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Metering with Pentax M lens

Discussion in 'Adapted Lenses' started by broadway, Mar 27, 2011.

  1. broadway

    broadway Mu-43 Regular

    66
    Mar 27, 2011
    UK
    Hi from a newbie,

    Searched on this and haven't found much in the way of information.

    I have a some Pentax-M lens left from my Pentax MX system. I bought a K10D + a few lens and have never found the Pentax M easy to use on K10D. I have been considering changing systems. I am thinking about a few more lens to fill gaps and then there would be an upgrade to a K5 sometimes which given the cost of lens is a fairly hefty sum. Also the K10D works better with Pentax A lens due to changes in the way the aperture ring was indexed.

    I understand that I can use Pentax M lens vias an adaptor, but am unsure how the metering is done. I assume it would work in stop down mode and work with both manual aperture priority exposure modes.

    Hopefully someone can clarify.
     
  2. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    That is about right...
     
  3. Gwendal

    Gwendal Mu-43 Veteran

    300
    Jun 6, 2010
    Yes - and it also seems that all the forum members who have used Pentax lenses on their m43 systems are very happy with it !
     
  4. iliakoltsov

    iliakoltsov Mu-43 Regular

    195
    Aug 7, 2010
    Paris
    I used to own a pentax K-M and i know the feeling with the approximate metering, on the G1 it is different it is true a TTL it meters the light that comes in , fine it is not so precise ( Pentax M is designed for 35 mm camera) but this imperfection is constant not like on pentax , where the algorithm makes you go crazy. I personally thought that pentax was a very good choice for legacy lenses then i discovered M4/3, no loss in quality in terms of the picture ( in fact i can use legacy lenses further than F8 due to the MF assist magnification) , the body is smaller the amount of legacy lenses you can use is just close to insane i am shooting on M4/3 and i never regret quitting pentax.
     
  5. broadway

    broadway Mu-43 Regular

    66
    Mar 27, 2011
    UK
    Thanks for the confirmation, a plus for M4/3:thumbup:
     
  6. usayit

    usayit Mu-43 Hall of Famer


    Curious why have you never found the Pentax M lenses difficult to use on the K10D. Since the aperture linkage between lens and camera is fully functional it should be very similar to that of a vintage film camera (in my case ME and LX). I have the old Samsung GX-1L (*ist DL clone) and it works just the same as the old film cameras.... Metering is dead on.

    IMO, I find it much much easier to use Pentax M-lenses with a digital Kmount camera than my Micro 4/3rds simply because the lens will auto-stop down via that linkage (allowing for focus wide open and aperture stop at the moment of shutter). That functionality is missing when you adapt to M-43 cameras. Meaning you either focus while stopped down (not totally effective, especially in low light) OR you have to open then stop down by turning the aperture ring just before shutter (takes practice as with most adapted vintage lenses). Often, you start having to count clicks on the aperture ring to make sure you end up on the intended setting. In fact, I even find it easier to adapt takumar M42 lenses simply because the auto-manual switch allows me to quickly stop down or open up the aperture diaphragm.

    I dug up my notes posted on another forum. Its specifically for the Samsung GX-1L but there should be similar setrings on your K10D. I hope it will help:

    * All my old lenses work Both K and KA even though the camera sepecifically mentions only KA and KAF. There are few settings that got the manual k-mounts without the "A" setting on the aperture work. 1) "AE-L on M expr" needs to be set to 2 to allow the "AE-L" button function as the stop-down metering in aperture priority. 2) "Use Aperture ring" has to be set to 2 to allow you to use lenses even though they are not set in the "A" setting. 3) Move the switch from "AF" to "M" or else the camera will try to focus prior to letting you trip the shutter. 4) The camera has to be set to full "M" manual mode. Once you set 1 and 2, you can leave it that way even though you switching between AF lenses and Manual K-mounts. Once all set, you basically focus, set your aperture via the lens ring, hit AE-L (stops down and sets shutter), and then press the shutter. Works pretty seemlessly. I got a kick out of mounting my older screw mount M42 lenses too.



    My minolta AF adapter I found at a local swap has a rotating ring that engages the lenses aperture diaphragm to stop down or open up. Does anyone know if such adapter exists for K-mount lenses? If one exists that would change everything and I would buy one in a heart-beat.


    Not trying to be negative (M43 is a joy for my collection of lenses) but just wanted to make sure you have all the information before jumping. In summary, the best digital camera specifically for K-mount is another K-mount compatible one.

    Notes: There is also a 2x crop versus 1.5x crop difference between the systems. If you want the metering to behave more like your MX, set to Center average instead of evaluative.
     
  7. iliakoltsov

    iliakoltsov Mu-43 Regular

    195
    Aug 7, 2010
    Paris
    From Ist ( film camera ) onwards ALL pentax had a crippled mount, Pentax removed the mechanical aperture , hence there is no way to tell the body that you are F2.8 or F8 it will approximate the exposure using an algorithm that is very annoying. In order to get a decent exposure you need a KA mount now.
     
  8. usayit

    usayit Mu-43 Hall of Famer

    There are TWO linkages.

    One is auto stop diaphragm

    Second is used to allow the camera to determine the position of the aperture ring on lens.

    ...

    As long as you have the auto stop down diaphragm linkage and have the appropriate settings, you should have no problems. Trust me.. It works absolutely fine on my Kmount DSLR. Once you have the settings proper, for M-mount the operation as follows:

    1) Av mode (M works too)
    2) Set the aperture of choice on the lens. (lens is wide open)
    3) Focus as usual
    4) Hit the AE-L button. The camera will STOP DOWN, THEN Meter, then Open wide.. The shutter speed will be automatically set (Av mode)
    5) Then trip the SHutter. Done.


    In "A" lenses, the process is like this (I have both in my collection):

    1) Av mode (M works too). Set the lens to "A" with the camera turned off and on.
    2) SEt the aperture of choice on the lens (lens is wide open). Camera will determine shutter speed automatically.
    3) Focus as usual
    4) Trip the shutter. Done
     
  9. usayit

    usayit Mu-43 Hall of Famer

    For Takumar M42 mount adapted its similar to M-mount BUT you have to turn the Auto-Manual switch to Manual just before hitting the AE-L button. This is due to no ability for the camera to stop down the lens aperture.


    btw... OP, if you do decide to jump, PM me with an offer. If its a very good deal, I'll take it. I prefer my Tamron 90mm macro adaptall for macro work but because of the lack of auto-stop down, its not ideal for M-43. Reason is that I typically shoot macro at f/11 or smaller making it impossible to focus stopped down while metering. I'd love to replace my Samsung with the K10D.
     
  10. usayit

    usayit Mu-43 Hall of Famer

  11. iliakoltsov

    iliakoltsov Mu-43 Regular

    195
    Aug 7, 2010
    Paris
    M42 is nowhere near similar to PK mount, it behaves the same way where you have to get the AF confirm wide open and then close the aperture otherwise from F8 onwards AF confirm doesn't find anything. I am not against pentax i think they have absolutely awesome gear ( still questionable AF speed) but the backward compatibility got broken and they never looked back to put it back , it would cost them nothing as KAF mount was backwards compatible and KAF2 is the mount used now the only difference is the SDM block on the KAF2. KAF is 100 % compatible with K mount lenses including the exposure. Why pentax stopped this , in my opinion it was a bad mistake
     
  12. usayit

    usayit Mu-43 Hall of Famer

    I didn't say it was.. read again... next...

    I have experience with Takumar M42, K-mount, KA-mount, 645 .. A collection that's in the several dozens. I have a 645, LX, ME, ME-F (rare), and a few screwmounts from the early times. I think I know the difference.


    I'm telling you, it works 100% fine if the steps are followed. I've been shooting with it for several years now.



    Wait.. what am I sayin. I should be saying the opposite in hopes of a cheap K10D. lol
     
  13. broadway

    broadway Mu-43 Regular

    66
    Mar 27, 2011
    UK
  14. broadway

    broadway Mu-43 Regular

    66
    Mar 27, 2011
    UK
    Are there any particular lens that work well, I have 20mm K f4, 28mm K f3.5, 35mm M f2, 50 mm f1.4 and f1.7, 100mm M f4.0 macro, 200mm M f4 and 70-150 M f4.0. I would guess the 35mm and above would be the most useful.
     
  15. usayit

    usayit Mu-43 Hall of Famer

    I've been looking around online and it seems to be an inconsistent theme with K10D's metering. To me this is seems more of an issue with a particular run of camera bodies rather than the system of adapting lenses.


    They work all about the same on m43 as with any other adapted lens. Remember there is a 2x crop factor with these cameras so your 200mm will have a FOV of 400mm and your wide angle lenses will not have the FOV you expect.

    If you decide to move are choice of M43 body, I find choice of body a more important factor.

    1) Panasonic implements IS in lenses (won't help your lenses) while Olympus implements in body (will help your lenses). You'll need to manually set the focal length on the camera itself each time you change lenses as the Olympus body cannot detect the focal length of adapted lenses.
    2) EVF or no EVF. EVF helps tremendously for manual focus lenses. The Quality of the EVF matters. EVF of the GF1 for example is far less resolution than the EVF for Olympus. The G-series camera bodies have excellent EVF.

    I'm finding myself liking Panasonic (bodies and lenses) for general native m43 lenses but Olympus for adapted vintage lenses. I find my G1 is more responsive for moving targets using native lenses.

    The K-mounts that have found some use on mine; 50 f/1.4 and 50mm f/2. The 40mm pancake was pretty good. Its slim profile made up for the K-mount adapters' length adding to its comfort. I'm not sure if my 200mm is the same but its long on these cameras. Especially at a max aperture of f/4. Requires at least a monopod with steady hands. Partially due to the 2x crop factor, the 100mm macro was difficult to use handheld without flash (unexpected opportunity). I needed to be in full sun to focus properly at f/8 (I generally prefer f/11-16 for macro w/ ring flash). I did get a good one with some work.

    [​IMG]

    The 35mm and 28mm versions I have are in SMC Takumar screwmounts. They work ok.. nothing special. I generally use native lenses for those focal lengths (9-18mm Olympus). Its kinda odd having those lenses on a 2x crop camera IMO.

    I don't have any zooms takumar nor Pentax M. So I cannot comment on that. How do you like the 20mm on your Pentax (1.5x crop)? Its one lens I haven't had the opportunity to own.
     
  16. iliakoltsov

    iliakoltsov Mu-43 Regular

    195
    Aug 7, 2010
    Paris
    Usayit it could have been the case of my Pentax K-M as well , i know some people that are very happy with it i had huge exposition issues
     
  17. stratokaster

    stratokaster Mu-43 All-Pro

    Jan 4, 2011
    Kyiv, Ukraine
    Pavel
    I have owned Pentax K-m and K-x and I can safely say that my Panasonic G2 meters with various adapted lenses MUCH better than any Pentax digital body.
     
  18. broadway

    broadway Mu-43 Regular

    66
    Mar 27, 2011
    UK
    A change of body would be an option, most of the time I use the 16-45mm on the K10D, but as an all day walkaround lens it is a bit on the short side. This means I would need a new body and another lens to fill in above the 16-45mm. I am also thinking of a shorter macro lens. Now seems a good time to consider a change of system.

    I realise the choice of body is important, I use reading glasses so find a viewfinder much easier to use. One of the reasons I finally bought a DSLR was my arms became too short to use the LCD without glasses. I intend visiting a store some time soon to have a look at the different bodies.

    I haven't used any of the wide angles on the K10D, the 100mm macro and 200mm have both given excellent results.
     
  19. drd1135

    drd1135 Zen Snapshooter

    Mar 17, 2011
    Southwest Virginia
    Steve
    The K10D and I didn't really appreciate each other :wink: I have a K7 now which I like much better. I have two M lenses, the 28 f3.5 and the 200 f4, but I got both after I got the K7. They work just fine on the new body. I need to get an adapter so I can use the 200 on the Pens. I'm curious to see how it compares to the high end of the 45-200.