Teleconverters

Using a telephoto/teleconverter combination like this AF-S VR NIKKOR 200mm ƒ/2G IF-ED and AF-S Teleconverter TC-20E III gives you great macro options.

Since they increase the focal length without changing the lens’ minimum focusing distance, teleconverters are great tools for photographers who want to photograph insects and flowers. Add a 2x converter to a 300mm ƒ/4 lens that focuses down to five feet (0.25x magnification), and you get a 600mm ƒ/8 lens that focuses down to five feet (0.5x magnification—half life-size—from five feet away).

The light loss isn’t that big a deal for close-up work because you’re stopping down to increase the limited depth of field at close focusing distances. Due to the high magnification compared to work at normal shooting distances, it’s best to work from a tripod, and either use flash or a higher ISO setting to get a faster shutter speed to minimize blur due to camera shake. The flash unit’s very brief duration at close range also serves to minimize both camera shake and subject-motion blur.

Kenko DG extension tubes. Extension tubes are spacers without optics in them.

The primary difference between a teleconverter and an extension tube is that the converter contains glass elements and the extension tube is just a spacer that moves the lens away from the image plane. The elements in the converter actually increase the focal length of the lens to which it’s attached. The extension tube doesn’t optically increase the focal length; by moving the lens farther from the image plane, it allows you to focus closer than would be possible with the lens alone, and that increases the obtainable magnification. Like converters, extension tubes reduce the amount of light transmitted to the film/image sensor; the longer the extension tube, the greater the magnification and greater the light loss. As with teleconverters, built-in TTL metering automatically handles the light loss, but you have to take it into account if using an external meter.

Adding a teleconverter to a lens like this Sigma APO 150-500mm F/5-6.3 DG HSM can give you extreme magnification, but you’ll have to expect significant image degradation.

If you want to get extreme, you can get a supertelezoom for a reasonable price, and when you add a teleconverter, the magnification is spectacular. This isn’t an everyday combination, and you need a steady hand and a sturdy tripod to use it. Also, image quality shouldn’t be expected to be perfect. Think of this sort of combination as similar to using ISO 25,600. Sure, you can set ISO 25,600, but it’s best left to situations when the only other option is no shot at all.

For example, the Sigma APO 150-500mm F/5-6.3 DG HSM carries a street price of $1,069, features a built-in optical image-stabilization system, and is available in mounts to fit Canon, Nikon, Pentax, Sigma and Sony DSLRs (full-frame and APS-C). The Tamron 200-500mm F/5-6.3 Di LD carries a street price of $949 and is available in mounts for Canon, Nikon and Sony/Konica Minolta DSLRs (full-frame and APS-C). The 500mm focal length takes you well into supertele territory, even on full-frame DSLRs and 35mm film cameras; on APS-C DSLRs, that 500mm setting frames like 750-800mm on a full-frame camera for even more “reach.” Add a 1.4x teleconverter, and you’re looking at a range of 700mm to over 1000mm, depending on your camera.

Using a teleconverter like this Tamron SP AF Pro model with a macro lens like this Canon EF 100mm ƒ/2.8 L IS USM Macro can bring you some wild supermacro images.

Although the term “macro” is thrown around loosely, true macro is generally accepted to be life-size, or 1:1 reproduction ratio, on the sensor. By attaching a teleconverter to a 1:1 macro lens, you can get into the realm of supermacro and shoot at higher magnifications. The result is very narrow depth of field and extreme close-up perspectives. The photographs can be spectacular. To shoot supermacro with a teleconverter, all of the same rules about keeping steady apply, only more so. Also, it can be quite challenging to find even a tiny subject looking through the lens, so a relaxed and patient demeanor is helpful. If you take your time, you can get some incredible photos.

In these illustrations, you can see how the subject-to-lens distance stays the same with and without a teleconverter. This is one of the main reasons why macro and supermacro photographers use them. You can also see the magnification at the image sensor. Notice that in Figure 2 the subject-to-lens distance is the same as in Figure 1, but the sensor, and, therefore, the photographer, is slightly farther away.

Teleconverter + eBay = Inexpensive BIG Telephoto

If you’re willing to focus manually, you can save some money on your telephoto setup and still get excellent optical quality. A new 300mm ƒ/2.8 supertelephoto lens can cost upward of $6,000. A new 300mm ƒ/4 is around $1,400. But an old, non-AF Nikon 300mm ƒ/4.5 sells for around $200 on eBay. In some cases, you can find an old telephoto lens that mounts directly on your camera (Nikon, for example); in other cases, you may need an adapter.

Lens adapters let you mount lenses for other cameras on yours, such as old Canon FD lenses on EOS bodies, Nikon lenses on Canon bodies and just about any lens for which you can find an adapter onto mirrorless bodies. The big concerns regarding lens adapters are availability for the lens and camera body in question, and flange-back distance (the distance between the lens mount and the image plane). If the camera body plus the adapter’s flange-back distance is too great, the lens won’t focus all the way to infinity, but you can use it for close-up work. This isn’t a problem with mirrorless cameras and their short flange-back distances. If the flange-back distance for the body and adapter is too short, the lens will focus past infinity—not a big a deal, but be aware of it. Many adapters are just connectors with no linkage; they allow you to attach a given lens to a given camera, but focus and exposure are manual (or aperture-priority AE). Some adapters (generally, those from the camera manufacturer) provide metering and even AF capability.

Depending on the lens-teleconverter-adapter combination, you may or may not be able to use all of your auto-exposure functions. There are so many possible combinations available that we can’t cover all of the nuances of each here. This can be an excellent solution, but you have to do some homework. Check your camera’s manual to determine compatibility or try contacting the manufacturer directly.

All-In-One Superzoom + Teleconverter = Compact Do-It-All Package?

The all-in-one, wide-ratio superzooms—typically, 18-200mm, 18-250mm, 18-270mm, 18-300mm, 28-300mm and the like—very conveniently package focal lengths from wide-angle to telephoto in a single surprisingly compact unit. That’s a wonderful thing for anyone who wants to travel very light while retaining focal-length flexibility in the field. Can you add a teleconverter for even more versatility? Yes, but it’s probably not a great idea. First, with some lens/converter combinations, damage can occur from rear lens elements contacting the converter front element should you zoom to a wide setting. Second, and more importantly, designing and manufacturing a lens with the huge range of an all-in-one superzoom requires a number of compromises. Optical performance at the longest focal length isn’t as good as with a prime lens of that focal length or with a shorter-range zoom (say, a 70-300mm) at that focal length. Add a converter, and image quality is compromised further. A third consideration is that superzooms have maximum apertures of ƒ/5.6 to ƒ/6.3 at their tele end, which means your DSLR’s AF system likely won’t function with a converter added. For these reasons, we don’t recommend using a teleconverter with a superzoom. (Note that Sigma’s 1.4x and 2x converters work well with the company’s 50-500mm superzoom, with manual focusing only, but that’s a normal-to-supertele lens, not a wide-to-tele lens.)