What Lens Should I Buy?March 21, 2008
This is the question most often asked by my students. So I thought I should take this opportunity to set down my thoughts on lens choices.
First let’s clear up a few basic issues about lenses. The most important thing to understand about lenses is that they are basically cropping devices. They simply serve to crop the scene in front of you, nothing more. You can accomplish the exact same task by holding a piece of black card board, with a rectangle cut out of it, in front of your eye. As you move the cardboard back and forth it crops the scene, performing the exact same function as various lengths of lens. Lenses do not “Control “ perspective or depth of field. These are controlled by where you stand in relationship to your subject matter.
The longer the focal length of the lens, the more it crops the scene, so a wide angle lens simply shows you more of the scene than a telephoto lens. It’s really just that simple.
Now for some definitions. Let’s start off with the “normal” lens. This is defined as a lens whose focal length is equal to the diagonal of the film (or digital) format. For 35mm film or “full frame” digital cameras this is around 50mm (actually 43.27mm for you Pythagorans). This lens gives a field of view approximately equal to what we see with out eyes (sort of… kind of)… at any rate, we call this a normal lens.
Any lens with a shorter focal length is a wide angle, any lens longer is a telephoto lens. Ah Ha (or Duh!) I hear you say.
So that was great when everyone shot with 35mm film….. but then came digital…. With various size sensors and the dreaded and much misunderstood Focal length factor (or quotient of confusion). Basically, what it boils down to is this: If you’re shooting with a DSLR that’s not a full frame camera (Canon 5D, 1Ds or Nikon D3), your normal lens is around 30mm. OK… don’t ask me why, just go with it! Otherwise, we’ll be here all night.
I’ve made a chart of lens lengths and what they’re commonly used for. I’ve put the focal lengths for both “full frame” 35mm and the more common reduced frame (APS-C size) used in most DSLR’s. This should help you determine what lenses might be most suitable to the type of photography you’re doing. Here’s the link
Ok, now for the zoom vs. prime debate! (Prime lenses are single focal length, while zoom lenses cover a range of focal lengths) Here’s my take on it. While zoom lenses definitely have some convenience advantages, these come at a cost. Most of you probably already have at least one zoom lens that came with your camera, but this is definitely not a very high quality lens. It’s OK for general shooting, but if you compare the results with a really good lens you’ll see a definite difference in terms of sharpness, contrast and flare. The other big compromise with zoom lenses is the widest aperture. While most of zoom lenses have a maximum aperture around f/4, a comparable prime lens will be at least f/2.8 or wider. This means you will be viewing a brighter image in the viewfinder, making focusing easier. As well, you have the ability to shoot in lower light levels. But, most important is the ability to shoot with a smaller depth of field so you can better control what falls into and out of focus. Yes, you can buy wide aperture (very high quality) zoom lenses, but you have to pay big bucks (in the $1500-2000 range), and most of these lenses are big, heavy clunkers. When I see students hauling out these massive glass behemoths all I can think of is the mounting chiropractor bills!
So I tend to lean towards prime lenses for a variety of reasons. In addition to the above issues, there’s also a more basic photographic/aesthetic point. When you shoot with a prime lens, you zoom with your feet, meaning you move around your subject rather than just standing still and zooming in. This means that you are forced to explore different perspectives and relationships with your subject, often finding new or unusual ways to see and explore. I won’t go so far as to say that zoom lenses make lazy photographers, but….
Now that I’ve written a ridiculously verbose introduction to the subject, I’m finally ready to answer the opening question! What lens should I buy????!!!?!
First off, if you have a reduced frame camera, you should definitely get a 50 mm f/1.2 or f/1.4 lens. It’s a perfect moderate telephoto lens, and at around $300 or less (around $100 for the f/1.8 version… still an excellent lens!), it’s one of the best lenses you can buy! Unfortunately, once you shoot with this lens you’ll be forever dissatisfied with your “Kit” zoom lens. Sorry. By the way, if you see one of these lenses in the used counter, or on ebay, grab it! They’re getting harder to find used as photographers discover how fantastic they are.
If you’re shooting full frame, an 85 mm f/1.8 is another great bargain lens, a fast, light lens for under $400, that is just a perfect all around lens for portraits, events, tabletop, whatever! Don’t be tempted by the very high priced “premium” lenses at $1500… you won’t see the quality difference, and you’ll definitely feel the difference in your neck and wallet!
On the wide angle side of things, a 35mm (on full frame) or 20 mm (on reduced frame) f/1.8 or f/2 is an incredibly versatile lens for less than $300!. It’s long been the “standard” lens for the documentary photographer, as well as for landscape work. If you want a great, small, light lens to keep on your camera for general shooting, this would be it! Again, the standard quality lenses, as opposed to the premium line, are a great bargain, and virtually match the image quality at a much lower price.
If you need a bit more wide angle coverage, the 28mm/ 17mm lens is a good choice, providing a bit more coverage without getting into the “extreme wide angle” feel.
Armed with just these two lenses, a moderate wide angle and a moderate telephoto (for around $400-600 total) you can handle probably 90% of all your photo needs, and get results that will surpass any zoom lens in that price range. Granted, you’ll have to change lenses occasionally (or you could use the money you saved to get a second camera body!). And think of the cardio benefits you’ll reap from using your feet to zoom in! Back in the film days (Oh so long ago), I shot most of my work on my trusty Hasselblad, using just this combination of lenses for virtually all my work.
Ok, I know this sounds like blasphemy to all of you who’ve been lusting after that ultra-wide-to-super-telephoto f/1.0 super-macro-zoom, but hey, it’s my blog and I’ll blaspheme if I want to! And I’m sure the camera/lens manufacturers don’t want you to think this way. But I figure if you can spend less money and get a couple of superb lenses that will handle the vast majority of shooting situations….. why not! Then, as the need arises for specialty lenses, like long telephotos, super wide angles, macros and Tilt/shifts, you can rent them as needed to try them out, then eventually buy them if you find you really shoot with them often enough to justify the expense.
There’s one area where I will concede that the speed and versatility of a good zoom is required, and that is the wedding/event photography (or sports) where the need to respond to quickly changing action is of paramount concern. Unfortunately, this type of shooting often includes less than optimum lighting situations, so a wide aperture is also required. This means dropping the big bucks on the “premium” zoom lenses with constant wide apertures, and weight to match! Hopefully, if you’re doing this type of work you’re charging enough that the clients can bear the cost, and maybe your assistant can help bear the weight!
There are definitely some other very nifty specialty lenses out there for those of you with $$$ burning a hole in your pocket, but that will be the subject of another post!
So there you have my very long and convoluted answer to a simple question (sorry for the eye strain!). Hope it helps!