Is the 15-85mm really faster than 18-55 or 18-135?

Started Apr 6, 2013 | Discussions thread
007peter Forum Pro • Posts: 11,313
Not "Substantial" between 15-85 vs 18-55, but substantial on Telephoto Lens

Messiah Complex wrote:

Substantially.  I'm not really sure how else to phrase it without having actual measurements on hand.  There's a significant difference in focusing speed between the two.

There is no simple answer to this question.  It really depends on:

1. Type of Lens.  USM is noticeably faster on Telephoto lens than it is on Wide-Normal Zoom

2. Distance of Focus Travel.  18-55mm IS has a very Short Focus Travel from MFD to Infinity.  As the result, 18-55IS can focus very FAST in spiteof lacking USM

3. MACRO lens have insanely Long Focus Travel = resulting in "SUBSTANTIAL" speed advantage.

I have owned over 19+ lens in my 8 years with canon.  I would say his based on my own hands-on experience:

  • 18-55 IS vs 15-85 "USM" = only about 10-20% faster
  • Tamron 70-200 f/2.8 vs Canon 70-200 f/2.8 "USM" = about 400% ~ 500% faster
  • Tamron 90 f/2.8 Macro vs Canon 100mm f/2.8 Macro = 400% ~ 500% faster

18-55 IS and most Sigma/Tamron standard zoom have very short Focus Travel, this makes Auto Focus faster at the cost of less precision.

Macro Lens are notorious Slow to AF due to its extremely Long Focus Travel, the trade-off is you gain "substantial" PRECISION on focusing.

For me, lacking USM on wide to standard zoom isn't a big deal.  But when it comes to Macro and Telephoto lens, the importance of having a USM really becomes substantial.

Like I say, is more complicated than a simple generalization.

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