Lenses With Fixed Focal Length

With my Nikon F3, I used 50 mm / f/1.4, 35 mm / f/1.4, and 24 mm / f/2 lenses with fixed focal length, to cover the normal and wide angle range. At that time (1982), this definitely was the right decision — even now, if you ask an expert what lenses you should buy for the best quality results (technically, not artistically, of course), you will be told to go for fixed focal lengths:

• they are simpler than zoom lenses, i.e., they typically use less lens elements and simpler mechanical constructions, they are therefore usually less expensive than zoom lenses of comparable quality;
• they are lighter than zoom lenses (OK, you will need more than one fixed focal length to cover a given zoom range);
• at least for moderately wide angles, for normal angles and for the tele range, fixed focal length lenses can be built such that there is virtually no optical distortion
• it probably is also easier to compensate / avoid other optical errors, such as chromatic aberration
• similarly, the achievable resolution (sharpness) and contrast are higher than with zoom lenses

Overall, it is probably safe to say that a good fixed focal length lens will beat even a good zoom lens at the given focal length, hence the recommendation to go for fixed focal length lenses.

That said, fixed focal length tele lenses (200 mm, 400 mm, etc.) have always been fairly expensive, especially if you asked for large apertures (f/2.8, f/2). Also, for the special needs of slide photography, I did decide for an 80 - 200 mm tele zoom already with my Nikon F3.

That was with analog / film cameras — with digital cameras (DSLRs in particular) things are a little different: whenever you exchange the lens there is a big, gaping hole, through which dust can enter the body. OK, there's a mirror, and behind the mirror there's the shutter, both covering and protecting the sensor, but the dust may still be in the housing, and with the next shot the mirror swings up (moving around any dust), the shutter opens, and then the dust may end up on the sensor (or the glass filter covering the sensor). Once dust sticks to the sensor, you will see it on all subsequent pictures. Most newer cameras (also the D300, not the D200) have dust removal systems, essentially a piezo element that shakes the sensor filter to shake off dust particles — but that only works if the particles don't stick. If you have sticky dust you may have to have the sensor cleaned (there are kits that permit doing that at home, though I would never try that myself: too risky!).

With analog film cameras, you may of course get dust particles deposited on the film just as well — but for the next photo you advance the film, and that gives you a fresh, clean piece of "film sensor" ...

With all this in mind, I decided not to use lenses with fixed focal length on my DSLR — I'd like to minimize the number of lens changes. My initial approach was the other extreme: to use an 18 - 200 mm super zoom lens that would cover all focal lengths (well, all lengths I was primarily interested in), hence avoid all lens changes. However that entails other compromises & drawbacks, so in the end I decided for an in-between approach, see my note about the Nikon D300.

Nikkor 24mm f/2.0
Image taken with Nikon D200, AF-S DX VR Zoom-Nikkor 18 - 200mm f/3.5 - 5.6G IF ED
ISO 320, f/36, 1/60, 200mm (300mm equiv.)

Nikkor 35mm f/1.4
Image taken with Nikon D200, AF-S DX VR Zoom-Nikkor 18 - 200mm f/3.5 - 5.6G IF ED
ISO 320, f/36, 1/60, 200mm (300mm equiv.) 

Nikkor 50mm f/1.4
Image taken with Nikon D300, Zoom-Nikkor 70 - 200mm f/2.8
ISO 200, f/22, 1/60, 200mm (300mm equiv.)

AF-S DX VR Zoom-Nikkor 18 - 200mm f/3.5 - 5.6G IF ED
Image taken with Nikon D300, Zoom-Nikkor 24 - 120mm f/4.0
ISO 200, f/5, 1/60, 120mm (180mm equiv.)