I prefer lenses made in the 1960s-1970s for these reasons - my most-used lenses are the Leica pre-aspherical 35mm and 50mm, and Canon 100mm and 135mm. Of these, the 50mm Leica is my favourite, though not used as often as the 35mm as the latter is a more useful focal length.
Most of the photos in my current exhibition (
http://www.richcutler.co.uk/exhibitions) were taken with such lenses.
I think medium-contrast lenses (none of the above can be called low contrast) suit digital better than modern high-contrast lenses because not only do they deal with highlights more elegantly but shadows roll off more gently too.
I only have five lenses - one for each major focal length: 25mm, 35mm, 50mm, 100mm and 135mm - and excepting the 25mm lens (a CV - my only modern, high-contrast lens) they are all medium-contrast, high-resolution lenses. I don't hoard lenses, so what I do is try different lenses, buying and selling the lenses so that I only keep one lens of a given focal length (never understood why, for example, some people have a dozen 50mm lenses!).
Take 50mm lenses. I've tried CV Color-Skopar, Canon f1.4, Canon f1.2, Leica Elmar f2.8 (the 1950s version), Leica Summicron collapsible, Leica Summilux aspherical, Leica Summilux pre-aspherical. Of these, as I've mentioned, I prefer the Summilux pre-asph - the only 50mm I now own (and have no intention of selling). All these were bought (and sold) within the past five years - I only took up photography in 2004 when I bought a digital camera.
I now know what I'm after in a lens: medium contrast, high resolution and flare resistance. Performance should change as little as possible over the aperture range.
Most lenses from the 1950s flare horribly - veiling flare is especially pernicious. Also, most lenses from this period perform very poorly wider than f2.8 or so compared with modern expectations - low resolution and an abundance of flare. For example, every lens designed/made in the 1950s from the above list was rejected because they couldn't cut the mustard. I must have tried at least dozen lenses from the 1950s or early 1960s, and every one performed poorly, so I have given up on them and will never try another.
Lens design and coating technology seemed to undergo a quantum leap at the turn of the 1960s onwards, and my preference is thus, as stated, for well-regarded lenses from this period.
My 35mm Summilux pre-aspherical is the odd one out - it flares at all apertures unless used with an efficient hood (that's not the useless standard vented one!), and flare wide open is abysmal yet somehow seductive! Luckily, stopped down to f2.8 and smaller and used with an efficient hood to control flare, it performs superbly. One day I will probably replace it with a 1970s Summicron...
Incidentally, the 100mm Canon may seem a strange choice of focal length. It performs well (not quite to 1970s Leica standards - but close enough) and the focal length is a better match for my Leica M8 framelines (which are notoriously crap at medium-long distances)!
