I’ll begin this entry by saying I am writing it without coffee. I went through the drive-through this morning and forgot to order coffee. Now this shouldn’t be a big deal, but my daughter has fallen asleep in the back seat, and this much-needed nap will help her get though pre-school today, so I’m going to just sit here and write this… without coffee.

OK, so you’ve got a nice camera, likely with the “kit” lens that came with it, and you’ve decided that one of the first things you want is another lens. Either really wide or really long- something to compliment the mid-range workhorse that came with your camera. But when you look at the prices from the camera stores, you are shocked and confused at the wide range of prices for some lenses. Why the big differences?

A couple of reasons, but first, lets make sure we’re comparing apples to apples. When you see prices on line, or in the back of magazines, beware the unscrupulous sellers. Some will, at best, bate-and-switch you or sell you gray market stuff. At worse, you’ll end up with junk and without your money. I have experience with both, as those prices can be tempting and my spirit was weak. But please, take my word for it; there are only a few places to trust: B& H, Adorama & Abes of Maine. Hopefully your first choice is your local camera store. We need to keep those in business so we have a place to go and touch and feel our goods before we buy them without flying to New York. But I digress…

There are two big differences in lenses that affect their price; construction materials and the speed of the lenses.

The kit lenses that often ship with DSLRs are a good example of materials. The lenses are probably a high quality plastic such as fluorite.  This isn’t bad as it does a great job and is lighter than glass. But, it isn’t as perfect as glass.

Even with glass lenses there are different qualities. Ground glass vs. cut glass and even composite glass, are all options for making lenses. The most expensive lenses are made from high quality glass blanks that are ground down to their final shape. The difference in quality is definitely that last 5-10%. Lens technology is such that the kit lens sold today with a camera is superior to a great lens just a few years ago.

The other, more important factor, is how fast the lens is. When I mention the speed of a lens, I’m talking about the smallest f-stop that a particular lens can be set to. The f-stop is a ratio between the focal length of a lens and the opening of the lens. The focal length is the number most people are familiar with; “I just bought a 200 mm lens.” 200mm is the focal length.

But an important factor with that focal length is the size of opening on the lens that lets light in. Comparing the two gives you a minimum “f-stop.” For example, if I had a 100 mm lens with a 50 mm opening on the front, I’d have an f 2 lens. (100/50=2). The smaller the front opening, the bigger this number becomes. A 100 mm lens with a 25mm opening is an f 4 lens. An lens is rated by its smallest f-stop.

It isn’t hard for a lens manufacturer to increase the focal length of a lens, just separate the glass elements further. What costs money is increasing the size of that front piece of glass (and most other inside too.) You can guess that time and materials increase greatly between a 25mm wide piece of glass and a 75 mm wide piece of glass.

So why do you care how big the front lens is or how fast lens is? If a 200 mm f 5.6 lens has the same magnification as a 200 mm f 2.8 lens, why not go photograph birds with the cheaper, and lighter, lens?

The difference is light gathering power. A lens with a bigger opening lets more light in. The results are brighter, crisper photographs and much faster shutter speed. Have a look at the sidelines at a pro football game. The photojournalists all have big lenses with HUGE front lenses. Those are 500 mm and bigger lenses that open up to f 2.8. They cost big bucks. (And don’t get lens envy, most of the photogs rent them.) But to stop action with fast shudder speeds and get crisp images, you need to let a lot of light in.

There is one other big benefit to a fast lens; depth of field. This is a whole posting in itself, but the f-stop you’ve got your lens set to determines how much of your image will be in focus.  If you’re on the edge of the Grand Canyon and want everything from the rock in front of you to the distant river to be in focus, you close down your aperture to a small opening, which changes your f-stop. If there is enough light, you might choose f 22. If there isn’t enough light, use a tripod for that long exposure. Everything will be in focus.

But if you’re taking photos of your daughter blowing the seeds from a dandelion, you want all the attention just on her. So you stop down to f 2.8 if you can, and only what you focus on will be sharp. Everything else will be soft and unimportant.

Most “kit” lenses are listed around f 4.5-5.6. This means that zoomed out, they can open up to about f 4.5. And zoomed in they’ll have a minimum f stop of 5.6. These will give you good general photographs, but won’t allow you the option of a short depth of field.

So that is the 10,000 foot view of lenses. When you open your camera catalog, you’ll see the wide range of lenses and prices. The difference between a $200 and a $1600 lens is that last 10% of quality and flexibility when composing a photo. Is the difference worth about $1400-1500? That is up to you.

I’ve always given the advice that pretty much all DSLR cameras now are fantastic. With cameras, like lenses, you’re paying for that last 10%. But lenses will outlast cameras. The glass is where you’ll see that last 10% for many more years. If you can afford it, buy a cheaper camera body and put your money in the glass. When you wear out your camera you upgrade the body and keep using those wonderful lenses.

But isn’t it nice to know that even if you are using the cheapest digital gear out there, you can still have great photos? It all comes down to you and when you push that button. The Moment. So whatever you have in your camera bag, get out there and…

Keep shooting,
Mark
www.MarkDuehmig.com