Focus test for telephoto zoom lens - please advice


New Member
Apr 15, 2009
Hi everyone,

I am thinkin of getting Tamron 70-300mm F4-5.6 Di VC USD to supplement my day to day Sigma 17-70mm F2.8-4 OS HSM on my Canon 60D.

I would like to ask if there are any "autofocus tests" that i need to perform on this telephoto zoom lens?

I have come across this focus test but i am unsure if this test can be applied to telephoto zoom lens as well....

another focus test i can think of is the "front / back focus" test...

are there other aspects that i should look out for when buying a telephoto zoom lens?

Best Regards!


Staff member
Jan 3, 2008
Pasir Ris
The focus test charts is meant for auto focus tests. Errors in manual focusing are .. well .. your own errors :)
The focus test chart is for all kinds of lenses, but should be done at minimum focus distance (read the specs, it's listed there). Some telephoto lenses have quite a long MFD (1.5m). You will need some space and also a tripod. Read the instructions.
But on the other hand: if you buy a set with local warranty then focus errors are covered. Bring it for calibration if necessary.

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