My friend from New Zealand read my posting on photographing people out on the surf and thought using a long lens from shore might be the best option. So, he asked, what should he consider when buying a long lens?
I have a blog posting all written up that I haven’t posted yet on how to choose lenses in general- and why some are so much more expensive than others with similar specs. I’ll put up that post shortly as it will be useful for this topic. But here are some points specifically for “long” lenses.
A long lens refers to great magnification and is measured by its focal length in millimeters. So a 200 mm lens is longer than a 50 mm lens. So the longer lens you get, the more you can “zoom in.” That’s the basics and you probably know all that.
As you’ll hopefully read in my next post, not all lenses are created equally. I’ll come back to this.
In this case, Paul is rightfully concerned about “lens shake.” The more you are zoomed in, the more your camera movement is visible. There are three ways to deal with this.
First: use a tripod or monopod. Either is good and has advantages. A tripod has more stability but is less easy to adjust on the run. And is heavier. Oh, you can buy carbon fiber, but look at the prices first…. A monopod might be good for this situation but you have to double check for straight horizons. Plant the camera, take a deep breath and compose the shot.
Second, pay a little extra for image stabilization. One of the best lenses I have is the Nikon 70-200mm lens with image stabilization. This lens has built in compensation for small movements and can help reduce shake a lot, especially in low light situations with slow shutter speed.
Third, pay for a “fast” lens. Remember where I said not all lenses are created equal? A fast lens refers to the “f stop” of a lens and is a ratio between the focal length of a lens and the size of the opening of the lens. In short, how big is that piece of glass in front? The bigger the opening, the more light that is let in and the brighter the image. The more light, the faster the shutter speed and camera movement is less of a factor. The smaller the f number, such as 2.8, the faster and brighter the lens.
You’ll notice that solutions two and three start with “pay extra.” Image stabilization isn’t too bad nowadays, but big, bright glass is expensive. My Nikon 70-200 lens with image stabilization is a fast f2.8 throughout its focal length but it cost about $1700. That’s more than 3x as much as a D40 camera with a standard lens. On the other hand, you can get a Nikon 70-300mm lens that is a bit slower at f/4-5.6 (This means it is f4 when at its widest point, and f5.6 when zoomed in) for about $160 US from B&H Photo. And that has image-stabilization built in to it! (Nikon calls it VR for vibration reduction.) So is that extra bright glass worth about $1500? That is up to you to decide. If you’re going to do this for a living, you’ll want the good glass. If you are shooting casually, go for the slower lens and shoot on bight, sunny days. And use a tripod.
One other big lens option when you need a LOT of magnification and just don’t have the pocketbook for really big glass (a Nikon 500mm f4 lens is $8500) you might use a mirror/lens. Technically a mirror/lens is designed like a Schmidt-Cassegrain reflector telescope and uses a big mirror to collect the light, rather than a lens. It is much easier to make a big mirror than it is a perfect piece of glass. So a 500mm mirror/lens is about $120 or so, and an 800mm mirror/lens is less than $250.
Naturally, there is a downside. First, most of these mirror/lenses are a slow f8. I’ve used these and actually notice the image is a bit dim. Second, they are all manual. No autofocus or other fancy 3-D metering blah blah. You put it on your camera and focus it and keep it focused while you take a picture. But, when it comes to high magnification at a reasonable price, these are it.
That is about all I can think of to help you decide about long lenses. If the price tag of a fast lens didn’t scare you, read my upcoming post on what makes a good lens good.
Thanks for reading,
Mark
www.MarkDuehmig.com