Zeiss 8×30 B (Porro)

Specifications:

Objective diameter:  30 mm
Magnification:  8 x
Exit pupil: 3.75 mm
Usable eye relief (measured from rim of eyecup): 13 mm
IPD: 50  – 73 mm
RFOV:  6.3  degrees = 110 m
AFOV (measured, rounded): 52 degrees
Minimum focus distance (measured): 3.7 m
Focus type: CF (direction of rotation from close to infinity: > clockwise)
Degrees of rotation of focus wheel from 3.7 m to infinity (measured): 225 degrees
Range of diopter adjustment (estimate): +/- 3 dpt
Excess travel of focus wheel beyond infinity position (estimate): 5 dpt
Prism system:  Porro I
Waterproof: splashproof ?
Weight (measured, with eyepiece cover and strap): 526 g
Made in: Germany

Remarks:

The legendary “Carl Zeiss 8×30” was produced by Zeiss West Germany between 1954 and 1978, both in individual focus and central focus versions. The sample presented here appears to be from the 1960s. Early versions came with a wide field of view of 8.5 degrees, but these had the disadvantage of a very short eye relief (9mm) which made the instrument unusable with eyeglasses and was also not comfortable to use without. Eyepiece design changes in the late 1950s led to the “B” version (B stands for Brillenträger) with an excellent eye relief of 19mm, but this had a high price: the field of view shrank to a mere 6.3 degrees, AFOV 52 degrees. From today’s perspective, this doesn’t sound that bad, but back in the 1950s there was an abundance of instruments on the market with 60-80 degrees AFOV. In later versions in the 1970s, with changes on both the objectives and the eyepieces, an increase of the field of view to 7.4 degrees was achieved.