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Specification

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Manufacturer description #1

From the Lentar 500mm F/8 instructions:

Compared with refractive lens system, the unique design of the MIRROR LENS gives superior optical performance. It is a compound catadioptric lens system which encompasses a 500mm focal length optical path into a barrel only 7 1/4" long. This perfect optical arrangement eliminates chromatic aberration and gives a well-corrected, sharp image over the entire negative or slide.

The MIRROR LENS is ideal for the sports and nature photography, especially when hand-held shooting is required. Distance settings range from 10 feet to infinity.

"T" system camera adapters are available for using the MIRROR LENS with most popular 35mm single lens reflex cameras. Tripod mount allows lens to be held by camera. Use of "T" Adapters does not alter focal distance of lens.

LENS SPEED AND DIAPHRAGM

The MIRROR LENS has a fixed aperture of f/8 as this particular lens system does not require a variable diaphragm. Exposure is determined by the proper combination of shutter speed and built-in filters. Aperture with no filter is f/8. An effective aperture of f/11 is obtained by use of a 2X neutral density filter. An effective aperture of f/16 is obtained by the use of a 4X filter. Remember that aperture with no neutral density filter is f/8.

HOW TO OBTAIN PROPER F STOP

A rotating diaphragm having 2X and 4X neutral density filters is built into the rear of lens barrel. F stops are obtained by turning it to the proper position: F = 8, 2X = F11, 4X = F16.

SKYLIGHT FILTER AND LENS HOOD

A skylight filter can be mounted onto the rear of the lens before mounting "T" system adapter. The front of the lens is threaded to accept a 77mm lens hood especially made for the MIRROR LENS.

FOCUSING

Focusing can be done correctly with the groundglass portion of the focusing screen, since rangefinder prisms and microgrid screens shadow out with long or slow lenses. The extreme shallow depth of field requires particular care in focusing.

Manufacturer description #2

This part of the text from the Hanimex 500mm F/8 instructions is different from what was quoted above:

HOW TO INSERT NEUTRAL DENSITY FILTER

Filter mounted with metal ring is inserted into slot made in the rear of the lens barrel. Determine "f" value required. When inserting filter, the ring on the slot is turned to the arrow and then it is closed automatically after the insertion of proper filter. Ring is be fully closed to prevent stray light!

SKYLIGHT FILTER AND LENS HOOD

Screw skylight filter onto the rear of the lens before mounting "T" system adapter. The lens has front thread to accept 82mm lens hood specially made for the MIRROR LENS.

From the Popular Mechanics magazine (August 1970)

High-power telephoto lenses are customarily long, heavy and cumbersome. Now there's a new breed that gives you the same long reach in half as much length. It's called a mirror lens because it bounces the light beam back and forth between reflective surfaces to create a long optical path in a small amount of space. In effect, it folds the beam in two so it can be shoehorned into a short, compact lens barrel.

Mirror lenses are made to fit most 35-mm single-lens reflex cameras. They're handy to use and surprisingly inexpensive. The 500-mm Lentar - a whopping telephoto by normal standards - is less than eight inches long, weighs under three pounds and sells for about $75. By contrast, a conventional 500-mm lens may measure as much as two feet, weigh up to 10 pounds and cost $400 to $500.

Unlike regular telephotos, most mirror lenses do not have adjustable f/stops. You vary your exposure entirely by speed. The aperture is fixed at about f/8. While this is a relatively small opening, today's fast films let you shoot at speeds up to 1/500th or 1/1000th of a second. High shutter speeds serve to minimize camera shake - a problem with all long lenses.

Where there's too much light for a proper exposure even at your highest shutter speed, you can reduce the brightness with a filter over the lens - a yellow one for black-and-white or a gray neutral-density type for color. Some mirror lenses, like the Lentar, have built-in filters that you swing into place simply by turning a ring to give you effective apertures of f/11 and f/16. Mirror lenses are available in a number of low-cost types ranging from $75 to about $100. One large mail-order source is Phoenix Camera, 129 E. 45th St., New York, N. Y. 10017.

Typical characteristics of mirror (reflex) lenses

• Catadioptric system consisting of curved mirrors and optical glass;
• Much shorter, lighter and less expensive designs than conventional super telephoto lenses;
• Outstanding correction of chromatic aberrations;
• Since the aperture is fixed, neutral density filters are used to obtain a smaller aperture;
• Doughnut-shaped out-of-focus highlights.

From the editor

The same lens was sold under the following names:

• CAMRON 500mm F:8
• CHINON 500mm F:8
• HANIMEX 500mm F:8
• KALIMAR 500mm F:8
• LISTAR 500mm F:8
• PRINZ MIROFLEX 500mm F:8
• QUANTARAY 500mm F:8
• REXATAR 500mm F:8
• SAMIGON 500mm F:8
• SOLIGOR 1:8 f=500mm
• TELESAR 500mm F:8
• VEMAR 500mm F:8

The lens came with three rear filters: plain glass (F=8), 2X=F11 and 4X=F16.

The Lentar version accepted 77mm front filters, while the Hanimex version used 82mm front filters.

There were also very similar (in design of the lens barrel) SIGMA MIRROR TELEPHOTO 1:8 500mm and accura MIRROR-ULTRATEL F:8 500mm lenses with the closest focusing distance of 3m / 10 ft., but without the filter slot.

Considering this, the original manufacturer of all of the above-mentioned lenses was most likely SIGMA.

SOLIGOR lists the following specifications for their T2 version: closest focusing distance of 3m, 35.5mm filters, weight: 1400g, length: 200mm. The lens was shown at Photokina 1970.

Lenses with similar focal length