tilt

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dear experienced and generous lf users

ok, i've had a few months to work a bit with my new (to me) tecnica, so i have skimmed the books on movements and have used them albeit slowly and carefully at the moment. looking into the gg i can see thay using the front tilt a horizontal plain will "snap" into focus, all very nice, but tha top of any vertical object along this plain (tree, road sign) goes out of focus. am i missing something or should i forget the tilt and stop down?

thank you

-- adrian tyler (tyler@nova.es), April 29, 2002

Answers

Adrian,

No you are not missing anything. But each movement in a LF camera has a specific effect. You are finding out what you can achieve (and what you can't) using the potential in your LF camera. Perhaps try setting yourself some photographic challenges and work out how to achieve the effects you want.

Good luck.

Colin

-- colin carron (cicarron@aol.com), April 29, 2002.


I'm pretty new to LF, too, so others can can correct me on this if I'm off. I've found that the thing to remember is that there is only one plane of sharp focus no matter how much you tilt/swing/shift. The photographer's job is to select the most advantageous plane of focus with tils/swings & then stop down enough to bring things ouside this plane into focus, if desired.

-- Tom Westbrook (tom@twestbrook.com), April 29, 2002.

You will need to establish a plane of focus that "splits the difference" so to speak between objects in the horizontal plane and those in the vertical, and use depth of field to bring acceptable sharpnes to them all. Making a simple sketch of the scene from a vantagepoint perpendicular to the direction that you are shooting will bring a greater understanding to the geometries involved. Don't "forget the tilt", since in most cases it will buy you the freedom to open up a couple of stops from a straight-on shot (otherwise we'd all be shooting at f/64 and smaller most of the time). Good luck.

-- Wayne DeWitt (wdewitt@snip.net), April 29, 2002.

Using camera movements on 3 dimensional subjects is always a bit of a compromise. As a general rule, use lens tilt or swing to get the focus you want on the nearest and furthest points of interest in the scene, and then stop down to take in any objects at right-angles to the plane of focus you've created by tilting.
In your example: It's perfectly possible to tilt the lens and get the ground sharp from just in front of the camera to the horizon, but, as you've found out, anything outside of that plane is going to go out-of-focus. Yes, you need to stop down to bring these objects back into focus, but, it doesn't take much stopping down to bring a 25ft tree at 200yds into sharp focus from top to bottom; whereas, getting 3 miles of ground into sharp focus by stopping down alone is next to impossible.

-- Pete Andrews (p.l.andrews@bham.ac.uk), April 29, 2002.

what you are seeing is what is supposed to happen. So what do you do?

What you do is think a little differently and a little abstractly 9frankly, this is an aspect of large format photography that I reaaly love). You obviously know to use the Scheimpflug principle to get the film plane, the lens plane and the subject plane to intersect in a common line so that everything in the subject is in focus. And you know how to tilt the film plane or the lens standard --or both-- to achieve this common line. But have you thought about the subject?

Obviously you cannot generally tilt the subject if you are shooting a landscape but since the subject is three dimensional there are a near infinite number of planes the extend through that 3D subject. The trick is to pick the one that gives you the best compromise through the subject this will be a plane that isn't aligned with the ground and doesn't (usually) extend from the closest point in the foreground to the top of the tallest element, but somewhere in between.

If you are having problems visualizing this, take a look at a wedge of cheese that is laying on its side. The entire wedge is the subject and the side it is laying on and the side that is on top describe those two planes i just described more abstractly. You need to determine where to slice that wedge to find that subject plane. To ripen the cheese metaphor, that slice does not need to be parallel to either of the existing sides, nor does it need to extend to the sharp end of the wedge.

Now according to the Scheimpflug principle if you make it so that plane that you decide on intersects with the line formed by the intersection of the film plane and the lens plane, everything on that subject plane will be sharp at all apertures. But what about the stuff that is above or below that plane? To achieve that you need to stop down if you want those areas in focus.

So if you need to stop down, why bother with all of the above? Because you won't need to stop down as much and if you can keep your aperture in the f/16 to f/22 range your images will be sharper (at least have greater resolution of fine detail) than if you need to stop down to f/32, f/45, etc.

Now if you can get the quality of image you want by using f/16 to f/22 without tilting the front or the back standards, I say go for it. why make life more complicated.

Are there any tools out there that can help you determine these tilt (or swing) angles, or for that matter just how much you need to stop down? Yes, there is the Rodenstock Depth of field / Scheimpflug calculator ( Walter E. Schon) The best part is that it is easy & fast to use, it works with any view camera and lens, is cheap (less than US $40.00), and measures about 3.5" x 4" x 1/8" (it fits in your pocket).

-- Ellis Vener (ellis@ellisvener.com), April 29, 2002.



ok, nice work guys, i get it.

i'm gonna try it out this weekend.

thanks you are a great team!

adrian

-- adrian tyler (tyler@nova.es), April 29, 2002.


One thing I'd add, as a beginner in LF photography, is that you can see what is going on pretty easily on the gg if your eyes can focus that close. What I've done is buy the strongest pair of reading glasses that I could find at the drugstore (3.25 diopter 10-15USD) and that allows my tired old eyes to focus close enough to the gg to readily perceive when things are going in and out of focus on the whole ground glass. I swing and tilt away until I've established a plane of focus I'm pleased with and then check it with the loupe, first wide open, and then again after I've stopped down. Initially I tried establishing the plane of focus only with the loupe, which magnifies too much to see what is going on globally.

-- Tony Galt (galta@uwgb.edu), April 29, 2002.

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