A7r 24-70 vs Nex-7 16-70 vs EM1 12-40

Started Mar 2, 2014 | Discussions thread
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forpetessake Senior Member • Posts: 4,788
Re: EM1 12-40 vs Nex 5r speed booster with 24-105L

bigley Ling wrote:

forpetessake wrote:

Not just unscientific, it's flawed. The 12-40/2.8 is full equivalent (disregarding aspect ratio) of 24-80/5.6 on FF, not just DOF. You set it on f/2.8, i.e. f/5.6 on FF. And 24-105/4+SB on APS-C is full equivalent of 25.6-112/4.26 on FF, which you set at f/4, i.e f/4.26 on FF. So what are you comparing?

The best argument against democracy is a five-minute conversation with the average voter -- Winston Churchill

The 12-40mm pro lens I believe still takes in light at f2.8 ,and yes the effective DOF is 5.6.

That's what stubborn people on m4/3 forum believe, they invented perpetuum mobile and don't even realize that. To calculate the light received by the sensor you need to integrate the light flux hitting the sensor over the area. The size does matter. In the final analysis, it's the lens physical aperture that collects the light, f-stop is just a ratio = aperture/FL, so you can as well integrate the incoming flux for a given field of view over the aperture area of the lens, there is no magic in the world that can make 12mm/2.8=4.28mm aperture on m4/3 to collect more light than 24mm/4 = 6 mm aperture on FF for the same FOV.

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