BIOGON T* 28mm ZM vs BIOGON T* 28mm G

Last updated on 2026-01-13

A review and sample photos of the Carl Zeiss BIOGON T* 28mm F2.8 ZM used with the film rangefinder camera HEXAR-RF and the digital rangefinder cameras LEICA M8 and EPSON R-D1.

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Gallery
Review
Specification and more
Reference links

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Gallery

The following cameras were used to take the sample photos:

KONICA HEXAR-RF +KODAK E100G +NIKON LS-50
LEICA M8
EPSON R-D1

1．Overview

The Carl Zeiss BIOGON T* 28mm F2.8 ZM is a Leica M-mount compatible lens developed by Carl Zeiss and manufactured and sold by Cosina, and released in 2005.

The lens construction is perfectly symmetrical, with four elements in the front group and four in the rear group. The lens length from the mount is 37mm, which is shorter than other BIOGON series lenses. Additionally, the back focus, the distance from the very end of the rear lens element to the film sensor, is designed to be longer for digital cameras.

The main specifications are as follows, and the details are listed in the table.

Aperture 2.8
Lens construction 6 groups, 8 elements
Aperture blades 10
Minimum shooting distance 0.5m
Leica M rangefinder camera rangefinder coupling 0.7m
Hood Carl Zeiss Lens Shade 25mm/28mm
Lens color variations Silver and black

The cylindrical Carl Zeiss Lens Shade 25mm/28mm is used as the lens hood.
The shape of the hood attachment part on the front of the lens is the same for the BOIGON 21mm, 25mm, 28mm, and 35mm, so the wider-angle Carl Zeiss Lens Shade 21mm/25mm can also be attached. The hood is angular and looks good, but as it is designed for focal lengths wider than 28mm, it provides less shading.

2．Usability

The Carl Zeiss BIOGON T* 28mm f/2.8 ZM is the most compact of the ZM lenses, excluding the C ZM lenses.

I used it with three different camera sizes: the HEXAR-RF for 35mm film, the LEICA M8 with an APS-H sensor, and the EPSON R-D1 with an APS-C sensor.

Based on the results with reversal film, it shows flawless rendering even to the edges. Because it’s 28mm, you can’t expect much bokeh, but it still doesn’t produce poor rendering in either the front or back. High-resolution rendering is a hallmark of other ZM lenses.

Because the rear lens and sensor are farther apart, it’s unlikely to exhibit the color cast common to older 28mm designs when used with cameras equipped with 35mm full-frame sensors.

When used with the LEICA M8 with an APS-H sensor, this lens has a wide-angle focal length equivalent to 37mm.
Looking at the results, there is no distortion or vignetting, partly due to the cutting of the peripheral areas, and the photos are likely to be of a higher quality.

The Epson R-D1, equipped with an APS-C size sensor, has a focal length of 42mm, which is close to that of a standard lens. It lacks the feel of a wide-angle lens, but because it crops the area seen through the viewfinder, the resulting image feels natural.

The lens has a manual focus ring with just the right amount of torque, as is common to all ZM series lenses, and the focus knob is curved and therefore has a good grip, making focusing easy.
The aperture ring is located at the front of the lens and ranges from f/2.8 to f/22, in 1/3 increments, as is the case with the Zeiss ZM series.
A minimum focusing distance of 0.5m means that when used with a mirrorless camera, you can get closer than with a rangefinder camera.

3．Summary

To summarize the Carl Zeiss BIOGON T* 28mm F2.8 ZM, it has a compact lens barrel typical of a rangefinder lens and produces stable images.

As of 2025, the BIOGON 28mm ZM is available new and could be a good choice when purchasing a wide-angle lens.

Lenses currently available for purchase new in the 2020s

Carl Zeiss Biogon 28mm ZM
Voigtlander ULTRON Vintage Line 28mm F2 Aspherical TypeII VM
Voigtlander COLOR-SKOPAR 28mm F2.8 As VM Type II
Voigtlander NOKTON Vintage Line 28mm F1.5 Aspherical
Leica Summilux-M f1.4/28mm ASPH.
Leica Summicron-M f2/28mm ASPH. 11618
Leica Elmarit-M f2.8/28mm ASPH.
Leica Summaron-M f5.6/28mm

Specifications, considerations, etc.

The Carl Zeiss BIOGON T* 28mm F2.8 ZM shares the Biogon name with the CONATX G BIOGON T* 28mm F2.8, an older lens that was well-received, and boasts the same focal length and maximum aperture, making it a head-to-head competition.

The lens construction, with four elements in the front group and four in the rear group, is symmetrical, as seen from the cross-section. Zeiss appears to have refined the design with the intention of surpassing previous Biogons. This design is also likely supported by advances in coating technology, which minimizes the impact of increasing the number of lens elements.

The CONATX G BIOGON T* 28mm F2.8 is a lens from the film camera era, with the rear element positioned close to the film. In digital cameras, the sensor and rear element are closer together. This can lead to color casts around the edges of images captured with some digital cameras. However, this design also reduces the lens length by about 7mm, even when including the difference in flange focal length.
Unlike the ZM BIOGON, the lens construction is not perfectly symmetrical with three elements in the front group and four in the rear group, but this is the result of the lens being able to deliver the performance it is designed for, and it is also thought that a smaller number of lenses means lower manufacturing costs.

Items	ZM BIOGON	G BIOGON
Focal length(mm)	28	28
Max aperture	2.8	2.8
Min aperture	22	22
Lens Construction	8elements in 6groups	7elements in 5groups
Min distance(m)	0.5	0.44
Lens length(mm)	37	31
Max diameter(mm)	55	56
Filter Size(mm)	46	46
Hood	25/28 common bayonet type	46mm screw-in type
Weight(g)	220	150
Release date	2005.4	1994
Price(Yen/No-tax)	￥95,000	¥57,000

ZM lens list

Distagon T✻ 15mm ƒ/2.8 (Made in Germany)
Distagon T✻ 18mm ƒ/4
Distagon T✻ 21mm ƒ/2.8
C Biogon T✻ 21mm ƒ/4.5
Biogon T✻ 25mm ƒ/2.8
Biogon T✻ 28mm ƒ/2.8
Distagon T✻ 35mm ƒ/1.4
Biogon T✻ 35mm ƒ/2
C Biogon T✻ 35mm ƒ/2.8
C Sonnar T✻ 50mm ƒ/1.5
Planar T✻ 50mm ƒ/2
Tele-Tessar T✻ 85mm ƒ/4
Sonnar T✻ 85mm ƒ/2 (Made in Germany)

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