1. ## Scheimpflug Question

Here is my understanding of the Scheimpflug principle: If the lens plane, film plane and object plane meet at a single point, the object plane will be in sharp focus. Question: If the film and lens planes meet at a single point, are there not an infinite number of object planes that will also intersect with this point and, therefore, be in sharp focus?

TIA

2. ## Scheimpflug Question

You're right there are an infinite number of planes that interest the point were the lens and film plane intersect, but only one of them will contain the point you've focused on, which is were the plane of focus will be be. Hope that helps, and makes a sense enough.

Peter

3. ## Scheimpflug Question

Yes, you are quite right. There is a second constraint that Merklinger calls the hinge line. Some consider his writing and approach somewhat hard to follow or laborious, but many seem to find it helpful. So, you could take a look around http://www.trenholm.org/hmmerk/ for a start. If you decide you ar eone of the former group, take a look at the precis below.

The Scheimpflug principle defines one constraint but as you point out, there are potentially an infinite number of planes that could pass through the scheimpflug line. There is a second constraint that helps to locate the exact one of those planes that is in sharp focus. The hinge line is located as follows. One focal length in front of your lnes' nodal point, draw a plane - let's call this the front focal plane - perpendicular to the lens axis (i.e., parallel to the front standard). Also drop a plane that Merklinger calls the parallel to film lens plane (i.e., a plane passing through the lens' nodal point that is parallel to the film plane). the line where the front focal plane passes through the parallel to film lens plane sets a second constraint. Now you have two lines on the plane in sharp focus and there is only one plane that can pass through both these lines (the object plane in sharp focus).

So, in practical terms, if you are having trouble setting the Scheimpflug relationship, you can try the following. In addition to visualizing the Scheimpflug line (where the lens plane or the plane containing the front lensboard, and the film plane intersect), try also visualzing the hinge line (where a plane passing through the lens nodal point parallel to the film meets a line parallel to the lensboard but one focal length in front of the lens).

Hope this helps. Cheers, DJ

4. ## Scheimpflug Question

I think the sequence is important. First Set the back, usually vertical unless you want to change the perspective. The back swing can be at whatever setting you want for the perspective. Now visualize the plane of focus you want, mentally continuing it until you intersect the plane of the back. Already, you have the intersection point established. All you have to do now is to adjust the front tilt or swing until a mental line from your lens plane goes to the intersection point.

5. ## Scheimpflug Question

As mentioned, there are other constraints in Scheimpflug's math. IMO, all the photographer really needs to understand about Scheimpflug is, which way to tilt the lens or film plane to make the object plane conform to the desired plane of focus. Everything else you need to know is displayed on the groundglass and is available for inspection...

6. ## Scheimpflug Question

Here is my understanding of the Scheimpflug principle: If the lens plane, film plane and object plane meet at a single point, the object plane will be in sharp focus.

Your understanding is very wrong. The correct way of stating the theorem in plain English is: When the lens plane, film plane and a subject plane meet in a single line, all points in that subject plane will be in sharp focus.

When the three planes intersect only in a single point, only that point in the subject will be in focus.

7. ## Scheimpflug Question

Actually, Ellis, my understanding, as far as it went, was fine. A "point" referred to the top-view of the line in the 2 dimensional diagrams common in the view camera texts. Ease off the coffee, dude.

8. ## Scheimpflug Question

John: For the last word on the issue try the link to Merklinger.

http://www.trenholm.org/hmmerk/HMArtls.html

Among his literature on the web, Dr. Merklinger has a simulated video-diagram that helps visualizing better than anything I know the principles involved. His analysis is thorough. I do not know for sure if this link has the video but if you poke at the links you will get to it.

9. ## Scheimpflug Question

John,

Everyone is right on above (especially Ellis, who was only trying to add a little precision to an easily-misunderstood topic. I'm sure his post was only in the spirit of contributing and completely without rancor, so, perhaps we should all "ease off the coffee" a bit??).

Just to give you another perspective (sic): In all those infinite planes which can intersect along with the film and lens planes, there is one, and only one, that any particular focal length lens can focus on. If you had in infinitely-variable focal length lens you could focus on all of them by changing focal length.

If you have the camera perfectly set to focus a non-parallel plane with one lens and you change lenses, there is, somewhere, (unless you exceed infinity focus) a plane that is in focus. Try it: focus on a plane with a longer lens, then, without moving the camera at all or changing focus, put on a shorter lens. Move objects around in front of the camera until you can find the plane of sharp focus. There you have one of those other planes you were postulating about.

Regards, ;^D)

10. ## Scheimpflug Question

John,

Thank you for your suggestion. I'm trying to cut back from 24 cups a day to 19.5 cups per day! My doctor just looked at my bloodwork and said I have type C+ (for caffeine) blood. :-)

Since I didn't know what diagrams you might be referencing It was hard to referto them. I assume other people read these threads so I get a littl pedantic sometimes.

Special bonus slightly OT question 1: Does anyone know who Scheimpflug was and when & why why he needed to solve the problem the theorem solves?

2nd bonus OT question: Does anyone know what Professor Merklinger has his degree in and when he discovered his "hinge" method (basically Scheimpflug with a lot of complicating factors)?

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