AF Biogon T* 28 +CONTAX G1,G2

A review and sample photos taken using the CONTAX G BIOGON 28 with the CONTAX G1.

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Gallery
Review
Specification and more
Reference links

Gallery

The sample photos were taken with a CONTAX G1 camera body and Fujifilm TOREBI 100 reversal film.
The film was scanned with a COOLSCAN 5 ED.

1．Overview

The CONTAX G BIOGON 28mm F2.8 is an autofocus lens for the CONTAX G released in 1994.

Its main specifications are a focal length of 28mm, maximum aperture of F=2.8, and a minimum shooting distance of 0.5m.

The dedicated hood is the GG-1, which is the same as that of the Planar 35mm and Vario-Sonnar 35-70mm.

2．Usability

I used the CONTAX G BIOGON 28mm F2.8 with the CONTAX G1 and CONTAX G2 digital cameras.

The CONTAX G1 allows you to adjust the focus with autofocus. The CONTAX G1 and G2 viewfinders cover the 28mm focal length range, so you can use the built-in viewfinder to determine the composition.

The CONTAX G viewfinder does not show the focus position, so the general shooting style is to use the built-in viewfinder to determine the composition and leave the focus to the camera.

Using manual focus is troublesome, as there is no distance display on the lens barrel, so you rely on the rangefinder displayed in the camera viewfinder and adjust the shooting distance with the focus ring on the top of the camera to take the picture.

I shot under clear skies with the aperture set to around F5.6, so the autofocus rarely focused on a place that was far from the intended focus position. Therefore, I rarely used the troublesome manual focus mentioned above.

The Biogon 28mm is designed so that the rear lens goes inside the camera, which makes metering a little tricky, but the TTL (Through the Lens) actual aperture metering (center-weighted average metering) of the original CONTAX G series body determined the exposure with satisfactory accuracy.

I have uploaded examples of photos taken with a digital camera using a lens modified by Ms-optics.

3．Summary

In conclusion, to sum up the CONTAX G BIOGON 28mm F2.8, it is best suited to use with the CONTAX G series cameras. As it is a wide-angle lens, focusing accuracy is rarely an issue with film, and the lens resolution is sufficient for film.

With the release of various mount adapters, it can be used with mirrorless digital cameras without modification. Some cameras are even capable of operating the autofocus mechanism. When used with digital cameras, color casts and image distortion may be noticeable in the periphery due to the lens configuration in which the rear lens is close to the sensor surface.

Specification

There are two 28mm focal length lenses for 35mm format bearing the Biogon name. The Biogon 28mm for the CONTAX G is the only autofocus lens, and the other is the Biogon 28mm ZM, designed by Carl Zeiss and manufactured by Cosina, which has the same specifications for maximum aperture. The Biogon 28mm ZM was released in 2005 and is a lens that is more conscious of the symmetry of the lens structure than the G Biogon.

The BIOGON 28mm was released at the same time as the CONTAX G1, and if you purchase it at the same time as the camera, 28mm and 45mm are convenient focal lengths for general use. If you consider a camera + lens, it is obvious that photographers who prefer standard lenses will choose 45mm and photographers who prefer wide-angle lenses will choose 28mm.

In the 2000s, there was a wide stock of used Biogon 28mm lenses and they could be purchased at low prices, but in the 2020s, the price of the 28mm has risen to around 40,000 yen. Because the rear lens element is designed to fit into the film plane, there is a possibility of color casts on the edges of the image depending on the camera model, so care should be taken to test the lens before purchasing.

Lenses in good condition are becoming scarce, so prices are unlikely to drop dramatically in the future.

The lens construction diagrams are quoted from each company’s materials, and the sizes have been adjusted by us, so they are not exact.

Item	BIOGON	BIOGON
focal length(mm)	28	28
Maximum aperture	2.8	2.8
Minimum aperture	22	22
Leaf blade	6	10
Lens configuration	7 elements in 5 groups	8 elements in 6 groups
Minimum distance(m)	0.5	0.5
Lens length(mm)	30.5	38
Lens max diameter(mm)	56	53
Filter type	46	46
Weight(g)	150	220
Hood	GG-1	Carl Zeiss Lens Shade 25mm/28mm
Lens mount	CONTAX-G	ZM
Release date	1994	2005.4.29
Price	¥57,000	¥95,000