Prime vs Zoom : The F number decides!


Prime lens or zoom lens? Is 30mm enough for all life situations, or would you like an 18-55mm to cover landscapes and portraits? Or maybe an 18-200mm for sports and street photography as well? Here is my take on the matter, and why I go for primes.

What is a prime lens anyway? Sounds weird. But it isn’t really! It’s all very simple:
prime lenses are lenses with a fixed focal distance. The most popular are 30mm, 50mm, 85mm, 135mm and 200mm. So this means you can’t zoom in or out, you only get the value your prime is built for.

Most lomo cameras are prime lens cams. The Holga 120 has a 60mm prime lens, the Diana Mini has a 24mm wide prime and a Lubitel 166B has a 75mm prime.

Prime lenses are easy and cheap to build, have a very simple construction and this allows them to have a very clear advantage over zoom lenses: big apertures.

What are zoom lenses? Simple: lenses where you can zoom in and out. There’s a bunch of popular ones: 18-55mm, 18-135mm or 18-200mm. Zoom lenses are made usually as all-round lenses – created to cover most life situations and made in a way that you wouldn’t have to carry around a bunch of interchangeable lenses to fit your needs. In this way your 18-200mm would be fit to shoot some wide-angled landscapes, some nice portraits at 50mm and perhaps some stalking street photography at full 200mm. This versatility, however, makes them more expensive.
And of course, they have a clear disadvantage compared to prime lenses: aperture.

Because of the way they are built, prime lenses can achieve very high aperture values. The cheaper lenses go up to f2.8, some go to f1.8, and the top-notch lenses go up to f1.4 or even f1.0 (like a certain Leica lens, which even if already used costs close to €3000).
Zoom lenses change aperture depending on the focal distance. Say you have an 18-200mm with f3.5-f5.6. This means that at 18mm the biggest aperture you get is f3.5, but at 200mm the biggest you can get is f5.6 which in poor light conditions can be fatal.

What do big apertures mean?
Most and foremost: MORE light! With an aperture of f1.4 you can without a problem use ISO50 or ISO25 films and still use shutter speeds of 1/500 or even 1/1000 – fantastic if you shoot moving subjects. Or you can get away with shooting in a poorly lit room without a flash, and without the bulb mode, and without a high ISO film, and without camera shake!
Also, with high aperture values, you get shallow depth of field which gives you fantastic emphasis on your subject!

I currently own 2 fantastic prime lenses for my Konica SLR:
a Hexanon 57mm, f1.4 and a Hexanon 135mm, f3.2.
Notice the difference:
Picture 1 – F1.4 (so fully open). Pic 2 – F2.8 which is what the LCA lens has. And Pic 3 is f4.5 – what a Lubitel 166B uses. The Holga goes to f8, so even smaller than that.

The following pictures were taken with the Hexanon 57mm prime, with apertures varying between f1.4 and f2
See for yourself and be impressed by the depth of field:

Yes, zoom lenses ARE nice. They really do prevent you from dragging along 20 different cameras or 20 different lenses. However, I’ve grown too fond of shallow Depth of field, and I’ve grown too fond of my hexanon prime to get any zoom lenses in the future.

For those who’d like to read up on Depth of Field in detail, especially how big apertures affect it, here you go:

written by xxxanderrr on 2011-05-11 #gear #tutorials #camera #tutorial #aperture #lens #may #lenses #tipster #depth-of-field #depth #zoom #prime #dof #requested #shallow


  1. disasterarea
    disasterarea ·

    Yay for prime lenses! (love my Canon 50mm f1.4)

  2. awesomesther
    awesomesther ·

    Loving the article and yes prime lens is awesome.. cos I love bokeh.. :) I've a 50mm f1.4 for my Minolta. a 50mm f1.8 for my Canon and 50mm f2 for my Pentax. ALL AWESOME stuff :D

  3. lislisdotnet
    lislisdotnet ·

    Ditto on the cannon 50mm f1.4 love!

  4. catherinejcruz
    catherinejcruz ·

    ahhh, what a great article! thanks for writing this. :)

  5. xxxanderrr
    xxxanderrr ·

    thank you all for the kind words :))

  6. aeroektar
    aeroektar ·

    Very much in agreement; I very rarely use a zoom. If you want really extreme subject isolation, your cheapest bet (still a few hundred $ by the time you've put it together) is a Speed Graphic and a 178mm f2.5 Aero Ektar. On a 35mm camera, the equivalent would be around 50mm F0.7.

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