In praise of Panny's 2.8 zooms

Started Jul 30, 2013 | Discussions thread
EEmu Forum Member • Posts: 69
Re: In praise of Panny's 2.8 zooms

Mark B UK wrote:

I've participated in a few of these 'equivalence' debates. They usually descend into I'll feeling

Which is ridiculous because the whole concept is hard science.

The only point of value I can add is this:

If the light is such that I need to shoot at 1/250 sec at f/2.8 on ISO 200 on my E-M5, if I then pick up a Canon or Nikon FF DSLR, select the same shutter speed and ISO and an aperture of f/5.6, I should expect the image to be underexposed by two stops. Anyone who disagrees with this should take some time out to re-learn the basics.

Of course it would be underexposed: You're using an equivalent aperture but not an equivalent ISO.  Increase the FF's ISO 2 stops to compensate for it having a 2 stop larger sensor and you'll have a correctly exposed picture with the same quality.

Remember that ISO is a number that has no physical meaning; it's just made up so that shooting a fixed aperture/shutter/ISO results in a properly exposed (within 1 stop) picture regardless of sensor size.  It has no bearing on image quality across systems.  If you don't believe me, then you can compare the LX7, GF1, and 5DIII at ISO100.   (Spoiler: I'd take the 5DIII at ISO1600 over the LX7 at ISO100.  Same-ish noise at 1:1 but more pixels.)  If you care about image quality you need to look at the amount of light received by the sensor and not ISO.

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