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critical focussing


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#1 rob spence

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Posted 27 September 2005 - 07:28 AM

Hi All,
Does anyone know of any critical focussing systems for the above cameras , I'm sure someone must have developed one in the past,
Many thanks
Rob
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#2 Robert Glenn

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Posted 27 September 2005 - 08:16 AM

sorry but what is a critical focusing system?

Hi All,
Does anyone know of any critical focussing systems for the above cameras , I'm sure someone must have developed one in the past,
Many thanks
Rob

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#3 Stephen Williams

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Posted 27 September 2005 - 08:25 AM

Hi All,
Does anyone know of any critical focussing systems for the above cameras , I'm sure someone must have developed one in the past,
Many thanks
Rob

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Hi,

Normally focusing is achived by looking through the eyepiece and looking at the ground glass, or by using a tape measure.

If you mean follow focus unit there are many available.

Stephen
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#4 rob spence

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Posted 27 September 2005 - 09:38 AM

Hi
I'll expand on the question.
Critical focussing is where you can optically enlarge a smaller segment of the ground glass in order to focus more accurately. In large format stills photography we use a loupe on the ground glass, this magnifies what you can see and thus aids focussing. 35mm cameras ( film ) utilise a split screen, as seen on pentax, nikon etc. , this similarly aids in fine focussing. I know that the cameflex had a system where a loupe could be used on a ground glass positioned in the gate...this aided critical focussing .
My question is whether aaton or both the eclair 16mm cameras ever had a facility to ( temporarily ) magnify the eyepiece ground glass to aid focussing.
Thanks
Rob Spence
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#5 Stephen Williams

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Posted 27 September 2005 - 09:47 AM

Hi
I'll expand on the question.
Critical focussing is where you can optically enlarge a smaller segment of the ground glass in order to focus more accurately. In large format stills photography we use a loupe on the ground glass, this magnifies what you can see and thus aids focussing.  35mm cameras ( film ) utilise a split screen, as seen on pentax, nikon etc. , this similarly aids in fine focussing. I know that the cameflex had a system where a loupe could be used on a ground glass positioned in the gate...this aided critical focussing .
My question is whether aaton or both the eclair 16mm cameras ever had a facility to ( temporarily ) magnify the eyepiece ground glass to aid focussing.
Thanks
Rob Spence

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Hi,

Some cameras do. However if you are using wide angle lenses focusing on the ground glass is not perfect.

If your lenses are collimated and the depth is correctly set then the markings on the lens should be the most accurate way.

Stephen
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#6 Dimitrios Koukas

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Posted 27 September 2005 - 01:35 PM

Hi All,
Does anyone know of any critical focussing systems for the above cameras , I'm sure someone must have developed one in the past,
Many thanks
Rob

<{POST_SNAPBACK}>


My friend u can't trust the eypiece sometimes.
You need to adjust your diopter properly and this is done by removing the lens and point to some bright point of your set, then adjust the crosshair to your eye.
But I would recommend a test with lenses wide open.(So you can see if the readings on the lens are accurate).If there isn't any Back focus issue, most are.
Dimitrios Koukas
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