I don't know whether this is OT, but since Monaghan does include EOS stuff in
his rant, I suppose it is.
Ken Durling wrote:
> I'd like to hear from some of the pros here on the
> data expressed and interpreted at this site:
>
> http://www.smu.edu/~rmonagha/third/af.html
Not a pro, but here goes:
I've seen this site before. At first glance it appears impressive, but on closer
inspection there's a lot of, um, chaff. Without making a thorough inspection I
wouldn't want to challenge any of the empirical material, but the
interpretation--or at least the "spin"--is open to criticism. Most obviously,
the way he uses "resolution" is highly misleading. He *seems* to be suggesting
that AF reduces the resolution of lenses, when in fact all he's talking about is
focus error. By shooting a flat resolution target he (or Herb Keppler) makes it
appear as though AF lenses have lower resolution than non-AF lenses (or AF
lenses focused manually), whereas all that's being demonstrated is that measured
resolution decreases when focus is inaccurate. In the real world, where we
mostly photograph 3D objects, there will be no loss of resolution using AF--if
the focus is off, the desired plane of focus may appear to have decreased
resolution, but (setting aside camera or subject movement) *something* in the
frame will be in focus, and the resolution in that plane will be whatever the
lens is capable of producing. So, basically the claim that AF "cuts" resolution
is really an obfuscating rhetorical tactic.
The rant about not being able to use manual focusing with an AF camera appears
to be little more than unsubstantiated assertion. How are we to know whether the
claims he makes regarding the deficiencies of AF focusing screens are indeed
true? And, how do we know that they may be true for the Nikon equipment he uses
but not for EOS equipment, with which he appears to have little familiarity?
Well, we don't, and so have no basis for giving much credence to these claims.
What he basically says here is that with AF focusing screens it is impossible to
manually focus by eye, and we must therefore rely on the focus-confirmation
indicator in the viewfinder, which places us at the mercy of the inaccurate AF
system. I for one have not found it at all impossible to focus manually by eye
using either an EOS 3 or EOS 5; perhaps this is more of an issue with Nikon
cameras?
He asks: "If autofocus were really all that great, then why aren't all the pros
using it (e.g., on medium and large format)?" Well, Doh! Maybe it's because
until recently autofocus wasn't available on medium- and large-format cameras.
Can you image what an AF 8x10-inch view camera and lens would look like? Would
it even be possible to make? There are, of course, several AF 6x4.5 cameras now
on the market, from Pentax, Mamiya, and Contax, and I would imagine that many of
those that have been sold are being used by pros. Oh, and how may photogs do
*you* see at major sporting events using an F-1 and big FD telephoto lenses??
"One reason the photo-industry benefits so much from the shift to autofocus
cameras is that it usually obsoletes the previous camera lens mounts in the
process of switching to autofocus designs. So your huge investment in lenses for
last year's non-AF model is now unusable on your new autofocus camera."
Now we're clearly into Nikon territory. How long has it been since "last-year's"
Canon model wouldn't work on this year's model? My point is supported when he
goes on to say:
"Almost as bad, last year's autofocus lenses often don't work with all of the
new AF camera body features (e.g., AF-D vs. AF-S..), so you may feel it
necessary to 'upgrade' and trade-in those nearly new AF lenses you just bought
for the latest and most current models."
Monaghan tries to suggest that Canon went with an all-new mount for the EOS line
out of avarice rather than for technological reasons:
"Keppler asked the tough question - was it avarice and greed that made Canon and
others change mounts, thereby obsoleting past lenses and forcing new lens
purchases? Then he ducked answering it directly, but I got the distinct
impression the answer was often yes ;-) ;-) Perhaps with the smallest camera
mounts (pentax and minolta) the bore size was optically limiting and justified a
new mount. But could the others have copied nikon?"
This conveniently overlooks the engineering and functional superiority of
Canon's all-electronic interface compared to various hybrid and "kludge" designs
that are required to maintain backward-compatibility with MF lenses. The
long-term benefits of Canon's decision are apparent in their products' superior
AF speed and performance, the compatibility of EOS products regardless of age or
price level, and, on the other side, Nikon's gradual abandonment of backward
compatibility, as seen in the F80. While Nikon's decision for backward
compatibility may have made sense at the time, given their large "installed
base" of professional photographers with substantial capital invested in Nikon
equipment, in the long run Canon's choice to go with an all-new design may turn
out to have been a better one. I doubt that the Canon folks regret that they
didn't "copy Nikon."
Monaghan writes:
"At the least, most AF cameras could and should be designed to make it possible
to use our investment in older lenses on the newer AF bodies in manual mode. AF
mounts tend to be somewhat larger to accommodate the extra electrical contacts,
so there is room to mount the older lenses in most cases. Pentax and Nikon AF
mounts both provide this facility, so it is possible to mix manual focus lenses
with autofocus ones on some of their cameras without losing any functionality.
At the worst, all it should take is a simple mechanical adapter to mount the
older lenses and the ability to enable the autofocus camera to recognize and use
the manual lenses."
Ah, were it so simple, I'd be using my FD 100/4 Macro and FD 300/4 lenses on my
EOS 3! But of course there's a lot more to it than the simple mechanical
coupling between lens and body: issues like lens-to-film distance, how to make
an EOS camera actuate a mechanical diaphragm, how to get that EOS body to
recognize the aperture set on the FD lens. This is little more than sour grapes.
"And many AF cameras 'just happen' to lack the stop-down or DOF controls needed
to meter with manual adapters and T-mount lenses."
Back in Nikon territory again. :-) Same for his complaint about "lost" MLU.
The rest of the stuff about the benefits of using a tripod, problems using AF in
low-light conditions, the benefits of fixed-focal-length vs. zoom lenses, DX
encoding, noise, battery use, etc. is pretty pedestrian.
Someone else mentioned that Monaghan seems to have an axe or two to grind. Let's
look at his basic argument:
--AF is, or can be, inaccurate, resulting in an apparent loss of resolution when
photographing flat subjects
--If you rely on the focus-confirmation indicator when focusing manually, you
are subject to the same AF inaccuracy
--The relatively brighter focusing screens of AF cameras make manually focusing
by eye difficult
--Slow zooms perform less well than fixed-focal-length lenses
--AF systems require more light than the human eye
--Some manufacturers include DOF preview and MLU only on their top models
--We should be able to use our old MF lenses on our new AF bodies--that we can't
is due to avarice on the part of the camera manufacturers
--AF cameras eat batteries
To boil it down further, his argument is, in essence, that AF cameras are
neither magic nor perfect--not exactly a news flash. Beyond that, he seems to
resent the move away from *his* preferred type of equipment--Nikon manual-focus
gear, and fixed-focal-length lenses--and is inclined to attribute this to greed
on the part of Canon, Minolta, etc. rather than to legitimate engineering (and
marketing) decisions. Although Monaghan manages to make some valid points
(rather in spite of himself), this page is largely a good example of
Shakespeare's "sound and fury." In my view, he's just a techno-grouch with a web
site. He doesn't like AF and is looking for all the reasons he can possibly
scrape together to justify his dislike, all the while characterizing those who
find AF equipment useful as "autofocus fan(atics)."
In closing, I would add that less than 25% of his page is devoted to his
arguments; the rest is a compendium of comments and complaints gathered from
various mailing lists and newsgroups (including at least one from our own
W-JM--see below)--not exactly a controlled sampling.
fcc
-------------------------------
W-JM's "contribution" to Monaghan's website:
From: [EMAIL PROTECTED] (Willem-Jan Markerink)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: What do Nikon users think of Canon EOS3?
Date: Sun, 25 Oct 98
> Someone on a mailing list said Canon states that it has a semi-permeable
> mirror, resulting in some light loss in the viewfinder. Supposedly it
> was necessary to accomodate the 45 AF points. If this is true, it's
> going to be another strike against it.
No EOS (moving) mirror is 100% reflective, and the same goes for every AF
camera. You simply need light behind the mirror, for AF and some light meter
cells to operated. This is mostly a 66/33 reflecting/transmitting ratio, exactly
the opposite from the EOS RT and 1n RS (33/66). Note that this difference causes
a 1 stop difference in the viewfinder (and not a 1.5 stop difference that a 100%
reflective moving mirror would have resulted in)....and in case of the 1n RS
this 1 stop is compensated by a very bright viewfinder screen (which you can
also use in the normal 1n, but it makes manual focus more difficult).
--
Bye,
Willem-Jan Markerink
*
****
*******
***********************************************************
* For list instructions, including unsubscribe, see:
* http://www.a1.nl/phomepag/markerink/eos_list.htm
***********************************************************
