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Another goofy contest


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#1 Paul Bruening

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Posted 25 August 2008 - 05:40 PM

Trip on 'dis thread. Then, enter your fav name for these lenses.

http://www.cinematog...t=0#entry248126

I vote: Hyperspeeds (any lens faster than f1).
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#2 Paul Bruening

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Posted 25 August 2008 - 07:43 PM

C'mon, guys. Someone, play-in
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#3 Chris Keth

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Posted 25 August 2008 - 07:55 PM

From a focus puller's point of view, I suggest the name "Stupid Speeds." ;)
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#4 Paul Bruening

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Posted 25 August 2008 - 08:00 PM

I haven't gotten a comment on DoF yet on these. Wouldn't it be the same as f1.2 on an SLR or would the reground element change DoF?
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#5 Chris Keth

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Posted 25 August 2008 - 08:21 PM

I haven't gotten a comment on DoF yet on these. Wouldn't it be the same as f1.2 on an SLR or would the reground element change DoF?


Assuming the focal length is the same, an f1 has half the DoF of an f2. An f0.7 has half the DoF of an f1.4, etc.

So that f0.2 would have about 1/8 the DoF of an f1.4.
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#6 Paul Bruening

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Posted 25 August 2008 - 08:30 PM

Hmmm. These alter the light value by concentrating light at the back element into a smaller area instead of opening the iris wider. I don't know if they are subject to the normal DoF/f-stop calculations. It would be nice if the chief optic engineer from Zeiss could conveniently chime in at this point since this is an important issue on this idea.
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#7 Paul Bruening

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Posted 25 August 2008 - 09:18 PM

I just thought about this: If it is correct that these lenses increase speed without altering DoF, then wouldn't that mean that the lenses would actually be deeper DoF at any given lens-marked f-stop? If, in the case of the 50mm, f1.2, Nikon, the lens would deliver (for example) an equivalent f2.8 or so of light with a lens mark and DoF of f5.6. It may be counter-conceptual to the normal assumptions of lenses' DoF/f-stop.
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#8 Paul Bruening

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Posted 25 August 2008 - 09:38 PM

F-stops stay the same (aperture and DoF). T-stops change (actual light value on the film plane). The lenses could use a new F and T-stop scaled ring.
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#9 Paul Bruening

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Posted 25 August 2008 - 09:47 PM

So, then, if you need T1.4 to hit the film you'd be set at f2.8 on the lens's DoF. It would actually make the job easier for pullers.
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#10 Paul Bruening

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Posted 25 August 2008 - 09:53 PM

If you need the f-stop to match the T-stop use ND filters. Am I thinking right?
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#11 Chris Keth

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Posted 27 August 2008 - 11:00 PM

I'd be willing to bet that the entrance pupil changes as you add those diopters. You generally can't sidestep physics. ;)
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#12 Evan Pierre

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Posted 27 August 2008 - 11:34 PM

I'd be willing to bet that the entrance pupil changes as you add those diopters. You generally can't sidestep physics. ;)


That won't stop me from trying!
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