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next PZ lens test report: Fujinon XF 50-140mm f/2.8 R LM OIS WR
Sorry, but the "bullshit talking one" is not me.


There you go, you figured out that the exposure meter does NOT tell you that an ISO number is fixed. That is half a step to the right direction.


Your film ideas are about.... film with a set sensitivity. This may for instance be ISO 60. ISO 60 film has a quite fine grain. Rather comparable with a very high resolution sensor. If you a more sensitive film, like ISO 1600, you will soon notice two things: the grain is more coarse grain. And the resolution of that film is lower.  


Now expose those films the same time and with a similar aperture. You will soon notice that that "exposure per square unit" is a rather nonsensical thought experiment: the different films will show very different results now. Apparently exposure is not about "area" that much. Even in the film times it was rather a meaningless thing. 


It is not clear to me why you feel you can't/should not compare for instance X-Trans with Bayer sensors... Both use similar silicon sensors, both use CFAs of the R, G and B type. 


But you are free to focus on a meaningless things.


But lets then just use the Nikon D810. At FF it has about 36mp, when used in APS-C crop mode about 15mp.

When we look at images printed the same size, we should be able to notice that the APS-C crop image has less resolution, but that aside.


We shoot the FF image with 100mm f4. 

To get a similar FOV, we shoot the APS-C crop image with 100 / 1.5 = 66.7mm.

To get a similar DOF, we simply use an f-value of 4 / 1.5 = f2.67.


Now, the exposure times will be different, because of the different f-values. But fear not, we can set cameras easily to other amplification factors in the digital age. We call this "equivalent ISO settings". Suppose we shot the D810 in FF mode with ISO 800. We then can set the D810 in APS-C mode to 800 / 1.5 / 1.5 = ISO 355.

 Of course, focal lengths, aperture settings and ISO settings are not THAT fine grained, but you can set these to the next close values and you get pretty close to similar results.


Now we will look at the images we printed again. We notice that the images look pretty similar still, even though the ISO settings were different for both shots. Why is that? Because the higher ISO FF 36mp shot is much finer grained than the 15mp APS-C shot.


Darnet, even in this odd experiment with just one sensor used in different sizes we get similar results when using equivalent settings.


Maybe you want to argue against that the result is what counts, in photography, and across different formats?

Like for instance that the only thing that matters is is lumens per square foot?


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next PZ lens test report: Fujinon XF 50-140mm f/2.8 R LM OIS WR - by Brightcolours - 02-02-2016, 05:48 PM

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