Comments

Spot|DSE wrote on 3/28/2006, 12:28 PM
If you have the Z1 or A1 with the A/B scene transition, yes, you have a modicum of measure/mark. But for any servo lens, this doesn't really work. With the JVC, you don't have automated lens control, but as a totally manual lens, you can indeed, measure/mark.
winrockpost wrote on 3/28/2006, 12:45 PM
You are mad!!!! no .not really , I have seen it on filmshoots where the camera mans personal focus servant would use a laser to measure the distance and get the camera man ready to roll ,and then wipe the sweat off his forehead and basically do everything but actually roll.
rmack350 wrote on 3/28/2006, 2:55 PM
The measurement is from the film plane to the focus point. The camera has a mark on it indicating where the film plane is, and usually there's a post to hook the end of the tape onto.

I'm looking at our DV camera, a DSR500. It also has a post that seems to be for hooking a tape to, but I don't see the typical mark on the body.

If you wish to work this way, and you very well might if you're shooting in HD but monitoring in SD, then I'd start by checking the measurements ahead of time. Put the camera on a tripod and put objects at set taped out distances and check the focus.

As Douglass points out, some lenses are purely servo controlled and may never hit the same focus marks twice. In this case you can't measure things out.

Rob Mack
Patryk Rebisz wrote on 3/28/2006, 5:25 PM
Unless you are working with Cine lenses on your HD camera tape mesure doesn't really work that well with ENG lenses. Those lenses have the mesurements but they are always a bit off. A good viewfinder and zooming in for focus should work.
Serena wrote on 3/28/2006, 9:23 PM
A few days ago I made a throw-away comment that "there is always the old tape measure trick" for focusing. Obviously this is a very testable thing, so I've just done that with my FX1E. I used a few distances between 3 and 1 metres and found that at max focal length the focus setting is repeatable using the distance displayed. But the servo-ring setting is so sensivitive that in practice it's much quicker to focus through the viewfinder; you could pull into focus using distance (at max focal length), but it would be very difficult not to overshoot. I didn't try attaching a stop to the ring. Mecahnical follow-focus isn't practical. The extra problem is that as focal length is reduced the error in the distance reading increases and setting sensitivity increases rapidly. So yes, you can use a tape measure, but it's not a viable means of focusing. As Spot mentioned, the A/B facility on the camera works nicely and is about as close as you can get to mechanical follow-focus with this lens. And that's the obvious way for accurately pulling into focus in a setup shot. Of course, different story with those PRO35 type of attachments, since focusing doesn't involve the built-in lens.