Interesting write-up, Ken, although I will reserve detailed comment
until we see the pictures!
Let's just say that, lens "character" aside, I am skeptical of even
the theoretical possibility for two 100mm lenses at f/2.8 to display
different depths of field, or "asymmetrical" depth of field. In both
cases, the light from the subject travels to two holes of the same
diameter, in perfect straight lines. The "cones" (if you can visualise
it, from a point on the subject, to the aperture opening in the lens)
are thus identical in dimension front of, and behind, the subject.
So, "character" / "smoothness" aside, the "degree" of de-focus must be
the same, no?
But most important of all, I am really glad you could get your hands
on a fabulous lens like the 100/2, and that you truly enjoy it for
years to come.
Dawid Loubser
On 29 Sep 2011, at 3:32 AM, Ken Norton wrote:
> This weekend I did a little bit of a Zuikofest 100mm shootout. My
> storied
> 100/2.8 against this new king of the hill 100/2. To quote one of my
> favorite
> lines: "Veddy interesting!"
>
> Let's get two things out of the way first.
>
> 1. My 100/2.8 is an unusual one that has sometimes exhibited
> characteristics
> not found in other samples. Some people feel that I've made some
> unfounded
> claims, but I continue to stand by my claims and other people, who
> have
> experienced this specific lens, tend to agree.
>
> 2. The 100/2 is sharp enough WIDE-OPEN that it exceeds the resolving
> ability
> of either of my digital cameras. I don't know just how sharp it
> really is.
> But it definitely sharp enough that it's pretty much maxing out
> whatever
> film I normally use in my OM bodies.
>
> Oh, and one more thing. If you don't agree with me on my testing
> procedures
> or conclusions, I welcome a competing test. Don't just believe what
> I write,
> prove it yourself.
>
> To eliminate as much human factor as possible, I use live-view with
> the
> magnifier on the DMC-L1 to attain critical focus. I do a rock back
> and forth
> and adjust for the mid-point. Even at that, I discovered a very slight
> variance between shots. Or have I? Here is where things get a little
> interesting. When shot at exactly the same apertures, and carefully
> selecting the same focus point, the 100/2.8 always seems to have a
> touch
> more DoF on the near-side. At this time, I'm calling this a human
> error, yet
> time and again, when focused in exactly the same manner on exactly
> the same
> point, the 100/2.8 is sharper closer in. I've even focused the lenses
> stopped down and the same thing occurs. Before letting this go,
> totally,
> what I'm wondering is whether or not the rate of defocus either side
> of the
> plane of focus is assymitrical between the two lenses.
>
> So, that is where the second test came in, I did do a "bokeh/dof"
> test using
> the ultimate calibration and test tool--a farm implemement. That's
> right. A
> haybale conveyer. Again, the focus was ever so slightly off. In this
> case I
> focused almost exactly at 2 meters distance. The 100/2.8's plane of
> focus
> was probably 3mm closer. But, the bokeh expansion in the 100/2.8 is
> slightly
> more constrained than the 100/2 and has a tighter gradient. So, the
> rate of
> expansion is not the same between the lenses on the near side. On
> the far
> side, however, the rate of expansion is nearly identical, but the
> 100/2.8
> has a harsher bokeh. For instance, the wire fence in the background,
> even
> though out of focus, had more distinct edges than the 100/2.
>
> OK, what about sharpness at normal apertures of F5.6 or F8? It was
> pretty
> much a dead heat. Both lenses exceeded the ability of the sensor to
> capture
> any further detail. I'll call this a "good 'nuff" result. Again,
> this was
> through maximum detail extraction (complete with converter
> artifacts) of a
> DMC-L1 raw file which is similar to that of an E-3 raw file. Either
> way, it
> just confirms what I already knew--the 100/2.8 smokes most of the
> films I
> use anyway. The 100/2 is just more of the same in that regard.
>
> However, this is only part of the story. What about F2 to F4?
> Obviously, the
> 100/2 is better at F2 than the 100/2.8. Let's just say that it's
> good enough
> to be almost creepy sharp. A head-shot portrait last week was so sharp
> (where it was sharp) that I couldn't bear to zoom in too closely for
> too
> long. The intimacy was disquieting. At F2.8, the 100/2 is sharper and
> contrastier. At F4, the two lenses become almost identical, except
> the bokeh
> is a little harsh in the 100/2.8. F5.6 to F8, the lenses are
> essentially
> identical. I'm finding no significant difference other than what has
> already
> been noted. If you could restrict usage between F4 and F8, there is no
> reason to select the 100/2 over the 100/2.8. I'm happy with either.
> Outside
> of that narrow range, the nod is definitely given to the 100/2.
>
> Both lenses have a strong green/magenta color shift for front/rear
> blurred
> edges. In overlapping apertures, I think the 100/2.8 has more of it,
> though.
> Still not bad, but it is obvious that the 100/2 has a touch more
> correction.
> Stopped down to smallest aperture, I find less diffraction blurring
> with the
> 100/2. In fact, stopped down, the 100/2 remains so much constrastier
> that
> there is an implied sharpness to the image which far exceeds the
> 100/2.
>
> For close-up work, things do switch around a little. When at 1:2 to
> 1:4
> image magnification, I like the 100/2.8 a little more. Any specular
> highlights which are within the 2X working distance seem to be a bit
> hard-edged with the 100/2, but have a nice penumbra with the
> 100/2.8. The
> 100/2 is a little sharper, but I can tell that the highly corrected
> optics
> are not optimized for this close of a range and you end up fighting
> those
> optics.
>
> Flare. The 100/2.8 is definitely more susceptable to an overall
> veiling
> flare, but the 100/2 will get wierd streaks and hotspots of flare in a
> manner I haven't been able to figure out the causation of yet. More
> research
> to follow.
>
> What about full-frame? I've tested both lenses on an OM body with
> Ektar 100.
> I'm going to call it a wash at the smaller apertures, but the 100/2
> is more
> flat-fielded across the entire image. The 100/2.8 has a touch of
> vignetting
> at F2.8, but the 100/2 is about as flat across the entire image as
> I've ever
> seen. No exacting tests yet, but even wide-open the 100/2 does not
> produce
> any noticable vignetting. I'm comfortable extrapolating corner
> information
> from either lens based on the trending seen on the crop-sensor
> camera. These
> two lenses are very well behaved, but the 100/2 is definitely more
> better
> behaved.
>
> So, tests aside, what do I think of the 100/2 as compared to the
> 100/2.8?
> This is a fascinating question for sure. The fact is, I like BOTH of
> them.
> They may share the same focal length, but the lenses do render the
> scenes
> differently. The 100/2 doesn't appear to have the "red spread" of the
> 100/2.8. I think that "red spread" is what makes the 100/2.8 such an
> amazing
> portrait lens. Each lens is unique, yet obviously from the same
> family. The
> 100/2 has no "sweet spot". It's good at every setting and is
> definitaly
> biased towards wide-open. The 100/2.8, at F4 and F5.6 is incredible
> for
> portraiture and has a bit more "glow". OK, maybe a lot more "glow",
> (whatever "glow" is). I' survived for 25 years shooting this 100/2.8
> and it
> has earned more money than all the rest of the lenses combined, so
> it does
> extremely well. The 100/2 had a very high bar to jump over.
>
> Comparing the 100/2 to the 35-80 is a fascinating experiment. I've
> only
> began that slippery slide. Those two lenses are so completely
> different, yet
> both exceptionally good. The 100/2 has the bokeh/dof advantage, but
> the
> 35-80 seems to have the 3D advantage. More to come there.
>
> Pictures? Well, yes. I'll be posting pictures at some point, but not
> until I
> have done a few more tests that try to figure out some oddities first.
>
> The funnest part of the 100/2 is handing an OM with 100/2 to another
> photographer. Without exception, they smile, laugh, exclaim praise,
> then
> furrow their eyebrows as they contemplate the equipment they
> currently have
> and wonder what lens in their mount they can buy to duplicate it.
>
> Is the 100/2 an expensive lens? Let's say it runs around $1000 USD.
> So, yes,
> for a used lens in a discontinued lens mount, it is expensive. But
> when you
> figure what $1000 buys you these days in brand new lenses, I'd say
> that the
> lens is a bargain if it provides the usefulness of which you seek.
> If narrow
> DoF is your game, combined with ultimate sharpness, I can't think of
> another
> $1000 lens that comes close.
>
> AG
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