On 7/1/2017 3:47 PM, Chris Trask wrote:
Thanks Moose - I'm sure that as several years have passed the lenses have
got better (even if software correction is needed for some distortions) so
I suspect that what were reasonable Nikon lenses in 2004 are probably
surpassed by cheap-and-cheerful 2017 lenses.
That certainly explains a lot. I could not understand why people were
saying positive things about those two lenses, but I did not understand that
there were NEW! IMPROVED! versions. But now I have to ask why one would invest
in a lens that requires software distortion correction when older MF lenses do
the same without the software crutch?
1. Because all lens design is a matter of compromises. Finding a good balance that does most optical and mechanical
things reasonably well, with none particularly bad. At what overall performance level that balance is achieved depends
on the allowed cost of design and production. Making wide angle lenses and the wide ends of zooms with minimal linear
distortion comes at a cost in other aberrations that thus can't be corrected as well. Moving that function to
firmware/software frees up resources for other aspects of the design.
Yes, correction after exposure with computation to move pixels around lowers resolution in the farther reaches of the
image circle. But what if it does so less than requiring the lens to be highly rectilinear? Or if it allows less coma,
CA and focal plane curvature? If the overall result is better, it's a good design, even if part of the design is post
exposure correction of distortion.
2. Those older MF lenses have linear distortion, too, just less of it. I first learned the corner resolution cost of
software correction to get nice straight lines in subjects, where it's obvious/important, using PTLens on film images
from OM primes, before digital and long before linear correction in firm/software became part of lens design.
2. I have hesitated to say this. You have posted quite a number of quite soft, sometimes downright fuzzy, images taken
with these paragons of ancient optical virtue. Some of the problems are undoubtedly limitations in technique under
difficult conditions. Nevertheless . . . Mostly in record shots of flora, and yes, good enough for identification, but
often photographically crummy. As I recall, I have used a couple of the lenses you like, and found them to be mediocre.
Some of the others are from makers that never had a good reputation for optical quality when they were current.
Another limitation of using the old, MF lenses is that they were, in the way discussed above, designed to cover roughly
four times the area of a 4/3 sensor. Compromises were made in other characteristics, including resolution, that need not
have been made to cover the smaller format.
I recently took shots of a bouquet of flowers with an OM 50/1.4 on a 24 MP, FF sensor, and with a Leica/Panasonic 12-60
zoom, set at 50 mm, on a 4.3 size sensor of 16 MP. I took them at different physical distances from the subject, such
that the subject area covered was close to the same. The old prime made attractive looking images, in "drawing", but
just didn't resolve as much fine detail clearly as the newer zoom on the physically and pixel wise smaller sensor.
Contrast, both overall and edge, were also lower. Color was also different, to me less accurate, but I can't separate
the effect of different camera sensor systems, and ideas of WB. (Both were focused using live view image magnification,
so very precisely.)
There is nothing whatsoever wrong with liking and using such lenses to produce sometimes soft/fuzzy results, if they
please you. I own and use some ancient, pre-computer design era lenses specifically for what I like about their optical
faults. However, when people are asking about conventional qualities, resolution, contrast, color, etc., it seems to me
unhelpful to throw brickbats and sarcasm at all "new, improved" gear.
3. My personal experience is that newer lens designs, especially in the specified area that started this thread, of
inexpensive, "consumer grade" zooms, are simply better at the basics of good IQ than older ones. "Kit" zooms, in
particular, have vastly improved in IQ from early ones.
One thing that's generally true of them is that they are sharper at larger apertures than their predecessors. A lot of
contemporary lenses are sharp wide open, improving only slightly, mostly in the corners, when stopped down a stop or
two. I don't know about you, but I find this an important improvement.
--------------------------------
"But now I have to ask why one would invest in a lens that requires software distortion correction when older MF lenses
do the same without the software crutch? "
Because they are simply better, often much better, in the basics of image
quality.
--------------------------------
As you have never used any of these newer lenses, or newer "improved" sensors, I submit that you have no basis
whatsoever for commenting on their quality.
Moose D'Opinion
--
What if the Hokey Pokey *IS* what it's all about?
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