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#1 johnRender

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Posted 13 July 2010 - 02:21 PM

Hi colleagues!

Is there such a lens that keeps everything on focus, i.e. has no DOF ?
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#2 Al DeLory

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Posted 13 July 2010 - 02:41 PM

Is there such a lens that keeps everything on focus, i.e. has no DOF ?
[/quote]

Some very wide angle lenses have no focus ring. As an example, I have an Angenieux 10mm f1.8 c-mount I use with my Bolex and an ARRI bayonet mount Kinoptik Tegea 5.7mm f1.8 that I use with my ARRI S. Neither has a focus ring. They're called retrofocus lenses.
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#3 Chris Keth

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Posted 13 July 2010 - 05:43 PM

No. All lenses will have some parts in focus and others out. As Al points out, there are very, very wide lenses that have so much depth of field, they effectively do not need to be focused.

There are also tricks that can help bring more of the scene into focus or bring key parts of it into focus. See this wiki on the sheimpflug principle to read about the most key of those tricks. The scheimpflug principle governs how we use tilt-shift lenses and bellows systems (including lensbabies) and how still photographers use view cameras.
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#4 Dom Jaeger

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Posted 13 July 2010 - 07:48 PM

In the 90's an Australian named Jim Frazier finished designing a lens he had been working on for 20 odd years that had virtually unlimited dof. An object 3 inches away and another 10 feet away were both in sharp focus. I believe Panavision bought the patent and manufactured several.
The lens was a big hit in the late 90's early 00's and used on a lot of ads where the scale difference between two objects could be played with if they both were in focus. So for example an insect in foreground and person in background looked the same size.
Frazier won a technical acadamy award for it, but some sort of patent lawsuit disaster in 2003 brought him into disrepute. I don't know if Panavision still rents the lens out.
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#5 Adrian Sierkowski

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Posted 13 July 2010 - 10:39 PM

It's called the Frazier lens system, also I believe the "T-Rex" Is similar. As far as I know Panavision still has them, but the caveat being you need a lot of light. If memory serves, it's around a T7.1 and you'll also need to be using panavision cameras. It's also rather large:

http://www.panavisio...8&id=86&cat=196

and a video demo:
http://media.panavis...ml/Frazier.html
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#6 johnRender

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Posted 14 July 2010 - 05:45 PM

Great, lots of information, thanks a lot.
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#7 John Sprung

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Posted 14 July 2010 - 06:15 PM

Indeed, many years ago in the consumer market, Kodak made both Super-8 and still cameras with slow wide angle lenses and enough DOF to not need focus adjustment. The line was called "Instamatic."



-- J.S.
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#8 Phil Rhodes

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Posted 14 July 2010 - 08:19 PM

Pinholes, of course.

P
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