As usual Moose says it more thoroughly and accurately than I could.
Winsor
Long Beach, California, USA
On Nov 5, 2004, at 5:12 PM, Moose wrote:
> 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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