Paul Reading Posted June 19, 2012 Share #1 Â Posted June 19, 2012 Advertisement (gone after registration) What is the difference between the Leica Summilux-M 50mm f/1.4 Lens and the Leica Summilux-M 50mm f/1.4 Lens ASPH? Â and while you are at it what does APO mean? Â I am always confused as to the different terms from Leica such as Summilux, Summicron, Elmar, Summarit, Elmarit are these random names or do they convey a meaning? Link to post Share on other sites More sharing options...
Advertisement Posted June 19, 2012 Posted June 19, 2012 Hi Paul Reading, Take a look here What do all these different terms mean?. I'm sure you'll find what you were looking for!
andybarton Posted June 19, 2012 Share #2  Posted June 19, 2012 ASPH means that the lens has an aspherical element, which helps to correct distortions  Generally, the names relate to f-stops  Noctilux = f1.0 (or f0.95 today)  Summilux = f1.4  Summicron = f2.0  Summarit = f2.5  Elmarit = f2.8  Elmar = f3.5 or f4 (although sometime f3.4 or a very old f2.8)  Check the Wiki on the forum  http://www.l-camera-forum.com/leica-wiki.en/index.php/Main_Page#M_Series_Lenses_.26_Camera_Accessories Link to post Share on other sites More sharing options...
mmradman Posted June 19, 2012 Share #3 Â Posted June 19, 2012 Trade names, each name convey max F speed; summilux = f1.4, summicron = f2, elmarit = f2.8 etc. Â You have 80 posts, not LUF newbie, still no shame in asking. Â Edit; Andy was noctilux fast. Link to post Share on other sites More sharing options...
farnz Posted June 19, 2012 Share #4 Â Posted June 19, 2012 ... and while you are at it what does APO mean? ... APO is an abbreviation for apochromatic, which means that the lens contains an element that causes all three primary colours red, blue, and green to focus in the same plane. Normally different wavelengths (colours) are diffracted by a different amount by glass as can be seen in a rainbow. Photographic lenses are intended to focus a point of light that is reflected from the object so that it forms as smaller a point as possible in the image but if the different colours focus in different planes either in front of or behind the image then the image will contain some blur. Leica APO lenses are designed to correct this blur. Â Pete. Link to post Share on other sites More sharing options...
earleygallery Posted June 19, 2012 Share #5 Â Posted June 19, 2012 In the world of Leica snobs they are like postcodes, or school names. You will be judged by them! Â You need a Summilux at least to have any kudos - it's not that bad to use an Elmar or Summarit but you will find yourself constantly apologising or justifying yourself to other Leicaists "I know it's only a Summarit but it will do for now, actually I'm waiting for the new APO". Â Of course we all know that you lack 'connections' within Leica or the dealer network and are bottom of every waiting list! Â Link to post Share on other sites More sharing options...
andybarton Posted June 19, 2012 Share #6 Â Posted June 19, 2012 Although my 35mm Summicron is current, my 50 Summicron is a Type II from 1973. I really, honestly cannot see any reason to buy a new one. Â I've never been a "must have the latest" kind of bloke - never had the money - I'd rather spend what I have putting my kit in a carry on bag or boot of the car and taking it somewhere nice to be used. Link to post Share on other sites More sharing options...
TomB_tx Posted June 19, 2012 Share #7 Â Posted June 19, 2012 Advertisement (gone after registration) There was also the original Noctilux at f1.2, and the old Summarit at f1.5; just to confuse things... My Leica lenses are all 1940s to 1970s, so I think of the older models first. I also see no reason to replace my old lenses with new. Link to post Share on other sites More sharing options...
adan Posted June 19, 2012 Share #8  Posted June 19, 2012 APO is an abbreviation for apochromatic, which means that the lens contains an element that causes all three primary colours red, blue, and green to focus in the same plane.  Well, almost. APO refers to the overall performance of the lens, not necessarily to a specific bit of glass. I.E. it is not precisely synonymous with Nikon's "ED" lenses, which do have one or more specific "ED" (Extra-low Dispersion) bits of glass.  Leica's lens diagrams usually point out the specific ASPHeric surfaces, but in the APO lenses no particular glass bit is marked as the "APO" element. Leica does use extra-low or "anomalous" dispersion glass elements, just like Nikon. But "APO" refers to the whole cake, not any one ingredient.  ASPH means that the lens has an aspherical element, which helps to correct distortions  Again, ASPH glass surfaces are not specifically for correcting distortion - in fact, some ASPH lenses have more distortion that their non-ASPH predecessors (21 Elmarit ASPH vs. 21 Super-Angulon, e.g.).  ASPH elements can do various jobs within a lens, depending on the problem(s) the lens designer needs to solve. Their primary function is to bend light without introducing the "spherical aberrations" that regular spherical lens elements produce.  Spherical aberration  This property can be used to: reduce field curvature; make the lens smaller for a given performance; reduce the number of elements needed (lower cost/improved contrast); allow a larger aperture for a given performance; assist in producing "APO" performance; etc. etc. And, yes, in some cases, reduce distortion if needed. Not necessarily all in the same lens design.  For Leica, the original use of ASPHs was to create extra-large-aperture lenses without the usual result of fuzzy low-resolution images at full aperture due to spherical aberration, notably in the original Noctilux f/1.2 (Aspheric elements, but without any special label) and the 35 f/1.4 Aspherical (later redesigned as the ASPH).  Since the mid-1990's when Leica and Hoya developed a molding technique much cheaper than the hand-grinding required previously, ASPH elements have been added to various lenses to solve/prevent various problems. Link to post Share on other sites More sharing options...
farnz Posted June 19, 2012 Share #9 Â Posted June 19, 2012 Andy, Â When I wrote "element" I note that you've assumed that I meant "lens element" when actually I meant "feature" but thank you for clarifying. I understand, although I am happy to be corrected, that the method in which Leica delivers apochromatic correction in its lenses is conjecture since it is Leica's intellectual property and as such it has retained its confidentiality. Â Pete. Link to post Share on other sites More sharing options...
Paul Reading Posted June 19, 2012 Author Share #10 Â Posted June 19, 2012 Thank you so much for your explanations. This sounds silly but I have been a Leica user for nearly 10 years now and it was a bit like playing "Mornington Crescent"! Â I just got to the point where I had to ask, because I couldn't work it out. Â Paul Link to post Share on other sites More sharing options...
lars_bergquist Posted June 20, 2012 Share #11  Posted June 20, 2012 Moderators – maybe this is a subject for a sticky?  The old man from the Kodachromatic Age Link to post Share on other sites More sharing options...
philipus Posted June 20, 2012 Share #12  Posted June 20, 2012 you need a Summilux at least to have any kudos  funny. I need summilux because i use film.  There was also the original Noctilux at f1.2, and the old Summarit at f1.5; just to confuse things....  And the lovely f/2 Summitar of course. Link to post Share on other sites More sharing options...
jaapv Posted June 20, 2012 Share #13  Posted June 20, 2012 Moderators – maybe this is a subject for a sticky? The old man from the Kodachromatic Age When all has crystallized I'll put it in the FAQ.I haven't seen the Elmax and Hektor yet Link to post Share on other sites More sharing options...
rramesh Posted June 20, 2012 Share #14 Â Posted June 20, 2012 Is there a good site to read about the evolution of Leica 50mm lens design from the Elmax to the Noctilux and 50AA? Unfortunately the Leica Pocket Book, good as it is, does not provide details of the lens cross-sections. Link to post Share on other sites More sharing options...
jaapv Posted June 20, 2012 Share #15 Â Posted June 20, 2012 Site? Try a real book Erwin Puts' Compendium. Link to post Share on other sites More sharing options...
bpalme Posted June 20, 2012 Share #16 Â Posted June 20, 2012 Google Apochromatic telescope. There is a lot more about them to read about and it makes a bigger difference to astronomers. Basically it helps correct purple fringing and helps with sharpness White light goes in a lens as white and when it comes out it does not go back together perfectly. Mainly the blues and purple stray. Some telescopes have an extra lens to try and align the purple. Sometimes they add more than one lens to try and correct this. Non Apochromatic are referred to as achromatic. http://en.m.wikipedia.org/wiki/Apochromat#section_2 Link to post Share on other sites More sharing options...
SJP Posted June 20, 2012 Share #17 Â Posted June 20, 2012 Is there a good site to read about the evolution of Leica 50mm lens design from the Elmax to the Noctilux and 50AA? Unfortunately the Leica Pocket Book, good as it is, does not provide details of the lens cross-sections.In general they increase in cross secion as does their price. Link to post Share on other sites More sharing options...
Jeff S Posted June 21, 2012 Share #18 Â Posted June 21, 2012 Paul, you may also sometimes see the terms cron, lux or rit used on the forum. These have no meaning whatsoever. Â Jeff Link to post Share on other sites More sharing options...
120 Posted June 21, 2012 Share #19 Â Posted June 21, 2012 ...Non Apochromatic are referred to as achromatic.... Â could be neither, so this is not quite right Link to post Share on other sites More sharing options...
masjah Posted June 21, 2012 Share #20 Â Posted June 21, 2012 My understanding was that, in the old days, "achromatic" referred to making the focal length of the lens the same for red light as for blue light, that is to say, correcting axial chromatic aberration to first order. Even in my A-level school Physics, using simple-minded linearised thin lens theory to illustrate the underlying principles, we used to have to calculate the lens radii of "achromatic doublets", given the refractive indices of crown and flint glass for red and blue light! [On such a simple linearised theory, it was of course meaningless to try to correct more than two colours, because sensibly interpolating between them (e.g. for "green") involves higher order theory than good old linearised 1/u + 1/v = 1/f!!!] Â The term "apochromatic" seems to mean different things to different manufacturers - to the extent that the only common ground seems to be "something better than simply achromatic"; for example sorting out more than two colours, or looking more carefully at radial aberration as well as axial. Â To be honest, I get more confused than anything else. I'd be delighted to be enlightened further by the many much more expert Forum members here. Link to post Share on other sites More sharing options...
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