Thursday, June 12, 2014

Nikon Prime vs Zoom Lenses: Pros and Cons

Long-time readers surely remember that I generally favor prime lenses. These are the ones I use for my professional assignments, these are the ones I trust. Still, there are some very good zoom lenses around, and I have never claimed what is good for me is necessarily good for others.

The motivation behind this article was a photoshoot I had couple of weeks ago. On the eve of this occasion (where I was expected to take graduation photos of a pro skater), the weather report mentioned torrential rain. I knew two things: a) It would be a rushed, "let's-get-done-with-it-so-that-we-eat-cake"-kind of occasion; b) there would be a great chance I'd have to work in the rain. Although my Nikon D700 is water-resistant (tested!), changing lenses in the pouring rain is not something I'd like to try. The idea that we wouldn't have much time only added to the thoughts bothering me the night before.

When the lights go down, the aperture needs to get wide. Primes have the upper hand there.
And so, I decided to do something quite unprecedented for me: The primes were left home, a midrange zoom came along. The photoshoot was a success, and a large part of it was because I didn't have to waste time swapping lenses. Of course, I had used zoom lenses before - countless times. But that was the first time in my modern professional history that I actually left prime lenses behind and went to the...lion's den carrying only a zoom with me (Notice how I haven't yet mentioned which primes were left home and which zoom came along. There's a reason for this, read on!)

OK, let's cut to the chase. Let's assume a situation where the choice is between a fast midrange zoom (e.g. the Nikkor AF-S 24-70mm f/2.8) and two primes covering the wide and the tele end (say, a 28mm and an 85mm).

 First of all, before I proceed to give you the comparison list, I must stress one very important aspect of the "Prime or Zoom" discussion: There is no sense at all in carrying with you both types. If you plan to go somewhere with a 24-70 f/2.8 zoom, it is entirely meaningless to also carry the primes.

Primes are Better because:
* they offer larger max. aperture (two stops if we compare f/2.8 with f/1.4), which means better low light capabilities
* in absolute terms, they will always yield better image quality (when we compare equal caliber lenses) compared to zooms, although differences can be minimal
* they are individually smaller, lighter lenses (but not when you have to carry more than one!)

Zooms are Better because:
* primes have a very limited focal length range (well, only one per lens!)
* No time wasted for swapping lenses, no risk for e.g. rain or dirt getting into the lens.
* although individually larger, it is much easier to carry a camera and its single zoom lens than a camera and three primes.

Putting it all together:
- Start by asking (and answering) a simple but critical question: "What focal lengths do I need for the photos I'm planning to take"? If the range is too great (for instance, a wedding requiring both wide shots of a cathedral and intimate portraits), carrying primes can be highly impractical. A 24-70mm and a 70-200 zoom combo would be all you need (compared to, what? 24mm, 50mm, 85mm, 135mm, 200mm primes?)

- Let's assume the range required is not that extreme. However, let's also assume the light will be bad and you need to cover fast action (basketball in a dimly lit gym, for instance). The difference between an 85mm f/1.4 and an "only" f/2.8 zoom is two stops, or the difference between 1/125 and 1/500 (or ISO 3200 and ISO 12800). If that is something you can live with, depends on your camera.

- A lot of things happening in quick succession. Balloons are released in front of the church *click*, rising rapidly up in the sky in front of the majestic churchbell *click*, the bride is crying in happiness *click*. Three photos taken within 5 seconds from each other, requiring (let's assume/guess) focal lengths of 50mm, 24mm, 85mm. You don't need me to tell you that you missed at least two (if not all) of these shots if you had a prime attached. You could get all of them if you had a midrange zoom attached, instead.

Zoom or Prime? It depends. It really does
Reaching the conclusion of today's topic, I need to reveal which midrange zoom I used for the assignement. Well, the answer might surprise you. It was a humble Nikkor AF-S VR 24-85mm f/3.5-4.5Gand it performed flawlessly. Yeah, it was more than two stops slower than an f/1.8 prime. Did it matter? Not for daylight outdoor use. Would I have taken it for a dark club concert? No, I doubt it.

And that's the thing: Each lens (and each kind of lens) is made for a different purpose. I have another assignment in couple of days - it will be a studio portrait photoshoot, totally controlled environment. I will need only one lens for it - and it will be the Sigma 85mm f/1.4 (hint, hint: there is a review coming for it, long overdue!)

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