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Lens Resolution and Lighting Testing


Sam Flynn
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Hello everyone,

I'm a third year Film Production Technology student and I'm currently writing my dissertation titled, 'Determine the impact of different light sources on lens performance, investigating the effect on image quality between cinema lenses and still photography lenses.' As the title suggests I'm going to be looking at how different light sources might affect lens quality. I'll measure this by looking at resolution (using MTF charts), chromatic aberrations, distortion and vignetting. I'll use three still photo prime lenses (24mm, 50mm, 85mm) and test at different apertures and then use three cine lenses at matching focal lengths and test the same. 

I'm curious as to whether anyone has looked into this before? What kind of results did it yield? Do you have any good/reliable resources in this field (previous studies, articles, journals etc.)?

Thanks,

Sam 🙂

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  • 3 months later...

Sound like an interesting project.

Some lenses produce poor results wide open and once stopped down they are OK.  I've only tested still camera lenses at various apertures mainly because I wanted to know what lenses will work for wide open shots in low light. I didn't try different lighting as I work with available light.

 

Edited by Daniel D. Teoli Jr.
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  • 11 months later...

Some years back, I tested  a 16mm cinema camera lens set on the SI2K  with a focus card (Siemens Star) with lighting adjusted with each aperture change and the card carefully framed. The sharpness numbers given by the SI2K are most consistent when the wider focus "window" is selected. 

The sweet spots I found for a set of CP Ultra T* lenses were 9mm T1.35 =  T3,  12.5mm T1.25 = T3.8, 16mm T1.25 = T3.5, 25mm T1.25 = T4. The best of the cine lenses gave a 112 sharpness number. To the Super16mm sensor, the best of the Nikon AIS f1.4 stills lenses yielded a 65 sharpness number. The sweet spot tended to be in the zone f4-f5.6. 

The best of two old Cooke (Taylor, Taylor, Hobson) Speed Panchro Ser 2 cine lenses which had been distressed by fungus and inexpertly cleaned, surprisingly slightly bettered the best of the Nikons and was best at f5.6. 

There is a far more scientific way of testing to don't pay too much heed of my observations. 

Edited by Robert Hart
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