Re: all about the glass
- Original Message - From: "Jens Bladt" Subject: RE: all about the glass > In the days of no digital photogrphy, the lenses would set the limits to > resolution, sice film can resolve more than 100 lp/mm. Not many lenses can. > Today, as digital technology gain market shares, the sensors seem to be > setting the limits to resolution. The sensors cannot yet utilize very high > quality lenses. The sensor technology still have to develop further in orfer > to reach 100 lp/mm, or whatever is equals 35mm negatives (3600 linepars > across the long side of the image = 3x3600 = 10.800 pixel). This should > mean, that in digital photography - it's all about the sensors, not the > glass! This debate, of course, ignores all lens qualities other than resolution, and has to ignore resolution vs. subject contrast to work. Since you cannot ignore subject contrast when discussing film and lens resolution, the numbers stated are deceiving. Pray tell, what film can resolve more than 100 lp/mm? I haven't found one yet that will do it without the help of a 1000:1 target. Velvia 50 does 80, I expect that's about as good as it gets, maybe Tech Pan can do a bit better, but it's not well suited to colour photography. Lenses, OTOH, when used for pictorial purposes, don't usually get much more than 60 lp/mm resolution. One thing I have never seen answered definitively is this: Do digital sensors also lose resolution as measured in lp/mm when subject contrast drops? And if so, by how much? It seems to me that sensors wouldn't be as sensitive to subject contrast, but I don't know for sure. Anyone? I believe Rob calculated the istD sensor resolution to be somewhere around 43 lp/mm or some such. If sensor resolution can be brought up to 60 lp/mm and made full frame, then you are pretty much at a film equivalent for raw resolution, and have a tremendous advantage over film WRT granularity. This takes the lenses out of the equation, and ignores colour aberrations. No comparison is really perfect. William Robb
Re: all about the glass
Alan, It's highly unlikely someone shoots sceneries wide-open. From 135 up these really commands f/8 and tripod. And under these conditions I have found the SMC 135/2.5 combined with Provia 100F to result in bit too vivid colours for my taste. Also, the above lens delivers good saturation and contrast even wide open; of course chromatic aberrations towards the corners limits its resolution, but one can hardly say it is a low contrast lens wide open. Servus, Alin Alan wrote: AC> I belongs to the minority I guess. I think the wide open performance of most AC> Pentax 135 lenses is disappointing. I would be very surprised if they were AC> considered the best as most people have emphasized here. Also, due to the AC> relatively low contrast and less vivid colour rendition (noticeably AC> different from Nikkors), I have found Velvia 50 works best for scenery. AC> Films like Provia 100F do not really work for SMC lenses.
all about the glass
>From: Andre Langevin <[EMAIL PROTECTED]> >>2) ...there is very little difference in quality between comparable >>lenses from all the manufacturers. >I think it's true that differences are small. And that manufacturers >had a large part of their line comparable with others'. Ironically, if this is true then it's not, as somebody suggested, "all about the glass". It's either "all about the cameras" (which differ a lot more in features and user interface) or "all about the perception of the glass". > For example, >I though until last week that Pentax famous low distorsion (0.5%) >28/3.5 lens was unique in that respect but discovered that the >MC-Rokkor-X 28/3.5 had the same low distorsion figure. One usually sees comparisons within brand, presumably for the benefit of users of that brand who wish to make a choice. You rarely see comparisons across brands. It's not really useful, unless it turns out that most of brand A's lenses are better than the other brands at a given price level. If that were the case, everybody would buy brand A. I don't really think that's why everybody seems to be buying Canon these days. That 28/3.5 design is great in other ways too. It makes Pentax's collection of mediocre 28/2.8 designs a bit of a mystery. Fortunately Pentax also offered the 30, 31, 28/2, etc. >>Increasingly, manufacturers are tailoring optical quality more >>precisely to price class as they learn not only to engineer quality >>in but also to engineer it out. >Still, sometimes you feel a manufacturer has put a bit more for the >price, hoping to sell volumes of that item. This could be true of >the Olympus Stylus with the great 35/2.8. Unfortunately, this is probably true primarily of entry level and generic stuff. Sigma might outsell Tamron across all platforms if they make a better 24-240/4.5-8.0 zoom for the same price, but Pentax isnt' going to sell a better 135/2.8 to somebody with a Nikon camera. (Pity about that--I'd love to put that 135/2.8 IF on my Nikons...) A better P&S lens or starter 28-80 might help sell cameras, though. DJE
Re: all about the glass
>From: Matt Giess <[EMAIL PROTECTED]> >> Increasingly, manufacturers are >> tailoring optical quality more precisely to price class as they learn >> not only to engineer quality in but also to engineer it out. The days >>of >> a cheap lens potentially being a great lens are passing. This may >> account for the increase in popularity of the older equipment made in >>an >> era when this did not happen (and equipment was not cheap...) >I'd personally argue that a major factor in some modern lenses being a >bit poor lies in the refinements to the design process, in particular being >able to design to a particular price whilst ensuring the lens is at least >adequate for the target market. Yes. I was not saying that companies were deliberately designing lenses with the goals of low optical quality or poor build quality simply to give definition to their market line. I was saying that modern manufacturing technology makes it possible to make serviceable equipment much more cheaply by cutting corners optically and mechanically, and at certain levels of the market this is acceptable. There isn't nearly as much difference between any of the K series or Spotmatic series cameras as there is in the current Pentax offerings, and this is because they have figured out how to make a $150 camera for those folks who only need, want, or can afford a $150 camera. They still make "old-style" premium products, and they still carry "old-style" premium prices. Same goes for lenses. I've heard some very high prices quoted for what it would cost Pentax to put out a re-issue of the Spotmatic and 50/1.4 Super Takumar to the original specs. The thing is, while Pentax might find a way to make a good design more cheaply, or to produce a better design using an already cheap process, or invent a new process which allows better AND cheaper designs, they can't afford to simply make better lenses whatever the cost if they want to compete in the market. There is much better control now of the balance between quality and manufacturing cost than there ever was, I think. It does not mean that they can't make a great lens anymore, simply that users are now used to being able to get acceptable lenses cheap and out of the habit of paying the cost of premium products. Leica survives in a very small niche. DJE
Re: all about the glass
Well, you seem to have hit the nail on the head. All of the above (Opps, the below). Plus the tendency to claim "mine is better than yours" regardless of what the facts may be. -- [EMAIL PROTECTED] wrote: I've been thinking in the wake of some recent discussions of optical quality that every camera user community I've been exposed to (Pentax, Canon, Nikon, Olympus, Leica, Minolta) seems convinced that their lenses are at least as good if not better than the other brands. This includes people on this list and friends of mine who have switched from Nikon or Canon to Canon or Nikon, or to Pentax, guys like me who have moved from Pentax to Nikon (not for the glass), etc. The only real exception to this is the first string of the third party manufacturers--Sigma, Tamron, Tokina. People seem to debate which of them is better but only recently compare them to the manufacturer's lenses. There seem to be several possible explainations for this. 1) Somebody is wrong. Perhaps Leica IS better but those of us without the money will never know. Perhaps Minolta is NOT as good but the user community hasn't discovered it or can't admit it. 2) Everybody is right, and there is very little difference in quality between comparable lenses from all the manufacturers. It took me a while to realize that advertisements did not focus on the qualitative differences between products because in general there were no significant qualitative differences between products. Realistically, most modern lenses are "good enough" for the needs of the users in any given price class. Increasingly, manufacturers are tailoring optical quality more precisely to price class as they learn not only to engineer quality in but also to engineer it out. The days of a cheap lens potentially being a great lens are passing. This may account for the increase in popularity of the older equipment made in an era when this did not happen (and equipment was not cheap...) 3) There is enough variation in all the manufacturer's lens lines that everyone has some duds and some killers and user opinion depends a lot on what subset of the lens line he has experienced. Certainly there is a lot of difference across price lines within each brand, more so in some than others. I'm increasingly convinced that the reason most pros say Canon is better and most advanced amateurs on this list seem to be disgusted with Canon is that Canon has the greatest range of variation across its product line, whereas Pentax may have the least. 4) The various brands are optimized differently, with Nikon aiming for greater corner sharpness at the expense of bokeh and coma, Canon aiming for optical specs at the expense of distortion, Pentax aiming for center sharpness and bokeh at the expense of corner performance, etc. Thus, a given brand may be better at giving a certain "look", or under certain conditions of use. It may also be a question of what fault annoys a user more--distortion, coma, bad bokeh, lack of corner sharpness, bad color balance, etc. Eventually each user migrates toward the brand which offers the best combination of optimizations for his taste. DJE -- graywolf http://graywolfphoto.com/graywolf.html
Re: all about the glass
every camera user community I've been exposed to... seems convinced that their lenses are at least as good if not better than the other brands. I noticed it also. It goes farther. On one Minolta group, for example, I noticed that people took for granted that multi-coating was invented by Minolta and used since remote times on their lenses. I think they extrapolated from the fact that Minolta began to use a two-layer process (two coats of the same material applied with different thickness) in 1958. (...) There seem to be several possible explainations for this. 2) ...there is very little difference in quality between comparable lenses from all the manufacturers. I think it's true that differences are small. And that manufacturers had a large part of their line comparable with others'. For example, I though until last week that Pentax famous low distorsion (0.5%) 28/3.5 lens was unique in that respect but discovered that the MC-Rokkor-X 28/3.5 had the same low distorsion figure. Increasingly, manufacturers are tailoring optical quality more precisely to price class as they learn not only to engineer quality in but also to engineer it out. Still, sometimes you feel a manufacturer has put a bit more for the price, hoping to sell volumes of that item. This could be true of the Olympus Stylus with the great 35/2.8. Andre
