Aimlessly Pontificating on Photography

Shooting with Primes.

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My main reason for buying a Pentax DSLR when I outgrew the previous camera was the value it represented. Compared with the equivalent Nikon or Canon models it was significantly cheaper. And, according to the many reviews I had read, there were a lot of little features that were useful that weren’t present in competing models.

One of the things that I have now learned is of significant value is the number of fixed focal length (prime) lenses that are available for Pentax SLRs. Lenses that were made decades ago for Pentax SLRs can still mount the new digital SLRs that are available now. The Pentax “K” mount is well known and popular and has been around for over 30 years. And lenses from the preceding M42 mount can be fitted with a simple adapter.

The point of this is that, more than any other manufacturer, there are hundreds of cheap, excellent lens available for the Pentax DSLR. Most of them prime lenses. Having such an abundant resource is a major selling point for a manufacturer that always seems to appeal to the hobbyist, rather than the pro.

Zooms have become the pervasive standard but t wasn’t that long ago when the lens you got with your SLR would have been the standard 50mm lens. The ubiquity of the zoom lens sees most DSLR kits being sold with what is now called the “kit zoom”; a lens covering a reasonable zoom range usually from a wide angle to a moderate telephoto. These tend to be made as cheaply as possibly and, though competent for what they are, are not considered “good” glass. These kit zooms tend to be fairly slow also, having a fairly narrow maximum aperture.

Most camera manufacturers make a fast fifty, which is usually modestly priced. The fast fifty is a 50mm lens that has a wide aperture usually between f/1.4 to f/1.8. It is usually made out of plastic and is intended to be inexpensive. The Pentax equivalent is the FA 50mm which is a f/1.4 aperture lens.

Kiran at Kingston Promenade - FA50mm @ f/2.8

The real gems in the Pentax lens arsenal are the “Limited” lens. A series of prime lenses made to exacting standards, with metal construction and aiming to be as good as they can be. They were always fairly expensive, but they have become even more so with the recent popularity of Pentax DSLRs.

I have 5 prime lenses that I used to use quite frequently; the 21mm Limited, the 31mm Limited, the 43mm Limited, the FA50 and the Vivitar Series 1 105mm.

So why would you use a prime lens when zoom lenses are so much more convenient and handy? Firstly because the prime lenses are usually smaller and lighter than the zoom lenses. Pentax in particular advertises their “pancake” primes. Lenses so small that they become almost unobtrusive.

Boating down the Conservancy - DA21mm @ f/5.6

I remember a little while ago going out to take photos with some friends and facing the consternation and agitation (and dismissal) of a friend to whom I mentioned that I was confining myself to just two focal lengths represented by two of my prime lenses. Why would I “limit” myself rather than use the zoom lens I had available? Well apart from the technical superiority represented by prime lenses as against the compromises that are inherent in the design of any zoom (and particularly the kit zooms) there is also the way you see.

Although there is some correlation between the focal length of 50mm (on a full 35mm frame) and approximate angle of view of the human eye we typically do not see precisely the way a camera lens and image sensor combination “sees”. As a result, looking at a scene with your unaided eye is not going to look the way a camera sees it, even when you use the supposedly “normal” lens.

One of the attractions when using a zoom lens is the ability to adjust the field of view visible in the viewfinder to try and match whatever it might have been that caught your eye in the first place. On the other hand, frequent use and familiarity with a fixed focal length “prime” lens trains you to see the scene the way it is eventually going to look in the resulting photograph and causes you to be able to compose the photograph even before bringing the camera to your eye.


Bougainvillea Profusion - FA31mm @ f/6.3

The aesthetic consideration is not the only reason to consider prime lenses for regular use. The technical characteristics of the lenses are also a major consideration. It is not as simple an issue as to say that the Pentax FA50mm, f1/4 lens (ouch, I paid about half of what it is now going for) is twice as fast at 50mm than the DA*16-50, f/2.8 wide open. But it does give a frame of reference. By the time you stop the FA50 down to f/2.8 it is very sharp, sharper than the zoom at the same aperture. And 2 stops faster wide open means you can use ISO400 instead of ISO1600 in a dark room (unless you need the greater depth of field).

Not every prime lens is faster than the equivalent focal length of a zoom, but the odds are that a reasonably high quality prime lens will not have been designed with the optical compromises necessary when designing a zoom lens and will thus produce a higher quality photo all other things being equal.

It seems to me also that the bad characteristics, technically speaking, of a prime lens can also become quite desired. Adding a character and personality to photos that you may not easily find in other lenses. My favourite of all the prime lenses I have is the FA43 Limited. Firstly, the focal length often immediately causes a query with people who aren’t familiar with Pentax gear.

Reputedly this represents the diagonal of a 35mm film frame and is therefore closer to a “normal” focal length (on 35mm full frame) than 50mm. Whatever the reason I find it to be an amazing lens when taking pictures of my favourite subjects, my children.


Mira on the Couch - FA43mm @ f/2.2

There is a sublime quality to the contrast and bokeh (out of focus areas) that I cannot explain. As long as the background is not too busy (grass or leaves, for example) the resulting image is just extraordinary to my eyes.

The last of my prime lenses which I use regularly is the Vivitar macro. This one is often a challenge to use because it is very heavy and manual focus (feels like about 6 turns of the barrel from infinity to close focus). Most of the virtues of prime lenses that I extolled above; light weight and unobtrusiveness, are simply not present here. But one outstanding quality is: sharpness.

Even wide open this lens is fiercely sharp. There is no zoom lens made that can match this lens for image quality although many of them claim to have a macro feature. But the lens is not usable only for macros.


Leaves of Grass - Vivitar Series 1 105mm Macro @ f/2.4

Many of the qualities I’ve mentioned before; lightness, unobtrusiveness and others, although I touched only peripherally on them, should not be underestimated. My DA*16-50mm zoom is a huge lens, take it out on the road and point it at someone and they get nervous.

The point of this extended post is to highlight the usefulness of fixed focal length lenses. While they do not have the flexibility in framing that you will get with a zoom lens, their utility and benefits cannot be doubted. If you find yourself stuck in a rut with you zoom, it may be time to explore the pleasures and simplicity that using a single focal length can give you.


3 responses

  1. Quite an article. Personally, I have always liked the versatility of a zoom lens, but then again, I don’t own any primes. As someone in the graphic arts field, I can see the benefits of the extra sharpness of the primes that you mention, someday in the future I may own some primes and be able to boast as you have. 🙂

    August 17, 2010 at 7:58 am

  2. fidal

    Hey I really love your article. I discovered primes by accident! Someone bought some for something other than photography and I started using them. They have really turned my world upside down. I own a nikon, it was cheaper than canon 🙂 but like your input on the Pentax model.

    August 24, 2010 at 10:35 am

  3. Satya Ramnarain

    My first cameras all had 50mm “normal” lenses, and when I got a new replacement for a stolen one, I bought it with a zoom lens. I couldn’t figure why my pictures from my Guyana 2001 trip wasn’t quite as sharp and clear as my previous work. I realized it was the lens, it wasn’t a “kit lens” but it wasn’t the sharpest lens out there. Even so it hard to get away from using zooms because of the ease of use. It makes you lazy. A lot of people buy SLR cameras and wonder why their pictures aren’t good. The fault is usually their lens, sometimes it’s just no talent for taking pictures :). Another feature that makes one lazy is “live view”. My new camera (a 3 yr old model) doesn’t have live view and after a readjustment period I don’t miss it and prefer it this way.

    August 25, 2010 at 3:53 pm

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