[Leica] Are Leica lenses muliticoated?

[henningw at archiphoto.com (Henning Wulff)]

>Henning I always respect your expertise and experience. I don't understand
>how you can achieve outstanding resolution without good contrast, nor
>outstanding contrast without much resolution. I was thinking of
>micro-contrast especially as part of achieving theoretical high resolution.
>'Flare' that I would understand as veiling glare must certainly be a factor
>in 'glow'. I would add aberration there. Personally I haven't seen anything
>on my M8 that exceeded the sensor's dynamic range when shooting DNG's with
>all modern, contrasty Leica lenses. I can make the images clip at both ends
>of course in smaller colour spaces on conversion. I don't doubt what you say
>there, only that it hasn't been a problem for me with my camera and amateur
>use.
>
>
>Cheers
>Geoff


Hi Geoff; resolution is, once above a very minimal contrast level is 
quite independent of contrast. Some of the highest resolution lenses 
ever made have relatively low contrast but these are special purpose 
repro lenses. The trick for photographic lenses is to achieve a 
reasonable balance of resolution and contrast so the subjective 
perception, to the limits of the sensor (film) is one of 'sharpness'.

Aberrations certainly can cause various other aspects of an 'old' 
look as old lenses had more of them. Spherical aberration in 
particular can be very pleasant, whereas over-corrected spherical 
aberration can be very nasty, as seen  particularly in some Nikkors 
of the mid-60's and 70's. Sharp but very jarring bokeh. Coma and 
astigmatism can be relatively benign and pleasant on the right 
subjects as long as most of the significant content is near the 
center. Colour aberrations tend to be less benign, and just degrade 
the image.





>-----Original Message-----
>Sent: Monday, 24 November 2008 14:15
>To: Leica Users Group
>Subject: RE: [Leica] Are Leica lenses muliticoated?
>
>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.
>>
>>
>>Cheers
>>Geoff
>>http://www.pbase.com/hoppyman/e
>>http://gallery.leica-users.org/v/gh/
>>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...
>>
>>
>>Steve
>>
>>
>>
>>
>>
>>
>>_______________________________________________
>>Leica Users Group.
>>See http://leica-users.org/mailman/listinfo/lug for more information
>
>--
>     *            Henning J. Wulff
>    /|\      Wulff Photography & Design
>   /###\   mailto:henningw@archiphoto.com
>   |[ ]|     http://www.archiphoto.com
>
>_______________________________________________
>Leica Users Group.
>See http://leica-users.org/mailman/listinfo/lug for more information
>
>
>
>_______________________________________________
>Leica Users Group.
>See http://leica-users.org/mailman/listinfo/lug for more information

-- 
    *            Henning J. Wulff
   /|\      Wulff Photography & Design
  /###\   mailto:henningw@archiphoto.com
  |[ ]|     http://www.archiphoto.com