STF 135mm

Sony 135mm STF ‘Smooth Trans Focus’ – A Bit of Lens GAS Come Good – By Vincent Ferrier

September 10, 2020

I am an amateur photographer, shooting family and friends and also doing outdoor / travel photography. I don’t think I suffer from GAS but I like to test gear, so I suppose I may suffer from GAS a bit. For my 50th birthday last year, I went for a Sony A7 III. Before that I tested a few systems, mostly Fuji APS-C format and some Sigma Foveon cameras. I really enjoyed them for different reasons but then I wanted to switch to FF and the Sony system because of the dynamic range of the camera that is really usable from ISO 100 to 6400, and for its autofocus performance for indoor action sports.

At the time one of my sons was playing basketball and I was the photoshooter of the team and felt limited with my old Fuji X-E1, that was a bit slow to focus. So I bought the A7III camera with the excellent SONY zoom F4 24-105 mm, a very sharp and versatile lens, though with it “only” being an f/4, bokeh performance can be a bit limited.

Aside from this zoom I had also acquired a Sony Zeiss f/2.8 35mm tiny lens with overall good qualities, which is ideal for street photography. In the meantime my son stopped playing basketball. As the Sony A7 is super versatile, I started to test some vintage manual lenses, old Takumar, Hexanon, Zuiko. Quickly, I ended up having many lenses that I rarely used – so that was that: I really do have GAS…! I decided to go “rational” again (for a while at least) and sold most of these manual lenses except one Takumar 50mm f/1.4mm – a lens that has a nice personality.

After this manual focus lens period, I wanted to go back to some autofocus lenses – a reduced set of them, while not wanting to spend tons of money for a single lens. the Sony E-Mount lenses are very good, but very expensive. Back to the 24-105 zoom bokeh “limitation” (actually the bokeh look of the zoom is quite Ok to me but you can’t get the super blur bokeh addicts can be looking for).

So I started to look for a fast 85mm lens – the so called ideal portrait focal length – with an f/1.4 or 1.8 aperture. I had read internet reviews about many E-Mount compatible 85mm lenses. I was not convinced by the Sony FE 85mm/1.8 that looked “clinical” or too neutral. Other good genuine E-Mount alternatives were either the f/1.4 GM, the 1.8 Zeiss or 1.4 Sigma, but all of them were too expensive.

I had set up a limit of 500 € per lens which is already a lot. Cheeper alternatives had been considered like Samyang or Viltrox, Tokina… but from the reviews I read, I felt like these lenses were missing personality. At this point I started to consider to the old Minolta/Sony A mount lenses lineup that I could adapt with LA-EA3 or 4 mount adapters.

So you may wonder why buy an E-Mount A7 III system and use old A-mount lenses? Well, why not? The reputation of these old lenses can be very good and the price tag is more reasonable and with my A7 III I did not need super high res lenses anyway. So I ended up buying an used Minolta 85mm f/1.4 for less than 400 Euro and it came along with a 50mm f/1.7 and a 28mm f/2.8. Adapted with ring LA-EA4, it works perfectly well. The AF is slower than with a native FE lens but I am not doing sports photography anymore. The eye AF works too, which is a great feature and balances well the slower AF performance.

At f/1.4 the resulting DOF is really thin and the bokeh is great. But, in some situations it can be a bit “vintage” and distracting especially when foliage/highlights are presents yielding to many balls with some outlining. Overall this lens is a marvel for portrait with balanced contrast and excellent color rendition. It feels like the lens loves people.

Typical bokeh balls with background foliage, shot with Minolta 85mm/1.4:

ypical bokeh balls with background foliage, shot with Minolta 85mm/1.4:

Blurry bokeh from the Minolta 85mm/1.4:

Blurry bokeh from the Minolta 85mm/1.4

This lens is also excellent for bokehrama:

This Minolta 85mm/1.4 lense is also excellent for bokehrama:


But enough on the Minolta 85mm! – what about the Sony STF 135mm???

Well, while looking for the portrait lens, I had been very very tempted by the 100mm STF “Smooth Trans Focus” lens from Sony. This lens supposedly provides smooth bokeh, super sharp, AF, bulky, but not too much. It was checking all boxes except the price! I could not get one under 1100€. So I left this option aside.

The focal length was also a matter of reflection. OK, nowadays 85mm is considered as the new universal portrait focal length, but in the past l recall that 105mm or 135mm were THE focal lengths for portraiture, and having having 85mm covered by the 24-105mm range of my sony zoooom, I was also wondering if 135mm could be a better option too…?

So you see how GAS can affect you: endless weighting pros and cons and constant appetite for testing!

Sony STF 135mm

This is how I started to be tempted by the Sony STF 135mm. In fact, I was actually looking for STF 135mm on the web at the same time I was looking for the Minolta 85mm, planning to buy one of the 2. The Minolta was a clear winner on the price as I could not find an STF 135 mm below 800€ to 900€. But at the same time I found the Minolta 85mm (400€ with the 2 other Minolta lenses…), I also then found a STF 135mm that looked to be in excellent condition for a good market price… right here on the 35mmc shop!

So I said to myself, what the heck, after all one 85mm Minolta + one 50 mm/1.7+ one 28mm/2.8 + one Sony STF 135mm equals one STF 100 MM! This is how the STF 135mm joined my lens lineup. This is how lens GAS gets you!

Now I carry both 85mm and 135mm STF lenses with me when needed. They are both typical lovely portrait lenses. However the STF 135mm is truly unique. In all shooting conditions it gives a super blurry background. Some people also consider that it is not fast enough due to its minimum T-Stop of 4.5. Well this is true on paper but in practical use, such a focal lens is rarely usable in indoor anyway conditions because the field of view would be so reduced at indoor short distances. So clearly, I use it outdoor which is fine because I live in a super-sunny place.

The Sony STF 135mm is a very sharp lens but it is never harsh with faces. Contrast is very good but not extreme, and color rendition is very natural, so overall it makes a very balanced telephoto lens. One of its great strengths is actually the f/stop of 2.8. Unlike super fast lenses you are almost sure to have the entire face of your subject in focus whereas using a fast telephoto lens at max aperture will sometimes give unwanted out of focus areas on your subject face as the DOF is so small.

Blur, Blur , blur even in distance shot: telephoto+ STF features:

Blur, Blur even in distance shot: telephoto+ STF effects

No edgy bokeh balls with STF 135mm, super blurry background, some people actually do not like this look and prefer well defined edgy bokeh light balls:

No edgy bokeh balls with STF 135mm, super blurry background, some people actually do not like this look and prefer well defined edgy bokeh light balls:

I feel the lens prefers darker backgrounds: when a regular lens makes busy background with a lot of mixing edgy bokeh disks, the STF lens dissolves the background highlights (again foliage background here…the most challenging one) but making a kind of “plastic bag ” photoshop filter look, which is not my favourite. However I feel it is still less distracting as a the Minolta 85mm bokeh in such conditions:

Less distracting STF Bokeh vs the Minolta 85 mm bokeh in such conditions:
On the “downside” , the lens is purely manual focus. Even with original A-mount bodies you will not experience autofocus with this lens whereas the 100mm STF is. This can be a drawback in action portraits. I will not use it for moving subject – I would need a minimum of subject stillness to adjust the focus. Meals (family/wedding) are great for the STF 135mm – which is fine because this is a national sport in France.

Overall the Sony 135mm STF is a marvel of a lens for portrait or people shooting: it has good enough sharpness, a soft touch, pretty nice contrast and great color rendition. On the A7 III it feels not too bulky, even with the LA-EA3 adapter. The min T Stop of 4.5 is just no problem for outdoor shooting which the focal is made for anyway. The soft touch from this lens is of course the super blurry look of out of focus area. The lens is just missing auto-focus but on the A7 III it is really no issue to handle. Indeed it complements perfectly an AF 85mm lens, by providing you a changing experience. One of may favourite lens, a real gentleman.

I do not have a website for my photographs but for my paintings: One of the latest (actually not on the website…):

LA confidential by vince bank

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  • Reply
    September 10, 2020 at 1:53 pm

    I used this lens with a Techart-Pro Autofocus Adapter and it works quite well. You have to pre-focus just a little bit, but then the tech art adapter dials the focus then and also takes advantage of Eye-AF.

  • Reply
    September 10, 2020 at 10:06 pm

    Thanks for the thoughtful review, Vincent. I’ve been keen to get one of the 135 STF’s because I love that focal length. But, alas, my own chronic GAS needs to be managed and there’s always been a higher priority. However, it’s next on my list, so thank you for your article.

    One note, I found both the Minolta 50/1.7 and 28/2.8 to be borderline unusable on the new Sony FF sensors. Instead I use a Minolta 50/1.4 which is quite nice and compact and the 20/2.8. The wide angle prime is one of my favorite lenses – my copy simply renders colors beautifully. I have newer, more expensive, native E mount prime lenses in that focal range…but I find I keep going back to the 20/2.8 and it never disappoints.

    I also have the Sony 85/1.8 E mount and just can’t fall in love with it. I’ve been thinking of swapping for the old Minolta 1.4’s. I know they’re quirky and some people don’t think they’re as sharp as modern needs require – but I love the look of images from those lenses too. Given your luck, maybe I’ll try one of those too.

    See, here we go. Gear acquisition mode once again. Never ends…that’s part of the fun of it.


    • Reply
      vincent ferrier
      September 11, 2020 at 9:41 pm

      Hi Tim,
      Thanks for your comment. yes the 50/1.7 and 28/2.8 are not top notch on the A7. howeverthe 50/1.7 makes some 3D pics sometimes interestingly…but as you say a bit borderline on the A7. I thought about the 20/2.8, and read it was a nice lens too. I may try to get it as I like this focal lens. with practice I find out that I rather use wide angles and teleobjectives rather than 50mm or even 35 mm. well I have all of them in any case (you know: GAS…) so it is part of the pleasure of changing focal lens. What I do now is taking only one glass when I go out, like doing an imposed exercise. Yes reading about the sony 1.8 deter me from buying it. Not that it seems to be a bad lens but I rarely found enthousiatic reviews. looks to be a good allround lens. The Minolta 85 MM/1,4 is really an interesting lens. the focal length pleases me and the general rendition is just very lovely, it feels like this lens likes people. good vibes.The STF 135 mm is also friendly to people: sharp enough but not too much and this very special bokeh. you do not get the shallow DOF or 3D effects but your pics are always very balanced. as it is manual (looks like you can get AF with Techart adapter…another spending?), it fits relaxed protraiture, parties , wedding, family events, note really for sports. The tradeoff would be the 100 mm STF but geese the price is really too much >1000e. maybe in a few years when used copies would be cheaper. cheers!

  • Reply
    Chris A
    September 10, 2020 at 10:37 pm

    Very nice article, and some lovely images.

    I had often wondered about this lens for years and its unique ability to make bokeh ever creamier then normal. Im glad to hear it can work on Sony with Techart also.

    Maybe one needs to be made for rangefinder cameras, with RF coupling 🙂

    • Reply
      vincent ferrier
      September 11, 2020 at 9:47 pm

      Hi Chris,

      Thanks for the compliments. the bokeh from this lens are always very blurry/melted. very special. you do not get the shallow DOF of a superfast lens. it always gives you a very natural rendering. I use it manually and discoverde you could actually use it with Techart AF ring. hum worth a few hundred euros .not good for my wallet…

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