Re: Who's not so bright..........

[Eric Welch <ewelch@ponyexpress.net>]

At 06:09 PM 10/8/97 -0700, you wrote:
>The split image on the ground glass screen in R cameras is not a true
>rangefinder. There is no distance between the images. 

That is not correct. If there wasn't then there would be no "rangefinder"
effect.

>It's an aerial image

So, what does than have to do with whether it works or not?

>focus phenomenon. Compared with the M6 rangefinder, the R split image has a
>zero base and zero accuracy. When an M rangefinder/lens is aligned
>properly, with it's wide base, it is dead-on. This was one of Walter 

>difference. Since the R's dual ground glass prism is only simulating a
>rangefinder, I find it useless and in the way. I'm a big big fan of
>previewing depth of field on the ground glass. This was drilled into me at
>Brooks. It's almost impossible for me to shoot if I haven't "looked" at the
>DOF. Believe me... the split prism and other garbage in the center of the 

That is simply not true. Zero base of accuracy? That's ludicrous. The split
image device at the center of many focusing screens uses the width of the
front lens element for it's "base." That is one reason why SLRs using
lenses of 90mm and longer are more accurate SLR than rangefinders of
similar focal length. The effective "base" is wider than on the M6, which
does not change with an increase in focal length.

I've used split image rangefinders for years, and know they are effective. 

>R3's It goes black during DOF preview. And it's nearly black without DOF

That's right, they do go black. Any lens with less than an effective
aperture of 5.6 and they go black. That's because they use the edges of the
lens to measure the focusing distance. Cover it up with the aperture and
they go black. I don't see how this is such a disaster. Focusing should be
done wide open anyway.

>And it disrupts one's ability to see good composition on the GG screen.

That's a matter of opinion. If they don't annoy you, you don't even notice
them.

>Which is why my R cameras, as well as all of my colleagues R's and other
>SLR's, are all fitted with the plain GG with grid (helps keep the horizon
>straight) and no warts in the center. Even my Alpa 10D has an absolutely
>plain flat GG screen.

All your colleagues? Who? How many? I know quite a few who use different
camera brands that use the split image in the middle for certain kinds of
focusing. Or used to before AF.

>My Rolleis, Hasselblads, and view cameras did not and do not have such
>interruptions. So why does Leica continue to do this? Is this because they
>think that either amateur (don't know how to use a GG) or old (cannot see

It's simply because with some focal lengths and some situations, it's more
accurate to focus with that kind of device. It's been universal for many
years, and only since the advent of autofocus has there started to be a
trend away, and even then, you can buy focusing screens that have the split
image if you want in many cameras. Including my Nikon F5. Hardly an amateur
camera.

Leica includes them in their cameras to this day because they work. If they
didn't they wouldn't. To say they're increasing profits is a rather weak
argument, considering how much Leicas cost.

=============
Eric Welch
St. Joseph, MO


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