This is the eighth in a series of posts on the Fujifilm GFX-50S. The series starts here.
I got outside for this one. I put the Sony/Zeiss 55mm f/1.8 Sonnar (Zony 55) on a Sony alpha 7 R, Mark II (aka a7RII), and the Fujinon GT 63mm f/2.8 lens on the Fujifilm GFX-50S. Shutter set to EFCS for both cameras, which meant it really was EFCS for all the pictures with the Sony, and was EFCS at the narrower apertures for the GFX. Exposure compensation set to zero. AF-S used in both cases. 2-second self-timer used in both cases. Arca-Swiss C1 cube on RRS sticks. The Fuji images were about 2/3 of a stop darker than the Sony ones, indicating that the Fuji metering is a bit optimistic compared to the Sony. A more charitable way to look at that would be to say that he Fuji offers more highlight protection than the Sony. Base ISO for both cameras. Focus was in the center of the image. Tripod and head were not moved between series.
I developed all the images in Lightroom with default settings, except for Exposure. I adjusted that to roughly equalize brightness. ACR/Lr force lens distortion corrections for the Fuji 63, which probably reduce corner sharpness.
The scene, with the Zony set to f/2 and the Fuji lens set to f/2.8:
In the middle, at 250% magnification for the GFX, and the same sensor extent for the lower-resolution a7RII. This would give the same field of view if the lenses were equivalent focal lengths, but the 55 is longer than the full-frame equivalent of the 63.
Here’s how to use these highly-magnified crops. The dimensions of the GFX sensor are 8256×6192 pixels. If we make a full-frame print from the GFX on a printer with 360 pixels per inch native driver-level resolution, like the Epson inkjet printers, we’ll end up with a 23×17 inch (58×44 cm) print. The 318×246 pixel crop you’re looking at will end up 0.8333×0.6833 inches (2.12×1.74 cm). Let’s imagine that you or your viewers are critical, and will look at the 22×17 inch print from about 18 inches (conventional wisdom is that the distance would be a little greater than that, or 28 inches (the diagonal), but you did buy a high-resolution camera for a reason, didn’t you?).
The next step is dependent on your monitor pitch, which you may or may not know. Turns out, you don’t have to know it. Just take the 253% crops and view then at 1:1. How high are they? Get out your ruler and measure, or just guess. Let’s say they are 6 inches high. 6 inches is about 7 times 0.8333, so in order to view the crops the way they’d look from 18 inches on the print is to view them from 7 times as far away, or 10.5 feet.
Everything here scales proportionately. If the image on your screen is bigger than 6 inches, increase your viewing distance by the ratio of your image height to 6 inches. If you thin your viewers are going to almost get their nose to that print and look at it from six inches, divide that 10.5 feet by 3, and look at the image on the monitor from three and a half feet away.
The images from the a7RII are scaled to the same print height of 17 inches. Because it has fewer pixels vertically, that requires slightly greater magnification.
There in an argument in favor of comparing the f/2.8 Fuji image with the f/2 Sony one. That’s the equivalence approach. But you could also take the practical tack, and say that in a landscape situation, you’re gong to pick the best aperture for the lens and the scene, and use what ever shutter speed you have to. I favor the latter way of looking at things.
Either way, it’s clear that the Sony image is inferior. That is not to say that the Sony is a bad camera, or that the Zony 55 is a bad lens. In fact, in the past I have marvelled on how good my copy of the Zony 55 is, how well it does compared to spare-no-expense lenses like the Otus 55, and speculated that I got lucky when it came to serial number.
The Sony is getting better, but I’d sure rather have the GFX pic.
Are you detecting a pattern here?
I’m convinced. How about the corners?
I’m not looking at the same part of the scene in these, because the fields of view (and the aspect ratios) are different.
I call the Fuji a modest winner over the Sony at f/2.8, but they’re real close.
I call that a tie.
Now I think the Fuji is doing better.
The Fuji is clearly better.
What if we don’t go all the way to the corners, just to the horizontal extremes?
Sony is softer, lower contrast.
There’s a pattern here.
Both corner and left-center crops I chose were of a part of the subject somewhat closer to the camera than a plane normal to the lens axis passing through the center subject. The usually helps lensse like this, but not alway. Let’s chose a left-center crop slightly behind that plane.
My take on this is that the Fuji 63 has a focal plane that is a bit closer to the camera than the Zony 55.
Completing the series:
So the Fuji is markedly sharper except at the very corners, where the Sony comes close. As I said earlier, ACR/Lr force lens corrections for the 63, which probably reduce corner sharpness.
The corner performance of the Fuji system doesn’t surprise me, but the center and edge do. The GFX is quite a camera.
A few notes: The tiltable EVF of the Fuji was remarkably convenient for making this series. I ended up not using the a7RII’s EVF, but relied on the LCD screen, which is harder to see in bright light. To get the camera to a convenient height for the Sony’s EVF, I would have had to use more tripod extension. It’s really nice to have tripod height to be non-critical. Lightroom performs camera and lens-dependent sharpening when converting raw images. Thus, tests like this one are always a little apple/orangey. However, I messed around with sharpening on the Sony images, and I couldn’t get them to look anything like the Fuji ones, except is the cases where they were very close to begin with.