The Villages Loc: The Villages, Florida

My understanding is that the "3rd" generation is the Nano version which has the benefits of both the STM and USM features....both quiet and fast to focus.

DebAnn Loc: Toronto

I reported earlier that I'd never seen the problem with my 18-135 but didn't quote the version. Mine is the EFS.

Bob Boner

LR has a correction which eliminates the problem you are talking about. It is under "lens corrections" /Remove CA.

amfoto1 Loc: San Jose, Calif. USA

I've used about 3 dozen different lenses on my Canon cameras... and many more on other cameras.... all different brands and price ranges from $100 to $10,000. Frankly, CA can happen with any of them, given circumstances such as high contrast, slightly out of focus edges (sometimes referred to as "bokeh CA").

First thing I have to ask is if you're using a "protection" filter on your lens. If so, you might want to try without it. I've seen filters cause or amplify the appearance of CA.

Also, do you regularly use a lens hood? It might not help with CA, but sure can't hurt (and does a better job of "protection" than a thin piece of glass ever could).

Sometimes stopping down helps.... or slight change in composition.

In very general, primes do better avoiding or minimizing CA. Zooms are more prone to it, do doubt because of their more complex optical formulas. Zooms are especially prone to CA at their focal length extremes... widest and most telephoto. And, broadly speaking, the wider ranging the focal lengths the more likely there will be some CA at the extremes and the stronger the CA might appear.

Two Canon "walk-around" zooms that might work better for you are the EF-S 17-55mm f/2.8 IS USM and the EF-S 15-85mm f/3.5-5.6 IS USM. Both of them are optically excellent. The 17-55mm is one of the least prone to CA... while the 15-85mm isn't quite as good, but appears better than your particular lens. ( Canon claims the newer, more expensive EF-S 18-135mm IS "USM Nano" is 2X to 4X faster focusing than your STM model of the lens.... But both those 18-135mm lenses appear to use the same optical formula and show little to no difference in CA or other image quality factors.)

The Sigma 18-35mm f/1.8 "Art" also appears to keep CA to a minimum, may be ever so slightly better than the 17-55mm, perhaps thanks to it's more limited range of focal lengths (less than 2X... versus over 3X in the 17-55mm, nearly 6X in the 15-85mm and 7.5X in the 18-135mm lenses).

Right now, all three lenses.... Canon 17-55/2.8, 15-85mm and Sigma 18-35/1.8.... are selling for the same price in the U.S. $800. (The 17-55mm is on sale, the 15-85mm is not.)

The Sigma is the heaviest of the three... at over 1-3/4 lb. (800+ grams). The 17-55mm is a little lighter at about 1.4 lb. (645 grams) and the 15-85mm is the lightest of them at about 1-1/4 lb. (575 grams) and is closest in size and weight to your 18-135mm, at about 1.1 lb. (480 grams.)

The Sigma and 15-85mm use 72mm filters, while the 17-55mm uses 77mm (18-135mm uses 67mm). The Sigma comes with a matched lens hood, while it's a separately sold, added cost with the two Canon lenses.

The Sigma uses a 9-blade aperture.... while all three of the Canon use 7-blade (I think all use curved blades).

I'd recommend you compare these lenses with yours at the-digital-picture.com, which has test shot samples at various focal lengths and apertures and allows side-by-side comparisons. For example, to my eye the highly magnified image quality comparisons of the Sigma lens appears slightly sharper than the EF-S 17-55mm at the same aperture (f/2.8) and similar focal lengths (18/17, 24, 28, 35). I made a point of using tests done with 60D for both, because the Sigma lens tests weren't done on 7DII. The Sigma appears to have less vignetting at the wide end, but more at the other extreme. And the Sigma appears to handle flare very well, too. The 17-55mm has less distortion at the wide end, but ever so slightly more at 35mm. You can try other lens-to-lens comparisons, other focal lengths and other apertures yourself at that site. I find Bryan's reviews, lens tests and comparisons very useful.

amfoto1 Loc: San Jose, Calif. USA

Actually, all three Canon 18-135mm versions are EF-S ("crop only" for use on APS-C sensor cameras... not for use on full frame). All three also have IS (image stabilization).

The oldest and usually least expensive model uses a "micro motor" and is the slowest, noisiest focusing... it's not marked "STM" or "USM". It also uses a 6-blade aperture and isn't quite as close focusing as the two later models.

The second and usually slightly more expensive version is the "STM" with faster, quieter "stepper motor" autofocus drive. Otherwise, it's a modest upgrade compared to the first model.... a little closer focusing, an additional blade in the aperture to make for slightly nicer background blurs (and 14-point "sun stars", versus 6-point with the older model). Until recently quiet and smooth STM focus drive has been preferable for videography... micro motor was way too noisy and jerky and, although better, much faster USM wasn't entirely noise-free or smooth either. USM has been preferable for fast action still photography... sports, wildlife and such, where AF acquisition speed and tracking ability is important.

The newest and most expensive is the "USM" version. In fact, this was the very first lens Canon fitted with a new focus drive they call "Nano USM" (even though the lens is only labelled "USM"). The new type of AF drive is BOTH fast like USM and smooth/quiet like STM... so it's great for BOTH video and fast action still photography. Canon claims the USM lens is 2X to 4X faster focusing than the STM model (which, in turn, is faster than the micro motor version). In most other respects, the USM version and STM version appear identical.

One other difference, Canon also redesigned the USM version to be able to fit it with an accessory "PZ-E1" Power Zoom module. It's the only lens able to use that $100 accessory, which is something that may interest videographers in particular. Since then, Canon has introduced two more "Nano USM" lenses: EF 24-105mm f/4L "II" IS USM and EF 70-300mm f/4-5.6 "II" IS USM. I was surprised to see that Canon didn't also make these new lenses compatible with the PZ-E1. To me it just seemed like a "no-brainer" to make those lenses able to use it too. But, no. The PZ-E1 remains usable ONLY with the EF-S 18-135mm IS USM lens.

Finally, the first two versions used Canon lens hood EW-73B. The latest, USM version uses EW-73D hood.

BudsOwl Loc: Upstate NY and New England

Have you looked at the Canon 18-135 USM which may be better.