difference between rear and front swing?

[danlindberg]

Is there any difference from applying swing to the lens or swing to the DB? Actually, the same question goes for tilt as well....?

The question came up when I realised that the tilt/swing adapter will not fit my Alpa SWA for swing position between the handles. I know ofcourse I can easily put the back in front and adpt+lens on the back and then I get lens-swing, but I thought it would be interesting to know if the result is exactly the same either way

 

[Thierry]

Dear Dan,

There is of course a difference, doing a tilt or a swing either on the lens or then on the image plane, on a perspective level.

By doing the movement (tilt or swing) on the lens plane, one does not modify the perspective.

By doing the movement on the image plane, one does modify the perspective, either the horizontal or the vertical lines, or both, when a combined tilt and swing is setup. In this case, the projection position of the image plane receiving the light (rays) is changed, distorting the image, as if one would take a slide projector and tilting or swinging it when projecting the image on a wall.

The effect of the distortion visible on the image depends on the amount of tilt or swing (the angle), the more one tilts or swings, the more distortion.

Best regards
Thierry

Best regards
Thierry

Is there any difference from applying swing to the lens or swing to the DB? Actually, the same question goes for tilt as well....?

The question came up when I realised that the tilt/swing adapter will not fit my Alpa SWA for swing position between the handles. I know ofcourse I can easily put the back in front and adpt+lens on the back and then I get lens-swing, but I thought it would be interesting to know if the result is exactly the same either way

 

[danlindberg]

Ah, excellent Thierry. Thanks, then I learned something new today

So in my case with a SWA, I simply have to put the lens + swing adapter on the rear and DB on the front for normal lens swing.

 

[wentbackward]

Dan,

If you wish to affect the plane of focus, put it on the front, to affect perspective put it on the rear.

You can mount the back between the handles and the lens + tilt adapter on what would normally be the rear of the body, that should work.

Paul

 

[Jack]

In addition to correcting geometry, tilts on the rear will also affect the PoF! It is why the best technical view cameras had all movements at both ends.

An in-use summary: the whole point of rear tilts and swings is to allow one to get the sensor plane perpendicular to the subject plane(s) so as to keep spatial geometry correct, and at the same time without moving the lens position since moving the lens can alter viewpoint perspective. However, with a rear tilt or swing you have also (indirectly) altered the PoF with those movements, so you would then ideally use front swing and tilt to (directly) correct that PoF back to a more ideal position for the subject. These corrective tilts then maybe changed the composition slightly, so a little touch up with rise/shift was often required. All of these movements were referred to as "direct" movements, since we were making them at the end of the camera that directly affected the change we wanted.

Fortunately, you can usually accomplish the same net result with "indirect" movements: meaning the right combination of camera position, angle to the subject, tilt/swing at only one end, and rise/shift at only one end since they can all get you to the same relative positions between the lens and sensor -- it's just fussier and therefore slower to get it set up. The advantage for cameras that have the more limited movements is they are usually more compact, more portable (often hand-holdable) and often more rigid than cameras with full movements at both ends.

Hope that helps add more "perspective" to the discussion. (Sorry, couldn't resist!)

 

[DDudenbostel]

Keep in mind swings and tilts on the front require more image circle than swings and tilts on the back. This is due to the cone of light forming the image circle is swung or tilted off axis vs working within a fixed image circle on the back. Depending on the degree of swing or tilt the image circle required could be quite large. I use traditional view camera lenses on my Technikardan / digital setup for that reason. I do most of my movements on the front. Shift and rise would be the same whether front or back.

 

[danlindberg]

Thank you very much, this has been an important lesson!

I even thought the opposite concerning image circle since tilt/swing is a movement around the very centre of the lens (and not moving away from the sensor as in shift) I thought that image circle was of less concern...