How to Focus a View Camera Part II

[tgtaylor]

According to Euclidean Geometry two unique points determine a line and three a unique plane in space. Suppose you have a high-end view camera such as the Toyo Robos, GX, or Sinar P, PII that provide for both base and/or axial tilts and wanted to set-up a unique plane of focus in space. How would you proceed? Would you determine the line of focus using base tilt, axial tilt, a combination thereof, or something else? What about those points falling in the foreground or background of the plane that you also want to be in focus?

Thomas

[Bob Salomon]

Assymetrical axis cameras like the Linhof Master GTL, Sinar P & P2 and the Toyo Robos all have 2 tilt points and one swing point on each standard. These cameras are yaw free as one of the tilt points on each standard is below the swing point.

A camera like the Linhof Kardan Bi has both a single tilt point and a single swing point on each standard. It is not yaw free.

Unless you rotate the camera body 45° around the monorail. When you do this the swing point becomes the tilt point and the tilt point now becomes the swing point. As the tilt point is now below the swing point the camera becomes yaw free.

The Sinar system had a single line on the gg that the subject was placed on. If the subject didn’t lie on that plane a front shift, or rear shift, was required to place the subject on that plane.

The Linhof system had a continuously variable that the subject would lie on thus setting up frequently in 1 or more fewer steps then a Sinar.

[Mark Sawyer]

According to Euclidean Geometry two unique points determine a line and three a unique plane in space. Suppose you have a high-end view camera such as the Toyo Robos, GX, or Sinar P, PII that provide for both base and/or axial tilts and wanted to set-up a unique plane of focus in space. How would you proceed?

You'd need to get into Cartesian Geometry.

[tgtaylor]

Mark - I'm afraid that your knowledge of analytic geometry is far less than your knowledge of photography which appears to be on par with the typical high school photography novice. At one time - maybe 10 years back - there were people on the internet that could answer that type of question, but not any longer!

Thomas

[Mark Sawyer]

Mark - I'm afraid that your knowledge of analytic geometry is far less than your knowledge of photography which appears to be on par with the typical high school photography novice...

I think quite a few typical high school photography novices are feeling quite offended...

[Graham Patterson]

[...] What about those points falling in the foreground or background of the plane that you also want to be in focus?

Thomas

Stop down as needed. A Plane is a Plane - stopping down is the only way to get a third dimension.

Since I don't have the luxury of axial controls on most of my cameras, it has to be iterative - initial focus, movements for primary adjustment, focus review, movements for secondary adjustment, focus review and depth of field calculation.

Then pack up, because the light has gone 8-(

[Jim Noel]

Mark - I'm afraid that your knowledge of analytic geometry is far less than your knowledge of photography which appears to be on par with the typical high school photography novice. At one time - maybe 10 years back - there were people on the internet that could answer that type of question, but not any longer!

Thomas

There are still some of us around who can answer the question, but most, like me prefer to not spend the time doing so. There are several treatises on the web dealing with the subject fully. look for Merklinger on Focusing the View camera.

[tgtaylor]

Nope - I read thru the various posts on the subject and everyone seems to be fuzzy about it. I'm probably the only person alive that can give a crystal clear answer to it but I'll keep it to myself.

Thomas

[Jerry Bodine]

Nope - I read thru the various posts on the subject and everyone seems to be fuzzy about it. I'm probably the only person alive that can give a crystal clear answer to it but I'll keep it to myself.

If that's true, then why did you start this thread, sir?

[Doremus Scudder]

Three points do indeed define a plane. When using swings and tilts together to bring an oblique plane into sharp focus, it is helpful to choose three key points to focus on and use the movements to bring all three into simultaneous sharp focus. Visualizing where the PoSF should lie and choosing your focus points is critical here.

Keep in mind that the plane of sharp focus is where the camera is in focus and that objects on either side of the plane can be brought into acceptably sharp focus with adequate depth of field. The distance on either side of the PoSF that is rendered acceptably sharp varies not only with the aperture size (smaller = more DoF) but also the distance from the camera (nearer = less DoF).

How much you need to stop down for a given subject to render it acceptably sharp in a final print depends on the focus spread between near and far in the scene (i.e., how deep the scene is), the degree of enlargement, and your own personal standards of sharpness. Diffraction at very small apertures limits sharpness for subjects with extreme focus spread/degree of enlargement. Finding the optimum compromise here is what "focusing a view camera" is all about for me.

In truth, however, we're talking about several different things: Focusing on a chosen point or points by racking the bellows in and out and using whatever magnifying device you like (inaccuracies are easy here...) Placing the PoSF using movements, which is more or less complicated depending on the subject being photographed and, finally, choosing an optimum aperture to render the desired amount of sharpness (or out-of-focus) in the scene. It seems this latter provokes most of the discussion. I like the near-far split method described in the article about choosing the optimum aperture on the LF home page.

I don't really think we need a lot of higher geometry to do the focusing job adequately...

Best,

Doremus

[Daniel Casper Lohenstein]

According to Euclidean Geometry two unique points determine a line and three a unique plane in space. Suppose you have a high-end view camera such as the Toyo Robos, GX, or Sinar P, PII that provide for both base and/or axial tilts and wanted to set-up a unique plane of focus in space. How would you proceed? Would you determine the line of focus using base tilt, axial tilt, a combination thereof, or something else? What about those points falling in the foreground or background of the plane that you also want to be in focus?

Thomas

Mr. Merklinger writes in "Focusing the view camera", S. 6, about Scheimpflug rules:

Given J as "the height of the lens above the [intended] plane of sharp focus" and f as the focal length of the lens, then the inclination angle α of the lens is "α = arcsin (f/J)".

With a clinometer (e.g. a compass like the Recta DS 50G, Suunto PM 5 or a smartphone app) held on the front of the lensboard you can tilt to achieve the desired angle.

Then you increase DOF by changing the aperture diaphragm.

Merklingers figures show an axial tilt, eg. figure 5 and figure 23.

I think it could be difficult to mesure the height of the lens above the intended plane of sharp focus. Of course, you can make a drawing. Then you will have to mesure every distance. This is really a lot to do.

As a standard situation to avoid too much measuring you can make a proposition that this height J should be the height of the lens above the bottom on which your tripod stands.

This means that your plane of sharp focus begins right under your lens.

But this also means that you will have to tilt perhaps more than you initially intended. This means that perhaps you will lose far away details out of sight, excluding them from the picture.

It depends on the height of your tripod, too.

Another problem is the image circle. I think you will have to lower the front standard. Perhaps a base tilt could help.

But: you would be able to indicate the presumed "ideal" angle of front standard inclination on the lensboard then ...

Regards

[tgtaylor]

Merklinger didn't use a high end view camera that had both axial and base tilts so he wouldn't know.

Thomas

[Daniel Casper Lohenstein]

Merklinger didn't use a high end view camera that had both axial and base tilts so he wouldn't know.

Thomas

Gertrude Stein : "A tilt is a tilt is a tilt is a ..."?

[ic-racer]

With front base tilt or axial tilt (my camera has both) the focal point, in my experience, usually shifts as the movement is made. So I would have one hand on the focus and another doing the tilt. A little practice and the appropriate focal plane can be produced. Since any movement of the lens, moves the camera position in space, some re-composing might be in order.

[Willie]

I look at the ground glass and try to get it right as I finalize the composition. Use of a loupe helps at times. All the math, geometry and whatnot may help some but gives me a headache. When it looks right I put the film holder in and trip the shutter.

If you check the front page of this website you will find some articles on focusing the View Camera.

[Doremus Scudder]

When applying tilts and swings to change the position of the plane of sharp focus in the scene, the only thing that matters to the film (and the final image) is the relative positions of the camera back (read the film itself) and the front standard (lens position and orientation).

How you arrive at that depends on the adjustments available to you on the camera you have and your competency and familiarity using them. Period.

Asymmetrical swings might be nice, but you don't really need them. Same with axis, base and asymmetrical tilts. You can easily accomplish the same thing with any of them if you know what you are doing. Yes, some of the advanced features make life easier when you have to apply movements a lot, especially for table-top or close-up work, but that's largely just a savings of time.

I'm not really sure what the OP is after here... If he just wants to know what approach others use and how, then we're not answering the question.

I can't either, if that's the case, since I don't use "high-end" cameras; they're to heavy for my applications. I've mastered base tilts and axis swings, that's enough for me. Heck, the only thing I'd really like to add to my lightweight wooden folders is geared rise/fall... It's always a royal pain getting the lens position exactly right with "manual" rise.

Best,

Doremus

[Daniel Casper Lohenstein]

Merklinger didn't use a high end view camera that had both axial and base tilts so he wouldn't know.

Thomas

Hello,

today I tried a Mamiya Press 23 G - the one with the Graflok back and the possibility to tilt and swing the back. I thought: Ok, I don't have a Sinar, but this Mamiya 23 G has a base tilt on the front, the ballhead axis, and an axis tilt on the extendable rear standard.

I was in our local botanical garden and photographed plants, as usual.

In the long run, in the end, I presetted the focus on the lens to have some tolerance to focus a little bit. Somewhere in the middle, 2m.

Then I extended the back by pulling every corner of the groundglass separately until this part of the picture was sharp or unsharp, as I wanted it to be.

I didn't focus with the lens (front) - I pulled the parts of the picture into focus like smoothing a tablecloth or stretching a canvas.

Perhaps the conventional concept of focusing with the lens is too predominant (because most cameras are constructed in this way).

Perhaps the Sinar Norma with its base tilt on the front and his axis tilt on the back already showed the solution. With the later Sinars one can also use base tilt on the front and axis tilt on the rear standard.

It is very intuitive. there is no science at all. You set the picture, then you organize the focus in every corner, thats it. No Scheimpflug angles or planes etc.

This is also very instructive: pulling away the darkcloth an seeing the final movements you organized intuitively to get your intentions (un)sharp ...

Until now, I didn't realize this possibility to act like that, because normally I use cameras like the Wista 45N without such movements of the back.

So, your question how to focus a view camera gets another answer.

Regard