Zooms or prime lenses ?

[Ceci est de nouveau un article en anglais que j’avais publié à l'origine sur Ipernity en juin 2015, et que j’ai récemment mis à jour. Pour mes lecteurs français, désolé, mais rappelez-vous que c’est bon pour votre anglais...! Promis, je reviendrai à la langue de Molière sous peu!]

A photographic lens is a compromise between the various contradictory imperatives that engineers and opticians must face when they design a new device. Forcing light to go through a certain path or channel and through a certain number of polished glass elements will always induce distortions of the light rays. To combat these distortions, more and more sophisticated elements and techniques are used, and quite successfully, too. However, when you read a lens review, you see that, for example, coma has been beautifully mastered, but at the price of a significant light falloff at wider aperture values. It is always a trade-off between this and that, and even when the price point is not a problem, super expensive lenses have a very hard time getting it right in all departments.

The difficulties are such that, over the past few years, camera manufacturers have enlisted the help of on-board, in-camera software to automatically “correct” some of the distortions before the photographer even gets to see its photo on the back LCD screen.

When you consider all the optical challenges that need to be faced for a lens of a given, fixed focal length, you can only imagine how such challenges grow and multiply when one designs a zoom lens, meant to cover not just one focal length, but a more or less wide range of different ones...

All things being equal, a zoom lens will obviously be more complicated than a single-focal length (or “prime”) one. It will also be bulkier and heavier, and “slower” than a prime lens, meaning that when wide open, its iris will not let in as much light as a prime. Finally, in most cases, a zoom will not perform optically as well as a prime. Therefore, the trade-off for the user will be some degree of convenience (only one lens instead of several) versus some degree of quality.

I say “some degree” because if the zoom lens will replace several primes and allow you to select any focal length within its range, it will still be bulkier and heavier than primes, so some of the benefits will be thus offset. It will also be less discreet, which can be a downside. The fact that zooms are “slower” (not let as much light in) also means they will be less usable in low light situations (unless you seriously bump up the ISOs —but then, at the risk of generating noise, another trade-off) and that the auto-focus will work more slowly because of less light coming through the lens. Your ability to use shallow depth of field to isolate your main subject from its background will also be severely hampered when using small aperture zooms, even more so with variable aperture ones which become very dark indeed towards the longer end.

“Fast” (or sort of fast) aperture zooms do exist, but they are expensive. And when I say “fast”, I only mean ƒ/2.8, when wide primes routinely open at ƒ/1.4. That may not look like much of a difference, but in fact, it means allowing four times as much light in...! A very big difference indeed.

Between 2007 and 2014, I mostly relied on zoom lenses, as I'm a Nikon user and Nikon had released, together with its D3 camera, a set of three zooms that all opened at ƒ/2.8 and covered focal lengths from 14mm to 200mm. Those zooms were so good, sometimes even better than existing primes in their focal range, that they came to be known as “The Holy Trinity”, and were (and still are) the daily workhorses of most Nikon-using pros.

Nikon's 14~24mm, ƒ/2.8 Nikkor zoom lens

Then, in 2014, I felt the need to use primes more often, like I had done in the days of film, when good zooms simply did not exist (there were very few exceptions as of the 1980s). I also diversified and bought some Zeiss lenses, as well as a Sigma of the so-called “Art” lineup.

Zeiss' 15mm, ƒ/2.8 Distagon lens, the equivalent of the "shorter end" of the 14~24mm Nikkor

Nikon's 24mm, ƒ/1.4 Nikkor prime lens, the equivalent to the"longer end" of the 14~24mm zoom.
In between 15 and 24mm, you zoom... with your feet!

Switching from zooms to primes means, of course, more lenses in the bag. As it happens, they remain rather bulky, even though they're lighter, because unfortunately (for my back), I insist on good image quality, and in optics, quality inevitably translates into heavy glass, and very often all-metal lens barrels. In terms of fast lenses, I haven’t gained anything at the widest end (the Zeiss being ƒ/2.8 like the Nikkor), because ultra-wide angle lenses cannot be much faster than that without becoming enormous —as regards the size of the front element— and totally unwieldy, but at the 24mm end, I have gained two stops.

Nikon's 24~70mm, ƒ/2.8 Nikkor zoom lens

   

To replace the 35~70mm ƒ/2.8 Nikkor zoom, I once had Sigma's 50mm ƒ/1.4 lens (today replaced by a wonderful, small, lightweight manual-focus Voigtländer 58mm ƒ/1.4), and of course my trusty 85mm ƒ/1.4 Nikkor; here, I have gained two stops over the whole range.

Sigma's 50mm ƒ/1.4 Art lens

Voigtländer Nokton 58mm ƒ/1.4 prime lens

Nikon's 85mm ƒ/1.4 prime lens

In the telephoto department, I completed my lineup with a Zeiss 135mm ƒ/2, a truly outstanding lens, and most recently with a 300mm ƒ/4 Nikkor prime. This last lens does not really comply with my “fast primes” requirement, however I bought it (a) because I needed the extra reach beyond 135mm, (b) because it is an extremely compact and lightweight lens (using a Fresnel element), and (c) because it was said to be professional quality, albeit not professional build. My copy was affected by a factory defect that had to by fixed via firmware update.

Zeiss' 135mm ƒ/2 prime telephoto

Nikon's new 300mm ƒ/4 prime telephoto

Those two lenses replaced my 70~200mm ƒ/2.8 VR II zoom lens, while giving me increased reach in case of need (not mentioning the TC-III 1.4× teleconverter which does quite a passable job with the 300/4).

Nikon's 70~200mm, ƒ/2.8 Nikkor zoom, VR II version

So, after a couple of photo trips, how is this new set working out? From a strictly “laziness-oriented” viewpoint, of course, it is somewhat more cumbersome. I do have to change lenses more often, and if I were in, say, very dusty situations such as an African safari, it would be a less advisable option than the zooms. Secondly, having only primes forces you to keep mental pictures of how each of the lenses in your bag “sees”, because you want to minimize the occurrence of cases when you think you need the 85mm, where in fact you need the 50, or the 135. Carrying primes makes it necessary to memorize the angle of view of each of them, which is good for your photography anyway, not to mention your brain cells. Not having the convenience of just turning a zoom ring, but having to “zoom with your feet” instead also makes you a better photographer by forcing you to move around, look at your subject in a different way, think about other possibilities instead of simply snapping a shot from where you happen to stand.

Finally, the outstanding image quality produced by good primes is very rewarding.

Will it, overall, be worth the extra weight under hot summer conditions? I will see in a few weeks in southern Italy, where I will be taking this whole complement with a Nikon D810 body. Compared to the small Fuji X-Pro 1 kit I took to Turkey last year, and to Greece the year before, it will be a change, certainly. We'll see if I return with a broken back, curse myself and say "Never again!", or if I managed to enjoy taking pictures in scorching heat with heavy primes and a full-size DSLR body

UPDATE, FEBRUARY 2018

This article was written in June 2015 and today, in February 2018, I have not (yet!) gone back to using the “Holy Trinity” zooms which I, of course, kept in my safe. I have now upgraded from the D810 to the new D850, and even though I will admit that I don’t always take the full complement of my primes (especially now that I’ve also added an ultra-big and heavy tilt-shift 19mm ƒ/4 Nikkor!), except when I know I’ll be traveling by car, I still very much enjoy the incomparable image quality that those primes give me, and which I am not about to give up.