Quote Originally Posted by Jan Paalman


Quote Originally Posted by Richard Lane


I believe you on the primes, but the 100mm macro lenses definitely don't fit in the fastest focusing lenses section.


I have had both(still have the L) and the 70-200 f4L IS beats both of them easily on AF speed during sportsphotography.


Quote Originally Posted by Richard Lane


if you pre-focus then it can work, but that's not what this thread is about.


If you don't pre-focus and your focus is way off, finding the target might even take more time than the actual focusing [img]/emoticons/emotion-5.gif[/img] I know I had a hard time focusing/searching through the viewfinder at an airshow when the focus was way off at 400mm[img]/emoticons/emotion-4.gif[/img] Those times I zoomed back to 100mm, searched my target and zoomed back in, so it was pre-focusing after all...


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<span style="font-size: 10px;"]<span style="font-size: small;"]As far as pre-focusing I was referring to the very slow and delectable 85mm f/1.2L.


<span style="font-size: 10px;"]<span style="font-size: small;"]I agree that it would be tough to prefocus on a plane in flight with the 100-400mm f/4.5-5.6L, since you don't know where it's going and where it will end up in order to prefocus on a pre-determined distance point. I don't own this lens so I don't know how fast or slow it is. I would guess that it is on the slow side since it's a variable aperture zoom and f/5.6 @ 400mm. I certainly think it's a great zoom range for an Air Show. As HDNitehawk has mentioned, the super-telephotos have a nice pre-focus ring that is useful if you know what your pre-focus distance will be.


<span style="font-size: small;"]The 100mmL Macro IS focuses just as fast as any other 2.8 lens that I have. The key to the fast AF is to make sure that you don't manually rack the focus ring into the macro range. If you look on the barrel of the lens, make sure that you "don't start within the yellow markings on the barrel between 1:1 or 1:5", what you want to do is start with the white markings on the barrel at 1M, as Wickerprints has suggested, if you do that when you start shooting sports then this lens can AF just as fast as the other f/2.8's mentioned in this thread. If you accidentally, manually go into the macro range then you are no longer using it as a standard 100mm lens so all bets are off and you won't be able to AF on far objects. <span><span style="font-size: small;"]Also make sure that the distance limiter switch on the barrel is selected to the appropriate distance.<span><span style="font-size: small;"]


<span style="font-size: small;"]The same rule applies for the 24-70mm f/2.8L macro, however the non-macro range starts at 0.7m on the lens barrel. This lens however can seem to get itself out of macro mode much easier than the true macro 100mm f/2.8L IS.


<span style="font-size: small;"]Since I don't own the older model of the 100mm f/2.8 macro, I will refer you to Bryan's review;


http://www.the-digital-picture.com/Reviews/Canon-EF-100mm-f-2.8-USM-Macro-Lens-Review.aspx


<span style="font-size: small;"]Bryan's Quote:


<span style="font-size: 10px;"]<span style="font-size: small;"]"Utilizing USM (Ultrasonic Motor), the Canon 100 Macro internally<span style="font-size: small;"]focuses very fast<span style="font-size: small;"],<span style="font-size: small;"]quietly<span style="font-size: small;"]and<span style="font-size: small;"]very accurately<span style="font-size: small;"]. I've been questioned on the fast AF statement several times since writing this review. I've rechecked my lens and, though it takes a little time to go from 1:1 macro to infinity, it focuses very fast at normal focusing distances. The second person to question this exchanged their lens for another - the replacement was much faster than the original lens they received. This would indicate to me that there may be an issue with some samples of the Canon EF 100mm f/2.8 USM Macro Lens. Another site visitor emailed me - they were ecstatic that a firmware upgrade to theirCanon EOS 1D Mark III DSLR[/i]<span style="font-size: small;"]resolved their 100mm Macro focusing speed issue. Also note that there is a discontinued non-USM version of this lens. Keep these datapoints in mind if you run into a slow version of this lens."





<span style="font-size: small;"]I suspect the discrepancy in AF speed regarding this 100mm Macro lens may have to due with people accidentally or unknowingly wandering into the Macro range, where it will be as slow as a turtle. Anyone who owns this lens should give it a try, and then they'll understand the discrepancies from Macro AF Speed, to Normal Range Fast AF speed. Their also may be other explanations as Bryan has alluded to; such as an older non-USM version, a bad copy, or out of date firmware.


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Rich