[PKMike]

Can anyone out there who has both of these lenses give an opinion on image quality? I have 18-135 and am considering 20-40 because of weight, size,aperture speed and potential IQ. I have 18-135 and like a lot of things about it but if image quality is considerably better with 20-40 I may pull the trigger at its current price. Focusing is great on 18-135 and I really like WR. Image quality is good at shorter to mid focal length and F 8-11 (9-10 seems about best). If 20-40 is considerably better from 20 to 40 and wider apertures it just might tip the scale for me. Thanks anyone in advance. Also, is focus as fast, quiet and accurate? Thanks again, Mike.

[Aristophanes]

The 20-40 is more consistent across the frame but far less versatile.

There is, frankly, very little discernible IQ between lenses like this except when you get to their versatile end zones. The 30-40 is deigned to be optimum at its limited FL regardless of Av, and the 18-135 is more compromised at the long and wide (less at the wide).

I'd use the 18-135 outdoors mostly and the 20-40 indoors (as I do with my 18-135 and Tamron 17-50).

[hcc]

Apples and oranges. These are two different lenses, with very different use IMHO.

The HD20-40mm is a compact higher quality lens but with a short focal length range.

The DA18-135mm is a walk-around lens.

For a longer travel trip, where I would travel compact, the DA18-135mm is the obvious choice. For a day trip when I need a somewhat wide lens, the DA20-40mm would be my first choice (of these two).

I hope that the comment may help.

[JinDesu]

I don't have both lenses at the same time, but here's my thoughts:

The DA 20-40 is a bit smaller than the DA 18-135, especially considering the 18-135 at full zoom is actually pretty long. This is important when using in the rain, because the DA 20-40 doesn't really suck much air, and getting rain on the extended portion doesn't concern me. I had to pay attention when zooming in the rain with the 18-135 because at full zoom, the lens barrels would get wet and then get retracted all the way into the body.

I did not like the plastic and rubber body of the DA 18-135. The DA 20-40 feels more enjoyable to use.

Both lenses can get pretty close for focusing. The 18-135 gets a bit higher magnification at 0.24x vs 0.2x

Wide open, the DA 20-40 is definitely sharper than the DA 18-135. It's marginally sharper in the center (the 18-135 is pretty damn good in the center), and it definitely sharper in the corners. Unfortunately due to field curvature and DOF, corners wide open doesn't mean a thing on either lens when shooting a flat subject. Stopped down to F5.6 or F8, the sharpness comes closer but I would definitely still give it to the DA 20-40 throughout the range. If I am correct, the 20-40 is also a stop faster across the range (F2.8 @ 20-25, F3.5 @25-35, F4 @35-40) - and since it's sharper wide open that means stopping down to the same aperture as the 18-135 puts it quite a step ahead.

Bokeh has a huge difference with regards to specular highlights/bokeh balls. Both lenses will blur the background nicely, but the DA 18-135 has some onion rings/patterns within the specular highlights, but the DA 20-40 does not (the bokeh balls are smooth). I'll try to post an example or two tonight.

Starbursts may favor the 20-40 a bit due to the 9 blades (18 points) vs 7 blades (14 points), but also the DA 20-40 is very resistant to flare and aberrations so the starburst may be better defined. I haven't tested it on the 20-40 yet, but the 18-135 wasn't amazing for it.

Flare is definitely well controlled on the 20-40. Haven't seen it yet. The 18-135 is pretty good against flare, but you can definitely invoke it strongly across the frame.

Let me know if there are any specific questions beyond the above.

[Biro]

I have both lenses... and they're two different tools for two different kinds of jobs. As others have said, the 18-135 is a good, outdoor, walking-around lens. The 20-40 I would use more often (but not exclusively) for indoor work. Having one of these lenses doesn't preclude the other.

[PKMike]

Thanks all for your comments, good input. My intention with this lens if I were to buy it is to use it outdoors as main walk around lens when weather gets wet. Mainly I want to find out if it performs well at wide open or close to it. If so I might use it instead of 18-135 which I need to stop down considerably for good results. I like that 20-40 is smaller and lighter. Have DAL55-300 now with HD55-300WR to be shipped (hopefully) by PWS soon so all needed focal lengths will be covered for wet weather, which I seem to encounter frequently. I use Limited 15,21,40 and 70 (as well as 55-300) when weather cooperates and am hoping to find out if 20-40 can give results closer to said Limited primes. Thanks again, Mike.

[hjoseph7]

I have both lenses... and they're two different tools for two different kinds of jobs. As others have said, the 18-135 is a good, outdoor, walking-around lens. The 20-40 I would use more often (but not exclusively) for indoor work. Having one of these lenses doesn't preclude the other.

It must be pretty cold in your living room to use a weather sealed lens indoors, common now ?

[Biro]

It must be pretty cold in your living room to use a weather sealed lens indoors, common now ?

Well, as I wrote... not exclusively for indoor use. Believe it or not, until recently I actually used my DA* 16-50mm f/2.8 WR indoors if I needed both the speed and the flexibility of a zoom. Didn't feel chilly at the time.