W.Rokkor-QH 1:4 f=21mm

The 21 4 is known in one version yet:

The first version is a very classic ultra wide angle construction of the pre-retrofocal era. The rear lens is placed very close to the film plane, using an optical tunnel construction. Therefore the lens can be used only with cameras, that provide a mirror-up option. The interesting lear lens part requires a proprietary rear cap.

In mirror-up mode, the camera's viewfinder does not work anymore and the image field can only be seen by an additional viewfinder. It is absolutely necessary to use the lens with its proprietary external viewfinder. Without the camera's finder, any stop-down or depth-of-field control doesn't make sense anymore. Therefore the lens doesn't need any DOF-lever or pre-set aperture ring. It has one aperture ring only.

Any internal camera light meter lost relevance too. The finest use is to combine the lens with any mirror-up featured SR type plus the addon external light meter, for example SR-2. BTW: to use a SR suits this amazing lens better as any more modern body like a SRT.

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.

This lens is hard to find. Take care to get the rear cap and the external viewfinder too!

W.Rokkor-QH 1:4 f=21mm Version 1
Focal length: 21mm fixed
Aperture range: 1 : 4 - 16
Aperture type: One ring, 6 blades,
glossy electro-oxidised
Optical design: 8 elements / 4 groups
Detailed optical design, front to mount: 4 elements / 2 groups
- aperture -
4 elements / 2 groups
Close-up distance: 0.9m
Filter size / -mount type: 55mm screw-in, fixed
Shade type: Unknown
Length from mount plane, focus at infinity / close-up: 19.5mm / 20mm
Diameter: 65mm
Weight: 157g
Lens coating: Simple, orange-magenta.
DOF type: Not applicable
Supported aperture functions: Stopdown metering: No
Automatic diaphragm: No
Meter-coupled TTL: No
Aperture read-in: No
Supported camera modes: M, manual: No.
A mode: No.
S mode: No.
Program mode: No.
Front view:

Silver polished front.

Very short design, the rear lens group goes deep into the camera. Typical tunnel design of pre-retrofocal era.
Rear view:

Black mount without aperture lever.
Detail 1:

Very small focus ring with special lever.
Detail 2:

The tunnel design requires a proprietary rear cap.
Detail 3:

The rear lens is very close to the shutter and film plane and requires to lock the mirror in upper position.
Accessory 1:

The external viewfinder covers the wide angle of view and fits to cameras with circular ocular.
Accessory 2:

This is the larger 21mm viewfinder version, slightly suited even for use with glasses. The silver frame is the border of field of view.