On Thu, Nov 8, 2012 at 10:55 AM, John Sessoms <[email protected]> wrote: >> >> Sure any FF DSLR vievfinder is noticeably wider than those in APS-C >> DSLR's, but don't expect a viewfinder like the one in the LX. > > Is there any physical reason they can't do the kind of viewfinder they > did for the LX? Or is it just because they're cheapskate bastards?
They're not the cheapskate bastards, the customers are. Let's put it this way: An SLR viewfinder's brightness is dependent upon - the speed of the lens projecting light into it - the optical efficiency of the mirror - the optical efficiency of the focusing screen - the magnification that the focusing screen is set to be viewed at - the size of the focusing screen - the optical efficiency of the prism and viewfinder optics The imaging quality (or suitability for manual focusing) of an SLR viewfinder is dependent on the same things but add the textural qualities of the focus screen as well. The lens, mirror, and focusing screen provide the light source for the rest of the viewfinder optical system. An APS-C SLR focusing screen is typically about 44% of the area of a FF (35mm format) SLR camera. If all else is equal, the amount of light getting to the viewfinder optics behind the focusing screen is reduced by 56% on that basis alone, which means that if they grafted the entire LX viewfinder optical system onto a K-5, it would STILL be at least one stop dimmer than the same viewfinder in the LX. To achieve parity in viewfinder quality with a small format optical SLR takes extraordinary and expensive measures, like oversize, super high quality viewfinder optics able to eke out every last joule of light energy and direct it to the viewer's eye. And even then, there's a limit. A look at the FourThirds SLRs from Olympus is instructive here. Olympus went to great lengths on the E-3 and E-5 to improve the brightness and usability of the viewfinder. The E-30, a body very similar to the E-5, was about 60% of the price, and I wager that most of that additional money went into the viewfinder. Olympus also invested untold millions of dollars into designing and manufacturing very very fast pro lenses to optimize the system's performance. So there are physical limits, beyond just money, but money is a big factor. All that fancy optics work costs a bunch; most users don't want to pay $2000+ for a camera body. You can't get that level of optical reflex viewfinder for less on a small format camera, and there's a limit to what's possible due to the physics involved too. -- Godfrey godfreydigiorgi.posterous.com -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
