Thought I'd add a follow-up, lots of good information in this thread.
I've been out shooting with the M9 and the Color-Skopar 28mm lens the past week. A handy, nice feeling package. And carrying alongside it my M4-2 fitted with Color-Skopar 35mm or 50mm.
The recommendation to try the lens code for the Leica Elmarit-M 28mm f/2.8 ASPH on the M9/28 ... that's a magic trick, it corrects most of the Color-Skopar 28's tendency to color shift and vignette on the M9 sensor. And the lens profile for the same lens in Lightroom does a good number on rectilinear correction as well.
But ... there's always a 'but' ... what I find is that the 35 and 50mm lenses are more comfortable to use on the M9 unless I fit an accessory optical finder. I simply can't seen the frame lines or edges of the finder accurately enough with anything wider than 35mm with this body to frame accurately, it's always a guess. This is because of my glasses ... they push my eye too far back for the M9 finder and 28mm lenses. The accessory optical finder slows me down—not necessarily a bad thing, but there are times when it's quite inconvenient.
The difference between the M9 and M4-2 finders is marked: the M4-2 finder presents larger, clearer frame lines and a cleaner focusing patch. It makes no pretense about 28mm coverage so I have to use the accessory finder with it to get good framing accuracy. But the other difference between the M9 and M4-2 is also striking: the fact that once I load a roll of ACROS 100 film in the M4-2 I am stuck with one ISO for 36 shots is limiting, and the fact that I have to manually wind the shutter after every shot is another limitation. Having the choice of ISO and the motorized shutter re-cocking in the M9 makes me like using it more despite the extra bulk.
So you folks may have saved me a couple of grand for a new lens. I'm more comfortable when using either camera with the 50 or 35 lenses, the Color-Skopar 28 with the right lens code works beautifully on the M9. When I want wider (or longer than 50mm), the A7 and E-M1 do better. I already have the right lenses for those.
But that Super Elmar 24 and Summicron 28 do look appealing still. There's no rush... ]'-)
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Yes, sometimes the older lenses' imaging make a difference that pleases. This is why I still love my ancient Hektor 135 and not quite as ancient M-Rokkor 90. And the modern Color-Skopar lenses ... their character reminds me much more of the older Leica lenses but with more modern flare control.
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Leica M9 + Color-Skopar 28mm f/3.5
ISO 320 @ f/3.5 @ 1/30 second
So many fine ways to run this stuff. I'd like to have either of the Summicron 28 or Elmar 24 lenses. But a decision to buy one of them is going to be on hold until at least after I get back from my Hawaii vacation (leaving Thursday)...
Now what camera will I pack for Hawaii? Hmm... ?
G