OLYMPUS ZUIKO MC Auto-W 21mm f/2 Wide-Angle     Tested May 1981.

Lens number 100094                  

Specifications: Fixed mount for Olympus OM SLRs: Serial No. 100094; 55mm filter size; f/2 to f/16; min. foc. dist: 0.2m (8 in.): 1.7 in. long x 2.3 in. diam; 8 7/8 oz. (252g); $665.

Practical comments: Fine satin black finish;, clear, white numerals; easy, click-stopped controls, 5/8 in. wide diamond pattern rubberised focusssing ring; 90º turn from min. foc. to infinity; fine construction.

                          PERFORMANCE
Our Standard Tested
Focal length: + - 5%
(19.95 - 22.05mm) 		20.15mm
Max. aperture: + - 5%
(f/1.9 - 2.10) 		f/ 1.91
Distortion: ( 21mm + - 4%) 0.9% (barrel)
Light falloff; at f/ 5.6
+1 stop from theoretical limit
(0 - 3.00 stops) 		1.12 stops


                    RESOLUTION

OLYMPUS ZUIKO MC Auto-W 21mm f/2
at 1:49 magnification
f/ Center
(f/mm) 		Corner
(f/mm)
2 V. Good 49 V. Good 31
2.8 Excellent 62 V. Good 35
4 Excellent 87 V. Good 39
5.6 Excellent 87 V. Good 39
8 Excellent 78 Excellent 44
11 Excellent 69 Excellent 44
16 Excellent 62 Excellent 49
                      CONTRAST

OLYMPUS ZUIKO MC Auto-W 21mm f/2
at 30 lines / mm
f/ Center
( % ) 		Corner
( % )
2 Low 40 Low 18
2.8 Low 46 Low 20
4 Low 48 Low 30
5.6 Low 56 Low 40
8 Low 58 Medium 42
11 Low 51 High 42
16 Low 46 High 42


Field test slides: Slight flare at f/2, no noticable loss of image sharpness in corners at f/2. Pretty sharp image at f/5.6, slight flare still present at f/8. Slight barrel distortion typical for 21mm lens. Overall, a very good lens.

Optical bench analysis On axis - small, compact image and slight decentering on elements indicated at f/2. Slight red flare, slight over-corrected spherical aberration, image very good. Almost diffraction limited and slight red flare at f/5.6. Off axis - some high order coma present; slight yellow-blue lateral color; slight yellow flare. Image very good at f/5.6.

(May 1981)

Modern's Photo Buying Guide '85
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