I think it's funny how we pretend that optical manufacturers only really figured out how to make good camera lenses very recently. That computerized optical design only arrived in tandem with digital imaging and how constant optical upgrades are now de rigueur. Is the Canon 70-200mm II IS L really that much better than it's predecessor or have Canon learned how to tweak its design parameters to favor perceived sharpness and contrast over total resolution and longer tonal range? The truth is that almost every advance has been conceived and conjured into existence to lower production costs and keep quality control manageable. The better the lens the more hand assembly, and sample by sample tweaking, occurs. And if you want to see the true cost of building state of the art lenses; lenses that have price as a smaller part of the creation equation you need only look to Leica and Zeiss. While you may not value or need the final 5% or 2% of quality over your Canon, Nikon or whatever plastic lens it's an inescapable fact that there are very few manufacturers left who offer "better than required for profitable sales" quality.
And that brings me to the latest frenzy over lenses for the Olympus and Panasonic mmc's (mini-mirrorless cameras). The two lenses I've watched take off in the current market are Olympus's 45mm 1.8 and Panasonic's Leica 25mm 1.4. I've played with them both and they are excellent. And they are a good start for the systems if they want to garner widespread acceptance. But in truth, with the older lenses stopped down one stop, the modern lenses are just about equal with the lenses Olympus was making for their Pen F film camera system over forty years ago. Even in the late 1960's there were computers that could be used to create very good optical designs and, more importantly, there were craftspeople who could "customize" the performance of each lens they assembled. In many parts of the manufacturing process a craftsperson could eyeball an exact fitting that guaranteed the highest performance. Today's factory produced lenses have "tolerance targets" for their plastic mounted lens element and group modules. Fitting into the window of tolerance makes the lens "good enough" for sale. Not as good as it could be based on the theoretical designs! Just good enough so that most customers who buy one won't bother to complain or will instead blame their own photography techniques.
I got a used, Olympus 150mm f4 Pen F lens sometime in the late 1980's. I put it on a Pen film camera (what else could I use it for back then?) and tried some hand held shots. They didn't seem amazingly sharp to me and I didn't use long lenses much so I stuck it in the drawer and was glad to have the lens because it rounded out my collection of Pen gear.
But recently, on the occasion of getting a new lens adapter for the new Pen EP3, I decided to give the lens another try. I mounted it on the camera, set the IS menu manually to IS mode 1 and dialed in 150mm as the focal length and I headed downtown to shoot some stuff that might help me make a better evaluation. Here's what I learned: 1. Image stabilization makes a lot of difference in handholding longer lenses. I'm presuming I could do even better with a tripod but it's a good compromise between mortal and godlike performance. 2. Single focal length telephotos don't get less sharp at their longest focal length, like longer zooms. 3. The real promise of m4:3rds is in the enhancement of usability through size and weight reduction. Good for the cameras, even better for the lenses. With the 2X increase in equivalent focal length you really can enjoy the pull of a long lens without popping those lower vertebrae into the painful and queasy zone.
These images are straight out of the camera Jpegs and, if I had wanted to be disingenuous, and make my point about the quality of older lenses more obvious, I could have run them through some post processing to increase the contrast and some add some selective saturations, perhaps sharpen up the edges. But I'm happy with the way they look as raw material.
I think we've seen a sea change in lens design. It's analogous to what happened in color film in the ten years before the mass market for film crashed. Film manufacturers discovered that most users loved hot saturation and harder contrast in their images. It was more............obvious. So they started to pump up the eye candy volume. We thought the knobs on original Velvia slide film went up to ten but on the newer films you could turn the volume up to fifteen (a nod to the movie, Spinal Tap). While the films were no longer even remotely faithful renderings to the original scenes the same people who like monster trucks, Big Macs and now, full bore HDR, fell in love with the miracle of MORE COLOR. Eventually Kodak and Fuji had to issue specialty films for the professional market with the color and contrast dialed back down so professional photographers could make neutral and accurate images for product ads. And less aggressive films were also introduced for portrait photographers once they found out that contrasty and saturated are two things that DON'T flatter most skin.
So, in lens design, given lower resolutions from the last three generations of digital imagers, coupled with acutance robbing anti-aliasing filters, camera makers started creating lenses that added snap and sparkle back in at the expense of longer tonal ranging and high resolution rendering. You can design a lens for high resolution or high contrast but not necessarily both. Nearly every lens is a compromise between those parameters. Another change has been the push to even out lens performance over the frame. Again, there are two design philosophies in conflict. The first philosophy says that most images are of three dimensional objects and 2/3rds of images created in the U.S. are of people in or near the centers of the frames. Lens makers can optimize for center sharpness and let natural geometry takes its course or, with the use of additional (contrast robbing) elements they can even out sharpness over the entire frame to meet the theoretical needs of a generation of number worshippers.
While even-ness is important for tilt shift lenses and macro lenses it can be completely counter productive for many day to day uses. But I guess this is fodder for another discussion at another time. Suffice it to say that lenses designed in the 1960's and 1970's were based more on actual use parameters since most people weren't sitting in front of monitors doing "pixel evaluations" instead of shooting and printing. But I will end by saying that so many of the attributes we admire in the work of legendary photographers have to do with design decisions made in the glass labs and lens design labs by engineers who were far less encumbered by the current strait-jacketed, tunnel vision of marketing teams. And we are the poorer for it.
Do I like the 150mm lens for the Pen F? Yes. I like the feel of the all metal construction. I like being able to turn the well damped, click stopped aperture ring. And I love being able to focus the lens by hand and have a focus throw created with the human hand and brain considered. Couple that with well made glass that doesn't suffer from chromatic aberrations and I think we've found a nice, long lens to use with the Pens of today. But look for yourself.
Note: If you have any disagreements about my statements concerning contrast versus resolution please read this first: http://www.luminous-landscape.com/tutorials/understanding-series/understanding-mtf.shtml