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How and Why to Use a Teleconverter for Your DSLR

Sometimes, you need to get closer to your subject. Whether at a wedding or capturing strong images for your landscape photography portfolio, distance can limit you. A teleconverter exists to combat this.
They help you extend your focal length while keeping the comparative costs down. Here’s how they do it and why you should start using one today.
A photographer shooting through a DSLR camera with a teleconverter
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What Is a Teleconverter

A teleconverter is a solution to the distance problem. There are times where you won’t be able to get closer to your subject. Either physical constraints or not wanting to get closer to wildlife photography scenes that can be dangerous.
Even if you aren’t the adventurous type, you might want a closer crop while maintaining your distance.
Teleconverters, otherwise known as extenders or multipliers, are basically mounts for your lenses. They sit in-between your camera body and lens.
Their purpose is to extend your focal length. Similarly to (and not to get confused with) extension tubes with macro photography, they extend the lenses purpose.
They come in two different variations; a 1.4x and 2.0x teleconverter. I think you can see where I am going. When combined with a lens, usually a telephoto lens, they magnify the focal length by their strength.
You can use teleconverters with zoom lenses or prime lenses.
Image of a teleconverter attached to a minolta camera

How to Use a Teleconverter

Using a teleconverter is simple. It screws onto your camera body and the lens screws onto the other side. Simple.
Just like extenders for macro photography, you can stack the teleconverters. If a 2x teleconverter on a 400mm lens creates an 800mm lens, then two 2x teleconverters will give you a 1200mm focal length.
Although possible, you might not want to try more than a few teleconverters stacked together. As we will see below, the lens will have difficulty focusing, and the contrast will start to disappear.
NB: Not all lenses are compatible with teleconverters. Check with your lens manufacturer first. 

Why Use a Teleconverter?

There are two reasons why you would want to use a teleconverter. The first reason is that you want to capture an object that is too far away from you. This could be in the field of landscape or bird photography.
This offers you a closer standpoint to animals, whose environment you don’t want to disturb. To disturb their environment would mean missing out on the chance to photograph them at all.
The second is that you want that subject to have a tighter crop. If you are photographing birds or other fast-paced objects, you want to show as much of their body as possible.
This lens lets you cut out the negative space around them. Astrophotography is another great area for using teleconverters, allowing you to point the viewers’ focus to the important part.
 
A stunning mountainous landscape shot using a teleconverter

Pros of a Teleconverter

Focus Length

The biggest and most obvious benefit with these teleconverters is the extension and magnification of the lenses’ focal length.
For example, if you used a Canon EF 70-200mm f/2.8L IS II with a 1.4x teleconverter, the lens becomes 98-280mm. With a 2x teleconverter, the same lens becomes 140-400mm. 
Nikon has an extra version other than the 1.4x and 2x. The Nikon AF-S FX TC-17E II is a 1.7x teleconverter. With the Nikon 70-200mm f/2.8G ED VR II, the lens becomes 119-340mm. 
A 1.4x teleconverter gives you 40%, 1.7x gives you 70% and a 2x teleconverter will give you 100% zoom.

Cost

Also obvious is the saving in costs by buying a teleconverter vs a dedicated telephoto lens. If you have a 200mm lens but need a 400mm focal length, you have two options.
The Canon EF 400mm f/5.6L USM comes with a hefty $1149 price tag. A 2x teleconverter that will take your 200mm lens to a 400mm focal length will set you back $429.
The other benefit is the teleconverter can be used with other lenses, whereas a telephoto lens is only good at 400mm.
A photographer shooting through a DSLR camera with a teleconverter

Teleconverter Weight

Telephoto lenses are really heavy. Really heavy. The Canon EF 400mm f/5.6L USM weighs 2.8 lbs. Having a teleconverter in you bag, turning your telephoto into a super telephoto, weighs almost nothing.
If you were to compare a 400mm lens to a teleconverter with a 200mm lens, you would have two lens systems that would be similar in weight.

Minimum Focus Distance

An extender or teleconverter allows you to keep the minimum focusing distance. This is handy if you want to get close up to a subject and you don’t have a macro lens.
The 200mm lens has a minimum focusing distance of 1.1 metres, whereas the 400mm lens has a minimum focusing distance of 35m. That’s a big jump
A teleconverter attached to a DSLR camera

Cons of a Teleconverter

Lens Speed

The first problem with teleconverters is the change in the lens speed. By extending the length of your lens, less light reaches the sensor. This means you lose your fastest apertures.
When using a 1.4x converter this means you’ll lose one stop and a 2x converter will eliminate two stops. So, using the Canon EF 70-200mm f/2.8L IS II will give you the fastest aperture of f/5.6.
This is fine if you are shooting landscape photography. Yet, it might be a problem for those scenes where you want to utilise a shallow depth of field.

Camera Shake

When you extend your focal length of a lens, any movement becomes more noticeable. Not only does your focal length magnify, but so does the movement.
Here, you need to use image stabilisation, a tripod/monopod or readdress your shutter speed. When you add a teleconverter, it doesn’t necessarily help your shutter speed minimum.
NB: A rule of thumb denotes that the shutter speed shouldn’t fall below the focal length of your lens. So, if you are using a 200mm with a teleconverter, your shutter speed still needs to match your focal length output.

Focusing Speed

Teleconverters slow down the speed at which you are able to focus. This varies between lenses, but expect this to be extreme in low light conditions. Some entry-level digital cameras might not even find a focus.
Check your camera’s capability first before buying the teleconverters.
To get around this, use manual focusing paired with live view. You’ll get the hang of it in no time.

Image Degradation

The extenders magnify and multiply the focal length of your lens. They also magnify and multiply any aberrations or problems your lens has.
Here, you’ll notice the image suffer, especially when using longer extenders or through stacking them together.
To beat this, use your best lens to keep any degradation to a minimum.

Cropping Vs. Teleconverter

The biggest alternative to Teleconverters is cropping in camera or during the post-production stage. Cropping an image means you can change the ratio of the image, and cut out unwanted negative space.
This might be a viable option, especially for those with very high-resolution images. Large sensors from high-end DSLR cameras will allow you to crop into an image with little or no loss of quality.
It is certainly the cheapest option, especially if you already use and own Adobe Lightroom or Photoshop.
 
A teleconverter attached to a DSLR camera on a tripod

Teleconverters Currently on the Market

Canon Extender EX 1.4x II Teleconverter

The 1.4x extender from Canon isn’t cheap, but worth the money when compared to other brands.
Don’t use it at its maximum aperture – use it one or two stops back up.
Canon Extender EX 1.4x II - teleconverter

Canon Extender EX 2x III Teleconverter 

This extender from Canon doubles your lens’ focal length.
It doesn’t work with every lens and has been known to provide ‘soft’ results.
Canon Extender EX 2x III - teleconverter

Nikon AF-S TC-14E II 1.4x

Those who use these give glowing reviews. It isn’t compatible with all Nikon lenses, but it works well.
It isn’t cheap, but much cheaper than those super telephoto lenses.
Nikon AF-S TC-14E II 1.4x - teleconverter

Sigma 1.4x EX DG

The more I hear about this teleconverter, the better it sounds. Sigma makes these for all DSLR manufacturers, meaning they are compatible with many lenses.
This one works best with a smaller aperture. Get this for your Pentax, Minolta and Sony systems.
Sigma 1.4x EX DG

Sigma 2x EX DG

Like the 1.4x extender, the 2x teleconverter gives very strong results. Use this to double your focal length.
Sigma 2x EX DG - teleconverter

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