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Sharp film lenses


Eugene Lehnert
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Although I have not tested them yet, you can be sure that the Zeiss Master Primes are the sharpest 35mm lenses available.

 

The Zeiss Ultra Primes and Superspeeds are sharper than the Cooke S4s. In fact the S4s, even though they have very pleasing contrast are not really sharp lenses. There is never one point that is really in focus with them (unlike Zeiss lenses), which is very annoying if you have a shot that is low in contrast and high-key. In that case the shot looks like its slightly out of focus, a problem that I have noticed several times already on feature films where we had printed dailies.

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None of these responses really accurately answers his question.

He asked ""which lenses are designed to be their sharpest when the aperature is wide open"

 

Sure, there are lenses that are acceptably sharp wide open (or close to it), but there isn't really such a thing as lenses being AT ITS SHARPEST wide open, right?

 

In fact, (unless some propeller head here knows an exception), isn't every lens ever made, at its SOFTEST wide open?

 

MP

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According to ARRI literature the Master Primes look better at T1.3 than other lenses at T2. Still you are right, simple optical physics dictates that even they get sharper by stopping them down. Cooke S4s for instance look best at T4.

 

But one should never stop down lenses too much, because the optical performance goes downhill at too small stops.

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Would you say a lens performs its best somewhere around two stops from wide open?

This is a "fact" that I have always taken for granted. I don't recall where I first heard it, but it might have been from my photography instructor in college. We were working with 4x5 view cameras at the time, I think they were Schneider-Kreuznach lenses. Anyway, working on that assumption has never let me down.

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A theoretically aberration free lens would be sharpest at its widest aperture. That lens would be said to be "diffraction limited"

 

In reality there are trade offs between diffraction limiting and reducing various aberrations - spherical etc. Stopping down can help.

 

It does seem the latest Zeiss are getting very close to this ideal condition.

 

-Sam

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One of the interesting things that I was told by the DP/rental house owner I rented from recently was that professional motion picture lenses resolve beyond the capacity of film (and digital capture) to record them. He was speaking in reference to Zeiss Superspeeds and Standards, so I would assume that the same is true of the more recent lens series (Primos, Ultraprimes, etc.).

 

So if professional motion picture lenses are sharper than anything we've got to record the image, the trick is to get the sharpest medium you can afford to capture them on. Practically speaking, the lenses intended to be used with 35mm film are likely designed to the most rigorous specs, again because 35mm is recording the most detailed pictures and will show more flaws than HD, etc.

 

I have no idea how motion picture lenses would compare with large format still lenses, however.

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The problem you could run into here is that even if there were a consensus that Lens X was the sharpest wide open, doesn't mean that the actual Lens X you use is. In this scenario you really need to test from the variety you can get your hands on at your equipment provider and see what you find to be sharpest.

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I think that only applies to older lenses, modern lenses are manufactured to such high standards that there is no variation between individual lenses anymore. Any lens is as good as any other there.

 

Probably true, I'm referring to lenses that may be out of whack from misuse and/or poor upkeep.

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  • 2 weeks later...
I do find it interesting though, that everyone is seemingly obsessed with lens sharpness, then proceed to do things like put diffusion filters over them, shoot through car & house windows, fog rooms to lower contrast, etc.

 

MP

 

 

Ha ha, so true. I can't begin to count the number of times I've had to net a beautiful set of Zeiss Ultra Primes.

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So if professional motion picture lenses are sharper than anything we've got to record the image, the trick is to get the sharpest medium you can afford to capture them on.  Practically speaking, the lenses intended to be used with 35mm film are likely designed to the most rigorous specs, again because 35mm is recording the most detailed pictures and will show more flaws than HD, etc.

 

 

Yes but you should think of the 35mm neg or HD imager as the limiting resolution.

 

Sans possible digital trickery you will not resolve more than the weakest link in the chain (you will resolve less in fact) but you can leverage the "components" to your advantage, i.e. a Master Prime will obviously give you a higher resolution on a frame of 5212 than some old Baltar or Cooke S2.

 

OTOH you might love that look but might find that same glass lacking if you used it with your HD camera and a P&S or something.

 

Roughly if you tale the reciprocals of the resolving powers (@ a given contrast) of the lens and the film, and add them together you will get the reciprocal of the imaged resolution.

 

-Sam

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