Why not a 12-35 F1.8 - F2.8?

Started 8 months ago | Discussions thread
Anders W
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Re: Why not a 12-35 F1.8 - F2.8?
In reply to jennajenna, 8 months ago

jennajenna wrote:

Anders W wrote:

The fact that a 12-35/1.8-2.8 for MFT is equivalent to a 24-70/3.5-5.6 on FF with regard to total light on the sensor, DoF, and diffraction doesn't mean that the former can be constructed to be as small, light, and optically good as the latter. From a lens design point of view, the former is a more challenging task than the latter.

Hold on there Anders, What are you saying - that a 2.8 on a m43 is "equivalent" to 5.6 on full frame ON THE QUANTITY OF TOTAL LIGHT COMING IN?

Do you mean it's the "same" - first off the word equivalent is a lawyers word. It's either the "same" or "not the same".

But back to what you said - I was informed that 2.8 on m43 lets in the SAME amount of light as 2.8 on a full frame. The difference is in depth of field and difrraction; but mainly depth of field.

Now it seems you are suggesting total light comes into a m43 less at the same aperture as bigger sensors.

Can you clarify.

Sure I can clarify. The basic facts are the following:

With respect to exposure, which refers to amount of light per area unit (e.g., per square millimeter) on the sensor, f/2.8 on MFT is equivalent too (has the same effect as) as f/2.8 on FF.

With respect to the total amount of light on the sensor (light per area unit times the number of such units on the sensor) as well as with respect to DoF and diffraction, f/2.8 on MFT is equivalent to (has the same effect as) f/5.6 on FF.

Does that help?

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