Johnston's lens ramblings
Date: Thu, 21 Oct 1999 20:23:50 +0000
From: Mike Johnston <firstname.lastname@example.org>
To: MC Lau <email@example.com>
Subject: Johnston's lens ramblings
The following was written very hurriedly and it's not very well organized, but I hope you will find something of use in it.
Mike Johnston is the editor of Photo Techniques, a photographic magazine published bimonthly in the USA . It is specifically targeted at more experienced photographers and has extensive coverage on darkroom and darkroom techniques.
I tend to get in a lot of trouble when I talk subjective lens-talk in public. I love lenses, and maybe half of my photography is involved in simply trying lenses to see what they look like.
I'm no optical expert in the scientific sense, so I'm often left "thinking" that I see something and believing that "maybe" it may correlate to a scientific descriptive term. I'd be much more at home in Japan, where subjective connoisseurship of lenses is a well-established tradition. Here are a few of the things I believe about lenses:
Contax RTS with their Carl Zeiss T* Optic.
# That the "cult" of lens "sharpness" and quality evolved in parallel to the miniaturizing of film formats. It's very difficult for most lenses to look bad contact printed, or enlarged 3X; the smaller the film got, and the more it was enlarged, the more the characteristics of the lens were exposed; so along with the interminable push for more sensitive and finer-grained films and developers, the "cult of lens quality" emerged.
Case in point:
Nobody ever looked at a Daguerreotype and said "not very sharp. Too bad the lens was a dog." If you've seen a decent number of Daguerreotypes you'll know what I mean.
# Nobody knows what anybody else means by the term "sharpness." Resolution of ultra-fine detail? Contrast? At what degree of resolution? Edge sharpness that accentuates boundaries? Some people like one kind of "sharpness," others another.
# Sharpness doesn't matter. Seen from a gestalt perspective, images can be very diffuse and broad-brush and still be recognizable, in the same way extreme abstraction can still be "read": that is, a line and two dots can be a "face," and vague fuzzy patterns of light and shade can be figurative. Ever seen those "pictures" made from thousands of little pictures? Fine detail in that case is little pictures that don't have anything to do with Marilyn Monroe, or whatever the "big picture" is "of." (Forgive all these quotation marks.) Fact is, fine detail resolution doesn't have anything to do with why most pictures work as art--it almost never contributes to greater recognition of the subject, or to meaning. I could provide a list as long as your arm of great pictures in which even coarse detail can hardly be rendered.
Having said all this, why should a lens be "sharp" and what does that mean?
--Most lenses are loaded with aberrations of different kinds, most of which are visible in pictures. BUT PEOPLE DON'T SEE THEM, I guess because they don't know what to look for, or what they're looking at when they see it.
Case in point:
Many of our readers never noticed the quality of the out-of-focus blur until we did our articles on "bokeh" (bo-ke, Japanese for "blur"). We know because they wrote and told us. (Some people never wanted to notice it: we know because they wrote and reamed us out, highly indignantly, for presuming to discuss it.) Yet many, many photographs have large areas of out-of-focus blur and always have had and always will have.
It's a technical property of lenses. It's there in pictures. Why ignore it? Similarly, you can SEE color fringing, linear distortion, coma, spherical aberration, falloff, and on and on, in pictures. Some people don't "notice" flare ghosts or obvious falloff, much less the many, much subtler cues as to how a lens is behaving.
# Some lenses go "well" or "not so well" with different kinds of films.
Many color photographers are very preoccupied with the optical property of color transmission. This is not so much a concern with the film I use (Tri-X <g>). That's a blatant example, but you can get as subtle as you want. Many descriptions of a lens that begin, "This lens looks..." actually mean, "This lens with this film looks...."
# You can't buy wine by the label, books by the cover, etc. In the 1980s, German tycoon Heinrich Mandermann owned both Rollei and Schneider, and Schneider built a set of wonderful new lenses for the Rollei 6000 series. Guess what? People wouldn't buy 'em. They wanted the magic word "Zeiss" on the lenses, and they'd buy older, bigger, heavier, more expensive, worse-performing lens designs to get it. Most of those Schneiders are now discontinued. German lenses aren't "better" than Japanese lenses, Leica lenses aren't all better than any other brand, etc.
# On the contrary, there do seem to be "house tendencies" among optical companies. Zeiss lenses do tend to have lousy out-of-focus blur; Nikon lenses do tend to be super-sharp-looking but at the cost of a certain harshness that can make caucasian skin look pasty; Canon does favor a smooth, high-res but not quite so high-contrast look that works best with color film (because color can function as contrast: it can help distinguish adjacent areas and their edges. Imagine two areas of equal value, but one red and one green. In B&W, it may all be one undifferentiated gray; but in color, these two areas would tend to, ah, stand out from each other. ZAP). Re Leica, some Japanese savants, I'm told, can wax poetic regarding the philosophies of the era of Mandler vs. the era of Kolsch.
Always. There is no exception to this rule. Most of them don't even tell you how the disparate performance parameters are weighted! For instance, what if money is no object to you, and image quality is of paramount importance, and a lens tests weighs "value" highly in its final rating? What it if rates distortion as unimportant, and you're an architectural photographer who needs straight lines at the edge of the picture to look straight? What if it penalizes a lens for severe falloff wide open, yet every time you shoot wide open it is in "available darkness" with nothing but blackness and no important subject content anywhere near the edges? What if it rates ultra-fine detail resolution very highly but you use a grainy film with limited resolution? What if it "tests" the lens by photographing a test target four feet away at f/8, but you're an aerial photographer who needs to know how the lens does wide open for subjects half a mile away?
--Lens tests are meaningless. They almost never give you data, they almost never sample enough of the many parameters under which a lens can be used, they almost never adjudge sample variation, they almost never consider how well a lens will remain in spec over time, and they almost never contribute to your understanding of what the lens will actually do, with your film, in picture-taking situations typical for you. (The one single thing they can offer is a comparative grading to make shopping easier.) Most especially, lens "tests" which purport to reduce the quality of a lens to a single number, grade, or ranking, are ALWAYS invalid.
<<--- Canon discontinued FD lenses. Copyright-free image © 2000. leofoo ®
# Well, there's a lot more to it than this, of course. Where the fruit of all my investigations have led is that I sort of understand what properties I personally tend to value in a lens for my own work with my own film, and how a large number of the available lenses compare with each other within the focal-length ranges I work with. I.e., I don't know much...and the more I find out, the less I find I know. <g>
But here are my recommendations:
1. Believe the evidence. If you love a lens but it's not "supposed" to be good, believe the pictures before reputation, published test results, or the status of the brand.
2. Don't believe one or another property should be important to you unless it is. If a lens is universally admired because it is super-sharp, don't accept this uncritically as being a good thing. Maybe that lens looks harsh to you; maybe your work needs a softer look.
3. New isn't necessarily good. Manufacturers in many fields typically expend a lot of effort and engineering expertise learning how to suck value OUT of a product--that is, to make it possible to make a "good enough" or an "almost good enough" product that can sell more cheaply and/or have a higher profit margin.
<<<-- Old trusty workhorse like the Olympuses OM1n and OM2n models and the companion Zuiko lenses... Copyright-free image © 2000. leofoo ®
With one lens design I've investigated thoroughly, I can virtually trace the bell curve as the makers first learned how to improve it and pour value and performance IN, and then as they subsequently discovered how and where they could cut corners and suck value back OUT !
--i.e., how they could reduce the number of elements, where they could get away with planar rather than spherical surfaces, which surfaces could be single-coated or left uncoated as opposed to being fully multicoated, how they could cheapen the barrel. The lenses at the top of the bell curve perform best, and some of these were manufactured thirty years ago.
4. Good isn't necessarily that good. Science can make much better lenses than any photographer will pay for, or than can be purchased for use on any camera extant.
5. Bad isn't necessarily bad. There are two parts to this rule. First, some very inexpensive lenses are surprisingly good; and second, even many poor lenses are good enough....for some use or other. Artists are people who can take tools and materials, perceive the properties of these tools and materials, and apply them to good effect. Good photographers can make, and have made, great photographs with really, really "bad"
6. Never be blinded into thinking that good tools = good work. The world is full of photographers who churn out sharp but wretchedly poorly-seen pictures. They can break their own arms smugly patting themselves on the back for owning the latest apo-this or aspherical-that, but regardless, Johnston's eighth law still holds: crap is crap.
7. Despite the high popularity of testing lenses and the great relish with which photographers argue the topic, ever wondered why photographers have no enthusiasm for conducting simple surveys with pictures?
Credit: Satosh Oka *, for his superp imagery on the XK Motor and Minolta XD-7.
Actually, much of the seminal research into lens quality and exposure (in the 1930s and '40s) was done in just this way. Pay attention to what viewers of your pictures notice and tell you. Interestingly, the only lens I've ever used that got much in the way of compliments from non-photographer viewers was a 40mm f/2 Rokkor-M.
8. Finally--this is again apposite to the foregoing point--most viewers can't tell. Mushy feelings of delight at the optical prowess of this or that lens squelching up from within ourselves is something we photographers pursue for ourselves and for other photographers. Viewers of pictures just look at the pictures, not how grainy the film is or how luminous the bloody shadow detail is said to be or how many lp/mm the lens allegedly resolves on a test bench. How would they know anyway? They have no standard of comparison. So, much of lens connoisseurship is akin to masturbation: something one does for own's own diversion and gratification. Best not to confuse it with something done for the sake of another, or, for that matter, with anything important.
Photo: Minutes after Y2k in a cabin of LRT in Kuala Lumpur, Malaysia. Camera: Canon New F-1, lens: FD 14mm f2.8 L
Lastly, 9. Never sell a good lens ! The three best lenses I've ever used are gone with the wind, swept out along with the sundry detritus of this acquisitive hobby. Woe is me.
Hope this helps--
* Message Board for your favourite Lenses
Credit: Article, email content reproduced with permission from Mike Johnston and MC Lau
For another view on lens testing, abbreviation, bokeh, the relatioship between resolution and contrast and more, check up these pages by Erwin Puts.
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