f/1.8 on m4/3, ASP-C, FF; are they the same?

Started Nov 1, 2010 | Discussions thread
Dennis Forum Pro • Posts: 18,083
Re: f/1.8 on m4/3, ASP-C, FF; are they the same?

Peiasdf wrote:

If a picture is taken at 20mm, f/1/7, ISO 200, 1/100s on m4/3, will it come out similar (beside DOF) to a 40mm f/1.7, ISO 200, 1/100s picture on a FF?


If one image is brighter than another, it's because of measured v. actual ISO sensitivities, but that has nothing to do with the sensor size - just manufacturer preferences.

Some people mentioned m4/3 lens only lets in a quarter the light of a FF lens.

Same light per unit area over a smaller sensor. You can ignore this if you've already considered that the smaller sensor is noisier than the larger one.

So does it mean the camera have to reduce speed by a factor of four to get the correct exposure. It does not make sense to me, as P&S cameras do not require 15 times the exposure.

You have to give the smaller sensor more exposure (shoot at a lower ISO) to match total noise. Which is only an issue if you don't accept the compromises of a smaller sensor and insist on matching total noise

I am thinking about going from D90 + 35 f/1.8 -> GH2 + 20 f/1.7 for a night out with friends camera but the exposure thing is throwing me off. Maybe I need a Nokton 25 f/0.95?

Just so long as you're aware that images from the GH2 will be noisier than those from the D90 (though the GH1 and apparently GH2 have sensors that are much less noisy than other m43 sensors).

  • Dennis

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