Re: [Leica] here's a concept, Summilux vs. Noctilux

[Alan Ball <AlanBall@csi.com>]

Andrew,

The raison d'être of the Noctilux is to push back as far as possible the
limits of handheld photography in low light. For this usage, the lens is
obviously 'better' than the 50mm f1.4 Summilux, simply because the f1.4
does not open at f1. From f1.4 on, the usual consensus is that the
Summilux is the 'better' lens, because of its optical performance, and
that the competition from f2 on comes from the Summicron, not from the
Nocti. Hence the conclusion of Noctilux lovers that their favourite lens
should only be used at f1, and that the iris is superfluous.

The comparison between the 35mm f1.4 (asph) and the Nocti makes sense
for the application at which the Nocti is destined. The idea is that a
wider angle might allow a slower shutter speed and thus 'eat' at least
part of the 1 stop advantage of the Nocti. 

The 35mm f1.4 brings another advantage wide open with a more comfortable
margin of acceptable focusing error due to the much larger DoF. This is
real: at f1 at close distance, a very slight movement, backward or
forward, of the photographer or of the model, will make an out of focus
image. And in low light, even with the M advantages, ultimate precision
of focusing remains an issue.

The 35mm f1.4 Asph also has the advantage of being totally versatile at
smaller apertures, with no quality trade-off compared to the Summicron
Asph, if I read well all tests on the matter (I personally own the
Summicron Asph). It is also much more compact and lighter than the
Nocti. Furthermore, the wider angle of view offered by the 35mm is an
advantage indoors, which is probably the situation where most people
shoot available light images.

The only advantage the f1 50mm might have on the 35mm f1.4 is when
shooting moving subjects: 1/30sec leaves slightly less room to subject
movement blur than 1/15sec....

So, even if my conclusion is not automatically true, it seems probable
that the Nocti's physical 1 stop advantage might not be as irreplaceable
as generally argued on the LUG... 

Alan



A S Jordan wrote:
> 
> Attention lux lovers: This comparison of the 50mm f1 lens with a 35mm f1.4
> lens does not make much sense. If a f1.4 lens meets most of the users'
> requirements  why not compare the 50mm f1 Noctilux with the 50mm f1.4
> Summilux? Indeed very little is said about the 50mm Summilux even by Erwin,
> our venerable optical expert. Perhaps it is because the Summilux is a
> decades old design.
> Many of us would welcome a comparative discussion of the 50mm Noctilux vs.
> the Summilux. If at the same aperure(say, f1.4 and f2) the Noctilux is
> superior in performance to the Summilux that could stimulate Solms to
> produce a modern asph 50mm f1.4 Summilux-M.
> 
> regards, Andrew Jordan