So, what exactly does shooting at f/2 bring you?

Started 1 month ago | Discussions thread
OP bobn2 Forum Pro • Posts: 65,568
Re: So, what exactly does shooting at f/2 bring you?

OM-G wrote:

Low F-number is always good for AF.

There is no automatic advantage to low light AF for larger sensor.
AF has more to do with light intensity per area, and in that regard F2=F2.

I don't think you're right, for any kind of AF. Please  explain why you believe this to be the case.

A mFT camera with a F2 lens will have around a 2 stop advantage in low light AF compared to an equivalent FF F4 lens.


Focus sensitivity for the Sony A7S II is EV-4 (ISO 100 equivalent with F2.0 lens)
Focus sensitivity for the Olympus EM1 III is EV-4.5 (ISO 100 equivalent with F2.0 lens)

You can't tell much from claimed figures. It's marketing spin.

Same thing applies to exposure metering.

I don't believe that is the case, either. please explain your reasoning.

The point is that you cant just take a FF system with a 2-stop slower lens and think its equivalent in focus and metering. An eqivalent FF lens in this regard would have to be F2 and way bigger.

Since you're just presenting you're beliefs as fact, there's not much I can do except say 'I think you're wrong'. If you provided some theory, reasoning and evidence to back up your statement, perhaps we could discuss it.

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