CONTAX Planar G T* 45mm(Ms-optics)

Review of using a Kyocera CONTAX G-mount 45mm F2 lens modified by MS-Optics (Miyazaki Kogaku) to Leica M mount with Leica M digital camera.

Gallery

The photo examples were taken with the HASELBLAD X2D.

The photo examples were taken with the Leica M-P typ240

Review

The Planar 45mm is an autofocus lens released by Kyocera in 1994 along with the Contax G1. Here, we introduce a lens that has been modified by Ms-optics (Miyazaki Optical) to be Leica M mount (rangefinder camera rangefinder linked).

I also used this lens with the CONTAX G1 and CONTAX G2, but after selling them, I purchased a lens modified to be Leica M mount rangefinder linked by MS-Optics (Miyazaki Optical). The details of how I purchased the lens will be described later. The modified lens uses the MS-50 common helicoid for 50mm.

The main differences between the original lens and the Ms-optics modified lens are the following four points.

Fixing method for hood and filter frame
- The front part of the lens barrel where the filter is attached moves in a straight line, so the filter does not rotate when focusing, making it easy to use PL filters
- The lens barrel where the filter is attached rotates when focusing on the modified lens, making it difficult to use PL filters
Aperture click stop
- The original lens has click stops for each aperture
- The modified lens has a stepless aperture from F2.8 to F16
Rangefinder rangefinder linkage
- The original lens is G mount, so it is autofocus (AF).
- The modified lens is linked to the rangefinder of Leica M cameras.
Minimum shooting distance
- Original lens is 0.5m
- Modified lens is 0.7m

The aperture ring of this lens is located at the front of the lens, at the thickest part of the barrel, and it is often in a different position when removed from the camera bag. Therefore, it would be easier to use if the aperture ring was a little harder.

The lens configuration is a classic planar configuration, and the coating is old, so purple fringing may appear around the subject depending on the lighting conditions, such as in backlight, giving it the feel of an old lens.

Compared to the 35mm, the focal length is 10mm longer, which gives the bokeh a softer feel. There may be performance limitations, such as not being able to keep up with the resolution of digital cameras, but it can be enjoyed as a unique feature of the lens.
The M-mount version modified by Ms-optics is of course perfectly fine when used with an EVF, but it can also be used without any problems when used with a Leica M viewfinder, as it allows you to take slightly larger images with a 50mm frame.
When I used this lens with the film cameras CONTAX G1 and G2, the focus had to be adjusted by AF, so the film I took often had images that were not quite in focus.

As for the details of how I got this lens, I saw it in a now-defunct used camera shop in Shinbashi around 2007. I had already used it with the film cameras CONTAX G1 and G2, and I knew that I was satisfied with the image quality of the G-mount version, so I was tempted by the appeal of being able to use the Planar 45mm with an M-mount rangefinder camera in conjunction with the rangefinder, and purchased this M-mount lens.
When I attached the lens to my camera at home and adjusted the focus, I found that the lens barrel and helicoid were not properly fixed, and the lens barrel fell off the helicoid, making it a defective product.

The contact information for the modified lens was written on the diagnostics for the modified lens that was included with the lens I purchased, so I contacted Miyazaki Sadayasu, the founder of Ms-Optics, and he repaired the lens free of charge.

This was the beginning of my relationship with Miyazaki, who was an individual lens builder at the time. This lens is very memorable.

Starting with the acquisition of this lens, I modified G-mount lenses to M-mount, including the Planar 35mm, Biogon 21mm, Hologon 16mm, and Sonnar 90mm.

These modified M-mount lenses became easier to use after I acquired a digital Leica M camera, and although I have bought and sold M-mount lenses from other brands, I have always kept the modified G-mount lenses on hand and used them.

Also, since the lens was changed to a Leica M mount, it can be used with various mirrorless cameras by using a mount adapter.
The M-mount modification of this lens is also widely practiced overseas, and some places sell not only modified lenses but also just the helicoid (for details, see the website in the reference link).

When I looked up the market price of G-mount lenses in the 2020s, I was surprised to find that lens prices have risen. At the end of the film camera era, a 45mm lens could be purchased for around 20,000 yen, but now it is around 50,000 yen, which shows the large demand for reuse with mirrorless cameras.

Specification

Name	HOLOGON	BIOGON	BIOGON	PLANAR	PLANAR	SONNAR	VARIO SONNAR
Focal length(mm)	16.5	21	28	35	45	90	35-70
Max aperture	8(fixed)	2.8	←	2	←	2.8	3.5-5.6
Min aperture	16(Attached filter)	22	←	16	←	22	←
Lens Construction	5elements in 3groups	9elements in 7groups	7elements in 5groups	←	6eleme0nts in 4group	5elements in 4groups	13elements in 8groups
Min distance(m)	0.3	0.5	0.5 0.8(*2)←	0.5	←	1.0	←
Lens length(mm)	11	35.5	30.5	31.5	38.5	63.0	54.0
Max diameter(mm)	57	59	56	56	56	56	60
Filter size(mm)	– Dedicated ND filters are available. Changes to f/8 > 16 to alleviate peripheral light attenuation.	55	46	46	46	46	46
Weight(g)	120	200	150	160	190	240	290
Weight(g) M-mount	124	151	194 (222)*1	115	161	219 (259)*1	–
Release date	1994	1996	1994	1996	1994	1994	1999

*1:Hoo +Filter
*2: Minimum focus distance of AVENON modified lens

Planar 45mm lens configuration for CONTAX G (scanned and traced from the lens manual)

Reference links

Zeiss Photography Historical Products (There is a data sheet for the CONTAX G lenses in the middle of the linked page.)
Website of FUNLEADER (Website of FUNLEADER, which sells modified lenses and helicoids for modification)
Zeiss PLANAR description page by Wikipedia