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Thread: M42 Lenses

  1. #1

    Default M42 Lenses

    Dear CSers,

    I just got a EOS 350D recently, and I'm curious to learn a bit about M42 lenses or other mounts / manual lenses.

    First is about AF, I noticed some lenses have "Auto" Labels on them, but I am thinking that if I use a adapter, the AF will no longer function, am I right about this? Also noted that there are AF confirmation adaptors, how do these work? They also look much longer, does this change the focal length of my lens?

    Next, where can I buy these lenses? They seem pretty value for money to me. =) Is there any reason I should not buy them?

    Thirdly, how do I exactly tell which mount are they if its not specified? And if I use 2 adaptors together, is a bad option?

    Hope someone can teach me about these lenses or point me to a comprehensive website, thanks a lot!
    Looking for Canon 100mm F2 USM :)

  2. #2

    Default Re: M42 Lenses

    You are right about them being value-4-money. The only thing is that if forces u to think about the exposure and manually change Aperture / Shutter settings since it does not feed electronic info to your Canon body. And it's also manual focus.

    There are so many M42 lenses on sale in eBay and even in CS classifieds. So many to choose from, from Carl Zeiss Jenas, Pentax Takumars, to Russian ones and Japan ones. Premium ones to cheapo ones. Wide angle ones to Telephoto ones. Heck, some of them are even zooms.

    The 'Auto' labels refer to the aperture diaphragm opening, you can see it as a pin that sticks out in most M42 lens. This is alike most modern lenses, there is a lever at the back of the lens stopping down the aperture.

    To use on your Canon, u'd need a M42 to Canon mount adapter, which is widely available. A local seller has it on his website - . Only 1 adapter is needed. Some adapters assist you in manual focus, giving you a focus lock confirmation.
    Of course in Pentax bodies, this is in-built

    M42 lens only have 1 mount, which is the thread mount. It is mounted to the body by screwing it in.
    Here's a photo of one that is 'Auto'. You can see the pin sticking out.

    When switched to 'Auto', it allows you to focus in brighter light with wide open aperture. When u press the shutter on pure M42 bodies, the shutter mechanism will depress the pin and stop-down the lens to take the picture.

    Here's one that is without Auto diaphragm. When you stop down, the viewfinder WILL get dimmer.

    site with tons of data on M42 lenses

    Here's the balanced caveat:
    - It's manual focus, not too bad if u get the dandellions type that can confirm focus.
    - It may be hard to manual focus using standard focus screens that came with your SLR. May need to change to split-focus type to assist.
    - You'll probably take more time to take a photo since u will be forced to learn about exposure settings instead of just blindly snapping away and letting the camera think for you.

    in my 2cents, I think u should try getting a cheap M42 lens and an adapter to try it out yourself, immediately u'd know what it's all about, and whether you like it or not.

  3. #3

    Default Re: M42 Lenses

    Thanks Hamustar for the comprehensive reply. Just one more question, those AF confirmation mounts, it simply sets off the viewfinder lights when I'm in focus, is that right?
    Looking for Canon 100mm F2 USM :)

  4. #4

    Default Re: M42 Lenses

    I think so , heheh, never handled m42 on canon/nikon before though.

    For the pentax system , it is this way.

    One guy I know, his nick is merelyok, is using Canon system with these M42 lenses. you can perhaps PM him to ask for his comments?


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