Teleconverters are Lenses Too
Pity the poor teleconverter. People assume, for reasons I can’t understand, that it’s just a magical wizard’s tube that makes the image larger with no other effects. Teleconverters are actually quite complex little creatures with 3 to 9 lens elements inside:
Diagram of a Canon 2X teleconverter.
Never forget, when you mount a teleconverter you are using a lens to look through a lens. You can’t do that without some change in image quality.
Do any of these things make a difference? Probably not, or at most not often. But not a week goes by that I don’t answer at least one email about each of these topics, usually more.
But I saved the answer to the most frequent email I get for last, as a prize for those who’ve read this far.
Active Stabilizers (IS, VC, whatever) Rattle
The IS group is always near the base (camera end) of the lens, just in front of the rear elements. If you shake the lens, you can hear the IS elements rattle if they aren’t locked down. Why don’t they lock down? Usually because you removed the lens without turning off the camera. Put the lens back on the camera, take a shot, turn the camera off, and remove the lens. For most brands, this makes the rattle stop because the IS system was locked down when the camera turned off (its not true for every IS system, just most).
And while I don’t know for sure, I can see no benefit to shaking your IS system around and making it rattle. As my mom used to say whenever we discussed any plan I had: “No good could come of that. No good whatsoever”. So turn your camera off before removing your IS, VR, VC, Mega OIS, whatever they call it lenses.
This article is also available in German.