Fast lens != always good quality images
"A fast lens delivers pin sharp detail, perfect contrast and no cheap special effects like vignetting and colour shifts in the corners"
You sure about that? I think you'll find that a fast lens requires far more careful crafting of the elements if it's to remain free of defects and the likes of Nikon, Canon, Mamiya, etc. all charge a premium for their faster optics for a good reason: they're horribly expensive to make well.
You'll also find that most lenses perform at their best (if, by 'best' we mean free of distortions) when they're stopped-down 3 to 4 from wide open. If anything, vignetting is more likely to happen with /any/ lens when it’s wide open because, by definition, you're pushing the very limits of the optics. Stop down a couple and you'll also get more tolerance to focus because you'll get a greater Depth of Field.
Will you get punchier images with a fast lens? No, not necessarily. Arguably, it’ll help to some degree but in digital kit contrast is more affected by the anti-aliasing and pre-processing filters than by the f-stop. Oh - and colour shifting /brought on by aperture alone/ is usually associated with very high f-numbers (32 and above – well beyond the reach of almost all amateur-grade kit) but shifting will happen regardless; it’s even more frighteningly expensive to manufacture optics that bring the entire visible spectrum to focus on one plane than it is to make them distortion-free at wide apertures (the red dot that was a few degrees past the ‘normal’ focus marker on their old 35mm lenses was there to show the focus offset one needed to apply if shooting with IR film).
Aside from that, an interesting article.
Biting the hand that feeds IT
