Reach Out and Take It: Teleconverters

On the left is my 25-year-old Nikon TC-14B teleconverter, which is amazingly well-matched to my Nikkor 400mm f/3.5. On the right is my Tamron 140F-FNs 1.4x autofocus teleconverter. The optics are sharp, but autofocus with it is slow.
On the left is my 25-year-old Nikon TC-14B teleconverter, which is amazingly well-matched to my Nikkor 400mm f/3.5. On the right is my Tamron 140F-FNs 1.4x autofocus teleconverter. The optics are sharp, but autofocus with it is slow.

When I was 15, I bought my first Single Lens Reflex (SLR) camera, a Fujica ST-605n. At the time, I thought it was the coolest thing I’d ever held in my hands.

With flames spewing from a derailed train car carrying an unknown substance, emergency personnel kept us far from this scene south of Ada in March, 1996, but not so far that I was unable to get this image, with a 300mm and a 1.4x teleconverter.
With flames spewing from a derailed train car carrying an unknown substance, emergency personnel kept us far from this scene south of Ada in March, 1996, but not so far that I was unable to get this image, with a 300mm and a 1.4x teleconverter.

The camera arrived one July day with a light, small 50mm f/2.2 lens mounted on its even-in-1978-archaic screw threads. It was a decent lens, particularly since the camera and lens together cost, as I recall, $127. It focussed smoothly and the viewfinder was bright, so I was off and running in the game of SLR photography.

As I explored the potential of the 50mm, I also found that I wanted something telephoto. I looked on from afar at the spectacular telephoto lenses of the day (in the era before zooms) advertised in photography magazines and reviewed by Herb Keppler, an equipment reviewer for Popular Photography Magazine who influenced an entire generation of photographers, including me.

I found a bargain on a no-name 3x teleconverter from Cambridge Camera Exchange, which from that day to this remains one of the biggest rip-off stores in the business. In fact, when I ordered the converter over the phone, they forgot to ask me for what camera I was ordering, so a week later I got an envelope in the mail with the corner of a sheet of yellow legal pad torn off with the words “what mount?” handwritten on it.

I finally did receive the converter and immediately mounted it behind my 50mm. Wow! 150mm! The viewfinder was impressive, but the image quality was not. It was essentially junk.

So what is a teleconverter? “Teleconverter” is photography nomenclature for “telephoto focal length converter,” and uses optics placed between the camera and the lens to multiply the focal length of the lens by the number on the teleconverter. A 1.4x teleconverter multiplies your focal length by 1.4 times; a 200mm lens becomes a 280mm lens with a 1.4x converter, and so on. Also not inconsequential is the fact that you lose an f-stop for each increment of teleconversion. When your 200mm f/2.8 lens becomes a 280mm, for example, the maximum aperture is then f/4. With a 2x converter, a 200mm f/2.8 becomes a 400mm f/5.6. You can do the math yourself to see why: f/stop = focal length divided by aperture diameter.

This is my 400mm with the 1.4 converter looking down Main Street. Compare it to the image at the bottom of this entry.
This is my 400mm with the 1.4 converter looking down Main Street. Compare it to the image at the bottom of this entry.

So that leaves the obvious question: why would I use a teleconverter? For the most part, the only teleconverter I recommend is a 1.4x converter, and ever then I only recommend very good – and very expensive – ones. Using a teleconverter usually compromises a lens to begin with, and with a cheap one, things just fall apart. Some lenses, like the legendary Nikkor 300mm f/2.0 of 1985 vintage, have their own dedicated teleconverters.

When do I use a teleconverter? When the longest lens I have, which is usually a 300mm, isn’t giving me the reach I need, and the subject is too tiny in the frame to be effectively enlarged, I’ll use a teleconverter. A good example comes from March 1996 when a train derailed and caught fire. With unknown and possible toxic chemicals on the trail, fire department personnel wisely kept us back a quarter of a mile.

A dedicated telephoto or supertelephoto lens is always going to be my first choice, but a teleconverter is a decent option when I occasionally need to really reach out.

400mm + 1.4 converter = super tight, long, compressed composition that expresses distance is a very distinct way.
400mm + 1.4 converter = super tight, long, compressed composition that expresses distance is a very distinct way.
0
Share on FacebookTweet about this on TwitterShare on Google+Email this to someoneShare on TumblrPin on Pinterest

1 Comment

  1. “I only recommend very good – and very expensive – ones”

    Absolutely. I bought a Kenko 2x teleconverter a few years ago which isn’t completely unusable but isn’t the same as shooting through a high-quality lens. On all but the fastest lenses, you lose autofocus. As you noted, you also lose two stops of light and image quality.

    Very often, the resulting image would be better if I’d skipped the TC and instead cropped/enlarged a wider view.

    0

Leave a Reply

Your email address will not be published. Required fields are marked *