I had seen an article mentioned that when it comes to sharpness, professional lenses have no clear advantage compared to kit lenses.
While I can’t debate that suggestion without spending effort to search out or personally test kit lenses compared to professional, I still question the “sharpness” aspect, but there is a lot more to a quality lens than some measurement on a black and white scale.
1. build quality (use of metal, quality internals)
2. ergonomics (quick shift manual focusing, lens hood, etc)
3. Maximum aperture (eg. larger sweet spot, easier to produce nice bokeh)
4. Contrast and rendering quality (those lens coatings he talks about, or how the lens was engineered). As a lot of people mention the 3D effect that some Pentax glass can produce.
Not to mention what I consider important aspects to photography:
– Composition and framing
– Overall subject, idea, or thought
– Point of interest
I think the tool is a big aspect as sometimes a person’s idea requires a special tool to make it happen. A 10-17mm Fisheye produces a unique effect that can’t be replicated with a kit lens. That also goes for trying to create images of extremely small objects, which require 1:1 or larger magnification and most likely a decent add-on flash with a diffuser.
I’m not going to drive steel nails into solid wood with a plastic toy hammer. Okay, kit lenses are not as extreme as the example because they can suffice for their given range.