Archived posting to the Leica Users Group, 1999/05/18
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Erwin- Let me echo my appreciation for your in depth studies. My impression is that with the aid of computers, and advanced technology never before seen in the optical industry, it is refreshing to see that skill, craftsmanship and what can only be described as 'artistry' still prevails. You would think that a computer designed lens would be 'perfect' but there seems to be room for improvement, even at that! It would seem that since the Ricoh performs so admirably at the smaller apertures, that their programs for designing ashperical elements needs some work where the periphery of the lens is concerned! In turn, it raises the question- if the aspherical elements of a lens don't perform significantly better than traditional elements with sphrical surfaces- why bother? Is it a market ploy for some? Evidently, Leica has found a 'formula'- the aspherical elements they produce seem to eliminate additional correctional elements- sort of the optical equivalent of an integrated circuit!, and make for smaller, lighter and better corrected lenses. Others seem to produce aspheriecal elements to reduce the total number, perhaps, but without a significant improvement in performance. Any thoughts on this? Dan - -----Original Message----- From: B. D. Colen <bdcolen@earthlink.net> To: leica-users@mejac.palo-alto.ca.us <leica-users@mejac.palo-alto.ca.us> Date: Tuesday, May 18, 1999 11:35 AM Subject: Re: [Leica] copmarison Ricoh 28 and Elmarit 28. >Thank you, Erwin, particularly for the "real world" commentary following the testing results. > > >Erwin Puts wrote: > >> A comparison of the 28mm Ricoh GR and the Elmarit-M and R versions of the 28mm. >> >> The Ricoh (#02818) is a diminuative lens. The chrome version with the focusing aid is very Leica like. Mechanically it showed a slight axial play in the distance ring mechanism and a very slight decentring. >> At full aperture (2.8) the lens shows a medium to high contrast, with some light fall off in the corners. In the center very fine detail is recorded with medium microcontrast and slightly soft edges. Extremely fine detail is just recorded with very soft outlines. This type of performance holds on axis over a circle with a 4 mm radius (an area of 8 to 10mm diameter). In the field (the outer zones) fine detail is recorded with high contrast. The edges however show colour finges and there is also a trace of astigmatism. Fine and very fine detail is fuzzy, but just visible. The corners are very soft with outlines of large subject detail clearly visible. >> At f/4,0 the image crispens and the overall contrast becomes high. On axis the edges of fine detail clearly sharpen,. In the field the improvement is slight. At 5.6 the overall image is still a bit soft in the field. At f/8.0 we get an excellent image with extremely fine detail clearly resolved, with a faint trace of softness. At f/16.o the performance drops. >> The close-up performance ( 1 meter) is identical to the infinity setting. >> >> The Elmarit-M 2.8/28mm (#3793205) at full aperture shows a high contrast image with very fine detail crisply rendered. On axis over an image area 0f 10 to 12mm diameter) the extremely fine datail is very clearly visible with some softness at the edges. In the field (outer zones) the contrast drops, and the outlines of large objects show a very faint colour fringe. Extremely fine detail is recorded with good clarity, with a slight fuzzyness at the edges. This performance holds into the corners where extremely fine detail is still visible, but with fuzzy edges. >> At f/4,0 the image crispens in the detail rendition. Extremely fine detail is now clearly resolved with great clarity and sharp edges and exceedingly fine detail is now crisply resolved on axis, with some fuzzyness in the far corners. >> At 5.6 the outer zones improve a bit, but the center is already past its optimum. >> Close-up performance is equal to the infinity setting. No decentring could be detected. >> >> The Elmarit-R 2,8/28mm (#3701134) is almost identical in performance to the M version. The R version exhibits slightly more chromatic aberrations and the performance in the field is a bit lower. Generally however this lens is equal to the M version. Close-up performance till 30cm gives excellent imagery comparable to the infinity setting. Again no decentring. >> >> Conclusion: the use of aspherics (two surfaces ) in the Ricoh is not automatically a 'free' ticket to best perfomances. We have been evaluating here absolute performance and on this quite lofty Olympic heights the Ricoh is clearly not as good as both Elmarits, which deliver superior imagery. To stay for a while in this comparative field. The Ricoh is better (by a good margin) than the first and second generation of the Elmarit 28mm M lenses. The third generation of the Elmarit however shows better performance in all areas, as of course does the current (fourth ) generation. Absolutely speaking: the Ricoh at 5.6 and 8.0 is almost as good (but not quite) as the Elmarit 's at 2,8. >> >> But we can also look at the performance from a slightly more casual perspective. If we assume that the Ricoh and Elmarit pictures will be taken on colourneg films or higher speed B&W films and enlarged to let us say the ubiquitous 20x25cm format, then the performance differences shrink. Of course on close scrutinization the overall softer rendering of the Ricoh will show. In the center area however the margin between the Ricoh and the Leica lenses is under these conditions is not that big.Stopped down to 5,6 or 8.0 you would be hard pressed to notice any difference. >> >> There is one area where the Ricoh has an advantage: the mechanics of the separate viewfinder. It is a solid chrome metal piece of work. Optically the finder distorts quite a bit: that mars the joy a bit. >