Choosing Focal Lengths
|The Bread and Butter Lenses|
|Go Wide, Young Man|
|Reach Out with a Tele|
It's no secret that we love rangefinder cameras around here. But we have to be honest. Like any tool, there are things it does well - and things it does not so well. You wouldn't use a screwdriver for driving nails, right? If you like to shoot macro or hunt big game with lenses that frighten small children, perhaps rangefinders aren't for you. That's not to say it's not possible, but let's be realistic here. So then, what exactly, is the rangefinder's "sweet spot" as far as focal lengths go?
The Bread-and-Butter Lenses
Rangefinders work best with focal lengths centering on - or perhaps up to the "standard" 50mm lens. Let's see why that is.
When shooting the 35mm format, be it film or full frame digital, the 50mm lens is considered to be the standard. The most common reason is that the lens sees more or less what the eye sees. On a more technical level, it's the focal length about equal to the diagonal size of the film or sensor format. With a medium of 24x36mm, the diagonal being 43.3 mm - makes the closest match either a 40mm or 50mm lens. On the M8 with its roughly 17×25 mm sensor and a diagonal of 30.1mm - this means either a 28mm or 35mm lens. This makes sense as once you apply a crop factor of 1.33x, these become roughly 37mm and 47mm lenses, respectively. This is why you'll see an absolutely bewildering array of lenses in these focal lengths, and less so towards the extremes.
Other considerations lie in the very design of rangefinders themselves. Unlike an SLR, you're not looking through the lens but rather a fixed optical viewfinder containing framelines, indicating the boundaries of your image at a given focal length. Most rangefinders, and especially Leica - have a viewfinder magnification of around .72x. You can go wider, or you can go narrower - but not by much. The digital Ms in fact, are at a .68x magnification. This covers the most focal lengths typically used, from 28mm to 90mm or so. Some go wider to 21mm as is the case with the Voightländer Bessa R4A/M, and some go longer up to 135mm. No single body covers the entire range. So it's important to figure out where your own sweet spot when considering a body. In a nutshell, as far as Leica bodies go - if you prefer wide angles err towards a .58x viewfinder - and conversely, if you prefer telephoto lenses err towards an .85x. For straight 50mm shooters, it's hard to beat a true 1:1 viewfinder such as the Voigtländer Bessa R3A/M or the Leica M3 (at .91x). This allows for shooting with both eyes open, the panacea for being able to anticipate the decisive moment...
There are other issues with using lenses at extremes of the range. If you designed a viewfinder to show you what a 15mm lens can capture - the rest of the framelines would become too difficult to use as they'd be far too small. Likewise in the other direction. Then there's the accuracy limitations of the rangefinder system in general. Take for example the early Leica Elmarit 135mm f/2,8 lens with goggles. The goggles (or "bug eyes") serve two purposes. The first is to magnify the 90mm framelines such that it would show what you're capturing with the 135mm lens and secondly, to increase focusing accuracy by magnifying the focusing patch. The only other way to improve focusing accuracy is to increase the "baselength" or the amount of distance between your normal viewfinder window and that for the RF patch. The Zeiss Ikon has a great baselength and among the longest, followed by Leica bodies and finally the Voigtländer Bessa - just to give examples. Though the differences aren't huge in the grand scheme of things.
Another reason that these focal lengths are so popular is that these lenses are relatively simple designs - unlike wide angle lenses, which typically involve more lens elements and require stronger corrections for things like distortion. Making a wide angle lens isn't hard, but making a good one can be. 35mm and 50mm lenses provide a very natural perspective that's normally free of distortion (e.g. barrel or pincushion distortion, or the stretching effect of things near the edges of the frame). They're also not large in diameter like wide angle lenses nor long in length like telephotos - but rather somewhere right in between.
Go Wide, Young Man
One area where rangefinders are very popular is street photography. This generally entails wider lenses than the standard. Once you go wider than 28mm, depending on the body, you'll generally want an external viewfinder for accurate framing. In practice, you can go as wide as about 25mm or so by just using the entire internal viewfinder, provided you don't wear glasses. With an external viewfinder you can actually go as wide as 12mm! Rangefinders enjoy particularly good performance from wide angle lenses due to a simpler design than their SLR counterparts, which must take into account the increased distance from the film/sensor with additional lens elements; a so-called retrofocus design.
A lot of street photographers don't even bother looking through the viewfinder let alone focusing. How? By setting a moderate aperture to ensure enough depth of field and focusing the lens to roughly the distance you expect your subjects to be at. Note that this is different from the hyperfocal distance but it's kind of the same principle - maximizing depth of field, at least where it counts. So using an aperture of f/5.6-8 with a wide angle lens focused at 3m will ensure that essentially everything in front of you will be in focus. With practice, you can "shoot from the hip" without even looking and still keep your frame relatively level.
For the more considered shooters, such as in landscape or travel - framing accuracy and focusing is more of a concern. You don't want to have to rotate and crop all your images because the horizon is crooked. This is where an external viewfinder comes in handy - both to ensure proper framing and to aid in holding the camera straight (though even the internal finder can do that much for you). Some people love external viewfinders - and with finders like those from Zeiss, it's easy to see why. You'd be hard pressed to find a brighter, clearer viewfinder on any camera! Though they're an added expense (and a fairly hefty one at that for the better models), an extra piece of kit to drag around and finally, make your camera just a bit bulkier and less coat pocket friendly.
Reach Out with a Tele
On the other end of the spectrum are telephoto lenses. The reason they're not quite as popular is similar to what we discussed above for wide angle lenses. The framelines in the viewfinder get progressively smaller the longer the focal length is. This makes for harder and harder framing as you're looking at only a fraction of your viewfinder. Focusing accuracy also gets more difficult and pushes the mechanical rangefinder to its limits and the thinner depth of field with long lenses doesn't help either. In the case of the Leica Elmarit 135mm f/2,8 lens with goggles a reasonable workaround for both is provided. Unfortunately, between the speed of the lens and all the goggle hardware, this makes for a beastly lens. Depending on how good your eyesight is, how accurately your rangefinder mechanism is tuned and in spec and finally, if you have a viewfinder magnifier or not - will determine your chance of success in shooting with 90mm and 135mm lenses (that lack the goggles). If you regularly shoot 50mm, and especially 90-135mm lenses, a viewfinder magnifier is something worth considering.
If you're new to photography, or rangefinders and trying to decide which lens to get... Consider a 35mm or 50mm lens to start with. How fast a lens you'll want is for you to decide based on what you like to shoot and budget. Generally, slower lenses are smaller, lighter and sharper and faster lenses are larger, heavier and softer (wide open anyway). Of course, this is not a hard and fast rule as there certainly are fast lenses that border on perfection (e.g. the Leica Summilux 50mm f/1,4 ASPH is among the best 50mm lenses in the world). But speed and quality usually mean a big jump in cost. To start off with, consider something like the Leica Summicron 35mm f/2 or Summicron 50mm f/2, or the Biogon T* 2/35 and Planar T* 2/50 ZMs from Zeiss just to name a few. These are excellent lenses at a moderate speed and size that won't break the bank. Shoot with your selected lens and learn to know what you like - and go from there.
One neat trick that's unique to rangefinders is the "preview lever" - the lever that lets you switch framelines. If you're wondering what lens to get (or get in the future) - spend a little time playing with the preview lever while looking at a scene and noting the coverage of the other focal lengths. It's a great way to visualize what a particular focal length will give you!