Center/Axis Tilt vs Base Tilt

[Greg Liscio]

Is one type of tilt more versatile than the other? Is having both worth the extra cost? Which is the better to have when combined with asymmetrical tilt?

[Archphoto]

What kind of camera are you looking for ?
A field or a mono rail ?

Both tilt versions have their adapts and once you are used to one type of tilt it does not matter anymore.

E.i. Sinar has both base tilt and asymmetrical tilt, the base tilt being simple, the asym tilt being geared on my P2. I use the asym tilt only.

At one point or the other you will have to refocus anyway.

Peter

[Gem Singer]

The Ebony 45SU has asymmetrical tilt on the rear standard and axis tilt on the front standard.

This is an ideal combination. That's why Ebony offers those movements on their top of the line cameras.

Makes for easy tilting adjustments.

[Bob Salomon]

The Linhof Kardan GTL-AMS has all three. Continuous variable assymetric front and rear tilts, front and rear axis tilts and front and year base tilts to make the camera yaw-free. But it weighs almost 20 pounds and you would not want to carry it in the field.

[Greg Liscio]

I'm looking for a field camera.

[Gem Singer]

Greg,

As far as i know, Ebony is the only manufacturer to offer asymmetrical rear tilt on their wooden flatbed field cameras, both folding and non-folding types.

[Frank Petronio]

If you are a landscape photographer who wants to do the classic "foreground in focus out to the horizon" then focus on the horizon and simply use the BASE tilt of the back to bring the foreground in focus.

Sufficient for 95% of the shots you see here ;-)

[timparkin]

If you are a landscape photographer who wants to do the classic "foreground in focus out to the horizon" then focus on the horizon and simply use the BASE tilt of the back to bring the foreground in focus.

Sufficient for 95% of the shots you see here ;-)

Am I right in saying that following this procedure, your horizon will now be out of focus if it appears in your frame somewhere? (i.e. with base tilt, every part of the frame will move focus slightly except the very top edge of the frame). So the real procedure is to focus on infinity, base tilt for the foreground, refocus on infinity, retilt to check foreground, focus on infinity again, retilt to check foreground.

Tim

[rdenney]

Am I right in saying that following this procedure, your horizon will now be out of focus if it appears in your frame somewhere? (i.e. with base tilt, every part of the frame will move focus slightly except the very top edge of the frame). So the real procedure is to focus on infinity, base tilt for the foreground, refocus on infinity, retilt to check foreground, focus on infinity again, retilt to check foreground.

Tim

When you first focus on infinity, the distance the lens's rear nodal point to the film has to be maintained when you tilt to keep those infinitely distant objects in focus. For those sorts of landscapes, the horizon is high in the composition and low on the ground glass. When you use base tilts, the infinity part of the tilted focus plane will be at the bottom edge of the ground glass, and the tilted focus plane will come toward you as you go higher on the ground glass (presumably to keep the foreground in focus). The further the focus plane is from the camera, the greater the depth of field above and below it, and at the horizon focus is maintained.

If the horizon is low because the main subject is clouds, then everything in the image is at infinity and beyond the hyperfocal distance--no need for tilts there.

With axis tilts, the bottom of the ground glass will get closer to the subject, which will always be outside the focused domain when you originally focused on infinity.

For me, axis tilts have some usefulness on the lens standard, but I was constantly refocusing my Cambo when using axis tilts on the rear. Thus, I mostly did things with lens tilts. With the Sinar's base tilts, the above trick is far easier. One key advantage to using rear tilts (assuming the perspective projection of the scene can handle it): the film stays within even limited lens coverage.

Rick "just getting used to base tilts" Denney

[timparkin]

The further the focus plane is from the camera, the greater the depth of field above and below it, and at the horizon focus is maintained.


Hi,

Hope you don't mind me quizzing you as my understanding differs a little and I've probably got a lot less experience than you so would like to learn...

So if your horizon is an inch away from the top of the frame, and you use base tilt to bring something at the bottom of the frame into focus (lets say a nice flower at 2m away) then the focus shift caused on the horizon line by tilting is negligible and encompassed by depth of field?

Even a 1 or 2 degrees of tilt will move the focus at infinity to a focus at 100m or so - I know this will probably not be noticed much but it must reduce the resolution at infinity significantly for large prints?

Tim

[Heroique]

As you consider which field camera is best for you, keep in mind that you might be able to “give” it several movements you never thought it had:

For example, when I turn my Tachi 4x5 90 degrees (on a sturdy tripod), the camera’s front swing instantly “converts” into front axial tilt. The same position also “converts” the camera’s front rise/fall into front shift. Heck, there’s more: back swing “converts” into back axial tilt!

How’s that for expanding a field camera’s spec sheet! :p

[rdenney]

So if your horizon is an inch away from the top of the frame, and you use base tilt to bring something at the bottom of the frame into focus (lets say a nice flower at 2m away) then the focus shift caused on the horizon line by tilting is negligible and encompassed by depth of field?

If you focused on the horizon, and then tilted the back, you'll now have two points in focus: The top edge of the frame (focused at the distance of the horizon) and the near foreground at the bottom edge of the frame. The depth of field will be a wedge, thin around the close focus point, and thick around the far point.

Depth of field is the same as ever, but it is measured in front of and behind the focus plane. It varies with distance just as when you are not using tilts. According to DOFMaster, with 4x5 film and a 150mm lens, at f/5.6 the hyperfocal distance is 131 feet. That's with a circle of confusion of .1mm. If we adopt the "Zeiss Formula", but make it even tougher, of the height (rather than the diameter) of the frame divided by 1700, then we get a circle of confusion half of that. Even with that stricter standard, the hyperfocal distance is 261 feet. At f/22, which is a more normal aperture for landscapes using a view camera, the hyperfocal distance is 66 feet, again using the stricter standard.

It's unlikely that your horizon near the edge of the frame focused on infinity will fall outside the depth of field.

Remember that the standard we apply to depth of field is less strict than with small format cameras, because we won't enlarge the circles of confusion as much.

Rick "who uses a loupe and not a calculator in the field" Denney

[Emmanuel BIGLER]

Hello all !
There is one subtle technical point, "yaw", not mentioned in this thread, but mostly relevant for traditional studio work.
With a conventional field or view camera with axis tilts only, it is likely that when pointing the camera board or rail downward to the subject from above, you'll get some effects of yaw when combining various horizontal & vertical tilts.
With a base tilt axis located under the vertical tilt axis, you do not get yaw. This was important for studio work in the past in the pre-digital era.
Read more about yaw in the excellent article by Tuan Luong on this web site.
http://www.largeformatphotography.info/yaw.html

For landscape use I do not think that yaw is a real nuisance but this may explain why some view cameras designed with studio work in mind have base tilts instead of axis tilts... or have both kinds so that you can choose axis tilts when yaw cannot interfere in your setting.