Whatever its commercial builder, this cylindrical device can reach 55-65mm (up to 2.5 inches) of Diameter.
It is otherwise close enough to the lens so that a large chunk of the nadir of the panorama is eaten out by this unwanted obstructive circular object as seen from its top.
I have designed and handbuild what I think is the slimmest rotator. I intend to use it with the Sigma 8mm fisheye when shooting four photos around the 360° on a tripod.
Click on the pictures to enlarge
The pictogram above shows dimensions
of the bracket that is mounted on top of the rotator (click for full scale)
Its diameter is reduced to the minimum that can replace the central tube of my Manfrotto tripod : exactly 24mm (a little bit less than one inch).
A 22mm Diameter tube (B) was inserted into the main central tube (C) and locked tight by two elastic 4mm Dia.spring pins mecanindus(®).
A four part helicoid ramp was made at the bottom of another sleeve (A) that shall cover (B).
While it is free to turn, (A) is however stopped to go further down by a produding pin at the lower part of (B) that slides on the helicoid ramps profile.
The camera shall be oriented by this means to take four shots at 90° angular distance one from the other. The rotation is constrained to be easier done when clockwise oriented, but it is possible to forceturn in the opposite direction if it would be absolutely necessary to do so.
The weight of the camera could be very off-centered (this is fortunately not the case here with the EOS 20D + Sigma 8mm combo). The small Diameter increases considerably the pulling force that would act on the central 3/8" screw in such a case compared to the larger (but bothersome for an unobstructed Nadir shot) larger interface circle that is usually provided . The arm of lever being about two to three times shorter, the force is increased by the same factor...
That is the reason why I have secured the design with multiple pins (only some of them can be seen on the photos) to increase the strength of the assemblies.
If the external sleeve (A) is removed, I can still put a panoarama head bracket on top the internal central fixed shaft (B): I have also fitted it with a 3/8" screw even if it is not necessary for the "rotator" function.
All the basic parts where bought at a local hardware store. Fortunately the metric dimensions of the standard tubes in Europa fits well with the Manfrotto's original (24mm external Dia).
These two Nadirs were extracted with PTEditor from panoramas done with PTools.
Click on pict to enlarge
The highest possible is about five meter when the pole is fully extended as well as the tripod itself.
On this image the camera stands at about 4.2 meters high:
(Click to enlage the image)
Enlarged view of the base of this Slimest Rotator:
(Click to enlage the image)