What is the difference between a teleconvertor and an extension tube. This video explains it in just three minutes …
So to summarize: the two devices do entirely different things.
- Extension Tube, it has no optical components. It’s role is to move the lens further away from film/sensor. This results in a “closer” focus, which makes it more ideal for macro photography. The downside is that with some extension tubes you lose AF, and with all tubes, you require more light for the exposure, as light falloff becomes an issue.
A teleconverter, increase the focal length of a lens. Common TC are 1.4x and 2.0 multipliers. The TC has optical elements which increases the zoom range of certain lenses (not all lenses will work with a TC). The downside is a reducing in the maximum aperture of the lens and some degradation in overall image quality. TC’s are a low-cost way to go “long” with your telephoto lenses. When you need the extra reach of a super telephoto lens, pairing a TC with an existing telephoto lens is a very economical solution, at the expense of optical quality, a darker view finder, and potentially manual focus only scenario (most bodies lose AF abilities unless the lens has a certain max aperture)
The question I want to know though is can you tell the difference. I used a 2x teleconvertor, and 3 different extension tubes (13mm, 21mm and 31mm) on my 17-70mm lens at full zoom.
In all instances I had to manually focus as the lens would not do it for me. It was hard with the extension tubes as I can to get very close to the drawing pen, which actually meant the lens was almost casting a shadow. With the extension tubes the ISO was a stop more than with the teleconvertor, as there is further for the light to travel, the teleconvertor enabled me to get closer and more detail from further away – all the shots were taken with a shallow depth of field (large aperture) and I was amazed at just how shallow they were with the extension tubes.
Honest opinion…. I don’t think I will use either options often… the teleconvertor does not work on all my lens in, and on the telephoto lenses I have to be aware that I can not shoot at their widest settings as I would damage the glass, changing macro extensions I feel increases the risk of dust and dirt getting onto the sensor…. and I don’t want to do that too often, I think I prefer my macro lens solo!