Monkeying with Focus
Sony just announced two new lenses, one of which was a 100mm f/2.8 STF, which stands for "Smooth Trans Focus". This is an interesting lens design that diffuses sharp edges in the bokeh into softer transitions, which creates an overall smoother and more silky rendering of the background.
This would be especially nice for portraits, but also for any kind of close up shots, like flowers. The cost of achieving this effect is about 1.5 to 2 f-stops. So the 100mm f/2.8 is really a 100mm T/5.6 in terms of light transmission.
I don't know if I will get the 100mm lens, but I discovered that Sony also made a 135mm f/2.8 STF lens in the A-mount. This is a manual focus lens, something I am eminently comfortable with. I figured if the 100mm f/2.8 was any good for portraits and bokeh, then surely 135mm f/2.8 ought to be at least as good, if not even better.
I also discovered that the 135mm f/2.8 lens has been around for some time, and nobody is paying attention to it. So it can be bought for around $800-850 brand new, almost half the cost of the new 100mm f/2.8. Of course, it needs a Sony LA-EA3 adapter to work, which could be bought on eBay for about $130 brand new, less for used.
Long preamble, but the net of it was, I got myself a brand new Sony 135mm f/2.8 STF A-mount version for about $800, and it arrived today. The lens looks great, is made very well, and feels well-balanced and comfortable to use with a nice focus throw.
The only negative is, the focusing is not internal. So over time, it could suck in dust. Oh, well. It is not a disaster – I just need to be careful with how I use the lens.
With all that out of the way, this is a very interesting lens. I’ve been taking some test shots comparing this with the Sony 70-200 f/2.8 GM. There is no question that the STF renders a much smoother bokeh, if you prefer not to see sharp edges to OOF points of light.
Below are some comps, with the 70-200 the top image (pretty obvious), and the 135 STF the bottom image. The effect is less noticeable, as expected, when the camera-to-subject distance is large compared to the subject-to-background distance, as in Comp-1. It’s a lot more dramatic when the subject is much closer to the camera. See Comp-2 and Comp-3.
One ugly secret about the otherwise excellent Sony 70-200 f/2.8: Sony is cheating, as Nikon did for years. When you’re close to the subject, the real focal length is considerably less than expected. See Comp-4, and see how the magnification drops quite dramatically compared to the 135 prime, with the same sensor-to-subject distance for both lenses. I’m surprised that no one has yet thrown a flag on Sony for this.
DSC04091
Monkeying with Focus
Sony just announced two new lenses, one of which was a 100mm f/2.8 STF, which stands for "Smooth Trans Focus". This is an interesting lens design that diffuses sharp edges in the bokeh into softer transitions, which creates an overall smoother and more silky rendering of the background.
This would be especially nice for portraits, but also for any kind of close up shots, like flowers. The cost of achieving this effect is about 1.5 to 2 f-stops. So the 100mm f/2.8 is really a 100mm T/5.6 in terms of light transmission.
I don't know if I will get the 100mm lens, but I discovered that Sony also made a 135mm f/2.8 STF lens in the A-mount. This is a manual focus lens, something I am eminently comfortable with. I figured if the 100mm f/2.8 was any good for portraits and bokeh, then surely 135mm f/2.8 ought to be at least as good, if not even better.
I also discovered that the 135mm f/2.8 lens has been around for some time, and nobody is paying attention to it. So it can be bought for around $800-850 brand new, almost half the cost of the new 100mm f/2.8. Of course, it needs a Sony LA-EA3 adapter to work, which could be bought on eBay for about $130 brand new, less for used.
Long preamble, but the net of it was, I got myself a brand new Sony 135mm f/2.8 STF A-mount version for about $800, and it arrived today. The lens looks great, is made very well, and feels well-balanced and comfortable to use with a nice focus throw.
The only negative is, the focusing is not internal. So over time, it could suck in dust. Oh, well. It is not a disaster – I just need to be careful with how I use the lens.
With all that out of the way, this is a very interesting lens. I’ve been taking some test shots comparing this with the Sony 70-200 f/2.8 GM. There is no question that the STF renders a much smoother bokeh, if you prefer not to see sharp edges to OOF points of light.
Below are some comps, with the 70-200 the top image (pretty obvious), and the 135 STF the bottom image. The effect is less noticeable, as expected, when the camera-to-subject distance is large compared to the subject-to-background distance, as in Comp-1. It’s a lot more dramatic when the subject is much closer to the camera. See Comp-2 and Comp-3.
One ugly secret about the otherwise excellent Sony 70-200 f/2.8: Sony is cheating, as Nikon did for years. When you’re close to the subject, the real focal length is considerably less than expected. See Comp-4, and see how the magnification drops quite dramatically compared to the 135 prime, with the same sensor-to-subject distance for both lenses. I’m surprised that no one has yet thrown a flag on Sony for this.
DSC04091