Question: I've heard claims ranging from *"higher-quality lenses only make a noticeable difference for scientific applications and super-huge prints,"* to *"even the difference between high-quality and uber-high-quality lenses can be seen with the naked eye on 6x10 prints"*

Before I sell my house so I can take amazing pictures from a cardboard box, I'd like to actually see the difference. However, all the examples I've found compare photos not only from different lens, but also with different cameras/scenes/photographers!

**Are there any examples of the same scene, with the exact same settings on the same camera, taken with multiple lenses (of differing quality/price)?** Multiple comparisons with different scenes/cameras *(especially cameras of different qualities)* would be preferable, to eliminate any variables. I'd also prefer a non-biased source *(so, not the lens-manufacturer)*.

I'd also be interested in comparing telephoto to zoom+teleconverter *(of the same quality, focal-length etc.)*, or comparing zoom to fixed-length... but perhaps those are asking too much :)

Answer: 
Sometimes I think I could sit and play with [The Digital Picture](http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx) all day staring and lens quality comparisons, along with different camera backs. It's a highly useful site.
I'm not sure you'll find one site that compares all lenses with one realistic scene, but a few lens review sites I've found interesting in the past include

* [Ken Rockwell's Camera and Lens Reviews](http://www.kenrockwell.com/tech/reviews.htm) Has reviews of high-end Canon and Nikon lenses, and he's not afraid to tell you to buy the cheaper models if he doesn't see any real difference in image quality (and he offers photographic evidence to make his case).
* [Camera Labs' lens reviews](http://www.cameralabs.com/lenses/Latest_DSLR_Lens_reviews.shtml) Reviews and round-ups between mostly mid-range Canon and Nikon zooms.
* [Digital Photography Review - lenses](http://www.dpreview.com/lensreviews/) Technical reviews of lenses, which offers a comparison feature which comares lens sharpness rather than side-by-side scene images.

Pentax lenses don't feature hugely on these sites, but they might illustrate whether top-end lenses really offer enough extra quality to justify their considerably higher price. And Ken Rockwell's site will probably just tell you to save your money and spend it on going out to find things worth photographing anyhow.