Front and back focus for setting aperture when tilting/scheimpflug

[pkr1979]

Hi all,

I've been using a Linhof table for focusing lately. First I front focus, then back focus, then focus in between and set the correct aperture for the area I want in focus. Clearly, this works just fine.

But, is the good folks in here applying this focusing method when tilting (doing landscapes for instance)? It appears to not be as straightforward, which I hoped it would be but suspected it wouldnt.

Any experience on how to do this... Or any tip is appreciated really :-)

Cheers
Peter

[Bob Salomon]

There are two different tables from Linhof. One is a folded card that was shipped with their cameras through the mid 90s. The other is a Linhof branded version of the Rodenstock DOF/Scheimpflug rotating calculator which is currently available. That one computes DOF settings for all formats from 35mm to 810 as well as the back position and the required aperture for various magnifications.
The other side computes the proper tilt for those same formats at a variety of magnification ratios.
Which one are you using? The current, rotary one will compute exactly what you are asking for.

[Doremus Scudder]

Peter,

The "focus-near, focus-far, split-the-difference" technique works just as well when applying movements. It's just that it is a bit less obvious, once you've tilted or swung, exactly what you should be focusing on. When the the camera is in zero position, the plane of sharp focus is parallel to the the film plane; when you tilt or swing, it can be in a very different position. Knowing what is now the "near" and the "far" takes a bit of visualization.

An example: let's say you've tilted to get a close foreground object and a distant mountaintop both in the plane of sharp focus. That means the plane of sharp focus now runs flatter to ground and close to 45° to the film plane (or more) rather than being parallel. The "farthest" object in this scenario would now be something distant below the plane of sharp focus; the "nearest" would be the closest object "above" the plane of sharp focus. These might be the foot of the mountains and the top of a nearby bush, respectively. These would then become your near-far focus points.

It can be confusing at first to decide what to focus on, but you can always find the relative "near" and "far" by focusing on various parts of your image and seeing which ones need the most bellows draw ("nearest") and which the least ("farthest"). After you've practiced a while with this, it gets pretty easy to visualize where your focus points might be with any given movement(s).

As for the aperture to use: I use the method outlined on the LF homepage and have a chart with optimum f-stops for any given focus spread. If that's the way your calculator table works, then you should be able to use it to determine optimum aperture with or without movements.

Best,

Doremus

[pkr1979]

Hi,

And thanks for your replies :-)

The table I'm using is a chart with optimum f-stops for any given spread (not like the Rodenstock one - I've just googled it). Doremus, thanks, with your help my chart should be sufficient. I'm pretty sure I get it, its a good tip to pay attention to the bellows if, or more likely - when, insecure.

Again, thanks a lot for this.

Cheers
Peter

[pkr1979]

Hi again,

It might not be very practical or used very often, but just out of curiosity... I assume then that this also applies if you do an anti-scheimpflug? And then that the near and far would be opposite of the scheimpflug near and far?

Cheers
Peter

[Andrew O'Neill]

I don't use any tables. Just my eyes and a loupe.