Have you ever sat down with a group of photographer and gotten into a trivia face off. You know those kinds of discussion where one would go “Oh yea? So what is the F-stop that comes after F/64?”* Or “So, what is hyperfocal distance?”** or “what’s the fastest sync speed on a D70?”***
Those can sometimes get quite frustrating. Especially if all participants are quite knowledgeable.
Before you learn how I lost that contest, see if you can identify what the following lenses have in common:
- Canon EF 70-200mm f/2.8L USM
- Canon 17-40mm f/4L
- Canon 16-35mm f/2.8L II
- Tokina 11-16mm f/2.8 AT-X116
- Nikon 17-35mm f/2.8D
- Nikon 24-70mm f/2.8G
- Nikon 70-200mm f/2.8G mkI
Here is how I lost my last trivia photography trivia face off. After getting a few rounds with Roie Galitz (of Galitz phototeva photography expeditions) he asked me to name 3 parfocal lenses.
First, I had no idea what para-focal lenses are, and secondly, I had no idea which lenses are para-focal.
What are para-focal lenses
A Parfocal lens is a zoom lens that does not shift focus as it is zoomed in and out. While modern lenses can have the lens’s CPU adjust focus as the lens zooms in and out, a true parfocal lens will retain its focus distance even if there was no CPU at the lens at all. It is it’s optical quality.
There aren’t that many of those, but the top of the post holds a few from Nikon, Canon and Tokina.
*hyperfocal distance is a distance beyond which all objects can be brought into an “acceptable” focus
[Thanks for kicking my tush, Roie]