Ricoh GXR: M-Mount Unit with Zeiss 50 mm

Archive

After Ricoh's official announcement of the M-mount expansion unit, I decided to buy one, although I had not intended to do so originally. Here are my first personal experiences with the lenses that I bought (or tried to buy). This page is devoted to the Zeiss Sonnar 50mm f/1.5 lens.

Expanding the Equipment

In October and November, 2011, I expanded my lens collection and bought eventually three Zeiss lenses for the M-mount unit, after having some trouble with decentered Voigtländer lenses.

First, at the end of October, 2011, I bought a black Zeiss Sonnar T* C 50mm f/1.5 ZM lens (75mm equiv.), then my most expensive and fastest lens:

Photos: Arrived on October 25, 2011: Zeiss Sonnar T* C 50mm f/1.5 ZM lens (black) (75 mm equiv.)

This lens has a mixed reputation. On the hand hand it has been blamed for focus shift, and Zeiss gave an explanation of this. In addition, focus shift is primarily an issue with rangefinder cameras, not "when you see is what you get" (see the M-mount FAQ for details). On the other hand, this lens is also said to create 3D-like images, and posters in forums encouraged me to buy the lens. And that's what I eventually did.

On the M-mount expansion unit, it has an equivalent focal length of 75 mm and thus, works like a "portrait" lens. Using it instead of a normal lens took me some time to get used to...

Body with Lens Attached

Photo: Body with A12 M-mount expansion unit attached and Zeiss Sonnar 50mm f/1.5 lens

Some Technical Data

Focal length	50 mm (75 mm equiv.)
Angle of view (35mm film)	46° diagonal
Maximum aperture	1.5
f-stop range	1.5-16
Number of iris blades	10
Number of lenses/groups	6/4
Shortest distance	0.9 m
Weight	250 g
Length (w/wo cap)	63 mm (45 mm)
Maximum diameter	56 mm
Filter thread	46 mm
Lens hood	does not have one

Sample Images

Here are some samples taken with the Zeiss Sonnar 50mm f/1.5 lens (click the images to view the unprocessed original files in a new window):

Conclusions

Disclaimer: I am not a lens expert who sees marked differences between various Leica and/or other lenses. I can check for soft corners, find differences in color rendition, and, in rare cases, may discover a "3D look", but that's all. Please regard therefore my conclusions as the verdict of a "layman".

Manual focusing is difficult with the 50mm Zeiss lens wide open - here my results are still inconsistent. For example, at f/1.5 buildings that are 20 m or even farther away may not be at infinity. Thus, at least wide open you cannot simply set distance to infinity and expect sharp images at wide open.

The other issue is that every fast lens has a very shallow depth of field when wide open. The viewfinder of the GXR does not have the quality of a good optical viewfinder that allows to control depth of field with ease. Screen magnification with a factor of 4x or 8x helps, but you cannot oversee the whole scene. Focus assist is neither in mode 1 nor mode 2 my favorite...