help with focus

[ImSoNegative]

the i way is focus is this, i will focus on distant, then tilt the back till the near becomes sharp then i will usually adjust the back a bit more by going forward a b it then i stop down usually to at least f22 on a 210mm all should be good and sharp. i very seldom use forward tilt.

[ImSoNegative]

here is an example, this was shot with a 210mm fujinon @f22,

[jeroldharter]

Back tilt will exaggerate the size of foreground objects while front tilt will not. I use front tilt in 4x5 most of the time unless I am trying to exaggerate foreground objects. With 8x10 I find that I cannot reach the front standard much of the time so I use more back tilt as a matter of practicality.

[Rick Tardiff]

I just want to once again thank everyone for their patience and advice. I have been putting the advice to good use and I wanted to attach my latest effort. I was also trying to get to grips with instant film. but as you can see I am doing much better with focus.
ebony RW45, 210mm Rodenstock, F11@1/125 on Fujifilm FP-100B45

Thanks

[Brian Ellis]

It isn't just a matter of focusing correctly, it's also a matter of selecting the optimum aperture, which is the aperture needed to provide the depth of field you want while keeping the effects of diffraction and distortions to a minimum. The method of doing that is very easy. Attach a millimeter ruler somewhere on the bed of your camera such that you can see how many mms the front standard moves as you move it forwards and backwards to focus (or the back standard, if you're focusing with the back but I'll assume you're using the front). Many cloth or plastic tape measures have inches on one side and mms on the other and they're easy to find at a fabric store or a hardware store.

After attaching the mm scale (I used double-sided Scoth tape) focus on the nearest object in the scene that you want to be sharp in your print, note the position of the front standard relative to the mm scale, then focus on the farthest object you want to appear sharp and note the position of the front standard. Set the front standard half way between the two points and also note how far in mms the front standard traveled in moving between the two points. Consult a depth of field table that you carry around in your back pocket to see which aperture is the optimum aperture to use based on that distance. If you're using movements do all of this after you've made the movements, i.e. get everything as close to being in focus as you can first, then focus on the nearest object you want to appear sharp and the farthest you want to appear sharp, set the front standard midway between the two points, etc. etc.

If you don't have a depth of field table available there's a simple method of doing it by memory. If the front standard moves approximately 1.6 mms use f16, if it moves approximately 2.2 mms use f22, if it moves approximately 3.2 mms, use f32, etc. If you want to be extra safe stop down one additional stop.

This is one of those things that sounds a lot more complicated when explained than it is when you do it. It's a very simple and pretty much foolproof method of both focusing and setting the optimum aperture. IRC it's the same method that's explained much better and in greater detail in Tuan's article on focusing the view camera that's referred to in Jacque's message.

[Leonard Evens]

Both your examples probably require some front tilt in order to get everything in focus.

Let me tell you how I would do it.

I would choose a near point and a far point, focus on each and note the positions on the rail. Measure the distance in mm between those positions and multiply it by 5. That gives you an estimate of what you will have to stop down to in order to get everything in focus without a tilt. My guess is that you will have to stop down so far that the requisite time will be too long for acceptable subject motion and in addition at f/45 and f/64 diffraction may become an issue.

If that is so you need to til.

Let me first address the second picture. In that, everything of interest lies in or very close to a single plane stretching from the near foreground to the far background. As above choose a near point and a far point in that plane. Choose an initial tilt, say about five degrees. Then focus on the far point and refocus on the near point. If you have to increase the distance between the standards to focus on the near point, increase the tilt. If you need to decrease the distance between the standards to focus on the near point, decrease the tilt. Repeat this process until both near point and far point, and indeed the entire scene is all inf focus. At this point you can take the picture at any convenient aperture, say f/16.

Let me next address the first picture. Here not everything of interest lies in a single plane. Choose a near point on the ground in the foreground and a far point halfway up the trees in the background. Use the procedure outlined above to tilt so the plane through those points is in focus. Now consider points above and below that plane which you also want in focus, e.g, the top and bottom of the trees. Focus so that the top comes in focus , note the position on the rail, and then do the same thing with the bottom in focus. Measure the displacement between those positions, and again multiply that by five. That should give you a good estimate of how far you have to stop down to get everything in focus.
But you probably should stop down an additional stop to be sure.

The basic fact used in the second example is that when you tilt, the region of focus forms a `wedge' shaped region lying between an upper plane and a lower plane, with both these planes passing through a common line (called the hinge line) below the lens. Thus the region in focus is quite narrow close to the lens but opens up progressively as you move away from the lens. The plane of exact focus also passes through the hinge line and cuts the full region in half in the sense that any vertical section between the upper and lower plane is bisected by it.