How to properly compare RX-100 and NEX-6 kit high ISO noise?

Started Apr 29, 2013 | Discussions thread
tomhongkong
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Re: How to properly compare RX-100 and NEX-6 kit high ISO noise?
In reply to calterg, May 1, 2013

Calterg

This seems to be an increasingly common  misunderstanding which has been brought about by some sites comparing DOF for lenses used on sensors of different sizes.

Let's get it straight.  An F2.8 lens is F2.8, whether it is used on a pinhead sensor P&S or on a Hasselbad medium format.  If you use an FF lens on an aps-c body or RX100 (if you could) you do not alter the maximum aperture.

It is common to multiply the focal length to compare the effective field of view. (so the equivalent FOV in FF terms of a 100mm lens used on a aps-c 1.5x crop body is that of a 150mm lens).  However the true focal length of the lens (in simple terms how far the lens has to be from the sensor to get a sharp image) does not vary.

This article explains the concept of DOF and says it better than I would

http://photo.net/learn/optics/dofdigital/

I hope this helps

tom

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