Adam,
Some thoughts
:
First, just because you choose near and far focus points and then set the focus halfway between them doesn't mean that you have enough depth of field for the extremes; that depends upon the aperture. The farther apart the focus points are (call it the focus spread distance) the smaller aperture you'll need to get everything acceptably sharp. That's all in the article that I linked to in my first post.
Second, as Corran mentioned above, there's really only one sharp plane of focus; everything else is out of focus proportionally to how far it is from the plane of sharp focus and the aperture you've chosen. The object is to have the out-of-focus blurs (blurry circles/circles of confusion) to be so small in the final print that our eyes can't tell the difference between them and the really sharp points. You can see, then, that whether something ends up appearing out of focus also depends on the degree on enlargement. Make a contact print and it looks really sharp; enlarge it 10x and everything starts to look soft...
So, the idea is to find the optimum aperture for the focus spread you have and the degree of enlargement you are planning on making (or, conversely, knowing how large a print you can make from a particular negative before it appears soft in areas you want sharp). Again, the article I linked to goes into this. Really, it's worth doing your homework here to save yourself a lot of headaches later.
Lets talk about movements a bit while I'm at it: Movements are used for two reasons: image control (e.g., correcting converging parallels) and optimally positioning the plane of sharp focus in the scene. The latter is the important one here and is achieved with tilts and swings (note that rise/fall doesn't reposition the plane of sharp focus; just takes a different slice of the image circle).
When positioning the plane of sharp focus with a view to getting everything in the scene as sharp as possible (which I think is what you're trying to do), the object is to get it as close as possible to the near and far focus points. The problem is, when you move the plane of sharp focus around, the points that are nearest and farthest change around too. If you, say, tilt the front forward a bit, which results in tilting the plane of sharp focus down in the scene a bit more in that same direction, the points you choose to focus on are no longer the ones nearest to and farthest from your camera position. Let's say you tilt so that the top of a near rock and a far mountaintop are in the plane of sharp focus. Now, the farthest point from the plane of sharp focus might be a spot at the base of the mountain, and there may be no point nearer than the top of that near rock you focused on. Note also, that the mountaintop is just as close to the plane of sharp focus as the top of the near rock. (This scenario is a common mistake made by people just learning camera movements.)
You can see, in the above example, that the plane of sharp focus isn't at an optimal position between near and far points; it's intersecting the nearest point and some distance from the farthest point (which is at a point that seems counter-intuitive at first...). The solution is to choose better reference points; focus halfway down into that near rock and halfway down the mountainside so the tops of the near rock and the mountain are "closer" and the bottom of the near rock and the base of the mountain are "farther" from the plane of sharp focus.
Now, you've positioned your plane of sharp focus well, but you still need to focus the camera (many think they are done at this point, but no!). Find the closest point, i.e. which point in the scene needs the most bellows extension to be sharp on the ground glass. Note this position; it's your "near" focus point. Now do the same for the far; search around in the scene and find the point that requires the least bellows draw. This is your far focus point.
Once you have those, note the distance between the two points, set your focus halfway between them on the rail/camera bed and, importantly, choose the optimum aperture for your focus spread so that everything stays acceptably sharp.
If you've done your homework, you've got a sticker or a table that you can easily reference to tell you what aperture to use for what focus spread.
Alternately, you can set your focus and stop down, observing your focus points through your loupe until they become acceptably sharp and use that aperture. Many do this. The problems with the visual method, however, are that the ground glass can get too dark to view in many situations (low light, etc.), the grain of the ground glass can keep you from being able to tell when things are right, and you're not really balancing diffraction degradation with depth of field (unless you're using a really powerful loupe and a really fine ground glass, anyway). Still, many say, "stop down till everything is sharp enough, then stop down one more stop," and do fine. I like my focus-spread tables.
Finally, let's look at one of your photos as an example. I don't know what you find unsharp about it; I can't see things on the website very well, but I can till you how I'd go about setting up for it. The photo is the second one, the one with the hillside and rock outcropping that slope up to the left.
I'd want to place my plane of sharp focus diagonally in this scene, laying it down a bit with tilt and then tipping it sideways a bit with swing so that the near right corner of the plane of sharp focus was the lowest and the far left was the highest (hope that makes sense). I'd pick two points on the vertical center axis for my tilt reference points, say halfway up that cholla in the foreground and halfway up the rock outcropping. I'd apply the tilt first. Then, I'd choose two reference points for the swing on the horizontal axis, say halfway up the slope on the left and the middle of the bright rock on the right. I'd then apply the tilt.
After that, I'd search around the scene, focusing on different things to find which are actually the "near" and "far" focus points, all the time keeping in mind where my plane of sharp focus lies. So, I'd check the tops of the rock outcropping and the tops of the near bushes/cacti for near points. Ideally, they should all be in focus at roughly the same position (if there are large discrepancies, I might rethink my movements). I'd find the one with the greatest bellows draw and call that "near" and note the position on the camera (my cameras all have scales on them). Then, I'd look around for the "far" (this time, something below the position of the plane of sharp focus), likely the hollow at the base of the outcropping or the ground near the camera. After finding the one that needs the least bellows draw, I'd note that position and then proceed as described above; finding focus spread and choosing aperture.
Sorry this got so long; I didn't have time to write a shorter response
Doremus
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Originally Posted by Richard Wasserman
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