Reading resolution charts comparing MFT lenses to FX lenses

Started Mar 29, 2013 | Questions thread
Anders W Forum Pro • Posts: 21,468
Re: Ideally...

Great Bustard wrote:

Anders W wrote:

Great Bustard wrote:

However, here's what would be awesome:  take the make a bench that mounts the lens in front of the highest pixel density sensor out there.  Take some photos from various portions of the image circle, and use the same RAW converter with the exact same settings each time.  Now you're really testing the lens, and not the system.

Yes. I have thought of it. If all lenses were manual, it would probably have been done already. But you can't even focus or stop down an MFT AF lens without the right body electronics. And if it's an OIS lens, the OIS lens group could be anywhere without power.

I did not know that!

Isn't it the same with regard to aperture control as well IS on Canon EF? And with regard to IS on any system?

Of course, this now opens a huge can o' worms, since the lenses for smaller sensor systems will, on average, resolve better than lenses for larger sensor systems, and we'll have the ignorant masses chanting "lw/ph = lw/ph" to go along with "f/2 = f/2", and any attempts to educate will be met with "entertainment".

But, now that I think about it, I'm good with that. 

Not with you and me around to do the education.

Maybe not with you, but you know that "entertainment" always finds me and I always find "entertainment".

As you know, I am open to the idea that it is fair to compare an MFT X mm lens at f/2 with an FF 2X mm lens at f/4, since that's the point where they are equivalent in terms of DoF, diffraction and light accumulation (and thus photon noise so that there would no longer be any difference with regard to the possibility to sharpen in PP). And I much prefer such comparisons to those we can make on the basis of Photozone results.

Except that often the larger sensor system is simply using a longer shutter speed for the same DOF.

And what would prevent the MFT user from using the same longer shutter speed and thus getting the same amount of light on the sensor nevertheless?

Still, I had better add that such comparisons are no panacea either. One reason is that we ignore the complicated read-noise issue when we just go by the general two-stop difference rule. Another is that it is not reasonable to expect an MFT X mm f/2 lens to do just as well wide open as an FF 2X mm f/4 lens or to expect the two to have similar price tags.


There are physical reasons why the MFT lens faces a tougher job in such a comparison, and we should take that fact into account when we look at how well they accomplish. Naturally, we should also take it into account when choosing between systems. If you chose to go with MFT without realizing that the MFT X mm f/2 lens would probably cost more and perform worse wide open than the corresponding FF 2X mm f/4 lens (if it were available ), it simply means you haven't done your homework properly.

To be perfectly honest, I think we are well, well, well past the point where differences in resolution matter for the vast majority.  That is, if you took a pic of a scene with the kit lens and the 12-35 / 2.8, printed them even at 16x24 inches, put them both for sale, they'd sell for the same price and in the same amount.  Well, maybe you'll sell 53 of the pics shot with the 12-35 and 47 pics shot with the kit lens, but you get what I'm saying.

I'm just coming to the opinion that any IQ differential between lenses and systems is simply unimportant for the vast majority in the vast majority of situations, and it's only for the extremes that it matters.  And by "extremes", I mean the very extremes.

Well, that may be true for the majority but what about me?

Seriously, though, I can agree up to a point. The fact that good MFT primes do sufficiently well for my resolution standards at apertures about f/2 (and significantly better than anything but the newest FF lenses can manage at the same f-stop) although they don't do quite as well as an FF combo at f/4 was an important reason for me to dare take the plunge into the MFT world. Of course, given the circumstances in terms of DoF and photon noise, I would want/need to use an aperture as wide as f/2 on MFT far more often than an FF user would want to use the same f-stop, everything else equal. So fast primes that perform sufficiently well already wide open or thereabout become critical.

On a more general note, though, I am curious about whether what we can actually see in terms of resolution with current display or printing technology (and no peeping) will hold true in the future. What would the situation be like if we had displays of the same size but with 16 MP rather than 2 MP resolution. Would we still be unable to see much of a difference?

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