ago the so called mirror or catadioptric lenses were a hit. Many lens
manufacturers produced mirror lenses in focal lengths from 250 mm. up
to 2000 mm. and more. All these lenses are based on an old invention.
priest and teacher at the famous Pocquet College in Chartres (France),
Laurent Cassegrain (1629-1693) draw and constructed the first hollow/concave
primary mirror, catching light beams which reflected onto a secondary
mirror. This construction didn't produce nice images but made it possible
to construct a relatively short telescope with a - in those years -
large aperture. Cassegrain's design has become the base for nearly all
telescopes in the world. Even today Cassegrain telescopes are used in
astronomer Bernard Schmidt constructed in 1930 an improved mirror lens
with a positive or converging lens (of light beams) in front of the
primary mirror. This construction makes it possible to build a telescope
with a viewing angle of approx. 15 degrees and almost without spherical
Dmitrievich Maksutov of the St. Petersburg Optical Institute (Russia)
published in the Journal of the Optical Society of America (Vol.
34, No. 5 - May 1944) a design of a Cassegrain telescope improved
by him. He placed in front of the primary mirror a correction lens (meniscus)
neutralizing many aberrations. The Maksutov-Cassegrain-telescope was
A few years
earlier, however, Dr. Albert Bouwers (1883-1972), a Dutch scientist
and general manager (1941 - 1968) of the 'Olddelft - De Oude Delft'
Optical Industry in Delft, Holland, placed in the light beam two kitten
meniscus lenses of different kinds of glass, but with an identical breaking
index to neutralize colour aberrations.
Bouwers' handheld mirror monocular (Courtesy Louwman
He also invented
a lens system for wide angle projection, used in Super Technorama-7
film projection. This wide screen projection was first applied in 1959
for the presentation of the Walt Disney cartoon 'Sleeping Beauty'.
The Nikon mirror lenses are in their construction identical. The cylindrical
lens body has in front a large lens with in its center a small dark
plate. In the back of the lens body one can see the primary mirror.
This mirror catches/collects the light beams and reflects them to the
secondary mirror behind that small plate in front. This secondary mirror
enlarges the image because of its curvature and passes the light beam
through the central opening in the primary mirror via a group of enlarging
lenses to the film plane. These rear lenses are defining the focal length
of the entire mirror lens. This whole construction makes it possible
to produce a relatively short lens with a long focal length. To produce
a fast mirror lens a large front lens and primary mirror is necessary.
That's why the Nikkor 6.3/100 cm. and the Nikkor 11/2000 mm. are huge
lens producers may say that it is an easy handling lens which enables
you to make handheld pictures. Well, forget it!! A mirror lens with
a focal length of 250 mm. might work, but lenses of longer focal lengths
are very difficult to hold.
the small aperture (5 - 11) and heavy weight (up to 10 kilo) a tripod
is indispensable. Than there is the relatively long minimum distance
(up to 30 meter!) and the little depth of field. A nice or disturbing
effect of mirror lenses are the rings in the unsharp parts of the images.
Some mirror lenses also have a so called hot spot in the center of the
image, caused by a small secondary mirror. An advantage of a mirror
lens is the absence of chromatic aberrations. Spherical aberrations
may be eight times less than in a lens construction with an equal aperture
and there is no light absorption. Finally, when using infrared films
focus adjustments are not necessary.
Image made with Reflex-Nikkor 8/500mm. + Nikon D1X at
second hand mirror lens need attention. Inspect all mirrors thoroughly
(no fungus, moisture, etc.) and the front and rear lens. A mirror lens
with a 'squint' is difficult to adjust. Never open a mirror lens as
adjusting a mirror special tools are needed.
Let's have a look at the Nikon mirror lenses. A matrix of all Nikon
mirror lenses can be found here.
mirror lenses, presented below, are based on the Maksutov-Cassegrain
principle. They may be used with Nikon tele-converters (TC-200, TC-201,
TC-14 and TC-14A), but it is advisable not to do it.
Focusing is hardly possible and image quality is bad.
Reflex-Nikkor 5/50 cm.
Presented in August 1961 this lens was rather fast. At the front 122
mm. filters can be used, but at the rear end smaller (thus cheaper)
39 mm. filters can be fitted. It has a scalloped focusing barrel in
between the lens barrel and lens mount. Lens specifications are engraved
in the focusing ring. This black lens, weighting in at 1.7 kilo, has
been produced 9 years with an estimated production of 12,000 lenses.
Optical performance is not bad at all, given its age.
was presented at the 1968 Photokina Camera Fair in Cologne (Germany).
It has no separate focusing ring but the whole barrel should be turned.
At the rear filters (39 mm.) can be fitted. In fact the filter is a
part of the optical system. If a tele-converter is used that filter
should be removed. In 1974 an improved (= better coated) lens was introduced,
bearing the name Reflex-Nikkor-C. Both versions have a minimum focusing
distance of 4 meter and weighting in at about 1 kilo. A redesigned version
of this lens was introduced in 1984. Minimum focusing distance is 1.5
meter and its weight is 840 gram. Important is the much better performance:
no hot spot, very nice equal light distribution and no internal reflection
due to improved coating. Of all versions approx. 60,000 lenses were
Rare 100 cm Reflex-Nikkor with reflex housing for rangefinder
Only a few 100 cm Reflex-Nikkors were available in black
kilo for a lens is quite a load. This heavy barrel was shown to the
press in June 1959. A few months later is was taken into production.
In front a 224mm. (!) filter can be placed; better is to use 52 mm.
filters in the turret near the mount. On top of the barrel are two handles/grips,
at the bottom a massive tripod plate is mounted, enabling to turn the
lens barrel 90 degrees. Focusing, via a bellows (like the Zeiss Mirotar),
runs from infinity to a 'minimum' of 30 meters! This rare lens was available
with a lens mount to fit Nikon rangefinder cameras (S-mount), to fit
the Nikon SLR's (F-mount) and to fit Bronica cameras. Total production
is estimated at a mere 100 lenses.
A prototype of this lens was presented in October 1965. The front lens
has a filter thread of 108 mm., but at the back 4 filters (L39, Y48,
O56, R60) are built-in (like a revolver magazine). This lens weights
in at 2 kilo. In 1974 a second version, without a filter revolver, was
introduced, followed by a redesigned version two years later. The barrel
now has a tripod ring and a stylus/pin can be fitted in the barrel making
focusing a bit easier. Total production less than 35,000 lenses.
Reflex-Nikkor 8/500mm. - 11/1000mm. - 11/2000mm.
fast but huge 'beer barrel' of 17.5 kilo was shown at the 1970 Photokina
Camera Fair in Germany. The minimum focusing distance is 20 meters and
at the back 62 mm. filters can be fitted. In 1975 an improved version
was introduced. It has a better coating and the hot spot disappeared.
This colossus has to be mounted on a U-shaped tripod holder, which weights
in at 7.5 kilo, bringing the total weight at a heavy 25 kilo!
that handheld photography is possible with a mirror lens?!