This lens does hardly cover full format, it was built for 24x24mm
square format.
Focal length: 30mm
Mount: Robot M26
Aperture: F 4 fixed Fixed focus, min focus distance: ~2m in reversed mount focus ~0,70m to ~3m
Length (from flange): 8mm
Diameter: 31mm
Weight: 41gr
Some pictures:
A7 and the lens.
A7 and the lens in reversed position.
Sample pictures: You may click
on the sample image (except closest focus) for full resolution. The
full resolution image opens in a new window, so you can keep it open
for comparison. Focus is on infinity (except
closest focus). These pictures are hand-held, the first out of the window of my
holiday home. So there might be a little bit of blur from the absebce of a tripod.
F 4. Not the sharpness of the regular 30mm Xenon focussed, but a focus free lens is more difficult to build, it's a compromise.
The lens at about 3.5m. Quite o.k.
The lens at 3.5m in reversed position. A bit too far, the limit seems to be around 3m.
Closest focus in reversed position is about 70cm from
outermost
edge of the lens. The program wheel of the camera is at 60cm, the cap near the old Zeiss lenses is at 70cm.
Closest focus in normal position is around 2m from
outermost
edge of the lens. Focus on
the program wheel of the camera. This is a crop from a larger image.
The lens flares a lot if there is sidelight. Just to show the effect, no full resolution image.
This
lens hardly covers full format, it was built for the 24x24mm square
format of the Robot cameras. The adaption to the A7 is easy, the focal
flange distance of the Robots is 31mm. That's not far from the M39 which
is 28.8mm. So you add a 2.2mm adapter to a M39 one and you are there.
M26 to M39 adapters a readily available on the web and they can be
cheap. The Robot lenses are relatively small and they are fine for
APS-C.
This
is an interesting lens. It's a 30mm F4 fixed aperture and
focus free Xenagon lens. It's a "spy" lens, they called it
"Beamten-Objektiv" (civil servant lens). It focusses from about 2m to
infinity. The edges are soft. As it has a 26mm thread on both sides,
the lens can be reversed. In reverse mount it focusses from about 70cm
to 3m. With this lens, a 50 exposure wind camera and a cable release
the
camera could easily be hidden for spying purposes. These lenses have no
markings, no manufacturer sign and no serial numbers. They are
extremely small and light.
As
you can see on the sample pictures, there is a bit vignetting in full
format, not visible on the 24x24mm Robot
cameras. Even the very soft edges would disappear. For a focus free lens with F 4 aperture it's fine.
