[Note : Access the complete summary of our review of the Sony A7r system (camera review, native lenses, alternative lenses, opinions … )]

The lure of mounting a tiny & fantastic Leica-M lens on a (reasonably) tiny & (unreasonably) fantastic Sony A7r is one of the major reasons so many people took the plunge … only to be disappointed by the complexity of the lens compatibility issues on this sensor.

Count me among the grumpy as co-author Philippe’s Elmar 24mm f/3.8 was right up there in my shopping list for hiking purposes, yet doesn’t live up to its M240 or NEX-7 promise on Sony’s new mirrorless flagship.

Drat!

But there are two good reasons not to despair :

1. Many M-mount lenses work perfectly well on the Sony A7r
2. Leica-R lenses are superb in their own right and far cheaper

Great M-mount lenses for your Sony A7r

A tricky question that, as reports vary greatly – for identical configurations – on forums and review websites. Individual users have different photographic styles, display varying tolerance levels and use different adapters, rendering any statistical analysis totally pointless. I can’t recommend a list, sorry.

That said, you’ll find some interesting reports in the links below :

• SonyAlpharRumors : Many A7r related posts
• The Luminous Landscape : The world’s best sensor meets the world’s finest lenses.
• Fred Miranda : Sony A7r + Rangefinder lenses

But beyond this, I think a few guidelines for your personal evaluation are more important than other people’s point of views.

First of all, most long M-mount lenses will work perfectly fine, as the photograph above testifies. From f/2.8 to f/11 pictures made with the Elmarit-M 90/2.8 are very sharp from corner to corner. Aperture has far more impact on depth of field and subtle glow than on sharpness.

An old Summilux-M 75/1.4 will make you weep. An Apo-Summicron-90/2 on an A7r will be sharp enough to cut through adamantium as easily as through your wallet (please, Philippe, buy one and let me review it 😉  A nice APO-Tely 135/3.4 combines great sharpness with a tiny hint of wide open glow that softens contrasty images.

Secondly, try to understand your lens before evaluating technical performance :

• Landscape lenses should be perfectly sharp all over the frame at f/5.6 – f/8 at infinity. The rest matters little as you’ll probably be using a tripod if you are serious about landscape photography.  Any corner smear at that aperture is a definite reject in my eyes, particularly as better alternatives exist.
• Portrait lenses are designed to isolate a subject from its environment. They often have a curved focal plane and shooting test charts or brick walls will provide absolutely no indication of performance for the intended purpose.
  A Summilux-M 50/1.4 may disappoint in the corners, as Philippe’s account will show, but tone and image beauty are second to none in the right conditions. A specialist lens such as the SLR Magic HyperPrime 50/0.95 is ever worse. Forget technical reviews for these lenses.
• Generalist lenses don’t really exist. The excellent and heavy Zeiss OTUS 55 may fall in that category if weightlifting isn’t an issue, but most lenses of Leica-M caliber are designed with a clear purpose in mind. Judge accordingly.

Finally, it’s probably too early to draw any conclusions regarding WA M-mount lenses as it appears not all adapters on the market are designed for full frame many mess with image corners. When the new range of Voigtlanders and others arrive (Philippe will soon report on these), things may begin to look up.

Lens R Us

But remember there’s also Leica-R.

A few examples :

• Leica Elmarit-R 19mm f/2.8 version 2 on the Sony A7r, (March 2014). A stunningly good ultrawide with none of the M-mount issues.
• Leica Summicron-R 50mm f/2 on the Sony A7r, (January 2014). A lens for the artist that’s not quite ready to leave sharpness at home.
• Leica Macro-Elmarit-R 60mm f/2.8 on the Sony A7r (April 2014). Beautiful balance between technical qualities and natural goodness.

Snobs view this range of lenses as technically inferior to the M line and yet, in the 90’s Leica themselves called the (last generation) R range their Best Lenses Ever Made. Since then, a few M lenses have overtaken them in technical quality – albeit with a different rendering – and not that many.

“But they’re huge!”, I hear you lament. Not so.

Almost all R lenses are wider than their M equivalent, but also shorter, as you can see above. On the camera, the much longer adapter does make the lens protrude significantly more, but the handling is simply perfect – better than with the shorter Ms in my book, with the aperture ring closer to the camera – and, in the bag, size and weight are not any higher.

Plus, as explained by Thorsten Overgaard, looser tolerances in the design often make R lenses optically superior to their M counterparts ! In real life comparisons between the only 2 equivalent pairs I have owned (Summicron 50/2 and Elmarit 90/2.8) I have never been able to distinguish between the two.

Minimal focusing distance and wide angle compatibility are two additional reasons not to discard the Leica-R too hastily.

The twin lens picture above was made with a last generation Summicron-R 50 at f/2 (reviewed here on a Sony NEX-5n). Note the superb bokeh and the close up ability that is way beyond what the Summicron-M 50 could achieve.

Leica produced a wide range of very fine wide angles such as the Elmarit-R 19/2.8 (which I own but haven’t been able to review yet), the Elmarit-R 24/2.8 (samples here), the Elmarit-R 28/2.8 (expensive in its version II E55 guise) and the Summicron-R 35/2, which I use a lot and reviewed on a D800e. Their MTF curves may not compare favourably to the more recent M wides, but on the A7r, they’ll give you better pictures 90% of the time (no fringing, no smear).

Then obviously, there’s the price … A (technically superior) APO-Summicron-M ASPH 50/2 will set you back 10 times the cost of an A+ Summicron-R 50. Put another way, the AA 50 costs the same as a Sony A7r, an Elmarit-R 24/2.8, a Summicron-R 50/2, an Elmarit-R 90, filters, bag, tripod, adapters and a trip to a great location … Your choice 😉

A word of caution! Many of these lenses were produced in multiple versions and not all are great (eBay prices reflect this). A good starting point for information, brochure, MTF curves … is the Leica Wiki R page.

Closing thoughts

There is a very strong focus in lens reviews on sharpness at all apertures and focusing distances. And it is important to use sharp lenses, particularly on a sensor as fantastic as the A7r’s.

But image aesthetics are at least as important.There are many gems in the older M-mount lineups that I hope to explore, such as the old Summitars or the Summicron 40. These are nowhere near good enough according to modern reviewing standards but beautifully sharp where it matters and render scenes and portraits with a finess that is all but lost in the more clinical lab champs. The latter, however, offer a transparency and clarity unobtainable with the older designs. These considerations are far more important than sharpness.

So Leica-M or Leica-R is more a matter of compatibility with the sensor than relative technical merit. Stay away from any deisgn, however brilliant on a M240, that shows smearing in the conditions you plan to use it in. Compared to this, any wave in an MTF curve is absolutely negligible.

Finally, relax and enjoy shooting. In the picture above, the two chaps on the left were handing out tasters of truffle-butter on home-baked bread accompanied by a glass of their best white. That’s so much more enjoyable than lp/mm count, rigth ? 😉

---

NEW: Signup for DearSusan’s new tutorial on lens testing in the field. 7 aberrations explained plus tips on how to test for them and how to fix their effects in post-processing. It’s totally free and totally awesome 😉