Kowa 55mm f/1.0 review (suprise, it is a 90mm lens!)

3Dkraft.de tested the Kowa 55mm f/1.0 which has been modified to match the MicroFourThirds mount. The tester discovered that the modified version in reality has a 90mm focal length (180mm in Full Frame terms)!!! As you can imagine the lens is very soft wide open but pretty sharp at f/2.8 (and because of the tele characteristic it still offers a very shallow depth of field). You can buy the modified Kowa 55mm f/1.0 on eBay (Click here).

  • Mark

    Please. A lens being telephoto does not give shorter DOF. It’s aperture and magnification. Only. Saying that a longer focal length gives shorter DOF is like saying that you can’t get short DOF with a wide angle lens. You can of course get short DOF with both. In some cases you can actually get shorter DOF with a wide angle than a tele lens.

    Tele lenses and flat perspective is another misunderstanding, but I think this is enough for now.

    • API75

      I’m with Admin: the DOF of a 90mm@f/1 is shorter than the DOF of a 55mm@f/1, and this is just what he said.

      • WT21

        At what focus distance to subject? DOF is meaningless without the distance to subject.

        To get the same framing for a 55mm vs. 90mm on the same camera, you would have to step back farther with the 90mm (90mm/55mm = 1.636, so 10ft at 55mm would need to be 16.36feet at 90mm).

        Using DOF master (http://www.dofmaster.com/dofjs.html), you can see that the 55m DOF at 10ft and f/1.0 is .3 feet, and the 90mm at 16.36ft at f/1.0 is .3 feet.

      • Jonathan

        Mark is right. To preserve the object size one needs to shoot from a longer distance, linear to the FL ratio.

        This article in Luminous Landscape demonstrates this nicely: http://www.luminous-landscape.com/tutorials/dof2.shtml

        One thing that is immediately apparent from looking at those pictures is that using longer focal lengths changes the composition, resulting in greater magnification and therefore blurring of distant object.

        The above, along with the relatively flat field of view associated with longer FLs can contribute to a better looking image and – effectivly – better subject isolation.

      • Lindsay

        For the same framing it doesn’t matter what FL you use, the DOF is determined by the aperture.

        From DOFMaster, two identically framed images of the same object/scene:
        55mm f/1 at 10ft: 0.3ft
        90mm f/1 at 16.36ft (10*90/55): 0.3ft

        Incidentally the 90mm lens has a DOF of 0.11ft at 10ft, but that’s not much use if your distance is appropriate for framing the object correctly at 55mm. You’re not getting the same photo.

        What I don’t understand is why a lens would have a claimed FL of 55mm if it’s truly 90mm. That’s well outside the tolerance given for even zoom lenses.

    • Sorry, Mark. Three things will give you a shallower depth of field:

      Aperture (larger aperture (smaller f-number) = shallower DOF)
      Distance to subject (closer = shallower DOF)
      Focal length (more telephoto = shallower DOF)

    • admin

      Mark you are wrong. DOF depends also from the focal lenght. At the same aperture a 100mm lens has a thinner DOF than a 50mm lens. That’s easy ;)

      • WT21

        Eh? How’s that again???

        A 100mm f2.0 lens shooting a subject 20 feet away will have the same DOF as a 50mm f2.0 lens shooting a subject 10 feet away.

        For the same framing, the DOF is the same regardless of the lens FL. Check it yourself on the DOFMaster: http://www.dofmaster.com/dofjs.html.

        One thing people often confuse is framing and perspective for DOF. A wider angle lens gets in more of the background and “clutters” the background (or gives your subject a sense of place, depending on how you look at it). Telephotos de-clutter the background and isolate the subject. This sometimes lead folks to think that’s shallower DOF, but it’s not.

        • scott

          Thats the same thing as longer FL. At the same distance a longer FL will have less DOF

        • WT21, you’re changing 2 different variables (focal length and distance to subject).

          But either way, the admin is correct!

          Whether it gives you LESS depth of field, or the SAME depth of field (by making you back up), his statement stands:

          “it still offers a very shallow depth of field”.

          • WT21

            But if you change FL without changing distance to subject, who cares? You completely change the framing and the shot. Are talking about photography here or not? Photography is getting the shot you need first and foremost. The technical components are in service to the shot, not vice-versa.

          • WT21

            I do see your point though, technically (should have put that in my reply), but I still say it’s bullocks, because framing is the first factor you should be considering.

          • My framing changes depending on what lens I use. If I’ve got a wide angle lens, I don’t get up in someone’s face and take a head shot with it… I’ll take an environmental portrait. And if I zoom in, or switch to a telephoto prime, I don’t back up into a corner to try to fit everything in… I’ll take a closeup. And my depth of field just got shallower.

            If I’m taking a wide angle shot of a building, and then switch to a telephoto lens, I don’t back up 500 yards to get the whole building again. I’ll capture a detail instead. And when i do, my depth of field just got shallower.

            Ultimately we both know how this works. And we’re both correct. But you asked who cares about changing FL without subject distance. And I care. ;)

          • WT21

            That’s a good point and well made. In the end, the variables are rarely so laboratory precise, so it’s a fair comment, and I’m happy to let it conclude with your summary.

    • safaridon

      Tele lenses definitely can get you shallow DOF for portraits etc when used with m4/3. Only difference is you have to go much longer which may be an advantage in many cases as better for candid photos and you don’t have to push the camera into the persons face like FF poparatzi. For examples just look at some posts made with the 45-200 or Pany 100-300/f4-5.6 lenses for examples.

  • safaridon

    Very interesting. At first I though this must be a mistake as surely an effective 90mm and not 180mm but that is what the reference article claims and it certainly looks to be long enough but wouldn’t that also mean the lens speed is reduced to f1.4 also?

    At any rate this would be a very interesting fast telephoto option, I wonder what the price might be and availability? So this would be a 190mm/f1.4 add a 2x and you get 380mm/f2.8! With that fast a lens should be easy to pop into focus manually. I would hope that Pany and Oly would bring out a fast 100mm lens themselves for m4/3 and then we would have the the fast AF in addition to shallow DOF for portraits etc.

    If this lens costs $500 on Ebay why not just buy a fast legacy 100mm/f1.4 or 2 lens instead which is smaller shorter length and much less cost and probably less need to shut downn as much so same useable aperature?

  • russ

    Just get minolta mc/md 1.2 / 1.4

  • Never thought I’d see someone review one of these. What I really want to see is someone take it apart and see how jieying-usa (or whoever the seller is) make these. It’s just an x-ray lens, but because the modifier has to put some sort of doublet lenses between the back of the lens and the camera to make it focusable, etc., the focal length goes up and the effective aperture gets smaller (so DOF goes up). Personally I think it’s a waste of money. The original lens costs $30 max and the other parts can’t be worth much, what you pay for is the craftsmanship but why bother when the effect produced could be faked with software and the focal length is too long to be practical?

    @Safaridon: No, this is 55mm f/1 lens modified to a focal length of ~90mm, so with the 2x crop of Micro Four Thirds it acts like a 180mm, you accientally doubled twice.

    • safaridon

      Sorry I should have stated differently: effective 180mm/f1.4 and when combined with a 2x tele extendar would result in a super tele effective 360mm/2.8.

  • …or you can buy a Canon FD 85/1.8 at half price which is sharp wide open.
    Great product. :/

  • Mark

    There is no need to bring in focal length into this. It’s a sub set of magnification. When you start analyzing what is magnification, you can bring in focal length. Focal length is not a parameter that changes DOF, _magnification_ is.

    If you want to isolate an object with DOF, you can do it with a 300/2.8, but also with a 2.8/2.8 cell phone lens.

    • Jonathan

      “If you want to isolate an object with DOF, you can do it with a 300/2.8, but also with a 2.8/2.8 cell phone lens”

      I don’t see how you can do that with a smaller sensor.

      • He’s correct. One of the factors of DOF is distance to subject. So if you get really close to your subject — macro-close if need be — you can get a shallow depth of field. Even with a compact camera or cell phone.

        What’s absurd is that now he’s comparing different sensor sizes, just to complicate the discussion, derail the issue, and make focal length a moot point. ;)

        • Jonathan

          I don’t see how, have you tried taking portraits with cell phone cameras?

          Assuming one is taking – similarly composed shots – across different systems, sensor size is the only variable that actually affects DOF.

          25mm f/1.4 will produce the same DOF as 85mm f/1.4 when both are mounted on a m43 camera (shooting similarly composed images). An f/2.8 lens on 135 FF will the same DOF (but will collect less light).

          I can’t say what max aperture would be required for achieving similar results on a cell phone camera, I can only say it doesn’t currently exist. I doubt if such a lens can be made.

          • hd72

            He didn’t say portraits. He didn’t say similarly composed shots. He just said you *can* isolate “an object” with shallow depth of field, regardless of sensor size.

            It’s *possible*. Just not in very many useful situations, like you point out. :)

            That’s why I said he’s derailing the focal length discussion – bringing different magnifications into the equation. I don’t know about his fancy camera, but my GF1 doesn’t let me adjust the sensor size! ;)

  • Stopkidding

    Not another f@&$king DoF argument here. Don’t we have DPReview and flickr for that already. Razor thin DoF is a novelty at best and has only limited application in the real world.

    • Tomas

      If that’s how you feel then maybe next time you should avoid articles with “f/1.0” in the headline.

    • Jonathan

      A novelty at best?

      Photography has a long tradition and history. I would guess it dates back way before you switched from a P+S camera.

      • Stopkidding

        Yes indeed, I am sure you are an old fart that has been shooting with cow dung on copper plates since the Renaissance, but as a recent “P+S” convert, I rather focus my time on taking pictures than argue about ultra shallow DoF. By participating in this thread, I guess I am guilty of the same…


  • Cteve

    I got one of these, the Kowa 42mm f/0.75
    it doesnt have a focus ring and the depth of field is indeed super small. It’s only good for doing experimental work or some very soft/weird pictures. A great lens but not worth paying 500$ though. My guess is that the seller is Chinese right?

  • Cteve

    Took this with a the KOWA 42mm f/0.75 + SONY NEX5 (I hate Sony’s cam but my friend lent it to me to creat that shot).


  • As the lens opening is still 55mm in diameter, it means that it becomes a 90mm / 1:1.6 lens through the modification (which is still quite fast for that focal lenght).

    If you calculate the DOF (e.g. at dofmaster.com) you will get for a distance of 3m a DOF of 0.09m with 55mm/f1.0 on microfourthirds. For 90mm / f1.6 the DOF calculator shows a DOF of 0.05m.

    By the way: There was another photo (portrait) taken with that lens added to the article.

  • Jesus Kids
    who cares!?!?!!
    I wanna try it out f1.0 o a 90 sounds interesting
    who cares about how the post might be a little inaccurate

    lighten up there’s few enough interesting lenses out there

    thanks for the news will look here again

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