7
\$\begingroup\$

On my Canon kit lens, I could completely zoom in, focus on the object and then zoom out to take the picture with the object still in focus.

Now I have a Sigma 18-200mm (with a Canon 600D) and that doesn't work. After zooming out, focus is lost and I need to refocus.

Is this lens broken or is not every lens the same with focussing combined with zooming?

\$\endgroup\$
1

1 Answer 1

13
\$\begingroup\$

The lens is a varifocal lens. Basically, it's a lens that changes focus as the focal length changes and it's quite common. Parfocal lenses, ones that maintain focus on zoom change, exist but are typically more expensive as a result.

Long story short, it's normal for a large number of consumer zoom lenses.

\$\endgroup\$
4
  • 4
    \$\begingroup\$ is 100% correct. Interesting story on lensrental about a 70-200 lens that is Parfocal, its only $20K lensrentals.com/blog/2013/04/… \$\endgroup\$ Commented Apr 19, 2013 at 17:15
  • \$\begingroup\$ Really? I always thought cheap lenses would do that. I've mostly found it on kit lenses, as the asker has stated. \$\endgroup\$
    – BBking
    Commented Apr 19, 2013 at 21:55
  • \$\begingroup\$ @BBking - most consumer lenses are cheap lenses... \$\endgroup\$
    – Joanne C
    Commented Apr 19, 2013 at 22:05
  • \$\begingroup\$ The Nikkor 10-105 DX is a parfocal kit zoom, although not exactly one of the pits :) \$\endgroup\$
    – Ryccardo
    Commented Apr 21, 2013 at 12:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.