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-   -   how to manually focus while zooming? (https://www.dvinfo.net/forum/open-dv-discussion/101332-how-manually-focus-while-zooming.html)

Juni Zhao August 14th, 2007 03:32 PM

how to manually focus while zooming?
 
I have been practicing this technique but not too successful.
So when doing a paid job I still use AF while zooming. And also
when shooting car racing, I found it extremely hard to manually
focus as the race cars close in. So I would like to know if its possible
to do manual focus in all situations.....

Mike Teutsch August 14th, 2007 03:36 PM

Quote:

Originally Posted by Juni Zhao (Post 728933)
I have been practicing this technique but not too successful.
So when doing a paid job I still use AF while zooming. And also
when shooting car racing, I found it extremely hard to manually
focus as the race cars close in. So I would like to know if its possible
to do manual focus in all situations.....

What camera and lens do you use.

M

Juni Zhao August 14th, 2007 03:38 PM

Canon A1. Should I post this in A1 forum? I thought it was a general topic... :-)

Ben Winter August 14th, 2007 03:49 PM

I thought servo cameras can't focus and zoom at the same time. But I could be wrong.

Mike Teutsch August 14th, 2007 03:50 PM

Quote:

Originally Posted by Juni Zhao (Post 728941)
Canon A1. Should I post this in A1 forum? I thought it was a general topic... :-)

If it needs to be moved, a moderator will do it, best not to repost. That's called double posting and is not allowed.

The reason I asked what camera you had was to determine if it is even possible for you to focus and zoom at the same time.

I believe the answer for you is no! The Canon's, XL1, XL1s, XL2, and XLH1, with the removable lenses use one motor to zoom and focus. Therefore, you simply can't do both at once. I believe your A1 uses the same system, with servo controlled focus and zoom, off of a single motor. This has been a bane for Canon users for years, but it is just the way it is.

If you had one of the Canon's I listed above, you could change to a manual lens and do both at the same time, but the A1 does not have interchangeable lenses.

If you stop down the iris, go to higher numbers, it will give you a greater depth of field and you may not need to concern yourself with the focus as much. If you can leave the ND filter's off or an the lowest setting and close the iris, you will have a great depth of field and almost everything you point it at will be in focus. Then you just have to worry about the zoom.

Good luck----Mike

Heiko Saele August 16th, 2007 05:04 AM

Manual focussing is a pain with almost all mini-type camcorders (those without a "real" lens). With the canon XL-1 type lenses I find it almost impossible, with a DVX or HVX it's a little less impossible. With a good manual lens and crt viewfinder it's really easy in comparison.

Juni Zhao August 16th, 2007 12:08 PM

very helpful, so at least I don't have to master something impossible...
thanks

Mike Teutsch August 16th, 2007 12:14 PM

Quote:

Originally Posted by Juni Zhao (Post 729965)
very helpful, so at least I don't have to master something impossible...
thanks

If you do learn to master something that's impossible, let us and Guinness know! :)

Best of luck-----Mike

P.S.:Remember the trick I gave you! Close down the iris and most everything will be in focus! Like they say, try it and you'll like it.

M

Mark Sasahara August 18th, 2007 09:37 PM

The Canon Auto lenses and manual lenses for the XL-1/2 focus and zoom simultaneously.

Unfortunately the A1 doesn't allow you to be able to use tools that make focusing while zooming easier. Part of it is also learning that skill.

Using a follow focus rig makes focusing easier because you have a disc which you can mark with your focus points. It's large knob is easy to hold and turn.

The ability to mount a zoom control on the panhandle of your tripod is also helpful so that as you are moving the camera you can control the zoom and pan handle with the right hand and focus with the left hand.

You may have to rely on zone focusing, like with still photography, but for that you need to know what distances will be in focus at a given f stop at a given focal length. There are tables and calulators for cine lenses and some 2/3 inch video lense, but not for 1/3 chip cams. When in doubt, stop the lens down. If you arre at infinity, obviously, it won't matter, unless they are coming right at you, or fairly close to you. If you are panning, then minimal focus shift occurs, unless the arc you are panning is very wide.


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