Hi,
In considering a new/used large format camera, how important are yaw-free base t ilts?
As I am new on this format (information gathering stage before purchasing one), my understanding of the yaw free design is to tilt the standards at the base (I played with the Horseman LS). Now wouldn't this tilting result in having the nee d to refocus?
Comments appreciated.
My only interests have been in field cameras, so bear that in mind while reading. In short, it depends on the kind of work you expect to do.
To my mind, the ideal is to have both base and axis tilts, but that can complicate the design if it is to remain yaw free and of course increase the cost.
It is nice to have axis tilts to avoid or at least minimize the need to re-focus. However, depending on what kind of work you do and how much, the yaw-free feature may be more important. It takes some practice to get used to base-tilt only designs, but they have been in existance for eons and all mannner of photographers have used them. The old saw goes, "focus on the far and tilt for the near, re-focus and re-tilt until all is clear". You can actually tilt and re-focus simultaneously, depending on your dexterity and the particular camera design.
Depending on what you want to do, you'll find a yaw-free camera either important, or you won't care at all. Yaw free makes things nicer if you incline your rail (or camera bed), tilt the standards, then swing the lens. Table top shooters do this kind of thing all the time. Landscape and architectural shooters, do it much less often.
Note that base tilts don't guarantee yaw-free geometry. You need to have the swing mechanism above the tilt mechanism. Most field cameras have base tilts but are not yaw free. Most recent - maybe all recent base tilt monorail cameras are yaw free.
A yaw-prone camera (is that the right term?) can still be coaxed into the same relationship of lens to film as a yaw-free camera, you might find it a little bit more difficult to get to your final configuration.
Yes, you normally do have to refocus more with base tilts compared to axis tilts.
I have been spending a lot of time working in with this same dilema and I have concluded the following. As mentioned above, both base and lens axis tilt is nice, or the ultimate is multi axis tilt with base tilt. However, the main decision should come down to what you are using the camera for. If you plan to use tilt and swing, you have to go with base tilt. If you use just tilt or swing, but not both simultaneously, you will find the benefits of yaw free much less useful, or probably no benefit at all. If you plan to tilt the lens to change the plane of sharp focus, you will learn to set the lens tilt to the disired angle based on how far you want the hinge distance to be under the lens, then you focus the back. So, it is not much difference either way, base or lens tilt.
If you are after perpective control, then multi axis tilt is by far the way to go. You can change perspective in practicaly any way desired, vs. base tilt, which has only one angle of perspective control. If you want perspective control, you now must rear multi axis tilts which in most cases would then give you the same in the front also.
The Linhoff Technikardan 23s and 45 both have all these features in a nice lightwieght folding / callapsable rail design. And beleive it or not, it is actuall reasonably priced, suprise for sure! (Linhoff is high on everything, especially lens boards!) Most used ones sell for almost as much as the new ones, so they hold there value very well. The reason I regret not buying that camera, in addition to the items above, is because of the 485mm collapsable rail. All other cameras require you to add components to get this rail length.
The Horseman fixed rail cameras which also hae these features are excellent, however they are not field friendly at all. They are made for the studio, very heavy and not folding for transport or backpacking.
So my suggestion is (assuming you want all these tilts) is Linhoff for the field and Horseman for the studio. You are doing the right thing, research it to death, because once you buy it, get the right size lens boards and accesories you will probably stick with it for a long time, because it is not easy to sell this type of equipemnt, esp. the accesories with out substantial loss, except the Linhoff camera itself.
Base tilts are not what makes a camera yaw free. Look for instance at the Kardan B which has both base and center tilts but IS NOT yaw free.
To be yaw free the tilt at the base must be BELOW the swing point. Many dual axis movement cameras do not have the base tilt below the swing point.
On the other hand you can simply use any non yaw free camera on its side so the normal swing control becomes the tilt control and now the camera is yaw free. That is the reason for the extra bubble level on the Technik
The Technikardan is a center tilt only camera. It has no base tilts.
The dual axis tilt Linhofs are the GT and the GTL AMS.
Yaw free does not mean no refocusing. You seem to be confusing yaw free with 2 point focusing as is on the GTL and Sinar P2 cameras
...how important are yaw-free base tilts?
Yaw free tilts are most important when doing studio still life work where you mostly are using your camera at a downward incline. A yaw free design, where th e the tilt mechanism is located below the swing mechanism (as in the above menti oned Linhof cameras, but not the TK45s, also in the Sinar cameras and in the Arc a Swiss Discovery, F and M cameras as well the big Horseman and maybe a couple o f Toyos, as well as others) makes life much simpler for correcting perspective w ithout having the aggravation of continually having then to readjust other movem ents to compensate. A yaw free design is also handy occasionally when making arc hitectural photos, but once again, this is where the monorail or bed of the came ra is inclined. A "yaw free" design allows you to keep both the front and rear s tandards vertical even when the base of the camera is inclined. To reassert Bob Salomon: Not all base tilt cameras are of a yaw free design; the tilt pivot must be below the swing pivot.
...Now wouldn't this tilting result in having the need to refocus?
Virtually any movement is going to require you to refocus. If your real ques tion is "what is the value of base tilts?" whether they be yaw free or not, Thousands of Sinar, Arca Swiss, and Linhof GTL, and Toyo, Horseman, Wista, Wisner, & Canham field camera owners will tell you: increased speed, especially when doing near/far compositions. Assuming that the far point of your focus is at or near the bottom of the ground glass, you simply tilt the top of either the lens standard away from you (or the top of the rear standard towards you) to find a very quick approximation of the best focal plane that will carry your depth of field throughout the image without having to reso rt to very small f-stops. See the static content on the homepage for more about the Scheimpflug principle which explains why this works.
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