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Leica Telescope-Ocular To-R

The Ocular To-R (Leica order no. 14234) is an adapter that makes it possible to use standard, telephoto, or zoom-lenses as telescopes. It attaches to Leica R-lenses via the bayonet mount. The Ocular contains a Schmidt-Pechan-prism that rotates the image by 180°, so that the latter appears upright and correctly sided, as well as an eyepiece with a focal length of 12.5mm. It has a -3 to +3 diopter adjustment. Focus is achieved via the focusing mechanism of the lens. The adapter is no longer in production, but can be found pre-owned in excellent condition for 300-500 USD (check here for current offers on ebay).

The effective magnification achieved by attaching the Leica Ocular depends on the focal length of the lens. It is calculated as the ratio between the focal length of the lens and the focal length of the Ocular. For example, a 90mm lens would achieve a magnification of 7.2 (=90mm/12.5mm), and a 400mm lens a ratio of 32.

Eyepiece
Leica Ocular Eyepiece[longmilan84]

Ocular TO-R Specifications

The body of the adapter is a solid, all metal construction with the eyepiece cover being of high-quality rubber. It's core specifications are the following:

  • optical construction with 3 elements;
  • focal length of 12.5mm;
  • eyepiece magnification of 20x;
  • exit pupil diameter of 3.78mm;
  • usable aperture of 1/3.3;
  • field of view diameter of 12mm;
  • weight of 100g (3.5 oz).

The Leica Telescope-Ocular works rather well and can quickly turn a telephoto lens into a spotting scope. In good light, it can also be used in combination with Leica's 1.4x or 2x APO-Extenders. With long focal lengths, it achieves magnification ratios that are generally beyond those of binoculars, but the setup tends to require a tripod for comfortable use due to the heavy weight of the lenses. Also, some photographers report that it takes some time to get used to the "tunnel perspective" that the Ocular To-R provides as a result of a field of view diameter that is smaller than the display in a camera viewfinder. It might, hence, be desirable and useful to try out the Ocular To-R, if possible, before buying it in order to avoid disappointment later on.

Overview of R-System Tele-Photo Lenses
Tele-photo primes Leica
Reference
(#)
Filter
Type
(size)
Lens
Dimensions
(dia x len)
Lens
Weight
(g)
Production
Period
(years)
Price
2009
(USD)
Used
Price
(ebay)
Leica Macro-Elmarit-R 60mm f/2.8 11347 S7/E55 2.7 x 2.4 in 14.1 oz 1972-2009 3195 check
Leitz Elcan-R 75mm f/2 C-341 E60 2.5 x 3.0 in 24.7 oz 1965-1965 $$$$ check
Leica Summilux-R 80mm f/1.4 11349 E67 3.0 x 2.7 in 24.7 oz 1980-2009 4695 check
Leica Summicron-R 90mm f/2 11254 S7/E55 2.8 x 2.5 in 19.8 oz 1970-2000 3495 check
Leica APO-Summicron-R 90mm f/2 11350 E60 2.8 x 2.3 in 18.3 oz 2002-2009 3895 check
Leitz Wetzlar Elmarit-R 90mm f/2.8 (I) 11229 S7 2.6 x 2.8 in 17.6 oz 1964-1983 $$ check
Leica Elmarit-R 90mm f/2.8 (II) 1154 E55 2.6 x 2.2 in 15.9 oz 1980-1998 $$ check
Leica APO-Macro-Elmarit-R 100mm f/2.8 11352 E60 2.9 x 4.1 in 26.8 oz 1987-2009 3995 check
Leitz Wetzlar Macro-Elmar-R 100mm f/4 11232 E55 2.7 x 4.7 in 23.6 oz 1978-1995 $$$ check
Leitz Canada Elmarit-R 135mm f/2.8 (I) 11111 S7 2.6 x 3.6 in 23.1 oz 1964-1968 $$ check
Leica Elmarit-R 135mm f/2.8 (II) 11211 E55 2.6 x 3.7 in 25.8 oz 1968-1998 $$ check
Leica APO-Summicron-R 180mm f/2 11354 E100 4.6 x 7.0 in 88.2 oz 1994-2009 8295 check
Angenieux APO IF 180mm f/2.3 A180LR E82 3.4 x 5.9 in 35.1 oz 1986-1992 $$$ check
Leitz Wetzlar Elmarit-R 180mm f/2.8 (I) 11919 S8 3.1 x 5.3 in 46.7 oz 1966-1979 $$$ check
Leitz Wetzlar Elmarit-R 180mm f/2.8 (II) 11923 E67 3.0 x 4.8 in 28.6 oz 1979-1998 $$$ check
Leica APO-Elmarit-R 180mm f/2.8 (I) 11273 S8 3.0 x 5.2 in 34.2 oz 1998-2004 $$$ check
Leica APO-Elmarit-R 180mm f/2.8 (II) 11357 E67 3.0 x 5.2 in 34.2 oz 2004-2009 5295 check
Leitz Elcan-R 180mm f/3.4 C-303 E60 2.5 x 4.5 in 26.5 oz 1965-1965 $$$$ check
Leitz Canada APO-Telyt-R 180mm f/3.4 11242 S7.5/E60 2.7 x 5.3 in 26.5 oz 1975-1980 $$$ check
Leitz Wetzlar Elmar-R 180mm f/4 11924 E55 3.4 x 3.9 in 19.0 oz 1976-1996 $$ check
Leitz Canada Telyt-R 250mm f/4 (I) 11920 S8/E55 2.6 x 3.9 in 48.7 oz 1970-1979 $$ check
Leitz Canada Telyt-R 250mm f/4 (II) 11925 E67 3.0 x 7.7 in 43.4 oz 1980-1994 $$ check
Super-tele primes Leica
Reference
(#)
Filter
Type
(size)
Lens
Dimensions
(dia x len)
Lens
Weight
(g)
Production
Period
(years)
Price
2009
(USD)
Used
Price
(ebay)
Leica APO-Telyt-R 280mm f/2.8 11245 E112 4.9 x 10.3 in 97.0 oz 1984-1992 $$$$ check
Leica APO-Telyt-R 280mm f/2.8 Module 11846 rear 4.9 x 10.9 in 131.9 oz 1996-2009 11290 check
Leica APO-Telyt-R 280mm f/4 11360 E77 3.5 x 8.2 in 66.1 oz 1996-2009 6995 check
Leitz Telyt-R 350mm f/4.8 11915 E77 3.3 x 11.3 in 64.2 oz 1980-1993 $$$ check
Leica APO-Telyt-R 400mm f/2.8 11256 rear 4.9 x 12.4 in 220.1 oz 1992-1996 $$$$ check
Leica APO-Telyt-R 400mm f/2.8 Module 11847 rear 6.2 x 13.5 in 204.6 oz 1996-2009 17390 check
Leica APO-Telyt-R 400mm f/4 Module 11857 rear 6.2 x 15.0 in 136.2 oz 1996-2009 12490 check
Leitz Wetzlar Telyt 400mm f/6.8 11960 S7 3.1 x 15.1 in 64.6 oz 1968-1994 $$$ check
Leitz Wetzlar MR-Telyt-R 500mm f/8 11243 E77 3.4 x 4.8 in 26.5 oz 1980-1996 $$ check
Leica APO-Telyt-R 560mm f/4 Module 11848 rear 6.2 x 15.0 in 224.3 oz 1996-2009 18590 check
Leica APO-Telyt-R 560mm f/5.6 Module 11858 rear 4.9 x 14.7 in 142.9 oz 1996-2009 14290 check
Leica APO-Telyt-R 800mm f/5.6 Module 11849 rear 6.2 x 17.4 in 231.0 oz 1996-2009 20390 check
Leitz Wetzlar Telyt-S 800mm f/6.3 11921 built-in 6.0 x 31.1 in 242.0 oz 1972-1977 $$$ check
Minolta RF Rokkor-X 800mm f/8 for Leica R RF800LR rear 5.0 x 7.0 in 69.1 oz 1973-1981 $$ check
Tele zoom Leica
Reference
(#)
Filter
Type
(size)
Lens
Dimensions
(dia x len)
Lens
Weight
(g)
Production
Period
(years)
Price
2009
(USD)
Used
Price
(ebay)
Leica Vario-APO-Elmarit-R 70-180mm f/2.8 11279 E77 3.5 x 7.5 in 66.0 oz 1995-2009 8795 check
Angenieux 3x70 70-210mm f/3.5 A3X70LR E62 3.1 x 6.5 in 27.6 oz 1985-1989 $$$ check
Leica Vario-Elmar-R 70-210mm f/4 11246 E60 2.9 x 6.2 in 25.4 oz 1984-2000 $$$ check
Leica Vario-Elmar-R 75-200mm f/4.5 11226 E55 2.8 x 6.2 in 25.6 oz 1978-1984 $$$ check
Leica Vario-Elmar-R 80-200mm f/4 11281 E60 2.8 x 6.5 in 36.0 oz 1996-2009 2695 check
Leitz Wetzlar Vario-Elmar-R 80-200mm f/4.5 11224 E55 2.8 x 6.2 in 25.0 oz 1974-1978 $$$ check
Leitz Wetzlar Vario-Elmar-R 105-280mm f/4.2 11268 S8 3.5 x 9.4 in 68.8 oz 1996-2006 $$$$ check

Further reading

The Leica Ocular works well with many of the R-series lenses, including the APO-Telyt telephoto optics. It can also be used in combination with Leica's tele-converters, if the light is good enough. Moreover, if you are more generally interested in the now discontinued Leica reflex system, you might want to check out the comparison of Leicaflex and Leica R cameras.

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