaters too.
 
One thing that makes judder less obvious during pans is having shallow depth of field: if the subject that you are following is in focus and the background is blurred, judder will not occur.

Film cameras with their larger format and wide apertures have a distinct advantage over 1/3" cameras, but a 35mm DOF adapter would get you most of the way there.
 
THoff said:
One thing that makes judder less obvious during pans is having shallow depth of field: if the subject that you are following is in focus and the background is blurred, judder will not occur.

Film cameras with their larger format and wide apertures have a distinct advantage over 1/3" cameras, but a 35mm DOF adapter would get you most of the way there.
Click to expand...

Other users claim even with the 35 mm the strobing is still very apparent.

K
 
I'm a long time DP who has shot 35mm features, 16mm, and much video in most formats... I would have to say that YES, there is a difference between how the video cameras at 24 respond to pans - BUT - with the right settings it is a VERY MINIMAL difference.

If you pan quickly on film you get a streak - try the same pan with these video cameras and you get a streak but it's not as even a streak. There is more image strength at the ends of the streak. It is as if the CCD is stronger (for lack of a better term) at seeing image at certain points in time, as opposed to a film camera that sees it more evenly (It's an analogue world).

I think this VERY subtle difference is what causes the problems.

NOW - HOW TO FIX IT:

Note that strobing is a normal concern for film shooters and in the American cinematographers manual (Find it on Amazon) there has always been a section about this with formulas for rate of pan speed matching lens size, etc... also - Watch movies! Very often I see juddery moves in big budget Hollywood films. Especially noticeable in the opening shots that are the beauty crane downs to the ground - often with some strobe/judder!

I find that on the HVX200/DVX100 that 1/24 shutter is too swishy for common use but is great when doing shots that will require a fast pan look.

1/48 I find too stroby all the time. But when doing green screen you may wish to pushcloser toward 1/48 so your edges are a bit crispier.

I personally found the 'sweet spot' to be 1/32 as a compromise between the others. It works 99% of the time for me. Also being aware that medium/fast pans can still sometimes get juddery.

A side note. Played with higher shutter speeds (1/120 etc) and it makes for a very cool look. great for action sequences. It is the "Saving Private Ryan" beach sequence look.
 
hey Kris, this isnt relevant to your question but, i read your bio. I'm only 16 but ive been looking into future careers as a filmmaker(dont we all) but also either something with journalism or photography. It seems like you are undoubtedly involved in all of them and i was just wondering if you had any tips in how to get into the biz and be successful.
 
kss212 said:
hey Kris, this isnt relevant to your question but, i read your bio. I'm only 16 but ive been looking into future careers as a filmmaker(dont we all) but also either something with journalism or photography. It seems like you are undoubtedly involved in all of them and i was just wondering if you had any tips in how to get into the biz and be successful.
Click to expand...

I sent you a PM. It was late so ignore the grammer : )

Kris
 
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