Literally all of the Canon lens comparisons I posted were to show why FF lenses don't make sense on an APS-C body. The 400mm f/2.8 has gotta be marvellous on a FF camera, but on an APS-C camera its potential is mostly lost.
I am always told that in order to compare lenses between different formats, I must "divide the FL by the crop factor (to account for FoV), and multiply the aperture by it (to account for light gathering and DoF)". Now all of the sudden I am told I shouldn't be comparing lenses with double the physical focal length of one another at all, even if the FoV differs by just 50%.
And my original post was just to compare MFT and various APS-C systems, criticising some for the lack of APS-C glass, forcing users to use FF glass whose potential is wasted on an APS-C body it wasn't designed for. But I guess by comparing what are after all FF lenses, to MFT lenses, I ended up awakening the FF-Equivalence-Brigade, descending the resulting thread to the usual format war.
If you want to compare with the 200/2.8PL, then choose a 200/2.8 lens on APS-C to compare to. You said you were comparing lenses.
You won't do it because you are confused by "equivalency".
Equivalency is just a way to refer to the angle of view of the final image.
Nah. If you are composing a picture in your artistic mind, you are thinking of an angle of view and a DOF and light and shadow. You most definitely do not care one iota about equivalency at this stage.
Next stage is, how can I best realize this picture that I made in my mind. Now you start looking at your gear at hand.
If there is only one format of cameras in that bag equivalency is again totally irrelevant and useless. You have to use what is in that bag. Dreaming of anything else is utterly futile.
Equivalency does not make a memorable picture worse, or a boring picture better.
You can always crop in post on the APS-C camera using a 200/2.8 lens to get the same image as the M43 + 200/2.8PL.
Every full frame sensor has an APS-C sensor and a M43 sensor. Every APS-C sensor has a M43 sensor.
You just have to crop in post to get it.
For a M43 sensor to get FF results, you have to shoot 4 photos and stitch the quadrants together. It's much easier to simply crop a FF/APS-C sensor to M43 size in post to get M43 results.
Using M43 to get FF/APS-C results - hard (need to take multishots to compensate for missing areas due to smaller sensor).
Using FF/APS-C to get M43 results - easy (just crop).
FF/APS-C can always use the same focal length lens as M43 and crop in post to get the same results. Your entire thread and pointless comparisons assume no one can ever crop their photos.
It's not so easy. Smaller sensors have faster readout and faster frame rates, which may matter a lot for fast action pictures and not at all for others. There may be a pixel density penalty cropping FF or apsc, which again may or not matter. DR may be important for some pictures and not so much for others. Size and weight determines how far from your car or transport you can lug your bag. And there might be cost and affordability implications. These are all differences in formats, that are completely overlooked by the equivalency theory. As if they were irrelevant, when in practice they may be paramount.
You make your choice when you put gear in your bag, then you have to live with it for the day or the trip. If there is only one format in that bag, then you walk around looking for pictures that suit what is in your bag. Which necessarily limits your creativity.
Back in the film days, equivalence was simply that a 6x6 image (56x56mm) shot with the standard 80/2.8 lens was looking the same as a 35mm image (24x36mm) shot with a 35/1.2 lens with same exposure time and same film type and cropped for a square aspect ratio. Essentially, you did choose the format based on the grain that you were prepared to accept. Only recently has equivalency become a source of heated discussions and a justification for one's personal gear choices.
