Anyone with experience of 15-85 (and ideally 17-55mm, too)?

totleytom wrote:

I've got the 15-85 and have had it for some years. I've used it on a 500D; 60D; 100D; and currently a 750D. As that progression has been made, I've become increasingly dissatisfied with it. You'll note that the resolution of those bodies increases from 15mp to 18mp and now to 24mp. On the most recent body, I don't find it sharp enough.

It might just be a focusing issue but I don't think so - I know what a mis-focused image looks like and these aren't like that. I have a feeling that mine is simply not that good - slight centering issues, perhaps? - and the 24 mp sensor on the 750D is revealing that in a way the older bodies didn't. My 18-55 STM is almost as good, in fact, and the little 24mm STM prime is heaps better.

My 6D + 24-105 combination knocks the 750D + 15-85 out of the water.

Interesting comments Totlytom!

One of the revealing things that the website DXO Mark (https://www.dxomark.com) website shows is that the performance of lens varies with different bodies, which is logical, but I was surprised by how much it varies. You might find it interesting to try the site using the various combination of lens and body to see what they show.

The EFS 15-85 has a major challenge in that it goes from a very wide angle to a moderate telephoto, making it in effect a super zoom. The 24-105 L has a much less challenging range of focal length because it avoids the wider angle range, and of course it ISan L series lens!

I have two each of the 15-85's and 24-105's and I use them both depending on the type of image I am trying to capture and for what purpose. I tend to keep the 24-105's for my 7D and 5DIII bodies, and use the 15-85 on my 60D and 80D bodies - where they render good results for my purposes.

I would expect that a full-frame body combined with an L-series lens would offer a significant improvement, as you have experienced. That said, there is a bit of a myth that non-L series lenses are by definition, lower quality, especially EF-S class lenses. The nature of the optics design of these lenses immediately makes them lighter and cheaper than those for FF bodies, especially if compared against the L series lenses, which are not primarily meant to deliver optimum results for cropped bodies, with the possible exception of the 7D models. Many of the newer EF-S lens actually use high quality glass combined with composite components to make them lighter and cheaper, but they tend to feel less impressive than the non-EF-S units.

As I maintain what is the best for a particular photographer is dependent on a combination of things: what the budget is, what kind of photography one engages in and especially what kind of output is required.