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Old March 16th, 2007, 05:26 AM   #1
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Laser Rangefinder for precise focusing?

Hello,

because of the uneasy way to get my focus right (Peaking on, zooming in + magn.) on my XH A1, I thought of buying a Laser Rangefinder (thats how Babelfish translated from german...donīt know if its the right term for the tool).
Like that you just could measure the distance very fast and set Focus afterwards....what would take far less time then otherwise.

The price for such equipment begins at approximately 100 euros.
There are some really good ones from Leica (A2) for about 170 euro, they go from 0,05m to 60m.

Has anyone already tried this, any experiences?
I donīt want to spend that much money if it doesnīt work good (iīm a student ;) ).

Thx Rolf
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Old March 16th, 2007, 09:11 AM   #2
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You need good accurate focus scales on your lens if you want to use this method. You tend to only find these on cine style lens rather than ENG zoom lenses or consumer/prosumer built in lenses, which are software controlled varifocal length lenses rather than true zoom lenses. For the last two types it's more accurate focusing by eye than measuring and. unless you've got a camera assistant, a lot quicker.
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Old March 16th, 2007, 11:35 AM   #3
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Originally Posted by Brian Drysdale View Post
You need good accurate focus scales on your lens if you want to use this method. You tend to only find these on cine style lens rather than ENG zoom lenses or consumer/prosumer built in lenses, which are software controlled varifocal length lenses rather than true zoom lenses. For the last two types it's more accurate focusing by eye than measuring and. unless you've got a camera assistant, a lot quicker.
But when I focus, the cam shows me the actual distance where the focus is set.
So my workflow would be...laser rangefinder, measuring the distance (about max. 5 seconds...setting focus about another 5 seconds)
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Old March 16th, 2007, 11:50 AM   #4
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XH A1? The DOF must be so deep, why would focus need to be so precise? Using peaking the focus will be as accurate as you see it on playback, no need for super-precise lasers.
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Old March 16th, 2007, 12:29 PM   #5
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Quote:
Originally Posted by Rolf Seitz View Post
But when I focus, the cam shows me the actual distance where the focus is set.
So my workflow would be...laser rangefinder, measuring the distance (about max. 5 seconds...setting focus about another 5 seconds)
Eye focus is a lot quicker.

For focusing by tape or rangefinder you'd need to check how accurate those distance reading actually are and where on the camera they're measured from. For example cine lenses are measured from the image plane, ENG lenses from the front element.

Also what happens when your subject and or the camera moves? How are you going to adjust the focus. I know on the Z1 the focus read outs in the camera operate on an extremely compressed scale so far as the focus ring adjustment is concerned and it's easy to overshoot or miscue.
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Old March 16th, 2007, 05:37 PM   #6
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Ok, thanks for your answers! Thought I found something good...but it turns out to have too many downsides. Money saved....for my mattebox ;)
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Old March 19th, 2007, 12:24 AM   #7
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laser measuring

you might look into a laser measuring tool. they sell them at most hardware stores, and they are relatively inexpensive if you're still interested in one.

http://www.stanleytools.com/default....ASER+MEASURING
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