I Was Wrong, Teleconverters Are Useful Photography Tools

I admit it, I was wrong. Teleconverters are useful photography tools if used properly and paired with the right lens for wildlife and more. However, don't expect them to work in every situation.

What Are Teleconverters

Teleconverters increase the telephoto reach of your lens. As a result, your field of view is narrowed, making things which are farther away appear larger. Of course, they're most effective on what are already telephoto lenses. For example, you wouldn't get much use out of adding a 2x teleconverter to a 24mm wide angle lens. Doing so turns that 24mm lens into a 48mm lens. It also reduces quality (somewhat) and the amount of light entering the camera. 50mm lenses are widely available and rather inexpensive.

All that being said, placing a 2x teleconverter onto a 600mm lens, turning it into a 1,200mm lens has a massive impact. There are 1,200mm lenses available for major camera brands. However, they're in the $20,000 range. Understandably, few photographers own such lenses.

How Teleconverters Work

Teleconverters work by moving your lens away from your sensor (or film). However, moving the lens farther away usually results in a loss of the ability to focus on far away objects. Teleconverters correct for this by adding lenses within that space.

Extension Tubes Vs. Teleconverters

Teleconverters are not the only tools to move your lens away from your sensor. Extension tubes are widely used by macro photographers. First, extension tubes increase the magnification of objects just by adding that extra distance. Additionally, they thereby allow you to focus closer than your lens usually allows. However, extension tubes are hollow. As they don't have additional lenses within them you can only focus on objects close to the lens. On the other hand, the added glass inside of teleconverters allows them to focus to infinity.

I Used To Hate Teleconverters

I used to hate teleconverters based on personal experience. See, I bought a Tamron 300mm lens and a 2x teleconverter about 20 years ago. At the time I was still shooting film. The results were bad. Every photo was soft, dark, and it was nearly impossible to focus on anything.

After I bought my first digital camera I gave it another try. The low resolution of that camera, paired once more with that bad lens, gave me the same bad results. In addition, the internet was awash with articles about how teleconverters were useless, degraded image quality, and didn't work in almost any situation.

Teleconverter Revival

This April I decided to do some Spring cleaning. As a result, I found my old Tamron 2x teleconverter. I was contemplating selling it. Then I decided to give it one last chance. I decided to test it on both my D850 and Z6II along with a variety of lenses including my Sigma 150-600.

Important Things To Know About Teleconverters

Teleconverter quality varies with the lenses you use it with. More importantly, even if they have the electronics to allow you to autofocus, your camera might be limited due to the amount of light.

This is very important. Teleconverters drop the amount of light entering your lens. As a result, your photos with be an f-stop or two darker.

Autofocus and Teleconverters

Most cameras require a certain amount of light for autofocus to work. As such, the loss of light on already slow lenses can cancel your ability to use autofocus. For example, the Sigma 150-600 at 600mm has a maximum aperture of 6.3. As a result, the 2 stop loss of light with a 2x teleconverter means I've lost autofocus.

That said, with a mirrorless camera I've got focus peaking and digital zooming to check my focus. These tools have allowed me to find success with my teleconverter.

Limited Use But Ideal

So, my teleconverter, which sells for around $50 used on eBay, has limited use. However, it's perfect for very specific situations. For example, stationary birds like owls.

Take this photo for example. This is a Great Horned Owl fledgling siting up in a tree. I've photographed it on my iPhone 16 Pro Max with the regular or 1x camera. It's not very visible is it?

With only my Sigma 150-600mm I can get a nice photo of this owl. However, with the 2x teleconverter I get the following photo.

Teleconverter Uses

Teleconverters have limited but very helpful uses. Stationary subjects are a must if your aperture is already small. If you have a 500mm f4 lens then autofocus will work. However, if you're using a 5.6 or slower lens with a 2x telecon then you're probably out of luck. That said, a 1.4x teleconverter may still work for you at f5.6.

Learn More On Youtube

I'm working on a Youtube video about teleconverters that will be published by the end of May. Be sure to follow me on Youtube and turn on notifications to see it.