Photographers often like to speak about bokeh, the ability of a lens to render the out of focus area. Especially prime lenses with a fixed focal length and a wider maximum aperture are able to render a nice blurred background.
The blur effect is mainly influenced by the aperture size, focal length, distance to the subject and distance from the subject to the background. Blurred background is especially useful in portrait photography. You can isolate your subject and kind of remove a distracting background. For many people this effect gives a photo a more professional touch. It is a look, you will never get with your handy or compact camera. Micro Four Thirds cameras, APS-C cameras or full frame cameras can give you this effect.
For Micro Four Thirds there are many high quality prime lenses to get this nice bokeh effect. If you add adapted vintage lenses, you have even more choices. I tested three lenses on my Olympus OM-D E-M1:
Panasonic Lumix G 42.5mm F1.7: A nice pocketable and sharp lens. Results should be very similiar to the popular m.Zuiko 45mm F1.8.
Olympus m.Zuiko 75mm F1.8: Simply one of the best Micro Four Thirds lenses out there!
Carl Zeiss Jena Sonnar 135mm F3.5 adapted via M42 adapter: 40 years old vintage lens (lens design is even older), can it keep up with the modern lenses?
The first series shows you a head and shoulder portrait with background far away.
In my opinion the m.Zuiko 75 wins, but just by a slight margin compared to the Sonnar 135. The aperture of the Sonnar is just F3.5 compared to F1.8 of the m.Zuiko 75 but the longer focal length reduces this disadvantage. The Lumix is still kind of busy in the background because of its shorter focal length.
The second series is a half body portrait with background far away.
Still the Olympus comes out first, the Sonnar 2nd and the Lumix 3rd. In the Sonnar example I could have been closer the the subject which would have blurred the background a bit more. These photos are all taken free hand.
Let’s see in the third series, how closer background is rendered by these three lenses.
Still the m.Zuiko 75 is the king closely followed by the Sonnar and the Lumix.
The last series shows the rendering capabilities when shooting half body portraits.
Here we have the same picture as in the series above. The background of the m.Zuiko looks really smooth, but the Sonnar is really close. The Lumix in comparision is more busy in the back and exhibits a swirly effect that I know from my old Helios 44M 58mm F2.0 lens (a Russian Carl Zeiss Biotar clone).
So in conclusion if you want the best background rendering out of the three, the Olympus is the best lens you can get. It is costly compared to the other two but in relation to its capabilities IMHO not expensive and a beauty of a lens. A cheap Carl Zeiss Jena Sonnar 135 costs a lot less, has no autofocus, light gathering capabilities are not as good and you need an adapter. Just considering bokeh this lens is a very nice performer and I just like to use it for that purpose. The Lumix on the other hand has a more versatile shorter focal length, is much smaller and still it can deliver bokeh. It is not among the best but still ok.
Just a word sharpness wise. It is not a scientific test but my impression is that sharpness of these three lenses is outstanding in this battle. For short distances you can’t go wrong with either of these three. It is kind of astounding that the old Sonnar still can keep up with these two modern top notch primes.
Keep in mind that sharpness results can differ depending on the focus distance to the subject. Many lenses are very good with infinity focus but inferior when close focusing and vice versa. This fact gets ignored by many photography review sites.
So if you are on the budget and don’t need a fast aperture, the vintage Carl Zeiss Jena Sonnar 135 is a very nice outdoor portrait lens. The Lumix 42.5 is very versatile, has a fast aperture and nice to use indoors. The m.Zuiko is a perfect lens, I use it outdoors and indoors. I love its bokeh, fast aperture and superb sharpness right starting from F1.8, no matter if I focus infinity for really sharp landscapes or close focus for portraits. All three lenses are strongly recommended.