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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.

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Overview of R-System Tele-Photo Lenses
#  Lens
Designation
Focus
System
(type)
Lens
Construction
(elmts/groups)
Close
Focus
(m)
Filter
Type
(size)
Lens
Dimensions
(dia x len)
Lens
Weight
(net)
Used
Price
(USD)
Current
Offers
(USD)
1
 
Leica Macro-Elmarit-R 60mm f/2.8MF6 / 50.27S7/E5568 x 62 mm400 g400-800i
2
 
Leica Vario-APO-Elmarit-R 70-180mm f/2.8MF13 / 101.70E7789 x 190 mm1,870 g4000-8000i
3
 
Angenieux 3x70 70-210mm f/3.5MF13 / 90.90E6280 x 164 mm783 g600-1200i
4
 
Leica Vario-Elmar-R 70-210mm f/4MF12 / 91.10E6074 x 157 mm720 g300-900i
5
 
Leitz Elcan-R 75mm f/2MF.. / ..0.70E6064 x 77 mm700 g3000-6000i
6
 
Leica Vario-Elmar-R 75-200mm f/4.5MF15 / 111.20E5570 x 157 mm725 g200-400i
7
 
Leica Summilux-R 80mm f/1.4MF7 / 50.80E6775 x 69 mm700 g2500-4000i
8
 
Leica Vario-Elmar-R 80-200mm f/4MF12 / 81.10E6071 x 165 mm1,020 g800-1600i
9
 
Leitz Wetzlar Vario-Elmar-R 80-200mm f/4.5MF.. / ..1.80E5572 x 157 mm710 g400-800i
10
 
Leica Summicron-R 90mm f/2MF5 / 40.70S7/E5570 x 63 mm560 g1000-2000i
11
 
Leica APO-Summicron-R 90mm f/2MF5 / 50.70E6070 x 59 mm520 g3500-5000i
12
 
Leitz Wetzlar Elmarit-R 90mm f/2.8 (I)MF5 / 40.70S765 x 72 mm500 g400-800i
13
 
Leica Elmarit-R 90mm f/2.8 (II)MF4 / 40.70E5567 x 57 mm450 g500-1000i
14
 
Leica APO-Macro-Elmarit-R 100mm f/2.8MF8 / 60.45E6073 x 105 mm760 g1500-3000i
15
 
Leitz Wetzlar Macro-Elmar-R 100mm f/4MF4 / 31.10E5568 x 120 mm670 g400-800i
16
 
Leitz Wetzlar Vario-Elmar-R 105-280mm f/4.2MF13 / 101.70S889 x 238 mm1,950 g3000-4000i
17
 
Leitz Canada Elmarit-R 135mm f/2.8 (I)MF5 / 41.50S765 x 91 mm655 g500-800i
18
 
Leica Elmarit-R 135mm f/2.8 (II)MF5 / 41.50E5567 x 93 mm730 g500-1000i
19
 
Leica APO-Summicron-R 180mm f/2MF9 / 61.50E100116 x 179 mm2,500 g8000-12000i
20
 
Angenieux APO IF 180mm f/2.3MF8 / 61.70E8286 x 149 mm995 g2500-4000i
21
 
Leitz Wetzlar Elmarit-R 180mm f/2.8 (I)MF5 / 41.80S878 x 134 mm1,325 g300-600i
22
 
Leitz Wetzlar Elmarit-R 180mm f/2.8 (II)MF5 / 41.80E6775 x 121 mm810 g300-600i
23
 
Leica APO-Elmarit-R 180mm f/2.8 (I)MF7 / 51.50S876 x 132 mm970 g2500-7500i
24
 
Leica APO-Elmarit-R 180mm f/2.8 (II)MF7 / 51.50E6776 x 132 mm970 g3000-8000i
25
 
Leitz Elcan-R 180mm f/3.4MF7 / 42.50E6063 x 115 mm750 g$$$i
26
 
Leitz Canada APO-Telyt-R 180mm f/3.4MF7 / 42.50S7.5/E6068 x 135 mm750 g800-1200i
27
 
Leitz Wetzlar Elmar-R 180mm f/4MF5 / 41.80E5586 x 100 mm540 g200-400i
28
 
Leitz Canada Telyt-R 250mm f/4 (I)MF6 / 54.50S8/E5566 x 100 mm1,380 g300-600i
29
 
Leitz Canada Telyt-R 250mm f/4 (II)MF7 / 61.70E6775 x 195 mm1,230 g400-800i
30
 
Leica APO-Telyt-R 280mm f/2.8MF8 / 72.50E112125 x 261 mm2,750 g2000-4000i
31
 
Leica APO-Telyt-R 280mm f/2.8 ModuleMF8 / 72.00rear125 x 276 mm3,740 g8000-12000i
32
 
Leica APO-Telyt-R 280mm f/4MF7 / 61.70E7788 x 208 mm1,875 g3000-6000i
33
 
Leitz Telyt-R 350mm f/4.8MF7 / 53.00E7784 x 286 mm1,820 g500-1500i
34
 
Leica APO-Telyt-R 400mm f/2.8MF11 / 94.70rear125 x 314 mm6,240 g10000-15000i
35
 
Leica APO-Telyt-R 400mm f/2.8 ModuleMF10 / 83.70rear157 x 344 mm5,800 g10000-15000i
36
 
Leica APO-Telyt-R 400mm f/4 ModuleMF9 / 72.15rear157 x 382 mm3,860 g6000-12000i
37
 
Leitz Wetzlar Telyt 400mm f/6.8 MF2 / 13.60S778 x 384 mm1,830 g500-1000i
38
 
Leitz Wetzlar MR-Telyt-R 500mm f/8MF5 / 54.00E7787 x 121 mm750 g800-1200i
39
 
Leica APO-Telyt-R 560mm f/4 ModuleMF11 / 83.95rear157 x 382 mm6,360 g12000-18000i
40
 
Leica APO-Telyt-R 560mm f/5.6 ModuleMF9 / 72.15rear125 x 374 mm4,050 g10000-15000i
41
 
Leitz Wetzlar Telyt-R 560mm f/6.8MF2 / 16.40S798 x 530 mm2,330 g400-600i
42
 
Leica APO-Telyt-R 800mm f/5.6 ModuleMF11 / 83.90rear157 x 442 mm6,550 g15000-20000i
43
 
Leitz Wetzlar Telyt-S 800mm f/6.3MF3 / 112.50built-in152 x 790 mm6,860 g3000-7000i
44
 
Minolta RF Rokkor-X 800mm f/8 for Leica RMF.. / ..8.00rear127 x 178 mm1,960 g1000-2000i

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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