Samyang 135mm F1.8
This lens is priced over 700USD (even cheaper second-hand), and its advantage is its lightweight—only a little over 700 grams. But as mentioned earlier, the issue with Samyang is quality control. I asked a friend, and he told me that among six people he knows who bought the Samyang 135mm F1.8, some got lenses that were almost on par with the GM in terms of quality, while others got lenses with very poor quality.
This is why, even though I could have bought a Samyang to compare, I ultimately didn’t do so—I can’t guarantee that I would get a good copy, nor can I guarantee that you would get a good one either... so what’s the point of comparing?
Sigma 135mm F1.8 DG HSM | Art
As a photographer who owns the Sigma 135mm F1.8 DG HSM | Art, I have to say it surprised me a lot when I first got it. The lens offers excellent sharpness and bokeh, but its weight (even with the adapter ring) is not light. That’s why it has been sitting in my cabinet for a long time and is usually only taken out for creative product shots.
Of course, one of the advantages of Sigma lenses is that they can be adapted to virtually any mirrorless camera body while maintaining autofocus functionality. However, the autofocus performance inevitably takes a hit after adapting, especially when it comes to continuous tracking autofocus.