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[filmscanners] Re: film and scanning vs digital photography



From: "R. Jackson" <jackson.robert.r@comcast.net>
>>>>>>>>>>>>>>
So a birder, for example, will have a two-stop DOF advantage over a
FF guy right out of the gate just because of his format of choice.
Add in the faster Zuiko f/2.0 lens at ISO 100 and he can use a higher
shutter speed at a lower aperture all day long.
<<<<<<<<<<<<<<<

It don't work that way<g>.

The 5D user shoots at ISO 400 with the same image quality (photon shot
noise) and same shutter speed and sees the same DOF (and same background
blurring effects) at f/4.0 as the 4/3 user does at f/2.0.

It is seriously cool how digital cameras with the same pixel count scale
across formats.

(At ISO 100, the 5D should have a two stop dynamic range advantage, except
that the A/D converters don't have enough bits.)

Note, of course, that you have to use a larger lens on the 5D to get the
low-light high-ISO advantage. The 100/2.0 is a bigger lens than the Oly
50/2.0 (I'd guess, anyway.)

The bottom line is that if you think a smaller format buys you anything
other than lighter weight/smaller size/lower price, you've done your math,
physics, and/or optics wrong.

>>>>>>>>>>>>>>>>>>>>
You're right, though, when you get to the end of the day and the
light starts to fall the extra speed of the lens becomes a crutch
that attempts to overcome the limits of the sensor. Still, the high-
end Oly glass tends to be very sharp wide open and you don't have to
stop them down much at all to hit their sweet spot.
<<<<<<<<<<<<<<<<<<<<

You are already shooting two stops smaller with the 5D for the same DOF. And
for portrait work, you don't shoot at f/4.0 with FF, you shoot at f/2.0 and
wider. For a DOF effect that simply isn't available from the 4/3 format.
(Although I wish Canon had an 75 or 85/1.4. The f/1.2 is overmuch.)

> Note that to actually be equivalent, the 4/3 lens has to provide
> _twice_ the
> resolution (twice the lp/mm at any given MTF, or an MTF curve
> shifted up by
> a factor of two due to the finer pixel pitch) at f/2.0 than the FF
> 28-70mm
> lens does at f/4.0. (Interestingly, MTF performance does scale up with
> decreasing format sizes, so this point may not be a problem; but
> the need
> for twice the resolution at a much wider f stop may be problematic.)

This is the biggest problem with the format, IMO. You're always going
to be fighting that battle. It's the same thing with shooting 16mm
instead of 35mm cine stuff. The 16mm gear is lighter, has greater DOF
for run-and-gun work and is obviously a lot less expensive to work
with. But the frame is roughly a quarter the size of the 35mm frame,
so the glass always has to be much better than glass would have to be
on a comparable 35mm rig and obviously the grain is going to be
magnified on top of that. A grain pattern that looks subtle and
wonderful in 35mm may look really bad in 16mm, so you can't even use
the same standards of judging what stock to use because 5263 is not
the same at the end of the day as 7263 when you take the format into
consideration.
<<<<<<<<<<<<<<

That's the difference with digital: you can get a reasonable 10MP image from
the 4/3 camera at ISO 100. You really can't get a reasonable film image from
1/4 the area of 35mm.

>>>>>>>>>>>>>>>
So that's the rub when you have to decide on buying glass from
Olympus now. The 35-100mm f/2 is a really nice lens. Effectively a
70-200mm f/2 lens, but it carries a price tag of $2200. Is it equal
to a Nikon 70-200mm f/2.8 on APS? Or a Canon 70-200mm f/2.8 on a FF
camera?
<<<<<<<<<<<<<<<

Again, if you are using a 10MP 4/3 camera, then the comparison is with the
70-200/4.0 (IS). Without IS, it's half the price, with about 3/4 the price.
And those are phenomenally good lenses that you are putting in front of very
widely spaced pixels. There's no need to stop down with the 70-200/4.0.

>>>>>>>>>>>>>>>
 Hard to say. More than the MTF numbers of the lens play into
it, of course. Those Canon FF cameras have a sensor with a diagonal
nearly as wide as their lens mount where the 4/3 sensor is tiny in
comparison to the 4/3 mount. That allows a lot of advantageous
geometry when it comes to lens design and how the light strikes their
sensor it a big part of the "4/3 advantage" (to quote the nauseating
Olympus PR machine).
<<<<<<<<<<<<<<<<<

The "telecentric" bit strikes me as nothing other than lying snake oil.
(Real telecentric lenses aren't used for pictorial photography, they're for
machine vision applications, and the ray tracing diagrams on the Oly site
show optically impossible paths.) As before, it's not even a 30 degree angle
of incidence with the Canon mount, and there's no difference with longer
lenses.

>>>>>>>>>>>>>
At the end of the day I think it's about what camera you enjoy using
as much as almost anything else, unless you have some particular
application that draws you to one camera over another. I prefer CCD
sensors and my E-1 and now my D200 both have CCDs.
<<<<<<<<<<<<<

At the end of the day, one shoots a camera that meets one's needs. If the
4/3 meets your needs, there's no reason to move to a larger format (just
don't try to tell me that it's better; it ain't). Just as 645 meets my needs
but not the needs of someone making larger landscape prints.

>>>>>>>>>>>>>>
 I don't know what
options will be available to me in the future, though. I'd love to
see the Foveon chips get it together. I'd take full color information
over just about any other consideration, but so far I'm unconvinced
that they've got that format ironed-out.
<<<<<<<<<<<<<<

Foveon doesn't buy you anything the human eye can actually see. And not
using a low-pass filter reduces real resolution by it's snap-to-grid effect
which puts features in the wrong place; it's an artificial sharpening trick
at best.

David J. Littleboy
davidjl@gol.com
Tokyo, Japan


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