For those of you with legacy system lenses, compact system cameras seem to make sense, yes? You can use all of your old lenses on newer bodies via adaptors and you’ll not only get to use your favorite optics, but you’ll save money to boot. And the really short back flange distances of some of the lenses mean that just about everything from an SLR or RF mount will fit with the right adaptor.
Well, not quite: firstly, all the fields of view will be different unless you’re going between APSC and APSC. Then there’s also the issue of size: why buy a compact mirrorless systems with the intention of reducing weight when you then go stick an enormous lens on the front?
Bottom line: there are many disadvantages to using legacy glass on mirrorless systems; more so than advantages. I knew that going in, and only use my micro four thirds system with dedicated lenses; but I have got a whole drawer full of adaptors, mostly purchased out of sheer curiosity.
If you are hell bent on making unholy pairings, then read on.
Quick aside: ‘Good’ means lenses work well, and deliver excellent or outstanding optical results; better than the system’s native lenses. ‘OK’ means that they work about as well. ‘Bad’ means that you shouldn’t bother; most of the time this is due to non-telecentric wide angles not playing nice at the edges due to very short back flange distances and a lack of offset micro lenses on the sensor to counter sharp angles of incidence between image rays and sensor. This manifests as purple fringing, chromatic aberration, vignetting, and corner softness. It could also mean the lens just doesn’t have enough resolution to deal with a very high density sensor – for instance the 24MP Sony NEX-7. There are exceptions to this rule, and where I’ve found them, I’ve noted them. The Ricoh GXR M-module is an exception because it does have offset micro lenses and was specifically designed for RF glass.
Good: Legacy Sony/ Minolta telephotos and normals; new Sony midrange and high end zooms; Leica M telephotos
OK: New Sony wides; Leica M normals
Bad: Older wides; Leica M wides; C-mount/ CCTV lenses (won’t even cover the image circle!)
Micro Four Thirds
Good: SLR high end telephotos, SLR normals, RF telephotos. Exception: Zeiss ZF/ZF.2 glass, Leica 35/1.4 ASPH FLE.
OK: SLR midrange telephotos; some of the slower RF normals
Bad: Leica M wides (pay attention to your adaptor: cheaper ones probably won’t be planar, and land up causing obvious astigmatism. They may not even focus to infinity, or minimum distance!). The Leica Noctilux 0.95 does not do well on micro four thirds; it displays a lot of CA and blooming. I suspect that it is only optimized with the focal plane precisely at 28mm from the flange. Most C-mount/ CCTV lenses – these lack the resolving power and flatness of field.
Good: Any of the new Nikon lenses, say post-2009; almost all of these are telecentric and of sufficiently high resolving power. Any of the SLR high end telephotos, RF telephotos
OK: RF normals, all other cheap telephotos; older Nikon MF glass; RF normals
Bad: Cheap C-mount/ CCTV lenses – these lack resolving power; RF wides
Good: Any Leica M