how to use asymmetric movements

[Joseph Sacamano]

I have read postings describing the benefits of asymmetric rear standard movements, and seen the ground glass of an Ebony 45U, but would be grateful to know the step-by-step methods others use in focusing camers so equiped. How does this method differ from traditional large format technique?
Thanks

[Scott Soper]

Joseph,

Have you seen this article by Richard Sexton on the Ebony website?


http://www.ebonycamera.com/cam/assym.exp.html (http://www.ebonycamera.com/cam/assym.exp.html)

[paul owen]

Joseph, using the assymetric tilts is a breeze!! Compose the image on the screen and then to employ swing you simply focus the image on the left hand dotted line (on screen) and swing the back until the image on the right hand dotted line is sharply focussed. With tilt you simply focus on the bottom dotted line and tilt the back until the image is sharp on the top dotted line - that's it!!!!!!! Takes a few seconds!!!

[Bob Salomon]

"With tilt you simply focus on the bottom dotted line and tilt the back until the image is sharp on the top dotted line - that's it!!!!!!! Takes a few seconds!!!"

That's it providing the near and far points lie on the lines. But when they don't?

[paul owen]

Hi Bob, good point! However, I have found that I have yet to come across a situation where this has happened - the assymetric tilts are useful when the subject has a foreground/background sharpness requirement - ie general landscape shots (which is what I shoot). However, the camera can be utilised and provides centre tilts for other near/far relationships. Although I had to think long and hard to justify spending so much money on a camera, I am glad that I did - I, personally find the assymetric tilts invaluable when the light is fading fast, this feature combined with the non-folding design of the SU makes it a VERY user-friendly camera.

[Bob Salomon]

Paul,

There are more then one type of assymetric back set ups.

On a Sinar there is a line scibed top, bottom and sides on which the near far/left right objects lie. That is a fixed assymetric back in that those lines are fixed in place.
On the Linhof the gg is millimeter ruled and the assymetric points can be adjusted as there is an extra rise/fall mechanism on the back. These are variable assymetric axis movemet backs. And, yes, one of the points Linhof uses are the same as the ones on the Sinar.

[Joseph Sacamano]

Thanks folks,

I guess my problem with this concept is the point that Bob brings up about not having the intended focus points fall on the required dotted line. Paul re-assures that this isn't a problem in actual practice and Richard Sexton doesn't even mention this in his comments written for Ebony ( I wish that he had included a few more exmples to more fully walk one through the process). So maybe I'm anticipating exceptions when they don't exist. Any other thoughts?

Joseph

[paul owen]

Joseph, Bob is absolutely right when he describes how the assymetric movements differ in both cases! After all he has a great deal of knowledge!! I have always thought (rightly/wrongly) that the Sinar ? Linhof system is ideal for studio based shots - where near/far points are likely to be closer together eg in product/food shots etc. Bob will know more on this! The mechanism that is employed on the Ebony cameras appears to be a much "simpler" affair! It simply allows you to establish the plane of focus quickly under "typical outdoor/landscape situations". It sounds as if the Linhof system is much more complex! In my opinion I prefer the assymetric movements on the SU to "regular" field cameras with axis/base tilts as it allows me to pay more attention to the image than to applying the correct amount of movement! Having said that there are still occasions when I naturally reach for the tilt on the front standard! And end up using front tilt becuse my hand is already there! Elaborating on what Bob has said - there are other VERY sophisticated assymetric mechanisms, but as far as I know, to find this feature on a wooden field camera is somewhat unusual and more importantly, useful! Hope this has helped!!

[Richard Sexton]

Asymmetrical movement is based on a simple concept: The pivot point for the movement should logically fall within the foreground or background area of a photographic composition. Because the point of a swing (vertical composition) or tilt (horizontal composition) is to extend the plane of sharp focus beyond what can ordinarily be obtained by merely stopping down to a smaller aperture. The movement will work only in those instances where the primary subject plane is essentially two dimensional: a table top, the facade of a building, etc., which is being photographed from an oblique angle. If you are parallel to the primary subject plane, none of this is applicable. (This is all basic scheimpflug rule stuff, so to the extent that this explanation is somewhat mysterious sounding, review scheimpflug. A complete understanding of the scheimpflug rule is essential.)

The bold lines on an Ebony "U" focusing screen that form a squarish shape around the center of the frame show the pivot and refocus points for using the asymmetrical movement. The vertical lines are used for vertical compositions and the horizontal lines are used for horizontal compositions. A rear shift employed prior to an asymmetrical movement will render the vertical pivot point line inaccurate. The solution is to employ this movement (if needed) after the asymmetrical movement is set or employ the inverse shift movement on the front standard, which will achieve the same compositional effect. (Bear in mind that this particular issue only effects vertical compositions.)

With an Ebony U camera model, the technique for utilizing the asymmetrical movement is this: Use the appropriate horizontal or vertical line as a point of initial focus. (If you don't know which line is appropriate, review scheimpflug.) The subject detail that falls along the line should be in the same plane. If this is not the case, then the movement won't achieve the desired effect. Then employ the movement (don't refocus using the focusing rail) to bring the subject detail on the opposing parallel line into focus. As the subject comes into focus along the second line, the detail on the opposing line stays in focus. It doesn't matter whether you focus on the background or foreground first. The focusing sequence will merely effect the direction of the subsequent movement of the asymmetrical swing or tilt. If the movement is properly employed, critical subject detail close to the line, but not directly on the line, will fall into focus accordingly. In other words, the particular subject detail that falls on your initial focus line is arbitrary.

Perhaps this is an analogy that will be meaningful enough to press the "a-ha" button: Think of how a compass works. It points only to true north and it graphically displays the other points of the quadrant. It doesn't matter that the compass only knows where north is. The knowledgable user can readily figure out how to get where they want to go, once a single point has been established absolutely.

I hope this has helped clarify asymmetrical movements as they apply to Ebony cameras. I know that it can be difficult to grasp without visual aids or hands-on demonstrations. I don't routinely monitor this list, so if any posters have further questions, please feel free to e-mail me off list. Thanks.

Richard Sexton

[Richard Sexton]

Correction:

I realized as soon as I posted my message above that my choice of words was poor and bound to be confusing. When I referred to vertical and horizontal compositions, I didn't intend to refer to photographic compositions. I was referring to the arrangement or layout of the subject(s) relative to the camera position. Vertical composition is intended to refer to an arrangement or composition of subject matter along a vertical axis. Horizontal composition is intended to refer to an arrangement of subject matter along a horizontal axis. If the subject matter being photographed is on a vertical axis (a wall, for instance) then you would use the vertical lines on the ground glass for focusing. If the subject matter being photographed falls along a horizontal axis (a table top or landscape), then you use the horizontal lines for focusing. This applies regardless of whether your photographic composition will be vertical or horizontal. Use the vertical lines for vertical subject planes. Use the horizontal lines for horizontal subject planes.

My apologies for the ambiguous terminology.

Richard Sexton

[Michael Chmilar]

The assymetric movements are not revolutionary. All it really means is that, for many landscape photography situations, the axis of the tilt or swing is more conveniently placed than a "center" tilt or swing.



On the Ebony "U" cameras, the tilt and swing axes are in a fixed location. The location of the axes is clearly marked on the focussing screen.



(From what Bob Salomon describes, Linhofs allow you to change the location of the axes, which is a more complex approach.)



An example of using the Ebony assymetric tilt:




You are photographing dry lakebed, which is a large flat plane. You compose your shot. Now, it is time to focus.



The axis line on the ground glass is just below the horizon. Looking through your loupe, you rack the focus until the scene along the axis line is in focus. Lock down the rack focus.



Unlock the assymetric tilt on the rear standard. (Until now, it is in the "zero" position.) Look through your loupe at the foreground of the image (ie. the upper area of the ground glass). Tilt the camera back towards you, until the foreground is in focus. While you are doing this, the original focus point remains in focus. Lock down the tilt.



Now, if you check the focus, the entire lakebed should be in focus.




This is the simplest example, but it shows you the workflow.



As with all movements, the assymetric tilt or swing are not useful in all situations. Also, if you have a scene where it would be more convenient to use a center axis tilt or swing, the Ebony front standard has center axis tilt and swing.

[Carl Mathisen]

This all makes sense to me except for one thing. The horizontal asymetric tilt axis is located near the bottom of the ground glass. When shooting landscapes, this axis more often than not coincides with the portion of the image containing sky, since the image is upside down. Generally (again, for landscape photography) the desired horizontal plane of focus passes through foreground and background elements below the horizon. On the upside down image , both of these elements appear above the horizontal asymetric tilt axis on the ground glass. In this case, can the horizontal asymetric tilt be used to implement a non-iterative focus solution? I supose you could tilt the entire cameara towards the ground to foucs, and then recompose. How do the acutal users of cameras with this feature manage in this situation? Sorry if I've missed the obvious; large format is relatively new to me. Cheers!