Lens Convergence?

[Sirius Glass]

These are two photographs that I took learning to correct for convergence. The negatives were quickly flat scanned saved; then GIMP was used to reverse the images and adjust the contrast so that they would be viewable.

Both negatives were taken with a Schneider-Kreuznech Angulon f6.8 90mm lens. In both photographs I thought that I had corrected for convergence, but on the right of both of them there is convergence. The one of Haper's Ferry has slight convergence and the one of the church has a larger convergence.

Are the convergences an artifact of the lens or an Operator Assisted Failure [OAF]?

Steve

[Darin Boville]

>>but on the right of both of them there is convergence.<<

And on the left, too.

Image #1 has obvious convergence all over, not just on the right. Image #2 looks like it is just on the right side but it also looks like the horizon is not level. One you "level" the image you'll have convergence all over, just like image #1.

--Darin

[Sirius Glass]

Image #2 was aimed slightly uphill. Thanks.

[Darin Boville]

Image #2 was aimed slightly uphill. Thanks.

To my eye the whole image is tilted leftward. If you correct it by rotating the image back to the right a tad that "right only" convergence" will look like "all over convergence."

Just what I see at a first glance...

--Darin

[E. von Hoegh]

Image #2 was aimed slightly uphill. Thanks.

Use the front rise, keep the camera level.

[TheDeardorffGuy]

Square that back to the building !!! The back controls perspective and therefore convergence.

[Cor]

Use the front rise, keep the camera level.

The best solution, only that he has a 6.8/90mm Angulon which has barely enough coverage for 4x5..a f8 or even better a f5.6 90 SA would work..

Best,

Cor

[Walter Calahan]

OAF, for sure.

Best solution is to get a carpenter's angle finder to place on the ground glass to make sure it is parallel to the building.

[engl]

To me it looks like you did not have the camera level when taking the shots.

Correcting for convergence is easy. Use a level to make sure your camera back standard is level (left to right) and perfectly vertical (front to back). That is all you need to make sure that lines that are vertical in the real world will be vertical in your photo.

For even better results, a ground glass with a grid should be used to verify and fine-tune the back orientation. You could skip the levels and just rely on the ground glass grid, but that can be difficult if there are few (or perhaps even no) straight vertical lines in the shot.

[E. von Hoegh]

OAF. Get a GG with a grid. Speaking for myself, my little brain seems to "correct" for the convergence when I'm composing. Convergence doesn't reappear until the negative is almost dry.

The easiest solution is to use a GG with a grid. There's a reason architectural photographers won't do without one.