Sony is making a lot of their new 100mm f/2.8 GM lens with its Smooth Trans Focus technology. But what exactly is this so-called STF, how does it work, and why does it produce smoother bokeh? This short video explains all.
The Sony video was published by The Pixel Connection on YouTube, and it explains in simple terms how something called an apodization (APD) element helps create “breathtaking bokeh” in your photographs. Essentially, the APD element acts like a circular graduated neutral density filter inside the lens, letting progressively less light in as you move from the center to the edges.
This graphic shows the effect this produces with the bokeh in your images:
In real-world portraits, that should mean the difference between the two portraits below, where the bokeh in the image captured with the STF lens is smoother than without:
And here’s a closeup:
This technology is not original to Sony. The same thing appears in Laowa’s 105mm f/2 STF, as you might have seen in this review we shared a couple of weeks ago. Of course, given Sony’s massive R&D budget and dedication to making their GM lenses the best of the best, one would hope the 100mm GM would outperform Laowa’s more affordable option.
We’ll just have to wait and see.