View Full Version : Scheimpflug auxillary lens

Maris Rusis
10-Jul-2006, 17:00
I have just catalogued my lens hoard and find that I have several front-of-lens auxillary optics to give wide-angle, telephoto, and fixed or variable close-up effects. There is even a series of negative dioptre lenses to extend the effective focal lengths of any view camera lens they are set in front of.

What I REALLY want is a Scheimpflug auxiliary that will permit a tilted plane of focus with any lens it is attached to? Is it practically or theoretically possible? Has anyone actually produced one? What would be involved in calculating the optical formula?

Emmanuel BIGLER
11-Jul-2006, 04:41
If you keep the optical axis of the main lens perpendicular to the film plane, the only object plane yielding a sharp image is parallel to the film plane and perpendicular to the optical axis.
Now you want to attach something in front of the main lens without tilting the back, that would allow to get an equivalent scheimpflug effect.
If you add any lens element in front you will not be able to tilt the object plane even if you tilt the additional lens. By tilting the auxiliary lens you'll get some ugly aberrations and nothing valuable.

So we are left with adding something that bends rays evenly across the field like mirrors or prisms. Prisms suffer from severe chromatic aberrasions since they bend rays at different angles for different colors. Prisms were used in the Rolleiflex TLR close-up lens on the viewing lens but the bending effect was very small, used only to correct for the proper framing (parallax correction).

So we are left with mirrors, their effect for an attachment in front of the camera, would be equivalent to tilt the whole camera (plus the photographer) as seen from the object side. This would not be exactly a scheimpflug effect but yes, the proper object plane would be titled with respect to the film plane. The actual part of the plane that could be seen is quite difficult to imagine, it would depend on the combination of mirrors, theri size and how far they would be placed from the camera.
We could also add inside the camera something that bends rays, this would be equivalent to a back tilt, but more costly, "eating" available space inside the bellows ( a plague for wide-angle shots) and extremely cumbersome to operate.

So these are my 0,02 euro to the discussion, but I hope that this is far from extensive.
Any other ideas ?

Paul Fitzgerald
11-Jul-2006, 07:20
"Any other ideas ?"

While we're at it, I could REALLY use:

'phone-pole' filter
'con-trail' filter
'self-leveling' filter

the 'auto-exposure' filter would be a luxury, but nice to have.
the 'beer-goggles' filter would be real damn handy too.
the 'remember the rose and forget the thorns' filter is actually an antique portrait lens I already own.

More help needed!