NIKON SERIE DTM-801
| Model | 851 | 831 | 821 |
| Telescope | |||
| Magnification | 33x (21x, 41x with optional eyepiece) | ||
| Field of view | 1°20' (2.3 m at 100 m / 2.3 ft. at 100 ft.) | ||
| Resolving power | 2.5" | ||
| Angle measurement | |||
| Reading system | Photoelectric incremental encoder (Diametrical detection for H / V circles) |
||
| Minimum display increment (360°) (400 G) (MIL6000 / MIL6400) |
0.5" / 1" 0.1 mgon / 0.2 mgon 0.002 MIL / 0.005 MIL |
1" / 5" 0.2 mgon / 1mgon 0.005 MIL / 0.02 MIL |
|
| DIN 18723 accuracy | 1" / 0.3 mgon | 2" / 0.5 mgon | 3" / 1 mgon |
| Tilt sensor | |||
| Type | Dual-axis | ||
| Compensation range | ±3' | ||
| Distance measurement | |||
| Range with Nikon prisms | Under normal atmospheric conditions (ordinary haze with visibility about 20 km / 12.5 miles) |
||
| With reflector sheet | 5-100m/16.4-328.1 ft. | ||
| With mini prism | 1100m/3600 ft. | ||
| With single prism | 2,400 m / 7,900 ft. | 2,200 m / 7,200 ft. | 1,600 m / 5,300 ft. |
| With triple prism | 3,100 m / 10,200 ft. | 2,900 m / 9,500 ft. | 2,300 m / 7,600 ft. |
| With nine prisms | 3,700 m / 12,100 ft. | 3,600 m / 11,800 ft. | 3,000 m / 9,800 ft. |
| Under good atmospheric conditions (no haze with visibility over 40 km / 25 miles) |
|||
| With reflector sheet | 5-100m/16.4-328.1 ft. | ||
| With mini prism | 950m/3100 ft. | ||
| With single prism | 2,700 m / 8,900 ft. | 2,500 m / 8,200 ft. | 2,000 m / 6,600 ft. |
| With triple prism | 3,600 m / 11,800 ft. | 3,300 m / 10,800 ft. | 2,800 m / 9,200 ft. |
| With nine prisms | 4,400 m / 14,400 ft. | 4,200 m / 13,800 ft. | 3,500 m / 11,500 ft. |
| Accuracy | |||
| MSR mode | ±(2 + 2ppm x D)mm | ||
| TRK mode | ±(4 + 2ppm x D)mm | ||
| Least count | |||
| MSR mode | 0.1 mm / 0.0005 ft. (switchable to 1mm / 0.002 ft.) | ||
| TRK mode | 1 mm / 0.002 ft. (Switchable to 10mm/0.02ft.) | ||
| Lumi-Guide | |||
| Visible range | Over 100 m / 330 ft. | ||
| Display | |||
| Front | Graphic (256 x 80 pixel) LCD with backlight illumination 7-level adjustable with 20 keys | ||
| Rear | 16-character x 4-line, dot matrix LCD with backlight illumination with 5 keys | ||
| Battery | Clip-on Ni-MH Battery Type BC-80 | ||
| Output voltage | 7.2V DC, rechargeable | ||
| Continuous operation time | 5.0 hrs. / approx. 15000 measurements (angle/distance measurements) 7.5 hrs. (angle measurement only) with BC-80 | ||
| Battery charger | Q-75U / E (Q-75U for 115V, Q-75E for 220 / 240V) | ||
| Recharge time | less than 2.0 hrs | ||
| Discharge time | 7.5 hrs. | ||
| Dimensions | |||
| W x D x H | 166 x 168 x 365 mm / 6.5 x 6.6 x 14.4 in. | ||
| Weight(approx.) | |||
| Main unit | 5.6 kg /12.3 lbs. (with battery BC-80) | ||