Does Teleconverter Increase Depth of Field?

A teleconverter comes in handy in ensuring that you get closer to the subject you intend to capture. However, its effectiveness depends on the type of camera and lenses.

There has been an unending quest to know if a teleconverter increases or reduces the depth of field. And in this article, we shall be answering that question.

Does A Teleconverter Increase Depth of Field?

No, it doesn’t. It reduces it. 

Teleconverters are designed to increase the focal length of a lens by a multiple. But as they do that, they also cause a drop in the F/Stop.

For instance, a common TC is the 1.4X. This TC will increase the focal length by multiplying the current focal length by 1.4. But it will cause a drop in at least 1 stop of light.

Let’s say you have a 300mm F/4 lens. When you add a 1.4X TC, you’ll increase it to a 420mm F/5.6. So, your depth of field will not be the same as 420mm F/4.

The depth of field will correspond to the 420mm F/5.6, which is smaller than what you started with. There are many other types of TCs, including a 1.7 and a 2X. 

Effects on Image Quality

Besides affecting the Depth of Field, using a teleconverter also affects the image quality. How? They pick the area of interest and cut it from the rest. Then, they stretch it.

As a result, the image may appear blurry. The smaller the area the lens will need to stretch out, the poorer the image quality. That’s why you may get better image quality with a 1.4X TC than with a 2X TC.

Effects On Auto-Focus Performance

Teleconverters also affect the Auto Focus in the sense that the more magnification you apply, the slower the autofocus.

In most cases, you may not realize the drop, especially when you’re using a 1.4X TC on fast lenses, like F/2.8 lenses. But if the TC you’re using slows the F-Stop below F/5.6, Auto-Focus becomes very difficult.

Effects on Minimum Focus Distance

This is one area that a teleconverter will not negatively affect. In fact, it makes your images look better since you can comfortably increase the magnification without affecting the minimum focus distance.

This comes in handy when you’re taking shots of small objects that are further away. You can use a TC over your standard lens or a macro lens and enjoy the full benefits of a teleconverter.

How To Efficiently Use a Teleconverter

To avoid the negative effects mentioned above, below is how you can get the most out of your TC.

• Increase the ISO and shutter speeds – As mentioned earlier, a TC will decrease the F-Stop. To accommodate that decrease, always increase the shutter speeds. 
• Use high-quality lenses and teleconverters – The effects you get from a TC vary depending on the quality of the lenses and the TCs themselves. For a better experience and better images, it’s better to invest in high-quality devices.
• Always calibrate the camera lens and the TC independently.
• Always check the F-Stop every time you remove the TC. Sometimes, it may retain the TC’s F-Stop.
• Make sure the object of interest is not too far from you.

When Should You Use a Teleconverter?

A lot of photographers prefer not to use teleconverters, but that’s because they used them wrongly. As already mentioned, don’t go for a teleconverter for an object that’s too far.

As you already know, besides the focal length and aperture, the distance of the subject can also affect the DOF.

TCs are best used when you want the object to film the frame or when you want to get an up-close shot for an object that’s already close to you.

Frequently Asked Questions

Final Thoughts

Depth of light is a key concept in photography. You, therefore, need to know how to go about it for the best results.

As we’ve established, a teleconverter affects the focal length, which is one of the factors that affect DOF. To get better results, make sure you know the type of TC you have and its effects on your lens.