Using Pentax MX lenses on a Pentax IST DS

Discussion in 'Mirrorless Digital Cameras' started by robert_leggat|2, Jan 20, 2005.

  1. I chose a Pentax digital in order to use lenses I already possess.
    However, the instructions provided by Pentax are anything but clear!
    How does one control the aperture? The lenses are genuine Pentax ones.
    I would greatl appreciate advice.

  2. This works very nicely, it's like having a semi-automatic metering system. It took me a little while and a few questions to the Pentax SLR forum on DPReview to understand it entirely too.

    For Pentax A series and later FA, etc lenses, just fit the lens, set the aperture ring to A, focus and shoot ... All meter exposure and pattern modes are supported and the camera provides focus confirmation. (It will lock the shutter release in AF mode unless the confirmation light is illuminated, so set it to Manual Focus if you want it to make an exposure regardless of the state of the confirmation light.)

    For Pentax K mount, both pre-M and M series:

    1- In the Custom Settings menu,
    - Check the "Settings" checkbox to enable custom functions.
    - Set the "Using Aperture Ring" option to "2-Permitted".​
    2- When you fit the lens, set the exposure mode to Manual.

    The aperture setting is made with the lens' aperture ring and does not display in the readout. To meter, with the exposure mode set to Manual, press the AE-L button. All bayonet mount lenses will stop down briefly and the shutter speed will be set to what the meter suggests. You can modify the exposure setting by adjusting the shutter speed (with the control wheel) or the aperture ring.

    All other exposure modes (shutter priority, Program, etc) will default to Aperture Priority mode, and the camera will expose correctly, but it will not stop the lens down to the set aperture except in Manual mode. CenterWeighted Averaging and Spot metering pattern modes are supported for all lenses.

    Pentax screw mount lenses, fitted with an Pentax M42 to K mount adapter, will work just as K and M series bayonet lenses do but you must be able to close down the aperture manually on the lens as the camera cannot operate the screw mount auto-diaphragm mechanism. You must manually close the aperture down before metering or making an exposure.

    (Once you set the custom function for "Using Aperture Ring" to "Permitted", you can leave it set. It will have no effect on lenses with the aperture ring set to the 'A' setting or no aperture ring at all, they will all work normally.)

  3. Godfrey, I am most grateful for your clear answer. Pentax are not the best at providing clear instructions; they ought to ask you to write their operating manual. Many thanks again!
  4. Question for Geoffrey

    I just bought my Pentax ist ds but can't get the shutter to fire when using my mf 50mm f/1.7 M lens. I have followed your instructions to the letter but still can't make the camera to shoot. Please help. Thanks a lot.
  5. Probably the focus mode...

    If the focus mode is set to AF, the shutter release is blocked unless the green focus indicator
    in the viewfinder is lit.

    Switch the camera to MF and it should fire regardless of the state of the green indicator.

  6. Hi, Godfrey

    Sorry, I misspelled your name. Yes,the camera was on AF. Thanks a lot for your help. Regards.
  7. Actualy you can use in M mode every K mount lens, be it Pentax or other brand. That's great and having consider a Nikon D70 I choose the *ist because of this feature. Very nice DSLR indeed.
  8. Not a question, but thanks.
    I have been thinking of going digital for a while, and as I have a number of old manual 'K mount lenses from various manufacturers. These were mostly bought for my old K-1000, which I got bak in 1975 when they first came out, and I realy didn't relish the prospect of lugging around an extra set of lenses, just to suit the new camera. (Never mind the cost of buying them!)

    I have to say that the original Pentax manuals are not very clear on how to use these lenses, nor in fact wether they can be used. Which is a pity, as it is probably going to put some people off buying.

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