Maintaining focus when adjusting rise.

[Alan Klein]

Will you maintain focus if you lower the front standard after focusing when it's higher?

[Graham Patterson]

If the front and rear standards are parallel, yes. If you have some tilt in play then probably not. It is all to do with keeping the plane of focus matching the film. I always check the focus once all the movements are in, even if it shouldn’t change. That’s when the final decision about depth of field has to be made anyway.

[darr]

I always check the focus once all the movements are in, even if it shouldn’t change.

+1

[ic-racer]

For a metal camera in which the front tilt detent has been aligned to the film plane with a laser, the lens should remain the same distance from the film plane during a rise.
However, a wood field camera may indeed have the front standard pulled back at the top by a heavy bellows as rise is added. Thus one reason to require refocus.

[Drew Wiley]

I ALWAYS double-check focus after making any kind of view camera movement, as well as check corner coverage if a significant amount of rise or tilt is involved, even when my metal monorail Sinar is involved.

[Alan Klein]

I was thinking that the curvature of the lens might affect this at least in other areas than the center of the lens and film. Does it?

[Graham Patterson]

I'd be surprised if field curvature in a symmetrical large format lens at working aperture was identifiable separately from all the other possible focus issues (rigidity, alignment, film flatness, etc.). But that is why focus is the last check before an exposure - it cures all the uncertainties, except whether it is the right picture! Now I'm curious - is field curvature enough of an issue on its own?

Is there a particular reason where you can't check or alter focus after using rise/fall of shift? Doing stereo pairs with a single lens and a half dark slide, perhaps?

[Mark J]

I was thinking that the curvature of the lens might affect this at least in other areas than the center of the lens and film. Does it?
There's a small effect from the lens, for example a LF lens of around 210mm will have its field flat to about ±1mm over most of the quoted field circle - however it's not a simple spherical shape.

[Alan Klein]

I'd be surprised if field curvature in a symmetrical large format lens at working aperture was identifiable separately from all the other possible focus issues (rigidity, alignment, film flatness, etc.). But that is why focus is the last check before an exposure - it cures all the uncertainties, except whether it is the right picture! Now I'm curious - is field curvature enough of an issue on its own?

Is there a particular reason where you can't check or alter focus after using rise/fall of shift? Doing stereo pairs with a single lens and a half dark slide, perhaps?

My camera a Chamonix 45H-1 has asymmetrical rear tilt on the rear standard. There's a line on the GG that you focus first for the far distance that's on the axis so that point will stay in focus when the rear standard is tilted. Often, the line doesn't match where you want to focus on initially due to my composition. So first I raise the front standard, focus on the line, and then return the standard to its original lower composition position. Assuming the front and rear standard were initially lined up in parallel, would the focus point remain the same or would the curvature of the lens effect it since I was focusing using a different part of the lens?

[Drew Wiley]

I'd always double-check the fine focus with a loupe at critical portions of the composition. Any camera like that is not likely to hold position completely reliably after any shift. I've got a little 4x5 mahogany Ebony camera, which is allegedly the most precise line of wooden cameras ever made, and I need to double check it.

But there are other parts to your question which depend more on specifics, like the exact lens in question. But again, rather than trying to come up with some complicated formula, I'd simply defer back to the advice to double check everything pertinent visually before inserting the film holder and tripping the shutter. I do this in two steps.
First, I check the scene at full wide open aperture for sake of brightest viewing. Then second, I do so stopped halfway down to my working aperture, which still gives relatively bright viewing, but also a better indicator of any optical and depth of field improvements as the aperture gets smaller. And then finally, i set it at the working aperture for the shot itself. For example, if I'm employing an f/9 lens, and planning to shoot it at f/32, after applying my necessary view camera movements, I'll check the scene first at full f/9, then stopped down halfway to f/16, and if that looks OK, then shoot it at f/32.

[Doremus Scudder]

Just get in the habit of checking focus after all your movements have been applied and immediately before you make the exposure. That way, fiddling with the camera won't have a chance of ruining your exposure.

Doremus

[Alan Klein]

Thanks everyone for your advice.