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Thread: Out of focus

  1. #1

    Out of focus

    Hi I have a project to complete and I am running into focus problems. I am tryin g to take a picture of a tower that sits between two fences. The fences are abou t 15 feet high with razor wire on the top and bottom. This is in a Prison. I am using a 90mm lens. I focused on the tower and tilted the lens back until the for eground looked clear and sharp. I set the f stop at f32 and shot the picture. Th e tower was sharp as a tack the foreground was not quite as clear but OK. The to p of the fence was fuzzy. Any help will be appreciated. Tower was about 60 yards from the camera. space between fences was 12 feet

  2. #2

    Join Date
    Jan 2001
    Posts
    150

    Out of focus

    Well this is confusing. If I understand your post correctly, you should have tilted your lens forward to bring the plane of focus in line with the foreground fence and the top of the tower. Rear fence could be a problem. Actually as I read your post again, if you are 60yd away from the shot and the fences are only 12 feet apart, I would not use any movements, but would just use straight DOF with appropriate choice of f/stop.

    Scott

  3. #3
    Old School Wayne
    Join Date
    Dec 1999
    Posts
    1,242

    Out of focus

    we'll get you a hacksaw to cut down the fence.

    Are you between the fences, with them running parallel into the distance, or are you inside (gulp) facing fence-tower-fence running left to right?

  4. #4

    Join Date
    Dec 2001
    Location
    San Joaquin Valley, California
    Posts
    9,228

    Out of focus

    Ross, if you happen to cross paths with my lawyer, please thank him for the swell license plates he sent Suzelle and I for our wedding present, thanks!---------John
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.
    I'm not OCD. I'm CDO which is alphabetically correct.

  5. #5

    Out of focus

    Hi Ross,

    you want to use Scheimpflug to get both foreground and background sharp. This will happen if the foreground is on one half of the pic and the background is on the other half. So the bottom of the fence and the tower are both sharp. Because the fence is parallel to the focal plane and the tower (did I get it right?) Scheimpflug would't help you. You just have to focus on half the distance between tower and fence and stop down or move your camera back. Consult a good book about LF with sketches to get it all clear.

  6. #6

    Join Date
    Aug 2000
    Location
    France
    Posts
    151

    Out of focus

    Ross,

    if the tower and the fences are in the same plane of focus, you will not be able to find a perfect solution. Try using less tilt and trust on DOF for sharpness on the foreground.

    Regards,

  7. #7
    Robert A. Zeichner's Avatar
    Join Date
    Feb 1999
    Location
    Southfield, Michigan
    Posts
    1,122

    Out of focus

    The tower and the two fences are perpendicular and parallel to each other, if I'm understanding this correctly. To come as close to getting all into focus, you need to level your camera so the film plane is also parallel to the fences. You then need to focus on the furthest object you want to have rendered in acceptable focus and mark the focusing bed on your camera so you can refocus to that point without looking at the ground glass. Then, do the same for the nearest object you want rendered in acceptable focus. You then need to measure the distance on the focus bed between the two marks. If they are more than 5 or 6 millemeters apart, you may be unable to find an aperture that will provide adequate depth of field without causing some fuzziness due to diffracton. If they are only about 1.5 to 2 mm apart, an aperture of f22 may be enough to do the job. By the way, you will need to park the focusing bed between the two marks for this to work. If, you can't get the top of the tower in the frame, all you do is raise the front of the camera until it appears on the gg. This will allow you to maintain parallelism with the subject(s) and avoid variations in focus from top to bottom as well as convergence of the vertical lines. Got all that? It's really not that difficult, but may make more sense when you are under the focusing cloth. BTW, on which side of the fences are you? Just kidding

  8. #8

    Join Date
    Dec 1997
    Location
    Baraboo, Wisconsin
    Posts
    7,694

    Out of focus

    If you're trying to have the front fence, the tower (which presumably is a lot taller than the fences), and the back fence all in focus, neither front nor back movements are going to help you because the tower almost certainly is always going to extend up out of the plane of focus. I think you'll have to focus on the far fence, focus on the near fence, set the lens half way between the two points, stop down as much as possible, and hope for the best.
    Brian Ellis
    Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
    a mile away and you'll have their shoes.

  9. #9
    Old School Wayne
    Join Date
    Dec 1999
    Posts
    1,242

    Out of focus

    The man is standing between the fences, facing the tower with the fence on each side (according to an email reply). The fences are not in the same plane as the tower. This is why the top of the fences are going out of focus, *because* the backward lens tilt. I'm sure someone else can describe what he needs to do better than I (I'm spacially challenged;-), but I'll take a crack at it. My guess is he needs to try to bring the foreground fence tops in focus with the upper tower (but not quite the top) with foreward tilt, and then hope for the best when he stops down. I think though that tilt should be kept to an absolute minimum (or none at all), because as the lens tilts the plane of focus is going to come towards him along the middle distance fence tops. It sounds to me like this is what happened, only in reverse. But, I'm better at doing than I am at teaching

  10. #10

    Out of focus

    I see four planes of focus that you want to preserve. Each fence line, the tower, and the ground. In the crude picture below, the tower is the 'o' , the fences are the vertical lines, and 'x' is the photographer. Forward tilt will bring all of the ground into focus, but will compromise something on the tower. Getting either fence in focus would involve a swing, and to get both, you would need conflicting swings. To me (and I'll admit I'm not one of the LF experts here, but I'm pretty strong in geometry) it seems like your best bet is to maximize depth of field and possibly apply a slight forward tilt (to bring the plane of focus more in line with the rough average of the planes of focus in the image).

    | o | | | | | | | | | x

    You can increase your depth of field, albeit with some change in the framing/relational aspects, by going with a longer lens (would make the tower smaller), or by using the same lens and merely backing up more if possible (would make the tower more prominent compared with the foreground)(you could crop the final image if necessary)

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