+1 - for action shoot 50i

Marks I shoot a lot of stage shows from big Broadway productions to smaller theatre stuff and use a few different cams at 25 and 50 in PAL land. i hate 50i but that's me.
normal body motion is never an issue where you could have a judder problem is on your camera pans this will also depend on the cam and your stage lighting so we always get the stage guys to up the lighting a bit for shows with a media call.
Your pans will never give you serious judder because you will be fairly wide angle anyway.
I only shoot close if one of the production staff is going to direct me.

I only use the 50 stuff for slow motion and rip the 50 stuff back to 25 for the body if it is shot in 50 anyway and watch your audio sync when you shoot one cam 50 and one 25 = not cool to edit if the motion has to be spot on.

I have done many ice skating events and 60i is my standard for that. The camera has to pan and zoom a lot and movements are all fast paced which really doesn't look good in 30p. My camera doesn't do 60p but the same stands for the final product, DVD and BluRay can only handle 30p or 60 and I rather go with 60i from the beginning to the end. Maybe in the future we get DVD/BluRay players and TV sets that can handle 60p or even higher. If you are in PAL, as I was a couple of years back, 25p is really bad for any fast motion and I would only shoot in 50i.

Some fun at rehearsals last week St Petersburg Ballet, Swan Lake rehearsals Gumboot style

Thanks everyone for your feedback. You have given me a bit to think about.

And Rory, love the clip. We can easily forget that dancers are just people too. What camera was this shot with?

marks

what about shutter speeds, additionally?

Marks those particular clips come from a Sony nex VG20 with the standard lens 18-200 3.5 and a T1.4 Cine Lens close up.

The Sony Nex VG20 with the 18-200 on any zoom the judder is bad. A friend of mine bought one and sold it after a day or two because he hated it. But with other lenses it’s ok so the problem is that when shooting and something unexpected happens out of the ordinary like in the clip you have to go with it, you won’t have time to change lenses etc and what you get is what you get. The Audio pickup from the Sony Nex VG10/20/30 is really bad because of the close proximity of lens and mic.

That’s the thing your lenses will also affect how much judder you are going to get and with each lens set to shutter priority get a reading on auto, this will give you some idea where you should be filming around in relation to your lighting “which you may have no control over” then switch to aperture and compare the difference. It’s safer to shoot shutter priority and be underexposed and fix this in post.

Can someone explain to me why lens type should affect judder? I understand that with long focal length you are magnifying object size and hence perceived motion speed. Anything else?