dof: sensor size vs aperture

Started Dec 16, 2010 | Discussions thread
Joseph S Wisniewski
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The APS sensor wins...
In reply to itani, Dec 17, 2010

itani wrote:

would a camera with a aps-c sensor and a aperture of 2.8 get more depth of field or would a point and shoot compact camera with a cmos sensor size of 1.7 and a aperture of 2.0 get more depth of field?

i know, a very geeky question....

Couldn't have been that geeky, 4 people made comments without actually trying to answer...

OK, what's a "cmos sensor size of 1.7"

  • 1/1.7 inch, which, as far as I know isn't a standard size.

  • 1/1.8 inch

  • 1/2.7 inch

  • 1.7x crop like Sigma DP1 and DP2?

You figure equivalent apertures by looking at the ratio of sensor diagonals. APS is about 28mm. So...

  • 1/1.8 inch = 8.933mm diagonal, so f2.8*8.933/28 = f0.90

  • 1/2.7 inch = 6.592mm diagonal, so f2.8*6.592/28 = f0.66

  • 1.7x crop = 24.9mm diagonal, so f2.8*24.9/28 = f2.49

Basically, no compact with a 1/1.8, 1/2.7, etc. sensor has a lens fast enough to match f2.8 on an APS camera. f2.0 on the P&S won't do it, you need insane lenses like f0.9 or 0.7.

A camera with a 1.7x crop sensor could do it with an f2.49 lens, but the only cameras with the 1.7x sensor have f2.8 or f4 lenses.

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Rahon Klavanian 1912-2008.

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