My previous blog described the general use of rangefinder M lenses on the Sony A7R mirrorless camera. This is part II which focuses on the use of wide angle rangefinder lenses with this camera. 

After I bought my A7R, I found myself with a small, compact, and powerful high resolution mirrorless camera but still had to rely on bulky wide angle lenses for landscape and scenery photography. I am using the Canon 17-40/4 L and the rectlinear Canon 14/2.8 II L on my Canon DSLR cameras (also the 8-14/4 fisheye lens, but this is not a typical landscape lens). Those lenses are quite bulky especially when used in combination with the Metabones adapter on the A7R. So I started to look for alternatives which would facilitate size and weight of lenses which could be used for travelling and hikes. I already bought the Leica 50/2 Summicron-M rangefinder lens which amazed me by its sharpness and overall quality.

From experience I knew that I rarely use very wide focal lengths like 14 and 17 mm for landscape photography. Since I already had the 17-40/4 L lens, I also imagined to get something faster which pointed towards a prime lens. Zeiss also makes the very good Distagon 21/2.8 lens which comes with a (D)SLR mount - both price and size of this lens made me disregard this option. This Zeiss lens also exists in rangefinder ZM mount, but reportedly suffers form color shifts and vignetting on the A7(R) sensors. Alternatively, there is another option - the Cosina-Voigtlander (CV) 21/1.8 Ultron lens with Leica M mount. I liked that it is one stop faster than the Zeiss lens and came with a better price tag; also some reviews were positive to use this lens on the A7R. I found one con of the CV 21/1.8 lens - the fixed and not removable lens hood which would make it a pain or impossible to use this lens with graduated ND filters. 

I didn't find a good deal for a used CV 21/1.8 lens, so I bought it new. It arrived in the unopened original box. The lens was mint, but when I fist used it, I instantly recognized sort of scratching noise when moving the focus ring back and forward. It didn't sound right because my CV 35/1.2 II lens is very smooth when moving the focus ring. For my first test shots, the CV 21/1.8 lens performed extremely well and with sharp images even wide open, so I kept it. On my first hike with this lens, I had to demount the lens from the camera, when suddenly a metal flake fell out of the lens mount. It turned out that this was the reason for the scratching noise - after the flake fell out of the inner lens barrel, everything worked smoothly with the focusing ring! I was lucky it came off and didn't hit the sensor when the lens was mounted on the camera!

This lens is very well built, metal lens case and engraved clearly visible scales. The aperture ring clicks slightly and stops at half and full apertures. The lens has a 58 mm outer diameter with filter ring. I also decided to get a 3-stop full ND filter with 58 mm size to allow for longer exposure times (especially useful for waterfall photography or in sunny conditions). 

When taking photos with blue or grey sky in it, I observed some purple fringing and vignetting in the corners of the frame with the CV 21/1.8 Ultron lens (and independent on the aperture used). I couldn't tell from photos where the whole frame was filled with objects (for example inside a forest or more close up). Likely this isn't caused by the lens itself, more by the combination of this lens with the A7R. The A7 series has a thicker sensor stack than other rangefinder camera sensors have which might cause this.  You can remove this fringing and vignetting in post processing, but I found it rather cumbersome to do and to get it right in the RAW file. Fortunately, Sony offers a very good tool to facilitate this - it is called "Lens Compensation" app for A7 and NEX cameras. It costs $9.99, but it is worth the investment especially when using several MF lenses. Leica M cameras use coded M lenses to determine which lens is attached to do this kind of compensation internally. 

The Sony "Lens Compensation" tool lets you change peripheral shading (reduces vignetting and purple fringing), chromatic aberration (reduces reddish or blueish borders, and distortion separately for different lens profiles. It is a bit try&error to get the best outcome by changing the settings here - for the CV 21/1.8 Ultron lens, I am using +15 for vignetting suppression, -3 for red, -10 for blue fringing, +4 for red chromatic aberration, and +2 for blue chromatic aberration, no changes for distortion. This nearly removes all fringing, vignetting and aberrations which makes the post processing much more easier. This tool is extremely useful for third party MF rangefinder lenses on the A7 series - highly recommended! Also I should point out that this tool works both for RAW and JPF files!

In general, wide angle rangefinder lenses can be tricky or some even impossible to be used with the A7 camera series. I recommend reading reviews for a M mount wide angle lens with the A7 series before purchasing one. Unfortunately, this information is very scattered and sometimes hard to find in the internet - sometimes even with conflicting reviews. But there are still a few decent rangefinder wide angle lens options out there which work out great on the A7(R) especially when lens profiles are being used.