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35mm lenses used with a 16mm camera


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#1 Camila Freitas

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Posted 21 August 2006 - 11:05 PM

Hi there

I borrowed a set of Cooke Speed Panchro 35mm lenses to shoot a short movie with my university's Arri 16SR.
This set usually goes with that camera.

I'd like to know what difference there is in using 35mm lenses for 16mm cinematography, if there is any kind of adaptation the lenses or the camera have gone through and WHETHER I USE THE DEPTH OF FIELD TABLES FOR 35MM OR 16MM, FOR EACH FOCAL LENGTH.

Thanks a lot!

Camila
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#2 Kevin Zanit

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Posted 21 August 2006 - 11:31 PM

The focal length is slightly more than doubled when using 35mm lenses in 16mm. For example a 50mm (in 35) is about a 109mm in 16. So use the DOF table for a 100mm lens in 16 (essentially multiplying the original focal length by 2.1875).

Or use this:
http://www.panavisio...lenseqvform.asp

And then use your DOF table.
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#3 Dominic Case

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Posted 21 August 2006 - 11:35 PM

If you are shooting 16mm, then use 16mm depth of field tables, regardless of what gauge the lenses are primarily designed for.

The reason that DOF tables are different for each gauge is that a smaller circle of confusion is allowed for in 16mm, so the DOF is a little less. That is outweighed by the fact that you need a much shorter focal length (therefore with more DOF) in 16mm to cover the same field of view.
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#4 Stephen Williams

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Posted 22 August 2006 - 02:13 AM

The focal length is slightly more than doubled when using 35mm lenses in 16mm. For example a 50mm (in 35) is about a 109mm in 16. So use the DOF table for a 100mm lens in 16 (essentially multiplying the original focal length by 2.1875).

Or use this:
http://www.panavisio...lenseqvform.asp

And then use your DOF table.


Hi,

The focal length of a lens remains the same regardless of format.

However to match image sizes at a given distance (field of view) the conversion factor of 2.1875 is correct.

Stephen
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#5 Kevin Zanit

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Posted 22 August 2006 - 02:51 AM

That?s true, but I see it more as a matter of semantics. If you use a 50mm 35 lens in 16, it is like you are using a 100mm lens. Of course I wouldn?t ask the 1st to put the 100 on if I wanted the 50mm lens.

I think it may come from my brain being "calibrated" for 35mm FOV, so when I am shooting a different format I first think about what it would be in 35 and then convert to the format I am shooting.

That said, if he was using a 50mm lens designed for use in 35, when consulting his DOF chart, he should use a 100mm lens in the 16mm table to give the equivalent numbers.

Kevin Zanit
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#6 Hans Engstrom

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Posted 22 August 2006 - 03:04 AM

That said, if he was using a 50mm lens designed for use in 35, when consulting his DOF chart, he should use a 100mm lens in the 16mm table to give the equivalent numbers.

Kevin Zanit


If you´re using a 50mm lens on a 16mm camera it doesn´t matter if the lens was made for 35mm or 16mm when consulting the DOF chart, it´s only the focal lenght of the lens that matters.
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#7 Stephen Williams

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Posted 22 August 2006 - 03:15 AM

If you´re using a 50mm lens on a 16mm camera it doesn´t matter if the lens was made for 35mm or 16mm when consulting the DOF chart, it´s only the focal lenght of the lens that matters.


Hi,

As the CoC is different assuming the 16mm will be blown up to 35mm for projection, what Kevin says actually works! You can also use the 35mm tables but work 2 stops wider.

Cooke Speed Pancros were designed 50 years ago for 35mm, IMHO they won't resolve enough for a satisfactory blow up to 35mm. They will however look fantastic when used for close ups shooting 35mm. Modern 16mm lenses are very expensive, there is a reason for that!

Stephen
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#8 Hans Engstrom

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Posted 26 August 2006 - 11:35 PM

Now I´m confused. When I´m in a situation where I´have to decide if it´s possible to split focus or not on s16 I just punch in the numbers as if I was using a 16mm lens even if it´s a lens designed to cover 35mm or even 35mm still format.
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#9 Stephen Williams

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Posted 27 August 2006 - 12:45 AM

Now I´m confused. When I´m in a situation where I´have to decide if it´s possible to split focus or not on s16 I just punch in the numbers as if I was using a 16mm lens even if it´s a lens designed to cover 35mm or even 35mm still format.


Hi,

Yes, remember focus splits don't always work as you would expect!

Looking through the eyepiece will give you an idea of what is in focus!

Stephen
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#10 Hans Engstrom

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Posted 27 August 2006 - 01:54 AM

Thank you very much for this info, guess I´ve been lucky sometimes when I have been spliting focus. As you said I´ve however allways asked the operator if it looks good and usually the gut feeling one have is correct.
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#11 Stephen Williams

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Posted 27 August 2006 - 04:52 AM

Thank you very much for this info, guess I´ve been lucky sometimes when I have been spliting focus. As you said I´ve however allways asked the operator if it looks good and usually the gut feeling one have is correct.


Hi,

Its easy to get too technical looking at charts, sometimes you get a lens that has more DOF and sometimes less than a general DOF chart would indicate. Often I have opened up a stop or more because too much was in focus!

Stephen
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#12 Jon Kukla

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Posted 27 August 2006 - 05:10 PM

Focus charts are a good reference to get a general idea, but as stated above, the particulars of the circle of confusion, image projection, lens characteristics, film stock (and processing), image contrast, shutter angle, frame speed, and so on also figure into it.
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