鏡頭評測 唯卓仕af 75mm f1.2（索尼e卡口）鏡頭評測

Hi, it's me. Let's get stuck right into a lens that's super exciting, well, to me, anyway, the Viltrox AF 75mm f1.2, this time released on Sony E-mount. I knew it would make its way over from Fuji X-mount one day. It's an autofocus portrait lens, and its retail price of only US$550, or £450 here in the UK, makes it a potential bargain, if it's any good. Any 75mm f1.2 lens, even on an APS-C camera, will offer you images with stunningly autofocus backgrounds, absolutely perfect for portrait, subject and event photography. A lens like this is a lot of fun to use, whenever you can find an interesting subject. As I said, it's designed for APS-C or crop sensor cameras. Here is the image circle you will see if you shoot on a full-frame camera in full-frame mode. I'd like to thank Viltrox for sending me a copy of this lens for evaluation, although as usual, this is a totally independent review. All the test photos you will see in this review are new ones, taken with this lens on a Sony camera. The sample pictures are from my review of the Fuji version of the lens, though they're optically the same lens, and frankly, I just really liked those sample pictures. This lens's build quality on Sony E-mount is still excellent. Viltrox are at the top of their game here. The lens is tough and metallic, and a little heavy, with a really nice finish to it, even down to small things like the writing on the barrel being engraved properly into the body. The lens mount is made of metal, with a thick weather sealing gasket around the edge, as well as a USB-C port for firmware updates, which is always reassuring. Next comes an aperture control ring. On Viltrox lenses, this often turns completely smoothly, but this time, you have the choice of a smooth operation, or to set it to have nice, positive clicks to it every third of an f-stop, which is much more tactile, and you're much less likely to accidentally change aperture. The click to get it into automatic mode is a bit firmer, making it harder to accidentally move past the f16 point. Next comes a very large, metallic manual focus ring, which turns incredibly smoothly, although it doesn't always offer the greatest precision. The lens shows fairly substantial focus breathing, as you can see here, which will be a little annoying for video makers. The autofocus motor? Well, unfortunately, that's a weak point of the tested lens. On the plus side, it works silently, and when it reaches focus, it is accurate, but it works a bit slowly, with a bit of hunting, whether you're shooting in single-shot mode or continuous autofocus. The lens comes with a fairly deep lens hood made of plastic, the front filter size is 77mm wide, and the lens does not feature image stabilisation. But overall, this is premium build quality and functionality from start to finish. The lens is well thought out and a joy to use, although I do wish that autofocus motor were a bit faster and more confident. The Sony a7R III camera I was testing on is an older model, but its autofocus ability is still excellent, so we should have seen a better performance here. All right, let's look at image quality. This time, I'm testing it on a Sony a5100 with its 24-megapixel APS-C-sized sensor. In-camera corrections are turned on. Straight from f1.2, central sharpness is brilliant, with great contrast. Nice. Corner sharpness is fluctuating a little, losing its edge, but then getting sharper again rides into the edges. Nevertheless, a good performance there, too. Stop down to f2 for more corner brightness and a slightly better sharpness. However, stop down to f2.8, and corner sharpness is now top-notch. The lens stays this sharp down to f11. f16, however, loses its edge due to the effect of diffraction. So, while it's possible to get slightly sharper APS-C prime lenses than this, you certainly can't at this lens's price point, so it's a great performance overall. All right, let's turn off those in-camera corrections and take a look at distortion and vignetting. The further good news here is that the lens's image isn't really distorted in any way at all. Vignetting at f1.2 is really heavy, though, unsurprisingly. Stop down to f2 or f2.8, though, and those corners quickly brighten up, so it's a fairly good performance here, also. In my tests, this lens could only shoot as closely as about 90cm to your subject. Not especially close, really. At f1.2, close-up image quality is reasonably sharp, but with low contrast. Stop down to f2, and the image becomes excellent again. Let's move on and take a look at the quality of this lens's bokeh. On the most part, it's very nice and smooth, as usual for a short telephoto optic, although you can occasionally just see a slight jumbling to backgrounds in the middle distance. And finally, related to bokeh comes longitudinal chromatic aberration, which can be a problem for portrait lenses. Thankfully, even at f1.2, any kind of colourful fringing on bokeh highlights is very low. Stop down to f2, and it's just about gone.