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April 30th, 2008, 04:02 AM
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#1 |
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Regular Crew
Join Date: Mar 2007
Location: Paris
Posts: 72
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35mm hz-Ca13 equivalent ?
if a 16mm relay lens is possible, what's the problem not doing one 35mm relay to get shorter dof ?
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April 30th, 2008, 07:36 AM
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#2 |
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Major Player
Join Date: Dec 2005
Location: New York
Posts: 392
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This is very true, I have a feeling that it would need to be longer and larger in diameter for this to be possible... I'm wondering if it would be a problem getting the image upright for that depth though. The optics might be just too much distance and you would end up loosing light with all the lens elements.
It would be great if someone with more knowledge could chime in on this. I have a feeling if it were possible the price would be pretty high considering the optics needed would be extremely high quality. on a side note, is there someplace to see the difference between the stock lens dof and the adapter that has the 16mm depth? something with side by side comparisons would be so helpful, I heard about the jvc adapter but i never really saw any hd footage from it, and all the small stuff i did see, was quick. anyone with any info on both topics? |
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April 30th, 2008, 08:03 AM
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#3 |
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Inner Circle
Join Date: Feb 2006
Location: Belfast, UK
Posts: 6,152
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I believe optical design limitations restrict these adapter designs to 16mm lenses for 1/3" cameras and 35mm for 2/3" cameras - Angénieux make one for the latter
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April 30th, 2008, 08:25 AM
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#4 |
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Wrangler
Join Date: Aug 2005
Location: Toronto, ON, Canada
Posts: 3,637
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Actually... it is the laws of physics that make it unfeasible. (The 35mm to 2/3" version made by Angeniux/Zeiss about 10 years ago is known as the CLA35 - and it cost around $30,000.)
It would be entirely possible to create a 35mm "gate" to 1/3" purely optical adapter. However, because of the optical invariant (lagrange invariant) the maximum usable aperture would be around T5.6. This doesn't even put you into the "sweet spot" range of T4 so there wouldn't be much point as far as shortening depth of field. The maximum usable aperture on the HZ-CA13U COPLA is T2.8. You can open a high speed PL lens more than T2.8 but there will be no exposure increase or shortening of DoF. See this post for more info pertaining to the HZ-CA13U, the optical invariant and the possibility of a 35mm version.
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Tim Dashwood |
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May 2nd, 2008, 10:08 AM
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#5 |
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Regular Crew
Join Date: Mar 2007
Location: Paris
Posts: 72
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so what on earth could i do to shorten this except buying a Red One ?
http://www.tophos.com/images/jvcm2.jpg it's a real pain on a wedding :-) |
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May 2nd, 2008, 10:52 AM
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#6 | |
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Wrangler
Join Date: Aug 2005
Location: Toronto, ON, Canada
Posts: 3,637
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Quote:
There are loads that use the stock Fuji lens as a relay and some that use a proprietary lens as a relay which makes the rig much shorter.
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Tim Dashwood |
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May 2nd, 2008, 04:54 PM
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#7 |
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Regular Crew
Join Date: Mar 2007
Location: Paris
Posts: 72
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thank you Tim, you are always helpful.
I will take a look. |
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