Two Voigtländer lenses for the Bessa-L camera, tested October 1999.


Read Stephen Gandy's article about the >> Bessa-L <<


Available mounts: 39mm Leica/Canon L screw-mount.

We tested two lenses in conjunction with our Voigtländer Bessa-L report, the 15mm f/4.5 Voigtländer Super Wide-Heliar Aspherical, and the 25mm f/4 Voigtländer Snapshot-Skopar. All were designed and manufactured by Cosina in Japan and are of contemporary construction.

15mm f/4.5 Voigtländer Super Wide-Heliar Aspherical

Perhaps the finest ultrawide-angle lens ever made.

Specifications: (Tested values in italics)
Focal length: 15mm (Tested measurement not available due to instrument limitation)
Maximum aperture: f/4.5 (f/4.12)
Construction: 8 elements in 6 groups
View angle: Diag. 110º
Minimum aperture: f/22
Focussing: 90º counterclockwise from infinity to close focus, 11 13/16 inches.
Weight: 3 11/16ounces.
Filter size: 39mm (Leica-type) screw-mount thread. Includes soft-case and viewfinder.
Mount available: L mount
List price: $720
Street price: $550 - 575

Lens Test Results

aperture
F/
 lines/mm,
center 		rating lines/mm,
corner 		rating
4.5 96 Excellent 57 Excellent
5.6 96 Excellent 57 Excellent
8.0 85 Excellent 54 Excellent
11.0 68 Excellent 50 Excellent
16.0 61 Excellent 40 Excellent
20.0 48 Good 32 Very Good


Hands on: Remarkably compact and light, beautifully finished, satin chrome-on-brass mount with finely engraved black numerals for apertures and metre distances, and excellent depth-of-field scales with red footage numerals. Sharply knurled, extremely smooth turning aperture and focusing rings. Shallow, unusually contoured front ring accepts no accessories.

In the lab: Short focal length and design of mechanical mount made it impossible to obtain field curvature and SQF data but the lines-per-millimeter resultion test produced the best results we have ever seen for an ultrawide-angle lens, with central sharpness at f/4.5 and f/5.6 even exceeding that of the fabled 16mm f/8 Zeiss Hologon at its only aperture. (Our test Hologon yielded 90 l/mm centrally and 70 l/mm in the corners). Minimal pincushion distortion (0.45 percent) was about twice that of the Hologon's barrel distortion (0.23 percent), but still considered quite small. Exposure accuracy variation was under ½ f-stop at all apertures, principally caused by light falloff, a common occurrence with extremely wide-angle lenses. Flare was very well controlled.

At closest focusing distance of 11¾ inches (1:16), centre sharpness was excellent at every aperture, and corner sharpness acceptable at f/4.5, good at f/5.6, excellent from f/8 to f/16, and very good at f/22. The lens achieved optimum close-focusing performance at f/8.

In the field. Test slides were very sharp and contrasty from centre to corners at every aperture. Light falloff was seen at all apertures (as is common with such lenses, including the Zeiss Hologon).

Conclusion: A remarkable ultrawide-angle performance, unequaled in our experience, but no doubt aided by the optical engineers' ability to use modern aspheric designs with no need to clear the depth of an SLR retractable mirror. With judicious use of the depth-of-field scale, users should be able to get excellent sharpness even though the lens does not couple to a camera rangefinder.

It's superbly finished. We think the slip-on viewfinder might have benefitted from a slightly smaller field of view, more closely approximating the lens' picture-taking angle, as well as a parallax correcting tilt device for closeups.
25mm f/4 Voigtländer Snapshot-Skopar

Specifications: (Tested values in italics)
Focal length: 25mm (24.84mm)
Maximum aperture: f/4 (f/3.82)
Construction: 4 elements in 4 groups
View angle: Diag. 82º
Minimum aperture: f/22
Focussing: 90º counterclockwise from infinity to close focus, 2 feet 3 9/16 inches
Weight: 3 3/16 ounces
Filter size: No fitting provided.
Mount available: 39mm (Leica-type) screw-thread mount, includes softcase and viewfinder.
List price: $540
Street price: $400 - $425


Subjective Quality Factor     KEY:
A+
A
B+
B
C+
C
D
F

25mm f/4 Voigtländer Snapshot-Skopar   @ 25mm

MAG   >
6
8
12
17
22
Size (in.)   >
5 x 7
8 x 10
11 x 14
16 x 20
20 x 24
@ f/4.0
98.4
97.2
94.0
88.5
81.9
@ f/5.6
99.5
99.1
98.0
96.0
93.5
@ f/8.0
99.5
99.1
98.1
96.2
93.8
@ f/11.0
99.3
98.8
97.3
94.6
91.3
@ f/16.0
98.9
98.1
95.7
91.7
86.7
@ f/22.0
98.1
96.7
92.8
86.4
79.0


Hans on: Like the 15mm f/4.5, the 25mm f/4 Skopar is remarkably compact and light, beautifully finished in a satin chrome-on-brass mount with finely engraved black numerals for apertures and metre distances, and excellent depth-of-field scales with red footage numerals. However, instead of a knurled focusing ring, the lens has a lever and click detents at the 1-, 1.5, and 3- metre marks to facilitate setting maximum depth of field by touch. The lever is extremely handy except when the camera is close-mounted on a tripod head. Many such heads don't provide sufficient room to grasp and operate the lever. There is no way to attach lens accessories such as filters.

In the lab: SQF data indicated excellent performance at all apertures. Field curvature was virtually absent and barrel distortion (0.48 percent) was minimal. A ½ f-stop under-exposure at the film plane was noted at all apertures, which is considered average. At the closest focusing distance of 27½ inches (1:25), centre and corner sharpness were excellent at every aperture. Optimum performance was at f/11

In the field: Test slides were very sharp and contrasty, corner to corner, at all apertures. Flare was very well controlled and light fall-off gone by f/8.

Conclusion: Another splendid lens that, thanks to the click distance detents, is easy to set for maximum sharpness and depth of field. However, we would have preferred click detents at footage markings. While hardly a common focal length, it should be fine for photographers who prefer a wide angle for general photography. Its closeup ability is most impressive. Comments on the 15mm f/4.5 slip-on accessory viewfinder also apply here.

Tested October 1999.


SQF testing

This is some of what Pop Photo had to say about SQF testing in November 1990 when they were finally happy with their system.

In short, SQF is the way to relate the total of all our MTF measurements to the quality you can expect at any given print size.

Under normal conditions, a slight difference in SQF will hardly be noticeable. Experimentally, it's been shown that a difference of 10 SQF units will show a definite difference in quality level, with a difference of only 5 units producing a just noticeable difference (JND). SQFs below 50 yield unacceptable results.

SQF: making the grade
With five distinct quality levels to work with, it seeemed only natural to assign letter grades to each:   A for the best, then B, C, D, and finally F for anything below 50. We added "+" grades to A - C to characterize the quality, widening the group as quality diminished, giving a full 10 units to both C and C+ grades. In our system, we broke them down this way:
99.9 - 95.0   A+
94.9 - 90.0   A  
89.9 - 85.0   B+
84.9 - 80.0   B  
79.9 - 70.0   C+
69.9 - 60.0   C  
59.9 - 49.5   D  
          <49.5 F  

We expanded the C and C+ categories to fit actual experience. There was little point distinguishing between a D and D+. As overall quality goes down, it is increasingly difficult to distinguish between pictures. It's easier to tell which of two good prints is sharper than it is to determine which of two prints is fuzzier.

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