Out of focus

Hi

I have a project to complete and I am running into focus problems. I am trying to take a picture of a tower that sits between two fences. The fences are about 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 foreground looked clear and sharp. I set the f stop at f32 and shot the picture. The tower was sharp as a tack the foreground was not quite as clear but OK. The top of the fence was fuzzy. Any help will be appreciated. Tower was about 60 yards from the camera. space between fences was 12 feet

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.

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Scott

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

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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?

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

Hi Ross,

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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.

Ross,

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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.

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Regards,

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;)

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.

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

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).

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| o |

| |

| |

| |

| |

x

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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)

Ok, that diagram didn't come out the way it was supposed to, here it

is flipped 90 degrees . . .

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o x

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