Zum Thema Suchervergrößerung, Sichtfeld und Augenabstand hier noch ein ganz hervorragender Artikel von Mike Johnston auf Luminous Landscape in der Rubrik "The Sunday Morning Photographer":
http://www.luminous-landscape.com/columns/sm-03-03-16.shtml [en]
ZITAT[...] Oh, but you cannot have it all, friend. For two reasons. First of all, it turns out that some of these design parameters fight each other from an engineering standpoint. Secondly, if you are an average Amurricun, you want it all without having to pay for it. No such luck. Good viewfinders are e-x-p-e-n-s-i-v-e.
Roughly speaking, there is a trade-off between magnification and coverage. The higher the coverage, the lower the magnification. Ironically, magnification for 100% finders has to be made lower so that viewfinder information displays can fit in the finder and be within the user's field of view. That's why all the top pro SLRs have 100% coverage but only so-so magnification.
If you've been following along here, you've probably already realized that lower-magnification viewfinders, since they're smaller, are going to easier to see with your eye further away from the eyepiece — i.e., higher eyepoint. So magnification and eye relief also oppose each other to some extent.
Similarly, "focusing snap" and viewfinder brightness don't exactly go hand in hand. The super-bright screens are essentially bundles of very small fiberoptic cables, sliced crosswise, or miniature fresnel (flattened) simple lenses. While they transmit a ton of light, they can be very difficult to focus on. Everything looks pretty sharp; it's not very obvious what's in focus and what's not. (The effect is worse with wide-angle lenses, which have more depth-of-field.) Old-fashioned ground-glass screens had better focusing snap the coarser the grind (surface texture) was. But, the coarser the surface, the dimmer the finder.
One reason bright screens are so widely used today is that many SLRs are now autofocus, and focus isn't dependent on your eye, so focusing snap no longer matters. If you want to see what a really bright viewfinder looks like, take a gander through Minolta's Maxxum 7 next time you're in a camera store. It's an example of a finder with very good brightness, but it doesn't have very good focusing snap. The Maxxum 7's magnification is excellent as well, at least by AF-camera standards. Although manual focusing with this finder may be tough, it's an incredibly bright, contrasty, crisp and clean AF viewfinder. Frankly, compared to most cameras these days, the Maxxum 7 is a pleasure to shoot with because it's such a pleasure to look at the world through.[/quote]
ZITATOne industry insider let it slip to me that most camera purchasers aren't aware that their cheap SLRs have poor viewfinders simply because most camera purchasers have never seen a good one!
[...]
As more and more people buy cameras by the spec sheet, features and specifications have become more and more important, and manufacturers have loaded down their cameras with features to try to make them sell. Yet when it comes to the most important interface on the camera, most consumers are still ignorant of what the specifications mean — with the predictable result that most cameras have considerably poorer viewfinders now than average SLRs had twenty-five years ago.
[...]
Finally, don't be afraid to make a personal, subjective appraisal. Remember, the viewfinder is the single most important user interface on the camera. The user is you; the viewfinder is what you must use to connect your subject with your photograph. If you enjoy looking at the world through the camera, you'll very likely take more, and better, pictures. The viewfinder is important. You're justified in treating it as such[/quote]
Viele Grüße,
Matthias