EF-S 18-55mm STM kit lens is sharper than the 18-135mm STM lens - Photozone.de data

The 18-135mm STM lens has a very attractive focal length range, a benefit to those who don't want to change lenses much or have only one lens. However, high zoom ratio lenses typically suffer some loss of performance as compensation for the convenience they offer. And this is what we see with the 18-135mm STM.

I went to photozone.de and obtained resolution figures published by them for these two lenses. With some adapting of the data, it was possible to make graphs showing clearly how the sharpness of the lenses compares. The charts I prepared are below.

For those who do not enjoy interpreting graphs, I summarize the findings in words here.

In the center of the image, the 18-135mm lens is a bit less sharp than the 18-55mm over the whole range of focal lengths. The differences are greater at the shorter focal lengths, diminishing steadily until we get to 35mm, and then widening a bit again at 55mm.

At the border of the image, the differences are greater. The 18-135mm lens is significantly worse at wide angles and also at 55mm. The two lenses are pretty close at 35mm, but with a slight advantage going to the 18-55mm.

So overall, we can say the lenses are close at a focal length of about 35mm but deteriorate for the 18-135mm as we go shorter and longer. The biggest differences are at wide and long focal lengths and at the border of the image.

So it is not exactly surprising, nor is it news to many of us, that the 18-135mm is less sharp than its smaller sibling. But it has such a nice zoom range. It is up to the photographer to decide what is more important, zoom range or sharpness. Those that select for the 18-55mm can of course still increase their zoom range by changing lenses, for instance with the 10-18mm STM and 55-250mm STM lenses. Both of these have very good reputations.

I don't own the 18-135mm, but trust the PZ data as it agreed very well with the performance of three other lenses that I own.

Reminder: There are many properties of lenses that are important besides sharpness. They include build quality, light transmission, color, bokeh, chromatic aberration, vignetting, and distortion. Fortunately, these days the latter three qualities are easy to correct in post-processing, and therefore they are less important for most of us.

I also did comparisons of the 18-55mm STM with the 15-85mm and 17-55mm lenses.

I thought about the 18-135mm when I built my Rebel T6s "weekend warrior kit", but decided for the "inconvenience" of using the 18-55STM, and the 55-250mm STM instead. The complete Weekend Warrior Rebel T6s kit (add the 10-18mm to complete it) is pretty nice to carry around all day (meaning it should appeal to the weight wussies who do not want to compromise picture quality). I have really been enjoying the kit.

Good presentation of the data. I bought the 18-135 in the 70D kit recently. I prefer it for reasons which you mentioned - longer reach and desire not to be changing out lenses. The same rationale a few years back drove my choice of the 15-85 over the 17-55 on my 40D. I did a survey of thousands of shots taken while traveling with my wife, using a handy tool called ExposurePlot. I found that I shot a large percentage of my pictures over 55mm, a range I would lose with the 17-55 unless I wanted to switch lenses out a lot - which I didn't. I find that switching lenses when traveling with someone can be very tedious for that other person and involves carrying more gear. So I bought the 15-85 and I have been extremely happy with it. Now I'll be using the 18-135 for the same reasons. So, as you said, there are various factors that one needs to take into account when purchasing what is intended to be a walkaround lens - your shooting habits, desires regarding lens changeout, etc.

not surprising, superzooms tend to be more convenient than to be optically superior to a standard zoom range the same way that standard zooms tend to be less sharp over all than primes.

Yes, good, but the 18-55m is pants from 56mm-135 :0

Seriosuly these kit lenses are so much better than they used to be, it's a great advantage to actually be able to use them rather than just sell them off.

The 18-135mm is shockingly good for the focal range. From very wide all the way out to 135mm Telephoto portrait, and it's tiny! for that reason I shoot the 18-135mm all the time, where as the 18-55 that came with my SL1 is a shelf piece. (bench warmer?)

Slight advantages in sharpness play no role in which I choose, as they are both good in that regard.

Archibald wrote in post #17680441
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In the center of the image, the 18-135mm lens is a bit less sharp than the 18-55mm over the whole range of focal lengths. The differences are greater at the shorter focal lengths, diminishing steadily until we get to 35mm, and then widening a bit again at 55mm.

Where did you see any measurements for the 18-135mm @ 55mm?

CyberDyneSystems wrote in post #17681080
Where did you see any measurements for the 18-135mm @ 55mm?

Interpolation.

Ah, guesstimate

CyberDyneSystems wrote in post #17681121
Ah, guesstimate

Here are my interpolation charts. There is not very much wiggle room!

And then you compare real world examples.

There's basically no difference between the two, until you get at the 50-55mm range where the 18-135 STM wins.

http://www.the-digital-picture.com …omp=0&FLIComp=3​&APIComp=1