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Old September 27th, 2003, 03:17 AM   #1
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35mm cine prime lenses on 2/3 inch ccd pro cameras

Has any one used 35mm movie lenses (fixed focal length) on 2/3 inch CCD cameras? Agreed that only the central part of the lens would be used when the 35mm format lens is used on a 2/3 camera but then the high density/quality of such lenses would result in phenomenally good immages. There are many rental houses who rent cine prime lenses for quite cheap since these lenses have been used since a long time and probably have yielded their return on investment.

As I understand the effective f.l and angle of such lenses increases by roughly about 2 times. Does that mean that when used on a 2/3 camera, a 5 mm f.l prime lens for 35 mm format would give the same dof, aov etc as a 10 mm (approx) would give on a 35 mm format?

Even if the effective f.l. increases by a factor of 2 (approx) it is still possible to use wide angle (say 5 mm) to still get pretty wide angle (10 mm on the vide camera).
Is there any qualitative advantage in using such a setup in terms of dof and quality of image?

Also are there any adapters that would mount a zeiss super speed 35mm prime lens on a sony dsr 500 or a sony D35?
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Old September 27th, 2003, 11:33 AM   #2
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Hi,

There are B4 (2/3" lens mount) to PL mount adaptors out there. The magnification is roughly 2.2x. Your conversion math is essentially correct. I have never seen a 5mm lens for the 35mm cine format, it would be a full-on fisheye that would photograph the camera itself!

There would be a resolution increase, most likely. There wouldn't be a depth of field improvement, because to achieve the same field of view you'd have to use a wider angle lens which has more depth of field--you end up chasing your tail and ending up back where you started.

The PRO35 is the only "adaptor" of this type that I know of that allows you to retain the same field of view and thus depth-of-field of 35mm photography on a 2/3" camera.
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Old September 28th, 2003, 01:11 AM   #3
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Is the resolution increase significant?

Thx for the info. The p+S is not available on rent in Iran or Pakistan (where I am planning to shoot my full length feature) and the sale price is beyond me.

1. Is there any significant increase in resolution by using 35mm cine prime (fixed f.l) and zoom lenses rather than using the regular 19x sony zoom lens on a sony d35 or dsr 500? Would there be any other issues because we would be using only a small portion of the lens?

2. Would we get the same (or better) resolution increase if we used 16mm format cine lens instead of 35mm format lens?

3. Has anybody out there used such a setup??

4. Is there any other way to achieve a shallow dof on 2/3 inch sony camera (besides the P+S adaptor)??

5. Does optex make B4 to PL adapters? Who else?

The feature shoot starts in about 4 weeks so I have some time left to procure reasonably priced adapters etc.
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Old September 28th, 2003, 09:16 AM   #4
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The dof would be preserved I guess. Here's the math.

I have done some calculations but I am not sure if I am on the right track. If I am then the dof of 35mm cine lenses can be preserved when mounted on 2/3 inch cameras like the sony dsr 500. Here goes:

Subject Distance: 3 mts
Focal Length of lens: 30mm
Aperture: f1.4
Format: 35mm photographic


Dof Near: 2.6866m
Dof Far: 3.3962m
Dof Total: 0.7097m
Hyperfocal distance: 25.4558m
Angle of View (Horizontal): 43.6
Field of View - Width: 3.2m
Field of View -Height: 2.4m

As you can see, a subject at a distance of just 3 m in front of a 30mm cine lens for 35mm format @ f1.4 gives a very shallow dof of 0.7 mts and a high fov width of 3.2 mts. Since only the central portion of this image will be usable (the ccd being only 2/3 inch instead of 32x24 mm negative) the image size will roughly be 2.3 times smaller than the above fov of 35mm format. (Am I correct here?). It still produces good mid shots with film like dof of 0.7 m!!!

Larger fov with very shallow dof is also very easily possible if we increase the subject distance by a couple mts or so OR with a 25 mm lens instead of 30mm.

Such shallow dof for mid shots is just not possible with video lenses from a practical distance of 3-4 mts.

Any thoughts/feedback??
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Old September 28th, 2003, 12:59 PM   #5
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Muhammad, yes, that sounds right. The bottom line is that you have to be willing to shoot your work on significantly more telephoto lenses. If your location allows you to do so, then there it is, but in many instances this is unfeasible or undesirable. Your widest possible lens would be an 18mm effective, based on an 8mm lens being as wide as non-fisheyes goes in the 35mm format. You wouldn't start to see appreciable shallow DoF until a 25mm lens, which would give you an effective 65mm field of view.
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