Lens nodal point for panoramas with Sinar F ?

[BABartrug]

Is there anyone who has shot panoramas with a Sinar F? I would prefer to use 6x9 in the vertical position, and rotate the camera horizontally. I would use a 90 or 65 mm lens. Has anyone that has every tried this type of panorama managed an easy way to get the lens nodal point at the center of rotation?

I use the Sinar on a Vanguard ballhead which does allow a couple inches of movement when using their quick release plate.

Thanks,
BAB

[Struan Gray]

The easy way is to use a lens with 4x5 (or 5x7) coverage and shift the rear standard.

Otherwise, you can move the rail clamp close to the front standard (in front, if necessary) and use the focussing mechanism to get the entrance pupil over the rotation point. This works on my Norma, but I don't know if the F has enough movement.

If that fails, you can get a cone or recessed lensboard to move the lens further from the standard axis so that there is room for the rail clamp underneath.


NB: for stitched panoramas you want to rotate about the entrance pupil, not one of the nodal points. The method given in countless online forums for finding the 'nodal point' (rotate camera and eliminate parallax on the ground glass) actually finds the entrance pupil, so in practice it's hard to go wrong. Most LF lenses are symmetrical enough that if you're not doing closeups you can assume the pupil is at the lensboard - especially wide angles like 90s and 65s.

[BABartrug]

Thanks much. Especially for the information concerning the entrance pupil for wide-angle lenses, which simplifies locating the rotational point for the camera if and when needed. Rear shift is definitely more convenient, and should handle most situations.

Thanks again,
BAB


The easy way is to use a lens with 4x5 (or 5x7) coverage and shift the rear standard.

Otherwise, you can move the rail clamp close to the front standard (in front, if necessary) and use the focussing mechanism to get the entrance pupil over the rotation point. This works on my Norma, but I don't know if the F has enough movement.

If that fails, you can get a cone or recessed lensboard to move the lens further from the standard axis so that there is room for the rail clamp underneath.


NB: for stitched panoramas you want to rotate about the entrance pupil, not one of the nodal points. The method given in countless online forums for finding the 'nodal point' (rotate camera and eliminate parallax on the ground glass) actually finds the entrance pupil, so in practice it's hard to go wrong. Most LF lenses are symmetrical enough that if you're not doing closeups you can assume the pupil is at the lensboard - especially wide angles like 90s and 65s.

[el french]

One of the lesser known methods for finding the entrance pupil is to use the apparent position of the iris when viewed from the front of the lens. If your subject is fairly far away ( > 20 feet) then an approximate position will work fine. If you want closer objects in focus, then you can use a dslr with macro lens to measure the position of the iris. Just focus on the iris, replace the lens with a flat object, move the object until it is in focus. Transfer that measurement back to the lens and you have the location of the entrance pupil. It's probably easier to do this with the lens resting on a table instead of on the camera.

The entrance pupil on one of my dslr zoom lens changes from an inch or so from the front of the lens to >18 inches behind the lens when zooming. Needless to say it doesn't work well on a panohead, but handheld works fairly well as I can just look in the front of the lens to see where to rotate.

[BABartrug]

Interesting. That's one reason I prefer to use a 15mm prime when doing wide panos on a DSLR. Much simpler, and the lens is easier to position over the center of rotation.

Thanks,
BAB


One of the lesser known methods for finding the entrance pupil is to use the apparent position of the iris when viewed from the front of the lens. If your subject is fairly far away ( > 20 feet) then an approximate position will work fine. If you want closer objects in focus, then you can use a dslr with macro lens to measure the position of the iris. Just focus on the iris, replace the lens with a flat object, move the object until it is in focus. Transfer that measurement back to the lens and you have the location of the entrance pupil. It's probably easier to do this with the lens resting on a table instead of on the camera.

The entrance pupil on one of my dslr zoom lens changes from an inch or so from the front of the lens to >18 inches behind the lens when zooming. Needless to say it doesn't work well on a panohead, but handheld works fairly well as I can just look in the front of the lens to see where to rotate.