At 23:16 10/6/02, C.H. Ling wrote:
There is also no Zuiko can reach 120lpmm not to mention together with
film, forget about it.
The lowly single-coated 50/1.8 F.Zuiko tests out at 100 lppmm. That
equates to 200 pixels per linear millimeter. Having owned one that was in
mint condition until I sold it 20 years later, **all** my other Zuiko
lenses have noticeably exceeded it. The only lens combination that
achieved less was a dirt-cheap, no-name, generic two-element 2X
teleconverter on the back of a single-coated 75-150/4 Zuiko Zoom. No small
surprise there given the lack of optical quality in the generic 2X TC.
The resolution of Velvia 160lpmm is measured at 1000:1 contrast different,
at 1.6:1 it is only 80lpmm.
This is it's approximate rating by Fuji and why I backed off to about 120
lppmm. The nearly 50 year old Carl Zeiss Sonnar is more than capable of
this; not alone using aerial measurements, but as a practical system with
its camera body. It's what I've been able to achieve using exceptional
care with camera shake and focusing. It has been a learning curve to get
above the 80-100 lppmm barrier, but was necessary to produce 11x16 fine
prints that can withstand extremely close scrutiny and not find lens/film
limits. I can take a 5X loupe to them and find additional detail that
cannot be discerned by the unaided eye at 12 inches.
Don't ask me to do a calculation, just based on my experience on the E-10
and microscope analysis (yes, it is a Olympus... MPlan 10x, much much
better than any projection lens on earth) of some test slides, I would say
a 20MP will be equal to the best 35mm film system. Ok, just a guess.
I've done too much large screen projection of 35mm Provia and Kodachrome
slides to accept 20MP equating 35mm film systems. That's less than the
25MP size of a pro photo CD image, which is still about half the linear
resolution (a fourth of the areal resolution) of an original Kodachrome 25,
Kodachrome 64 or Provia 100F slide. Breaking the 80-100 lppmm barrier
requires care in making the image, excellent lenses, high resolution film
and an excellent projection system to see it. Dropping down to 100 lppmm
creates a 35MP system.
20MP is about 75 lppmm. A 1.6:1 contrast ratio is the bottom end of
contrast; 1000:1 is the top end. Nearly all practical photographs have
detail levels with edge contrasts that fall between these; usually toward
the upper end in at least some region of it. If the lens/film resolution
isn't there, it cannot capture it. Same applies to the CCD! I estimate it
requires a 35MP digital to equal a good 35mm film system (100 lppmm), a
50-68MP digital to equal an excellent one (120-140 lppmm), and 85-90MP to
overtake a "world-class" 35mm system (160 lppmm at current film upper limits).
The basic presumption is users of said systems, digital and film, will take
requisite care with making photographs to optimize system
capabilities. Introduce the same degradation for hand-held camera,
auto-focus error and less than stellar lens, and the system, digital or
film, is easily down to 40-50 lppmm. Heap on a horridly coarse-grain film
like Kodak Gold 100 and it degrades much further. Gold 200 and 400 are
even worse. Film *does* make a difference, as much as lens optics, focus
accuracy and camera shake mitigation. Remember also, that to optimize
resolution of this Can*n 11MP DC, the user must deliberately choose to make
32MB files with it. How often will that happen? How will the user handle
mega-file management if it's full resolution is used continuously? Is it
practical for the task(s) at hand?
Be cautious about DC claims. I've traced some back through reverse
engineering print sizes and maximum resolutions only to find the claims are
based on depth of field limits, and hyperfocal focusing, often using a
Circle of Confusion of 0.030-0.033mm when 0.025mm would be much more
appropriate for the print sizes being touted. This is Bad Science. I
*can* tell the difference if someone makes an 8x10 (or 8x12) using
hyperfocal focusing based on circle of confusion diamteters greater than
0.025mm. Old adage: "Figures don't lie, but . . . "
-- John
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