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05/16/2007 03:54:07 PM · #1 |
The Canon EF 85mm f/1.8 USM
At 1.8 what would you say is the minimum distance from subject required to get a reasonable plane of focus?
And at 2.8?
The documentation says that it has a min foc dist of three feet, but most of what I have read suggests it is much more.
What say you?
Message edited by author 2007-05-16 15:57:49. |
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05/16/2007 04:41:31 PM · #2 |
bump and...
I thought I might need to define reasonableâ€Â¦
To me, a reasonable plane of focus at 1.8 would allow me to shoot a head-shoulder shot and have both eyeballs in sharp focusâ€Â¦ while the neck down is thrown increasingly out of focus.
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05/16/2007 04:43:47 PM · #3 |
Its specs say 2.8 Feet so maybe 2.5? lol
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05/16/2007 05:29:26 PM · #4 |
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05/16/2007 06:13:44 PM · #5 |
First, at 3 feet, you will be framed *very* tightly. You will be basically only shooting the face (frame height, assuming portrait orientation, of 9.5 inches). You can calculate the DoF using the calculator linked by TechnoShroom. Believe me when I say that even at f/2.8, the DoF will be *plenty* narrow! Even with a subjet distance of 6 feet (framing about 20 inches of subject, or head/shoulders you will find that f/1.8 yields an extremely narrow DoF.
Here's a pertinent example:
The above was shot at 50mm, f/2.0 with the 5D; that's roughly equivalent to 80mm, f/2.0 on an APS-C camera, ignoring differences in CoC. It gives you a good idea what to expect. |
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05/16/2007 06:18:12 PM · #6 |
Originally posted by kirbic:
The above was shot at 50mm, f/2.0 with the 5D; that's roughly equivalent to 80mm, f/2.0 on an APS-C camera, ignoring differences in CoC. It gives you a good idea what to expect. |
wouldn't 50 mm on a 5D be around 33 mm a APS-C camera? and a 50 mm on a APS-C camera be 75 mm on a 5D?
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05/16/2007 06:20:39 PM · #7 |
Woops, you're right, I'm backward. So I'd have had to shoot that with a 135mm lens, at f/2. Hold on, I've gotta do a couple calculations...
Edit:
Yep, math still works. Whether I shoot it at 50mm or 135mm, as long as I maintain the same framing and same f-stop, the DoF remains the same. So this shot is a valid comparison, with the exception of the CoC differences.
In practice, if we both shoot the same framing with an 85mm lens at f/2 (he backs up to maintain framing) he'll get a larger DoF than I will, but we're talking the difference between 0.5 inches of DoF (5D) vs. 0.9 inches (APS-C).
Message edited by author 2007-05-16 18:34:19. |
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05/16/2007 06:21:00 PM · #8 |
Originally posted by jdannels:
Originally posted by kirbic:
The above was shot at 50mm, f/2.0 with the 5D; that's roughly equivalent to 80mm, f/2.0 on an APS-C camera, ignoring differences in CoC. It gives you a good idea what to expect. |
wouldn't 50 mm on a 5D be around 33 mm a APS-C camera? and a 50 mm on a APS-C camera be 75 mm on a 5D? |
Yeah but canons APS-C is 1.6 crop I think which would make it 80mm. 75 on the Nikon as it's a 1.5 crop factor.
Right?
Message edited by author 2007-05-16 18:21:38. |
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