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Pentax 135mm 3.5 Manual lens on K10d

Discussion in 'Pentax Chat' started by GrahamR, Apr 18, 2008.

  1. GrahamR

    GrahamR Well-Known Member

    Hi all,

    Has anyone used an old PK PENTAX 135mm f3.5 manual focus lens on there K10d.

    Who does it operate??
    I know its manual focus, but what about AP, SP, Manual modes??

    And how have you found the quality.

    These leses go quite cheap now. An ideal portrait lens I thought.

    Many thanks
  2. oliver28

    oliver28 Well-Known Member

    I can only get mine to work in manual mode, and even then you have to depress the green button to engage the aperture you have set with the aperture ring before taking a picture, otherwise it seems to expose wide open. As it has no A setting, the only other mode you can use is Av, and I can't seem to get it to use any aperture other than maximum, even if I press the green button and have custom setting 'use aperture ring' set to 'enabled'. I have to say I was more than somewhat disappointed to discover this. Unless of course I am missing something fundamental, in which case I would greatly appreciate enlightenment!!

    I'll try it for quality tomorrow, but I would have thought it a bit long for portraits (on digital), something in the 50-80mm range may be better.
  3. Monobod

    Monobod Phantom of the forum

    Look at page 208 of the manual. You need to know what the lens type is before you can work out its use (FA,F OR A).
  4. nimbus

    nimbus Well-Known Member

    These are good performers, but the degree of compatability is limited. They only work in manual mode on the Pentax dslrs, in other words there is no metering available. The A series lenses work in all modes, but are hard to find, indeed I owned a 135mm f2.8 A series, but I considered it to be a poor performer compared with the lens you are enquiring about.
  5. welshwizard645

    welshwizard645 Well-Known Member

    I have the Takumar Bayonet 135mm f2.5 which I have used on mine without any problems...

    First you need to be sure that you set in the custom function the camera to be able to use lenses with aperture ring...

    But the issue with pre-A lenses on the K10D is exposure, as long as you either press the green button or take care with your exposures you should be ok...

  6. jonboy

    jonboy Member

    I use one of these regularly (plus the wonderful 50mm 1.7). As previously said, set the K10D to use the aperture ring and use the green button to get an exposure setting. You'll also need to set the focus control to manual, too, otherwise the shutter release won't work.

    I use mine solely in manual mode, and although the exposure can often be a little wide of the mark, by pressing the green button a couple of times (and combining common sense) you can usually get a good result. And one of the big advantages of the LCD screen is being able to check the result without wasting any film (hoorah for digital).

    The 135mm 3.5 is a cracking lens, and makes a great manual focus telephoto. It's worth persevering with, and has shown me that it's often quicker and easier to use manual focus than rely upon yet another techno gadget to do it for you. So if it's out of focus you'll only have yourself to blame ;)
  7. Zou

    Zou Well-Known Member


    They do meter (centre weighted reading) when you stop down the lens (which is as simple as one touch of a programmable button.
  8. johnriley1uk

    johnriley1uk Well-Known Member

    Yes they do indeed meter.

    135mm lenses are going for ridiculous prices these days on eBay.
  9. nimbus

    nimbus Well-Known Member

    I stand corrected on this. I was given to understand that this was the case with all Pentax dslrs.

    These lenses fetch low prices simply because there were a large quantity produced, certainly it is not due to poor optical quality.
  10. tazio35

    tazio35 Well-Known Member

    If you're really in a hurry and don't want to mess about with the green button metering in manual, you can switch to Aperture Priority. It will always use max aperture (f/3.5 in this case) but the camera will adjust the shutter speed automatically.

    But how hard is it to press the green button?
  11. Zou

    Zou Well-Known Member

    Altrnatively set the custom menu to allow use of the lens' aperture ring, and use Ap. Pentax, it seems, have thought of everything us users of relic lenses would need. :rolleyes:
  12. PeteE

    PeteE Well-Known Member

    I haven't found the lens stays at maximum aperure - I read this before, so I put a M-series 135mm Pentax f3.5 on my K10D, put it to 'AV' and pressed the tit- well, it closed down as I looked into the lens. I find I have to use a little exposure compensation that's all, on the PLUS side or the pics are a bit underexposed, but after trying the 'Digital Preview' where it take a test without it going onto the card I can get the exposure perrrrfeck!
  13. oliver28

    oliver28 Well-Known Member

    That's very odd. I can only get max aperture. If I set it to, say, f/8, the meter increases the exposure time but the aperture doesn't close down and I get OVER-exposure... :D :D
  14. tazio35

    tazio35 Well-Known Member

    I can set my M lenses to any aperture I like, but in AP, the camera will meter and shoot at max aperture. My understanding is that this is because the modern cameras have the 'crippled' KAF mount and cannot talk to the lens about what aperture is set.

    When you 'green button' meter in Manual mode, it stops down with the depth of field preview and takes an actual reading. The camera still doesn't know what aperture is set, but that doesn't matter because it does now know how much light there is.

    That's why A lenses with the electrical contacts are so sought after.
  15. Done_rundleCams

    Done_rundleCams AP Forum Ambassador to Canada

    Hi Oliver,

    Here is the body of an email I sent to our Pentax Rep, to forward on a fellow with
    a K20D and the usage of Manual Focus "M -series" lens which will (hopefully) answer
    your question:

    Hope this helps :)


  16. oliver28

    oliver28 Well-Known Member

    Hi Jack,

    Thankyou for your post, but here is a can of worms if ever I saw one! If what you say is correct, it would appear that the K20D works slightly differently from the K10D in this respect (though I would have thought this doubtful). I have had a thorough play and my findings are these: half pressing the shutter release and then the AE-L to set the 'correct' exposure definitely doesn't work on the K10D, you need press the green button in M mode after setting the desired aperture. I cannot comment as far as the K20D is concerned. However, with both my M 50/1.7 and M 135/3.5, I found that the shutter speed did not change once the aperture was stopped down to f/8 or smaller (1.6" in rather dim light) and this was not entirely consistent either, I think maybe the low light impared the meter with stop-down metering. Anyway, I think I have it sussed at last, I suppose it's just down to getting new and old technology to work well together, and it does very well, if you're careful!

    Thanks all the same! I'm having great fun with my new K10D - what a smashing camera!! :cool: I'll save up any questions for when my final exams are over!
  17. tazio35

    tazio35 Well-Known Member

  18. Zou

    Zou Well-Known Member

    I bought a SMC-M 135mm f3.5 the other day for 4000 yen. Bargain - lovely bokeh and with a 50p close up filter is darn flexible. :cool:

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