We assume that megapixels matter more than anything, and that a good lens on a high-resolution full frame camera will still be better than an excellent lens on a lower-resolution camera, right?
Well, I thought I’d check.
I have a 42.4MP Sony A7R II and a Zeiss 16-35mm f/4 lens, and I have a 20MP Olympus E-M1 Mark III and an Olympus 8-25mm f/4 Pro lens (16-50mm equivalent). What would happen if I shot the same scene on both and compared the sharpness?
That’s a pretty huge 2x resolution difference, but these are the only two formats where I have equivalent lenses, and I thought a comparison like this needed a pretty blunt approach.
I’m not too concerned with the center sharpness. I know the Sony/Zeiss combination will win that battle. I’m more concerned with edge sharpness, which is where a lot of ultra-wide lenses fall down. I know my Zeiss lens is distinctly average at the edges at 16mm, and I’ve been impressed by the edge sharpness of my Olympus 8-25mm.
So what I want to know is whether the extra edge sharpness of the Olympus lens nullifies the resolution advantage of my Sony A7R II.
The results are interesting! In the center of the image the superior sharpness and detail rendering of the 42MP Sony are as plain as day. The difference is, if anything, greater than I expected.
At the edges and in the corners of the frame, however, the sharpness from the full-frame Zeiss lens fell away to the point where it was not resolving any more actual detail than the Olympus lens on the 20MP MFT camera.
I would still use the A7R II/Zeiss combo for outright quality but always with the niggle that the extreme edge definition will be poor.
As a quick reality check I resampled both images to 4K UHD width at a size that might be used online or even in print. They both looked so similar that the Sony had no advantage – though the corner sharpness fall-off of the Zeiss lens could still be made out, even at this reduced size.
For the record, I definitely do like the extra resolution of the A7R II. At the same time, though, what I don’t like is when this drops away at the edges. I dislike that about as much as I like the extra resolving power.
Of course, I could just get a better ultra-wide zoom for the Sony, but while the Zeiss and Olympus lenses are not too different in price, a Sony G Master ultra-wide would cost more (and weigh more) than both combined.