[Leica] Why spend more for a Summilux 50mm f/1.4?

[Andre Jean QUINTAL <megamax@abacom.com>]

Good Afternoon,

	Other than a full-stop extra speed,
	would someone care to step forward and comment
	on the actual benefits of choosing the new Summilux 50mm
	f/1.4 over the much less expensive Summicron 50mm f/2 ?

	In fact, I'm trying to understand what I might,
	for discussion purposes, gain or loose from choosing
	the much less expensive Summicron,
	while Mr Puts seems to put such high marks on both
	the 'M' and 'R' versions, if I understand what he writes.

	To a professional eye, is the 'M' Summicron 50
	that much better than the current 'R' Summicron 50
	in a 16" x 20" well made enlargement or through
	a good slide projector / lens ? Or should I put this question
	in such a way as to rather compare Summilux and Summicron ?

	What about color fidelity and 'finesse tonale' (tonal rendition) :
	is one of these four lens designs towering above the others
	in a immediate no non-sense way, to an extra-critical eye
	obviously, but even to the "casual bystander" ?

	What about
		- edge definition ?
		- the 3D impression on comparable subjects ?
		- color saturation and "quality" ?
		- contrast ?
		- highlights / shadows detailing ?
		- close range performance, up to 1.5 meter (4-5 feet)?
		- useable resolution or "micro-contrast" ?

	Is it wise to refer to useable contrast ratios in describing
	such a high performance lens, or is such a concept
	mostly limited by the types of films used or the ultimate use
	of a given photograph ( newspaper, high grade printing, decor or
	museum style uses, or digital scanning for web use)
	if we use a system analysis / limiting factors approach ?

	I don't dare talk " M.T.F. " because I don't understand "height"
	in these graphs and presume the most linear plot is preferable,
	hoping for the least performance drop-off . . . Perhaps is height
	an expression of ultimate resolution attainable at a given aperture
	or useable EV interval for a given lens design ?
	Some day, I'll find a resource
	that correlates these esoteric plots to actual photos,
	hopefully one of those "cultural" cable TV channels
	with an interested and thorough (add: very patient) teacher.

	My purpose here is to peg some basic notions that might prove
	useful to the greater number and to help assess or better
	appreciate other "basic" focal lengths, 35mm especially.

	OR: is there a standardized form, somewhere, to help assess
	a lens design in a really meaningful way ?

	Andre Jean Quintal