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Old December 28th, 2005, 05:01 AM   #1
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Circle of Confusion question

in this really amazing footage..
http://www.digitaliconstudios.com/sc...dex.php?vid=30
the circle of focus is really small....
does anyone know the technique for achieving this?
where the center of the face is in focus but the hair and the hood are out of focus?
Is it a matter of zooming in from far away? zooming out when you are up close?
thanks for any assist
cheers
Q
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Old December 28th, 2005, 05:18 AM   #2
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I believe this footage was shot on a DVX100 and a LETUS35, 35mm adapter. Its the adapter that gives the shot that shallow depth of field. There are many such adapters our there including the letus35, G35, M2 and my SG35
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Old December 28th, 2005, 05:22 AM   #3
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Wayne,

I believe Quito has Letus35 adapter. His question is how to use an SLR lens with the adapter to get that effect. Thanks.

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Old December 28th, 2005, 05:59 AM   #4
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yep

I have the Letus35a, its brilliant, i recommend it....
but its getting that uber small CoC that I am after
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Old December 28th, 2005, 06:02 AM   #5
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I believe to get that effect you need the largest aperture that your lens will support and get as close as you can to the nearest subject. This allows a very shallow DOF on the nearest objects. I have done this with a sheet of A4 paper where you can watch the focus go up the sheet, line by line.

As Wayne said, it's the SLR/Adapter combination. The further your subject is away, the more the DOF is perceived (or rather it's not as noticiable as more things will be in focus.

With the adpaters I have (Both SG35 & Letus35) I can get with 30cm of the nearest object giving great control of what is and what isn't in focus.
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Old December 28th, 2005, 06:26 AM   #6
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thanks for that

this board is a wealth of information....i really appreciate the time you took to answer it
cheers
Q
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Old December 28th, 2005, 02:15 PM   #7
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Also bigger glass = shallower DOF. Look for the 1:1.2 Canon FD on ebay and you'll get razor-thin DOF.
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Old January 2nd, 2006, 01:08 AM   #8
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I think I made a joke a while ago, and some people missed it...
In original it is "circle of diffusion" (not con-cough-cough-confusion)
Unless it came back again as a…joke!
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Old January 2nd, 2006, 05:25 AM   #9
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Circle of confusion

I think its Circle of confusion
From Wikipedia, the free encyclopedia.
The depth of field is the region where the size of the circle of confusion is less than the resolution of the human eye. Circles with a diameter less than the circle of confusion will appear to be in focus.
The depth of field is the region where the size of the circle of confusion is less than the resolution of the human eye. Circles with a diameter less than the circle of confusion will appear to be in focus.

In optics, the circle of confusion is a term relating to the fuzziest a point can be and still be called "in focus" (this is related to the depth of field). In photography, this value is often calculated as the largest circle on the film that will still be seen as a point when enlarged to 8"x10" and viewed from a normal viewing distance (2-3 feet).
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Old January 2nd, 2006, 11:19 AM   #10
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aahhh..... Could be, could be....
(If is from Whinkipedia.....)

I took a look last night on the "dof" adapters from the same source, I found some ...hmm..."less than ideal" explanations... I start some editing and then I realized the value of publishing there ...(it could be edited back and changed by anyone to anything and then taken for granted by many) so... I refrained.
Some years ago.. it was diffusion (as I remember it). Now the confusion rules.
OK! Let it be confusion....Who knows....
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Old January 2nd, 2006, 09:52 PM   #11
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Ben, that's a good point on the glass. Basically the larger the rear aperture of the lens, the larger the possible angles between incident and refracted light. It's this angular difference that allows a smaller circle of confusion...and hence shallower DOF. I just recently got my head around all of this researching a lens choice for my adapter...and ended up ebaying a 50mm F1.4 Minolta ROKKOR. The rear lens aperture is 30mm...10mm larger than my F2.0 45mm. The difference in the shallowness of DOF between the two lenses, just looking through the SLR focussing screen is startling.
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