I have owned some of the best Leica glass ever, the 28 Summicron, 35/2 Asph, 35 1.4 Asph & 50 1.4 Asph M mount lenses. I bought them to shoot some
35,000 Kodachrome slides from August of 2006 through January 2011. I also shot Nikon F mount and Hasselblad XPan with the film.
What I found in my very experienced professional eye is that the Leica glass was just a tad better in terms of color compared to the Nikon and Hasselblad in daylight or average light. But when the light got lower, mixed, etc, it came alive, made a noticeable difference. In terms of sharpness, it also made a difference back then. When the project was over, I compared my 35 1.4 Leica to a brand new Nikon 35 1.4G on slide film and could hardly tell the difference except for the sizes of the lenses.
That was with slide film, where I believe Leica glass makes the biggest difference. With color negative, and digital, there was far less of a difference so I sold most of it, re-tooled to a much smaller kit and then shot black and white for a year. What I saw with black and white film was much like what several on here are saying like Thomas. It just did not make that big of a difference in the final neg scan or print, it REALLY did NOT. I either carried the image with my talent or I did not, the lens did not matter nearly as much with black and white film as it did with color slide.
So again, I sold almost all of the small kit I had re-tooled about this time last year. What I have left is a M3, 50mm Collapsable Summicron and a KILLER Zeiss 50mm F/2 ZM. Honestly, I wished I had the Zeiss 50/2 instead of the pricey Leica 50mm 1.4 asph LHSA when shooting Kodachrome. It is lighter, just as sharp at F/2 for the most part and has third stop aperture increments which would have been stellar for Kodachrome.
If you do a side by side test and keep it purely scientific *and* shoot black and white film, you might find a slight difference in the lenses, but that is it. For example, the Zeiss 35/2 is supposedly a bit better in the center than the $3,000+ Leica 35mm F/2 Summicron Asph. The Leica is better in the corners. The Zeiss 50mm F/2 Planar is simply amazing, many great Leica shooters like it equally to the 50 Summicron. But I also kept the old 1956 Collapsable, mine is a rare clean one with a trace of cleaning marks and that is it. I love the old world look of it wide open and it is darn sharp from F/4 on down, but it flares like a Coke Bottle, hence my using the Zeiss instead.
I had a wonderful time shooting Leica with
Kodachrome, but when it was done, that overpriced gear was sold off as quick as I could get it done. If you have the money, don't mind babying the gear because collectors get ticked if you so much as put a paint mark on the lens, go for it. But if you are like some of us on here who are TRULY photographers and put the final CONTENT of the photograph first, don't think twice about using great glass like Zeiss instead of now GROSSLY overpriced Leica.
Yes, Leica is nice glass and with color slide it makes a marked difference in the kind of light where there are more than 3-4 sources all within a 1/2 stop of each other, it makes things really pop. But for black and white, just not that much.
Anyone who tells you different can kiss the object in this (there was a url link here which no longer exists) I uploaded, shot with the Leica I sold last week
