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  1. #1
    Join Date
    Apr 2006
    Posts
    242

    Question "Focus Trap" for Manual Lenses

    Came across an interesting approach for older, manual focusing lens using AF that may be workable and of interest...

    For anyone who doesn't know what we're talking about here, the "focus trap" technique is where, when using a manual focus lens, you set the camera to auto focus, hold the shutter button down, then adjust the focus. Once the camera sees focus it will automatically snap a shot.

    Not having anything other than AF lenses, I'm not positive if it will work w/Nikon units but, if so, makes older non-AF lenses a bit more attractive...

    http://www.stevesforums.com/... .../view_topic.php?id=572393&forum_id=80

    Anyone have any experience with this approach?
    Telecorder [Dave]
    Apple Valley, CA
    FZ30+TCON17+RDS
    D50+Nikkor 35 f/2; 18-70 DX; 70-300 VRii + BIGMA 50-500 EX HSM
    Kenko Pro 1.4X TC
    Sigma EX 1.4X TC
    SB-600
    My Image Galleries

  2. #2
    Join Date
    Aug 2006
    Location
    Chicago, IL USA
    Posts
    935
    Interesting approach, unfortunately it doesn't allow you to focus, then recompose your shot. Well, at least not for the first one. Maybe you use the "Focus Trap" technique to get your desired focal plane, then after wasting the first shot (its only digital), you can recompose the shot, flip the switch to manual and shoot your shot.

    Kind of a lot of work to get the shot, but I suppose it could work.
    Nikon D300 | MB-D10 | Nikkor 12-24/4 | Nikkor 50/1.8 | Nikkor 70-200/2.8 VRI | Sigma 18-50/2.8 | SB-800 | SB-80DX (x4) | Radiopopper JrX Studio |

  3. #3
    Join Date
    Apr 2006
    Posts
    242

    May be missing the point...

    With older, manual focusing lenses, this approach allows for a 'semi-AF' approach with the AF-motor function being the user rotating the MF ring on the lens and the camera taking the image when it senses an 'in-focus' condition.

    As the linked OP indicated, it allows for 'semi-AF' for moving subjects wherein your approach of recomposing wouldn't be applicable even for an AF lens...
    Telecorder [Dave]
    Apple Valley, CA
    FZ30+TCON17+RDS
    D50+Nikkor 35 f/2; 18-70 DX; 70-300 VRii + BIGMA 50-500 EX HSM
    Kenko Pro 1.4X TC
    Sigma EX 1.4X TC
    SB-600
    My Image Galleries

  4. #4
    Join Date
    Mar 2007
    Posts
    1,923
    So we turn non-AF lenses into AF lenses by becoming the lens focus motor ourselves. I like it!
    Nikon D40 + kit lens

    Nikkor 50mm f/1.8 D AF(...or not)

  5. #5
    Join Date
    Apr 2006
    Posts
    242

    Great Analogy...

    That's the concept... Not having any older MF lenses to confirm it with my D-50, it apparently works with Pentax and other digis.

    I know that when I have my Bigma mounted to my D50 with the Sigma 1.4X TC, the AF is disabled but the green AF dot does light up when it senses AF.

    Since I now have my Kenko Pro 1.4X DG TC, it allows for AF w/it mounted to my Bigma so I don't have this issue.

    I guess I'll have to try the digi in AF mode with the Sigma TC and try pressing the shutter to see if it will fire off when it 'gets the green light...'
    Telecorder [Dave]
    Apple Valley, CA
    FZ30+TCON17+RDS
    D50+Nikkor 35 f/2; 18-70 DX; 70-300 VRii + BIGMA 50-500 EX HSM
    Kenko Pro 1.4X TC
    Sigma EX 1.4X TC
    SB-600
    My Image Galleries

  6. #6
    Join Date
    Jun 2007
    Posts
    107
    i've a D50 and MF lens. the D50 (in M mode) takes pictures when the lens is out of focus.
    =========================
    "Conform but always be yourself."
    =========================
    Nikon D300
    Nikon AF-S VR 18-200mm
    Nikon AF-S VR 70-300mm
    SB-800
    SB-20 with optical slave trigger
    Tamron SP AF28-105mm F/2.8 LD
    Vivitar Series 1 (AI-S) 28-105mm F/2.8-3.8 Macro
    Super Cosina 100-500mm f5.6-f8 MC Macro

    Tripods:
    BOGEN 3021 with Cullman Ballhead
    Gitzo Tatalux
    Leitz Tiltall
    BlackRapid RS-2 strap


    http://www.flickr.com/photos/nikx/

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