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View Full Version : Limitations Of The DVX Compared To Panavision Film Cameras



andybiz_2005
05-08-2006, 09:04 PM
Hi all,

I have a few questions & doubts that I hope can be answered in this forum. Now I've read numerous threads here that while shooting 25p (as my DVX shoots PAL), the camera pans from right to left, or left to right or up & down should be SLOW & smooth because if the pans are too fast then the images will tend to strobe. Compare to shooting 50i, pans can be faster, yet there will not be as much strobing as shooting in 25p. I always wondered why this is so.

For example if you go to : http://movies.go.com/newandupcoming & view the Mission Impossible III trailers, most of the camera movements are very fast & action-packed to the theme of the movie. Most of the camera dollies, pans, etc are really fast & yet those images do not show any strobing or jerkiness. From what I know, they used Panavision 35mm Film cameras to shoot the movie.

So my question is : If my DVX can record 25p & the Panavison Film camera also records in 24p, how come my DVX images strobes when I do medium-to-fast pans, while the Panavision Film cameras can also do such fast pans & still the images can hold up nicely?

Is it a limitation of Standard Def. Digital Video, or the CCD size (1/3") of the DVX, or the fact that it's recorded to miniDV tape? I've been put off with recording 25p with my camera for weddings mainly because of keeping the pans smooth, slow auto focus & not very good low-light sensitivity shooting compared to interlaced.

I would also like to know how much does the Genesis® Digital Camera System from Panavision cost? Just curious as to it's price. Thanks in advance to the experts who can provide some answers.

Andrew

donatello
05-17-2006, 08:00 PM
most film camera's default to a 1/48th shutter speed when shooting 24fps ( 1/50th at 25fps) .. what shutter speed do you have your DVX set to when shooting 24p ??

panavision camera's/lens are NOT for sale - for rent only .. that includes the genesis ...

andybiz_2005
05-17-2006, 08:33 PM
I mainly shoot 50i & set my shutter speed to off. I rarely shoot 25p because of its slow autofocus, can't handle medium to fast pans & tilts & not good at low light shooting. Haven't experemented extensively in 25p. But thanks for your reply. Yeah, I recently found out too that Panavison only rents their equipment.

Aaron Marshall
05-17-2006, 10:10 PM
If you'll notice the fast shots in those action packed movies have something that's moving with the camera. The background is still strobing, but you don't really notice it. Your attention is on the car, or the person, or whatever.

Maintain a solid shot on a subject and it'll ease your strobing.

If you saw a shot with a top of the line camera shooting at 24 fps, you're going to see strobing if there's no subject. The camera needs to move with something.

andybiz_2005
05-17-2006, 11:55 PM
Hi Noct,

Oh, I get it now. So you're saying that as the camera is doing a fast pan, or dolly, it is locked on a moving subject. So the subject is in tight focus & perhaps the moving background gets blurred by the fast action. Besides, the audiences are focussing on the subject, so the background, whether it's strobing hardly gets noticed anyway. That's it?

Thanks Noct. You did clear up most of my misconceptions on film compared to my DVX camera. I guess the role of the DP or Director is crucial to composing this kind of fast action shot.

Anyway, if I record in 25p using my DVX, I figured I'll have to rely on manually focusing the image, cause the auto focus takes way too slow. How do you make use of the DVX's "peaking" function to focus an out-of-focus image sharply?

Thanks again.

Andrew

Yas Kassana
06-06-2006, 04:39 AM
You're comparing a prosumer DV cam to a pro movie camera? That's like comparing a ferrari to a kitted up Nissan. Film is actual 24p, whereas digital is emulating that feel.

Baluardo
06-06-2006, 05:31 AM
In theory shooting progressive 25p 1/50 shutter speed with a DVX you should get exactly the same strobing effects you would get shooting 25fps 1/50 with a 35mm movie camera.
It's a sequence of images. i dont see why a 35mm movie cam should make it more fluid. the only thing you can vary is the image blurriness shortening the image exposure time (getting sort of 'gladiator fight' kind of look).

the thing is this effect is more visible in medium speed pans, not really in slow or fast ones. but in my opinion is a thing the filmmaker shouldnt really worry about. it's in the feeling of 'film' itself.

Andrea

Petrus
06-06-2006, 06:13 AM
Baluardo is 100% correct in saying same shutter speed, same frame rate gives the same effect. It is the angular speed and exposure time that give strobing, not the medium on which the image is recorded.

There is one difference which helps to hide strobing in 35mm film: blurred out backgrounds. By focussing on the main subject and making the backround blurred the strobing is not as annoying, and also helps to keep the attention on the main subject (which is not strobing). With small sensor video cameras that is not possible without clumsy 35mm adapters.

Neil Rowe
06-06-2006, 08:45 AM
You're comparing a prosumer DV cam to a pro movie camera? That's like comparing a ferrari to a kitted up Nissan. Film is actual 24p, whereas digital is emulating that feel.


..well actually they are both true 24p. theres no "emulation" at all. they both capture 24 progressive images per second, and both of them create a jittery effect when doing faster pans. however the 35mm cams have one slight advantage which helps mask the jitter ...a shallower depth of field (for the most part.. of course pending lense and focal point.. blah blah) due to a larger imaging area, which helps blur the background and create softer lines and edges that in turn help mask any hard jittering effect.

David Jimerson
06-06-2006, 09:43 AM
50i doesn't strobe as much because it takes a lot more pictures per second than 25p does -- twice as many. The difference between each picture -- movement, etc. -- is less between the 50 fields than it is between the 25 frames.