UW Rokkor-PG 1:9.5 f=18mm


The 18 mm 9.5 fisheye is known in two versions yet.

The first version features 1:16 as smallest aperture and the second version stops down to 1:22. It is the first fisheye lens Minolta has produced and as a fix focus design, it lacks of a focus mechanism. Th short focal length combined with the low maximum aperture provide enough depth of field to practical flexibility.

Due to the huge angle of view, a front filter could not be implemented. The lens has a srew-in filter mount in the rear bayonet side. To keep optical performance, a filter must be used everytime. The standard filter is a UV-0, another remarkable aspect. Most other lenses with built-in filters use Skylight L1A as standard filter.

The lens cap and the shade are fitted by a mount and very important to protect the front lens surface, when used.

Be careful with dust, scratches or any destruction of the glass' surface. The combination of very short focal length and low aperture uses very sharp beampencils of lightrays in its optical projection. Scratches may cause very discrete images, dust causes shining spots under bright light and fingerprints will cause strong local loss of contrast. Please read our background article wide angle and dust.

These two lenses aren't easy to find especially with the full set of cap, filter and shade.

UW Rokkor-PG 1:9.5 f=18mm Version 1, still seeking for
Focal length: 18mm Focal length
Aperture range: 1 : 9.5 - 16
UW Rokkor-PG 1:9.5 f=18mm Version 2
Focal length: 18mm fixed
Aperture range: 1 : 9.5 - 22
Aperture type: One ring, 5 blades,
glossy electro-oxidised
Optical design: 7 elements / 5 groups
Detailed optical design, front to mount: 3 elements / 2 groups
- aperture -
3 elements / 2 groups
rear filter
Close-up distance: Fix focus at aperture 1:9.5
Filter size / -mount type: Special screw-in filter 37.5mm fixed
Shade type: Bayonet
Length from mount plane, focus at infinity / close-up: 42mm / 42mm
Diameter: 59mm
Weight: 229g
Lens coating: Simple, orange, rear filter blueish.
DOF type: one ring aperture, permanent DOF preview necessary
Supported aperture functions: Stopdown metering: Yes
Automatic diaphragm: No
Meter-coupled TTL: No
Aperture read-in: No
Supported camera modes: M, manual: Yes, stop-down mode.
A mode: Yes, stop-down mode.
S mode: No.
Program mode: No.
Front view:

Front without filter mount, but with bayonet shade mount.
Overview:

The lens doesn't feature a focus mechanism. Low maximum aperture and short focal lenght provide sufficient depth of field for fixed focus handling.
Rear view:

Black mount without aperture lever. Screw-in mount for rear filter.
Detail 1:

The huge angle of view requires a special bayonet lens shade and a special front cap.