Legacy Lenses and Metering

Discussion in 'Beyond the Basics' started by Jsun, Feb 7, 2018.

  1. Jsun

    Jsun TPF Noob!

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    Hello all,

    I just received my adapter, (I like to call it my decoder ring!) so i can mount my old 70's Zeiss lenses on my Olympus OMD EM10.

    After sorting out how to get focus peaking to work, (I had it working fine for my modern lenses but it's a bit of a different process with the old ones), I set the mode to "S". I figured that if I can't change aperture through the body of the camera, then at least I could control the shutter speed through it.

    I got some very good results. The one thing I couldn't wrap my head around is how does light metering work with these old lenses? I read that it would work but it didn't make logical sense to me if the camera had no idea what aperture I was using.

    Thanks for your help.


     
  2. Ysarex

    Ysarex Been spending a lot of time on here!

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    Do the opposite -- set the camera to the semi-auto mode A (aperture). The camera will them meter the light through the aperture (no need to know f/stop) and set the matching shutter speed. Additional control then is available with the camera's EC adjustment.

    Joe
     
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  3. Jsun

    Jsun TPF Noob!

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    Thanks Joe. I like simple explanations.

    I just need to take a bunch on test shots with each lens now to see what their niche is. I'm working on M43 so the cropping factor really changes the nature of the lenses.
     
  4. Ysarex

    Ysarex Been spending a lot of time on here!

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    Actually the crop factor has no effect on the nature of the lenses. A 35mm lens is still a 35mm lens and f/2.8 is still f/2.8. The only thing that would be altered by using a crop sensor camera would be a lens DOF scale if there's one on the lens and it was inscribed for use with a different format. An inscribed DOF scale for use with 35mm film would read approx. 2 stops different: e.g. the DOF that the scale indicates for f/4 would be reached at f/8 using your M4/3 sensor.

    Joe
     
  5. Jsun

    Jsun TPF Noob!

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    Thanks again Joe.

    I understood that too about the DOF.

    It does increase focal length X2. I have a new Panasonic Lumix 25mm 1.7 for M43 and it acts like a 50mm SLR equivalent. When I mount my old Zeiss 50mm 1.4 it turns into a 100mm focal length. I can't even use my Zeiss 135mm 2.8 indoors, there just isn't enough room at 270mm!
     
  6. Ysarex

    Ysarex Been spending a lot of time on here!

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    Crop factor does not increase focal length. It has no effect on focal length. A 35mm lens remains a 35mm lens. Crop factor does not change focal length. Your 25mm f/1.7 Panny lens acts like a 25mm f/1.7 lens. Your Zeiss 50mm lens remains a 50mm lens. Don't let the "equivalence" fools twist and distort your thinking.

    I used to shoot an Arca camera for which I had a 90mm Schneider lens. My Arca camera had the ability to change backs so that I could use either a 4x5 sheet back, a 6x7 roll film back or even mount my Nikon camera body. When I used that camera and my 90mm lens with the 4x5 back the lens was 90mm. When I used that camera and my 6x7 roll back the lens was 90mm and when I used that camera and mounted my Nikon body the lens was 90mm. A lens can't change it's focal length.

    Joe

    When you switch the size of the film/sensor behind the lens the field of view is cropped (smaller sensor). This is not a focal length change it's a field or angle of view change.
     
  7. Jsun

    Jsun TPF Noob!

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    Okay. I'm just going off of what my eyes are seeing.

    I think my terminology might be wrong, and I should have said field of view.

    At the end of the day, my old 50mm on the M43 makes objects appear closer than on my old Contax 139Q, where it represented a close proximity to my real life field of view.

    It just appears to be giving me the same field of view as a lens with a longer focal length.

    Is that what you mean?
     
  8. Ysarex

    Ysarex Been spending a lot of time on here!

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    Real life field of view? What pray tell is that?

    No. it's giving you the field of view of a 50mm lens, not a longer focal length lens. I have an APS-C sensor camera (Fuji). I'm very fond of my 14mm lens on my camera which on that camera produces an 80 degree angle of view. Years ago I used to shoot a 4x5 view camera. To get an 80 degree angle of view on my 4x5 camera I needed a 75mm lens and in fact I used to have a 75mm Schneider lens. To get an 80 degree angle of view on your Olympus you need a 10mm lens.

    I don't go around today saying the 14mm lens on my Fuji is really a 75mm lens. I don't think about my 14mm lens in terms of my older 75mm lens. In fact when I use the 14mm lens on my Fuji I almost never think about my old 75mm lens. Why the cr*p should I? I also don't think that when I'm using my 14mm lens on my Fuji it's really like I was using a 10mm lens on an M4/3 camera.

    I never did have a 21mm for my Nikon so I can't think about that comparison.;)

    Why do you care one bleepin' bleep if the XXmm lens on your Olympus is the same angle of view as some other lens on your old Contax? You're using the Olympus camera so then think in terms of that camera.

    Joe

     

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