Archived posting to the Leica Users Group, 2008/11/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Nov 23, 2008, at 9:14 PM, Henning Wulff wrote: > You need good contrast along with good resolution to achieve > 'sharpness', ie, a perception of 'good resolution'. yup... but even contrast without resolution can give an impression of sharpness...especially with small web jpeg files... > > > You don't need a lot of contrast to achieve outstanding resolution, > nor do you need much resolution to achieve outstanding contrast. so it seems the math would show two really independent parameters.... with sharpness being a "perception" yet this often can be misleading... thanks Henning, Steve > > > 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