focusing with tilt

[John Mauser]

Hi,
I've had my tachihara 4x5 for a few month's now and I've mada a few dozen exposures with it. So far I've relied on using f45 and parallel standards for max DOF and sharpness. I'm pretty happy with the results but would like to get closer to those "everything's in perfect focus ansel prints". I've been reading as much as I can on this sites old postings on tilts for focus. I've also been practicing out my office window as hurricane ophelia comes by. Tell me if I'm on track with what I've learned and if there's anything else. Set the camera up and pick two important objects that you'd like in focus (one far and one near). With the standards parallel, focus on the the far object and then the near and get an idea of about how far you need to tilt the front standard to have them both in focus. Tilt the front standard and refocus on the far object. Then see how far out of focus the near object is. If needed, adjust tilt and refocus again. Continue until the two objects are in focus. Stop down to f32 and hope for the best. Is this about right? Does everything in the middle usually fall into focus once you stop down? What if your main element is a tree 1/3 of the way into the scene...don't use any tilt? Thanks for any answers in advance. John

[Ralph Barker]

I think you have the basic technique, John. I remember it as "focus far, tilt near, repeat". Usually, three or four iterations will get both of the chosen points in focus.

The larger issue of using tilts (really, movements in general) is that we are adjusting (tilting and/or rotating) a flat plane of sharp focus within a three dimensional subject field. Sometimes, that doesn't produce the desired results, as interim elements of the scene may project up out of the plane of sharp focus, so compromises must be made. I find it helps to think of tilted depth of field to be a wedge on either side of the focus plane, and with the narrow end of the wedge at the camera end of the scene.

[Eric Leppanen]

As Ralph says, you've mastered the basic procedure for setting front tilt. However, you can do better than simply setting the aperture to f32 and "hope for the best." This thread provides an overview:

www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00Cf4H

Once you further fine-tune your focus point, you'll frequently get more elements of your composition in sharp focus.

[Sidney Cammeresi]

You don't need to stop down to f/32 and hope for the best. If you have a ruler, you can compute what aperture you need very easily. Look around for the formulas, since it depends on what circle of confusion you want which depends on how much you are enlarging. The formulas will reduce down to one number by which you multiply the focus spread between near and far focus to get your aperture. For my contact prints, the number is 2.5, which is the only thing I need to remember in the field.

What I do is focus on the far object using the front standard, then focus on the near object using the rear standard. I measure how far back the rear standard is, say it's 20mm. 20*2.5 is 50, so I'd set my lens to f/64 or maybe even f/90 to be really safe. Then I crank the rear standard forward half of the distance I moved it back, which puts it at the hyperfocal distance for the computed aperture. (So it would be 10mm back from the point of far focus, and everything from the near object to infinity would be in focus.)

It's all very easy and only requires only a ruler and one number, although I bring a slide rule with me to make sure I multiply correctly.

[James E Galvin]

The tilting tilts the plane of focus to best fit the scene. This works perfectly IF THE SCENE IS A PLANE. Your tree makes that scene NOT a plane, no amount of tilting will make the background seen through the tree branches in focus with the tree. But the foreground can be helped with some tilt. I look at the top half of the ground glass vs. the bottom, am I generally focussing one way for the top, the other for the bottom? Tilt to make them about equal. The same for swing. The idea is to minimize the total focus travel. Set the focus in the middle of that travel. Stop down enough to get the out of focus elements good enough. You can see what is happening with a 10X loupe. I generally use half way between f/22 and f/32, but may go to f/64 for that tree. If the scene is not very far from a plane, it gets simpler, focus in the middle of the ground glass, and tilt to get the top (foreground) in focus. Then look around with the loupe, you might be done.

[Eric Woodbury]

I am assuming that the tilt you are talking about is the rear and that it pivots at the bottom. Starting with the camera trued up parallel, focus at the bottom of the ground glass. This is usually the far object, but it is important because the bottom of the rear standard does not move far when you do the tilt. The tilting action affects the top more. So with the bottom focussed, tilt the top until the top is in focus and then continue tilting a little past (from the parallel case where you started) until top and bottom are equally (slightly) out of focus. That 'little past' makes up for the small amount that the bottom has moved (out of focus) during this tilt. Lock down the tilt. Refocus slightly and the whole thing should snap in sharp.

Hope this makes sense. It is quite fast. Good luck.

[John Mauser]

That's what I like about this site...that everyone's so quick to give a helping hand, thanks. I think the wierdest part about going from an experienced 35mm and medium format photographer to a 4x5 is that you are basically a beginning photographer again. It's a little frustrating to not get exactly what you want when you first start, but I look foward to learning this stuff and becoming a good large format photographer. Thanks, and feel free to add any other thoughts on the tilts. John

[Brian Ellis]

After focusing on the far I'd eliminate the "and then the near to get an idea of about how far you need to tilt to get the front in focus" step. That isn't going to tell you anything with much more than you already know, i.e. that the greater the distance between the near and far the greater the tilt you'll need to bring them both into focus. Just focus on the far, then tilt until the near comes into focus. Refocus on the far if necessary, tilt again as necessary. You shouldn't need more than two iterations at the most to bring the near and far in focus. You'll know you've tilted too much if the camera starts working backwards, i.e. the far comes into focus as you extend the bellows and the near comes into focus as you retract the bellows.

If there is something in the scene that's out of the plane of focus, e.g. the tree in your example, you'll need to stop down to bring it into focus once you have the near and far in focus, tilts help only with things that are within the new plane you've created with the tilts. Actually saying everything is "in focus" is a misnomer since there's only one plane that is truly "in focus," everything in front of and behind that single plane is technically out of focus and you're relying on depth of field to make those things appear to be in focus but that's a different thread.

[John Mauser]

You've probably stated this already but please humor me for a second. One you have your near and far objects in focus, do you leave the camera focused there or do you refocus 1/3 of the way into the scene, half way between the two objects? Or should I just pick an object 1/3 of the way into the scene to be my near object and be done with it? Thanks, John

[Hans Berkhout]

You should refocus but: you now have a different plane. The top of your tree is the near point, the ground probably your new infinity. Focus half way and close down.