AG Schnozz wrote:
><snip, snip>I think we might be seeing a conspiracy by the major
>manufacturers. Put lousy optical viewfinders in the DSLRs to
>prepare the customers for EVFs. There is no way an EVF can
>compete with an excellent optical viewfinder, so they have to
>dumbdown the optical viewfinders ahead of time to give the EVF a
>level playing field.
>
I'm not buying the conspiracy theory, at least not as an intentional
act. Lets look at some optical and mechanical facts:
The Can*n 20D, etc. sensor is 39.7% the area of a 35mm film frame. Using
the 1.6x factor, the 50mm equivalent for this sensor is 31.25mm. With
both lenses the same speed, the ratio of front element areas is 39.1%.
So about the same brightness level is delivered to both "sensor" sizes,
but the smaller one, with less size, has less total light energy on it.
If you then enlarge the viewfinder image to the same apparent visual
size as for the larger sensor, you lose between 1.3 and 1.5 stops of
brightness. That is simple optical physics, and pretty hard to work around.
Assuming loss of that brightness is acceptable, how does one make the
image larger?
The viewfinder lenses on SLRs are pretty simple, but one could certainly
make a larger, more complex eyepiece to enlarge the image. It will, of
course, be larger in diameter and deeper, so there will be a substantial
protrusion sticking out of the back of the camera body. It might also
require a larger and/or different pentaprism design. I cant imagine it
adding less than $100 to the price, perhaps more, on a high volume body.
I'm not sure how this would interact with the fineness of the matte
finish on the screen. A finer finish gives greater brightness, but is
less easy to focus. Enlarging the screen image could look rather grainy.
Another approach is to put a lens (probably at least 2 element) above
the mirror to project a larger image onto a larger viewscreen. With less
brightness on the screen, the usual problems with wedge and microprism
focusing aids with lower brightness would arise with any but fairly fast
lenses. Also, the top of the camera would have to be quite a bit higher
and the pentaprism larger.
So here's the question. What manufacturer is going to be gutsy/foolhardy
enough to make a bigger, more awkward looking and handling camera body
that costs more and has a dimmer, albeit it larger, viewfinder image?
The answer is no one is that foolhardy. So it isn't an intentional
conspiracy to avoid manufacturing a superior camera, but a "coincidental
conspiracy" of physics and financial and marketing common sense. Nobody
wants to lose a bundle of cash on an unsaleble camera. Oh sure, a few
crazies would buy it, but not near enough to cover the development,
tooling and manufacturing costs at any realistic retail price. Anybody
who wants that (and full brightness and interchangeable screens) can
just buy an EOS-1Ds, which costs no more than a smaller sensor camera
with a special, extra complex viewfinder design would in the volume at
which it would sell. And the very folks who want this will probably
appreciate the big sensor too (and the muscles developed carrying it
around :-) )
The reality is that the VAST, VAST majority of pictures taken with small
sensor DSLRs will be taken with AF, so all the viewfinder has to do is
act as a decent preview of the image that will be captured. At least for
me, the 300D finder does just that pretty well. Sitting here in my dim
study with the 300D in one hand and an OM-1 in the other (with the DOF
button pressed to get the same effective viewing aperture), the OM image
is much larger and thus shows more detail, but doesn't show what will be
in the frame or how it will look any better than the 300D. The OM may be
a tiny bit brighter. The human eye adapts so well that it is an
unreliable instrument for such measurement. The 300D uses mirrors rather
than the pentaprisms of loftier models, which would be a little brighter.
DSLRs already have auto bracketing of other photographic variables,
maybe they could add focus bracketing, starting with AF results, then
bracketing by 1/4 or 1/3 DOF steps around it.
Out in the world using both an OM and the 300D, I personally just don't
much notice the difference. Sure it's there, but it just doesn't
register as making it easier or harder to get the image. You still get
the realistic looking view with accurate tonality, brightness, contrast,
etc. And I sure like seeing the aperture in the viewfinder, a lot fewer
movements of the camera away from my eye to check the aperture. As to
manual focusing, I'm not a good sample. With hyper acute vision (20/10
or better) in my viewfinder eye, I find it pretty easy to focus the
300D with modest speed zooms in moderate to good light from about maybe
28mm on up (actual fl, effective of about 45mm & up), but I know this
will not be true for many.
Most of my picture taking is of relatively static subjects and I find
the multi-point AF to be a pain. I have just switched to center point AF
only and use the half press focus on the thing I want in focus, then
frame and shoot, method. It works better for me.
Moose
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