8 March 01

If you ever think you have enough reach with your long lenses. Think again! You never have enough. Okay, there's a limit to everything but sometimes it just seems like you can't get close enough without spooking what you're trying to shoot. Sure, it would be great to have the 1200mm lens to get those elusive critters. But, that kind of glass is simply out of the reach of 99.9% of the world. Shoot, 800mm lenses are out of the reach of 80% of the world. So how do you get that extra reach without spending your childern's college fund? Well, it's simple, There's a thing called a teleconverter. Essentially, it a small contraption that goes between your lens and body that "magnifies" the optical characteristics of your lens. In short, it's like adding a magnifying glass to your long lens. There are two basic types of teleconverters--a 1.4x and 2.0x converters. There were a couple of 3.0x converters out there in years past, but I haven't seen them recent.y. Good thing because there's severe problem with teleconverters which I'll get into later.

How do these thing work? Essentially, they just maginify/expand a portion of the image by the use of high quality lenses. This effecttively expands the focal length. A 1.4x converter multiplies the focal length by 1.4. A 500mm lens effectively becomes a 700mm lens. A 200mm becomes 280mm. You get the idea. A 2.0x converter multiplies the focal length by 2.0. It's the same idea. Is there a problem with this bonanza? As a rule of thumb, you can't get something for nothing. Teleconverters aren't any different. Most people say they sap light which means things get dimmer. Not as much light passes through. Sure, that's correct. In fact it works out that the amount of light lost is equal to the amount of magnification. Add a 1.4x converter, lose a stop or 50% of your light. Add a 2.0x converter, lost two stops of light or 75% of your light. What's really going on here is you're increasing the focal length but not changing the aperture size. Remember that f-stop is nothing but the focal length divided by the aperture size. If you have a 200mm lens with a maximum f/4 aperture, you essentially have a 50mm aperture size. Add a 1.4x teleconverter, you get a 280mm lens with the same 50mm sperture size. Do the math, 280mm divided by 50mm equals 5.6. Or, you lens combo now has a f/5.6 maximum aperture. So, light isn't really being suck away by these things. It's just the size of the whole that light passes through isn't keeping up with the increase of focal length.

Matched teleconverters are a term in the photography world that gets a bit of press. What it means is the optical formula of you teleconverter was designed to work best with a given set of lenses. Sure come company's converters may fit your lens, but is the combination "matched"? If not, you may have no idea if the setup will provide the highest quality available. As the magnification gets higher, the need for "matched" converters gets greater. As a rule of thumb, staying with the manufacturer of your lenses when buying a new teleconverter is the way to go. The big brained guys that designed your lens probably took into account how they'd integrate a teleconverter. I know Nikon has with theirs.

What's all this have to do with my Nikon teleconverters you may ask? It's a bit of background. Really it's important to know how your equipment works and why things work out the way they do. Teleconverters are great but there are a couple of things to worry about. Anyway, here's what I think about my TC-14e and TC-20e. In a word, they're "great". No, they aren't perfect but they do wonderful things.

First, the bad part. There's no kidding a tiny amount of image degradation with the TC-14e when used with the 300mm f/2.8 AF-S and 500mm f/4 AF-S. You can't really tell there's any change in the image quality without really getting close with a lupe or looking at an enlarged image. Fortunately, the image quality is totally acceptable. In fact, I have to say, the 300mm f/2.8 AF-S combined with my TC-14e is still produces my best images. Perhasp it's testimony to the tremendous quality of the 300mm f/2.8 AF-S but I think some of the credit has to go to the TC-14e. By the way, the 500mm f/4 AF-S combined with the TC-14e isn't a slouch either. I don't ever hesistate using the TC-14e with either of these lenses. I almost forgot my 80-200mm f/2.8 AF-S. If you remember, I bought that lens because I wanted a hand-holdable bird lens. 200mm is too short for most inflight bird photography, but with a TC-14e, it starts being acceptable. Add a TC-20e, now you're talking. A 400mm f/5.6 AF-S is a great bird lens. Which brings me to the supposedly next bad part of teleconverters. With the diminished light getting to the camera when a teleconverter attached, the AF sensors have less light to work with. Theoretically the AF speed is supposed to be less. I can't say I can tell the difference when my TC-14e is attached to any of my lenses. This teleconverter seems to defy convention. Don't look a gift horse in the mouth I say.

How does the TC-20e work? Great, but it's not as good as the TC-14e. Once again, the 300mm f/2.8 AF-S combined with the TC-20e is great. But, I don't think it's as good as either my 500mm f/4 AF-S alone or combined with the TC-14e. One nice thing with having that teleconverter around with my 300mm is I have a huge focal length range with only one small lens. Does that sound like an advantage when you're hiking and trying to save weight? It sure does. Shoot, it works great when traveling and you're trying to save space. Except for the smallest birds, 600mm is plenty of lens for most situations. Also, the AF speed seems to be quick enough. I don't have enough experience using that combo to really know if there's a severe reduction with AF. How about the TC-20e with the 80-200mm f/2.8 AF-S? I think it's suberb. The AF speed is fast. Fast enough as a bird lens. Is it as fast as the Canon 400mm f/5.6 IS? No clue. I've never had an opportunity to use that lens. But, for use as the Nikon hand holdable quick bird lens? This combo is great. Totally acceptable.

Now for the bad part. The Nikon F5 will not auto-focus with lenses that have apertures less than f/5.6. There simply isn't enough light. Sure, I've seen my F5 attempt to focus with my 500mm f/4 AF-S combined with TC-20e, but the images are mostly soft. I thought for the longest time that I was suffering from the physics associated with a 2.0x converter. But, occasionally I got a sharp image like the one above of the Horned Grebe. Why was that? What was unique about those images. In most cases, I manually refined the focus prior to shooting the image. I think for some reason, the F5 doesn't focus accurately with the 500mm f/4 AF-S combined with the TC-20e. Shoot, Nikon won't even say the combo will work. I tried to shoot with smaller apertures to increase the DOF. I even shot at higher shutter speeds. But, most of the time my images were slightly soft. It didn't matter I was using perfect long lens technique. So, in desperation I decided to manually focus my images when using that combo and the results have been much improved. Okay, the 500mm f/4 AF-S isn't perfect but it does an acceptable job when it works. Look at this Horned Grebe image. Sometimes having a 1000mm lens does have its advantages. The other less than perfect feature of the TC-20e is its size. Adding that teleconverter adds a non-trivial extra length to your lens. It may even significantly increase the possibility of vibration with long lenses by changing the moments of inertia of the overall setup. It's a theory for why perhaps I was getting soft images. So, even though I've apparently solved my soft image issue with the TC-20e, I still try my best at my long lens technique.

There you have it. My review of the Nikon TC-14e and TC-20e. the bottom line is they're great if you acknowledge some of their limitations. Without question, the TC-14e is awesome for the minimal sacrifices you have to make to increase your lens reach. The TC-20e, requires a bit more care and feeding. But, even that lens will improve your chances of making awesome images.

Cheers

Tom