Contituation of the Versatility thread

Started Apr 5, 2013 | Discussions thread
olliess
Contributing MemberPosts: 888
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Re: Advice for the thread starter
In reply to FoolyCooly, Apr 7, 2013

FoolyCooly wrote:

Correct my if I am wrong but a f1.4 lens still lets the same amount of light in regardless of the sensor size.

As pointed out already in several threads on equivalence in these forums, a 25mm f/1.4 lens is going to project the same light per area onto the sensor regardless of the format. However, a larger sensor is collecting light from a bigger area.

Think about it this way: to take the same picture as a 25 mm lens on m4/3, you need a 50 mm lens on FF. The entrance pupil on the m4/3 lens is 25 mm/1.4 = 18 mm, while 50 mm/1.4 = 36 mm, or exactly twice as big, meaning 4 times the area to admit light.

It's only when you compose the image the same way that the DOF becomes equivalent to f2.8.

If you're taking totally different pictures then comparisons and "equivalency" go out the window anyway.

If you remove the need for subject isolation and short DOF the the aperture advantage of FF goes away.

You may also desire to expose with a higher shutter speed to avoid motion blur, and here the greater aperture size gives you the choice. Versatility is about choice, you don't have to use it just because it's available.

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