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Olympus 12mm manual focus question

Discussion in 'Native Lenses' started by dtchan, Jan 5, 2012.

  1. dtchan

    dtchan Mu-43 Veteran

    364
    Nov 24, 2010
    Hi,

    I am wondering when you pull the focus ring back to manual focus, is there a way to zoom in? i.e. when i use a real manual lens, pressing the wheel button on my gh2 allows me to zoom in. I don't seem to be able to do this with the Olympus 12mm. Anyone know?

    Thanks
     
  2. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    My understanding is that pulling the focus ring puts the lens into manual focus, but the camera still thinks you're in auto focus. If you want access to any manual focus aids on the camera, those aids are linked to the camera being set to manual focus so you need to set the camera to manual focus as well—bit of a pain in many ways. OTOH, with a wide angle like the 12 mm with its depth of field, you may well be able to focus well enough without the zoom function.

    At least, that's the way things work on my E-P3.

    If I had to guess, I'd say the reason things work this way is that the lens acts as a "dumb slave" of the camera operating system so the camera tells the lens what to do and gets some feedback from it, but things aren't set up for a lens to be able to initiate a message to the camera. As a result, when you slip the lens into manual with the lens ring there's not enough of an operating system in the lens to be able to send a message to the camera saying "I'm now operating in manual focus, change your status accordingly", so the camera goes on operating as if the lens were in auto focus but the lens simply no longer follows any autofocus instructions it receives, that connection in the lens gets turned off when you access manual focus via the lens ring.

    Maybe if someone had thought of this sort of lens focus switch when the M43 standard was being worked out, they could have designed a way for the camera to check if the lens was in manual focus but probably no one had thought of this trick back then and they decided to put the auto/manual focus switching in the camera menu systems instead so now we're stuck with the need to change the setting on the camera as well if we want to access the camera's manual focus assistance functions.
     
  3. Sammyboy

    Sammyboy m43 Pro

    Oct 26, 2010
    Steeler Country
    On my E-P2 I assigned the Fn button to manual / AF. You should be able to do the same on the E-P3, don't know if this is possible on the Panazonics.
     
  4. Henk

    Henk Mu-43 Regular

    193
    Aug 18, 2010
    the Netherlands
    Did you switch the GH2 to manual focus ?

    The GH2 has a dedicated focus mode lever on top of the body.:cool:
     
  5. dtchan

    dtchan Mu-43 Veteran

    364
    Nov 24, 2010
    Thanks for the replies guy.

    I thought I didn't had to switch to MF on my GH2. I thought just pulling back the ring will engage it. Guess not.

    I guess this is what I have to do.

    1. Switch to MF on camera.
    2. Pull ring back for that MF feel.
    3. Tap on the screen to zoom in to focus.

    I was use to just pressing the wheel to engage the zoom in to focus.

    Another question....... I was trying to use the marking of the manual focus.
    I'm not sure how to read the markings. Seems like my infinity for F2 is setting the infinity mark to f5.6 on the lens. Is this right?
     
  6. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    I think you'll find that setting the camera to MF will work on its own, and you won't need to pull back the ring on the lens. I think the only advantage the ring offers is a quicker way to swap to MF than digging through the menu system.

    The red indicator line between the two 5.6 markings is the focus indicator. Line infinity on the distance scale up with the red indicator line and should be focussed on infinity regardless of what aperture you're using.

    You'll see 2 sets of f stop markings, one on either side of the indicator line with 5.6 closest to the line and 22 furtherest away from it. They're for indicating depth of field from in front of to behind the focus point. Set the focus at 2 feet and take a look at the distances against the 5.6 markings—they're 0.5 metre (20") and 1 metre (40"). That's supposedly your depth of field for a 2' focus at f/5.6. At f/22 depth of field ranges from probably around 15" to somewhere between 3 metres and infinity. I say supposedly because Ctein remarks in his review at the TOP site that he didn't find the scale to be all that accurate. I think there really aren't enough distances marked on the scale for it to be all that useful except as a rough guide, and you better be happy about converting between ft and metres if you want to make it a bit more useful indication of what's going on.
     
  7. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    One further point on the depth of field scale.

    One thing it should be good for is for focussing at the hyperfocal distance for a given aperture. The hyperfocal distance is the focussing distance at which depth of field extends from half the focussing distance all the way to infinity, that's the maximum depth of field at the aperture you're using.

    To focus at the hyperfocal distance, line the infinity symbol up with the right side f stop indicator for the aperture you're using. The red indicator line then indicates the hyperfocal distance and the left side f stop indicator indicates the closest distance within your depth of field at that aperture.

    Note that the usefulness of this depends on the accuracy of the scale so you may well want to run a few test shots to see how well it works for you.
     
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