Archived posting to the Leica Users Group, 2008/11/23

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Subject: [Leica] Are Leica lenses muliticoated?
From: henningw at (Henning Wulff)
Date: Sun Nov 23 20:14:59 2008
References: <> <><4AE8990C-C0EA-4C66-B><> <> <9B4C173E1A764301A715211C9ED9D6B6@dadquad>

You need good contrast along with good resolution to achieve 
'sharpness', ie, a perception of 'good resolution'.

You don't need a lot of contrast to achieve outstanding resolution, 
nor do you need much resolution to achieve outstanding contrast.

The 'softness' or 'glow' or 'glamour' that is ascribed to older 
lenses is a combination of low contrast and flare, both things that 
can be controlled by using correct coatings, multi-coatings or 
whatever for the glass types and curvatures of lenses. The latter 
also plays a part.

You can have low contrast without a lot of flare, but it's not easy. 
It's often proposed that to achieve a very high effective dynamic 
range a low contrast lens is desirable, but that often leads to 
flare, which tends to be localized and cannot be dealt with easily. 
Therefore, a lens that is chosen for its low contrast characteristics 
like the DR Summicron often causes problems due to flare. Of course, 
when the stars align the results can be outstanding, but a low 
contrast lens is not a panacea for dealing with large dynamic ranges.

As I mentioned earlier in this thread, the earliest multi-layer 
coated lens I know of is the 35/1.4 Summilux introduced around 1960; 
I'm sure there were ealier examples but this lens was one of the very 
first commercially produced lenses using this technology. Once 
designers were able to take advantage of reducing the reflectance and 
therefore scatter of specific spectral bands, it opened up a huge 
range of possibilities, especially in marketing :-). Whether one uses 
3, 7 or 20 layers is a bit like whether your razor has 2, 3, or 5 
cutting blades. Past a certain point it's mostly marketing, 
especially if your lens is for general photographic use under 
uncontrolled conditions.

Coatings for controlled conditions can be optimized to a much greater 
degree; lenses for reproduction, especially three colour or even more 
so monospectral reproduction could have highly optimized coatings 
that required only a few layers, with slightly different thicknesses 
varying from the center to the edges.

If you know a lens well, you can use it's flare characteristics to 
your advantage, in particular to achieve an 'older' look, but if what 
you're mainly concerned with is reducing contrast, there are usually 
other ways of achieving that that are more controllable.

I've had a lot of different lenses over the last 50 years, and still 
have quite a few. Among the latter are still a few low contrast 
lenses and a couple that have very specific flare characteristics, 
but on the whole I prefer lenses that medium to medium-high in 
contrast with as little flare as possible. Those are the easiest to 
work with. If I wish, I can create most types of flare after I take 
the picture. I can't remove it easily if it's in the negative or 
digital file if at all.

>Steve you really need good contrast to achieve good resolution, the two go
>hand in hand. The well recognised smooth look that you are describing may be
>partly from moderate contrast, but also from the degree of correction
>present. With more aberration present, the out of focus blurs can retain
>their general shape and be smoother by being more blurred! That is not meant
>to be a criticism of valid personal preference. Of course my taste there is
>probably well established.
>Has anyone else noticed that this evolving thread is almost a digest of
>perennial LUG topics?
>Lens coatings,
>Lens cleaning,
>Artistic vs. technical,
>Favourite lenses
>What great master photographers used etc etc
>Now I suppose I have introduced the B word.
>Pick up your camera and make the best photo you can.
>-----Original Message-----
>Subject: Re: [Leica] Are Leica lenses muliticoated?
>this same argument applies to some of the greatest and highest resolution
>lenses of the past...for example  the Summicron 50/2 DR...low contrast
>combined with very high resolution allows a unique smooth look...and you can
>always increase the contrast if desired...
>I am not sure how the coating impacts, or what the coating is for the DR...
>this look and behavior likely accounts for this lens being the desert island
>favorite of so many individuals...
>Leica Users Group.
>See for more information

    *            Henning J. Wulff
   /|\      Wulff Photography & Design
  |[ ]|

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