on axis vs base tiltsgreenspun.com : LUSENET : Large format photography : One Thread
I would like to know if its that big of a deal to have the standards tilt "on axis", as opposed to base tilts. I understand why on axis is better, but when shopping for a field camera, I've found it hard to find one that is on axis. Some have on axis front standards and base rear standards. Thanks, Raven
-- Raven Moss (email@example.com), April 11, 1998
The difference between axis and base tilts is simple. with axis tilts, the center of the film plane (or lens plane) stays in the same position, i.e. in focus. With base tilts, the entire rear (or front) standard is displaced, i.e. de-focussed. This requires that you refocus every time you tilt. This is fairly easy to get used to with the back, but front base tilts can tend to be confusing until you figure them out. Also, you must keep track of which way you need to refocus with base tilts. Have you made the camera longer or shorter with the tilt? Refocus the opposite direction. Base tilts usually require that you repeat the tilting/refocussing procedure a few times for really critical focussing. Axis tilts are certainly easier, but on field cameras can cause structural weaknesses or inconveniences (such as the combining of rise/fall lock down with the axis tilt raising the possibility of changing one when you want to change the other). I have a nifty little document called "dealing with base tilts" if you want it,. email me.
-- Doremus Scudder (ScudderLandreth@compuserve.com), September 03, 1998.
For my use in 4X5 and 8X10 I use the base tilt exclusively. Both of my cameras have axis/base tilt on the front and base only tilt on the rear.
If I wish to bring the foreground into focus and not affect the linear nature of the objects, I use the front base tilt. If I wish to bring the foreground into focus and have it "loom large' in the scene, with no concern for convergance of the vertcal lines, I use the rear base tilt. By focusing on the far and tilting the back to bring the foreground into focus, and continuing to refocus on the far, you can quite smoothly bring the image into focus on the ground glass. It sounds more difficult than it really is, practice makes perfect!
Now, to specifically answer your questions, for me it is not a big deal, actually, no deal at all. As to why rear axis tilt is less prevelant on field cameras, I believe it is an attemt to keep the of cost and weight down. Also, a desire by some manufacturers to keep field cameras as "simple" as possible, while still giving the most important elements of a full blown monorail view camera. Any additional points of movement add to the overall instability of the camera and add more points for the camera to "flex", if you will.
-- Marv Thompson (firstname.lastname@example.org), September 03, 1998.