Lens Convergence?

[ic-racer]

How are you "correcting for convergence?" If the back standard is plumb vertical no correction is needed.

[Sirius Glass]

How are you "correcting for convergence?" If the back standard is plumb vertical no correction is needed.

I am using a Pacemaker Speed Graphic so there are no back adjustments. I leveled the camera left-to-right with a 6 inch spirit level but in first photograph I aimed the camera up to cut out the excessive foreground. In the second photograph the church was on a small rise. In both photographs I raised the lens but I forgot to check the edges.

These are the first two photographs that I took using the front rise.

Steve

[BradS]

I am using a Pacemaker Speed Graphic so there are no back adjustments. I leveled the camera left-to-right with a 6 inch spirit level but in first photograph I aimed the camera up to cut out the excessive foreground. In the second photograph the church was on a small rise. In both photographs I raised the lens but I forgot to check the edges.

These are the first two photographs that I took using the front rise.

Steve

The back must be vertical for these shots. So, you need to level up and down - not left to right. You would normally make the lens "look up" by using front rise (sometimes tilt).

on the speed/crown graphic, you can set the level on top, oriented front-to-back. When level in this direction, you should not see convergence of verticals. Does that make sense?

[Sirius Glass]

The back must be vertical for these shots. So, you need to level up and down - not left to right. You would normally make the lens "look up" by using front rise (sometimes tilt).

on the speed/crown graphic, you can set the level on top, oriented front-to-back. When level in this direction, you should not see convergence of verticals. Does that make sense?

Yes. In both cases I knew that I was aiming the camera up. The church, so that I could get the top of the tower and there was too much foreground at Harper's Ferry.

Next time I will level the camera and see if the front rise will take in the top of the building.

[jnanian]

steve

there are ways people have made their speed graphics have movements to adjust for tilting the camera up ...
some folks reverse their front standard, so they can tilt the lens down ..
the best way to photograph the scenes you have posted is to get a view camera ... tilt the camera up,
and then straighten the back standard, and do the same for the front.
press cameras are great for portraits, and straight on photography like a 35mm or mf system, but when it comes to architecture
unless it is straight on ... they tend to fall flat... it is best to use a camera that has back and front movements.
a view camera will let you do anything you want - fix and distort and flare the tops of buildings to give the keystoning effect

john

ps post levels / bull's eye levels are much easier to use than a 6" level

[BradS]

too bad the graphic doesn't have a tripod mount on the TOP....

If it did, it could be mounted up-side-down and accomplish the "point it up and straighten out the standards" by dropping the bed.

hmmmm...perhaps, there is a way to do it using the tripod mount on the side and a fancy three way tripod head....

[Diapositivo]

Shift movements alone should provide the amount of correction needed for this kind of pictures. In 35mm the usual procedure is to level the camera (not just left-right but also front-back) and then "shift" the lens until the desired degree of "perspective correction" is achieved.

If the lens projects an image circle big enough one should be able to "correct perspective" with nothing else than shift movements.

I have no experience of work with LF cameras and don't know a fig about rear-standard movement, camera tilting etc. but I do know that shifting can "compensate" any kind of converging verticals within certain practical constraints introduced by the lens. So in the case of the pictures published by the OP if the camera has a shifting movement that should be enough or, in case, mounting a shift lens on it should be enough to reach the effect that the OP was aiming at, IMO.

Fabrizio

PS That doesn't mean there cannot be alternative or more comfortable ways. I mean one doesn't necessarily need a camera with complicated movements for this kind of pictures.

[David A. Goldfarb]

For vertical shots, you can only get about 1cm front rise with a 90/6.8 Angulon, before the image quality at the top of the frame becomes a problem. I'm not sure how that translates for horizontals. You might want to take some test shots to get an idea of what the limits are. Find a subject like a church with a tall steeple and a cross on top, take notes, and see how much front rise you can get away with before the cross goes uncontrollably blurry at a typical 4x5" aperture like f:16 or 22.

Once you know this, then you can split the difference by applying maximum front rise and tilting the camera on the tripod to get the top of the building, and apply a smaller correction at the enlarging stage by tilting the easel.

[BradS]

Shift movements alone should provide the amount of correction needed for this kind of pictures. In 35mm the usual procedure is to level the camera (not just left-right but also front-back) and then "shift" the lens until the desired degree of "perspective correction" is achieved.....

The key to preventing convergence of vertical lines, however, is to keep the film plane perfectly vertical. Front rise only affects what part of the image circle projected by the lens is "seen" by the film. So, front rise (vertical shift) is not what prevents vertical convergence but front rise is often used in conjunction with making what ever adjustments are necessary to either the tripod head, the camera back or both to get the back of the camera, and thus, the film plan vertical.