Quick basic question about adapting an 'automatic' m42 mount lens.

Discussion in 'Adapted Lenses' started by iamcanjim, Feb 4, 2014.

  1. iamcanjim

    iamcanjim Mu-43 Rookie

    20
    Feb 3, 2014
    Lacombe, Alberta
    Here's the background. Back in 2004 I was dating a hipsterish chick for whom I trawled the pawnshops for an old SLR 35 mm camera. I eventually bought a 'grab bag' consisting of 2 bodies and 3 lenses.

    One body worked, on the other the sensor didn't work. So I gave the working body and lens to her and ended up keeping the other body and 2 lenses. The body is some 70's or late 60's Sears (Ricoh) TLS. The lenses appear to be an 'Auto Sears' 50mm F2 (Rikenon) and a Haminex 'Automatic' 135 mm F2.8. The auto seems to refer to the fact that the aperture closes only when the shutter is pressed. This appears to be done by a pin.

    Obviously to be used on a micro 4/3rds mount, the aperture needs to be stopped done all the time.

    Is there is a particular adaptor that makes that happen? Or do they all do?

    By the way, I am aware neither lens is particularly good, but probably worth getting an adaptor to play with.
     
  2. RichardB

    RichardB Snapshooter

    443
    Nov 19, 2012
    Maryland, US
    Richard
    My Fotodiox M42 adapter has a kind of ledge beneath the lens threads, which pushes the lens's pin up when you screw in the lens. Looking at other M42 adapters on Amazon, it appears from the product photos that Fotasy also has an adapter with the ledge, while EzFoto sells a cheaper one without the ledge, so it's something you'll have to check before you buy.

    BTW, I love my M42 lenses. There was a lot of great glass assembled for that mount.
     
  3. iamcanjim

    iamcanjim Mu-43 Rookie

    20
    Feb 3, 2014
    Lacombe, Alberta
    Hmm. Wrote about my camera on my motorcycle forum and someone offered me 3 old minolta MD mount lenses for shipping. What's a good MD adaptor?
     
  4. RichardB

    RichardB Snapshooter

    443
    Nov 19, 2012
    Maryland, US
    Richard
    I don't know good from bad with MD adapters. I got mine with a lens. I'd look on Amazon or B&H or even Ebay and just take one that gets good reviews.
     
  5. fin azvandi

    fin azvandi Mu-43 All-Pro

    Mar 12, 2011
    South Bend, IN
    I've been happy with adapters sold by fotodiox and rainbow imaging (they have their own websites and also sell through ebay/amazon)
     
  6. dwig

    dwig Mu-43 Top Veteran

    624
    Jun 26, 2010
    Key West FL
    Not really. It only needs to be stopped down when you take a picture. It should be kept wide open when you focus.

    As others have said, adapters are available both with and without a "ledge" to hold the pin. Which is the best for you depends on the features on the lens.

    When Asahi (now Pentax) introduced auto-diaphram to the M42 mount they included a slide switch on the lens barrel to manually stop the lens to taking aperture to serve as a depth-of-field preview and to facilitate using the lens on extension tubes and bellows that did not press the pin. Many other manufacturers copied this initially, but most dropped the A/M switch as a cost saving move when their bodies acquired TTL meters that would operate the diaphram stopdown pin while viewing since such stopdown was required by the meter. Asahi always retained the A/M switch on their M42 mount Takumars.

    If your lens has a switch (usually labeled A/M or O/C) then you want an adapter that DO NOT press and hold the pin. That way you have a quick way to switch between shooting aperture and focusing aperture. Otherwise, you need the adapter to press the pin, but if you can find an adapter with its own O/C switch it would be preferable.
     
  7. RichardB

    RichardB Snapshooter

    443
    Nov 19, 2012
    Maryland, US
    Richard
    In most cases the sensor on a mirrorless camera can get enough light even when the aperture is stopped down. If there is enough light, it is good for the lens to use the shooting aperture so you can preview depth of field and shutter speed (if the camera is using aperture priority) and adjust aperture as necessary before taking the shot.

    Of course, when the light is dim, you may need to open the aperture enough to permit manual focusing.

    With an SLR's optical viewfinder, you keep it open by default for brightness, and stop down just to preview depth of field. With the light magnification in a mirrorless camera, you can use your shooting aperture by default, and open it up only enough to permit focusing in dim light.
     
  8. dwig

    dwig Mu-43 Top Veteran

    624
    Jun 26, 2010
    Key West FL
    You've misread my post. It's true that there's plenty of light for viewing, but I was talking about focusing, which is a totally different animal.

    When focusing, you need to open the lens to its widest f/stop so that depth-of-field is the smallest. This is necessary to get the most critical focus. If you attempt to focus at a smaller f/stop you are very likely to not achieve the best focus. Focusing should always be done at the widest f/stop, period.