Originally posted by kadajawi I think if you want a better viewfinder you might have to sacrifice AF.
While losing AF may be necessary to get a
fully optimal viewfinder, I'm not sure that it's
necessary to get a
better viewfinder. I think there is scope to increase viewfinder magnification, for example, without losing so much brightness that ditching AF is necessary.
All else being equal, the apparent brightness of the viewfinder is a function of the degree to which it is magnified. To my knowledge, the largest magnification currently used by any FF camera is 0.76x (Canon 1D X). The K-3's viewfinder magnifies at 0.95x and is considered to be one of the best available on an APS-C camera. If a FF camera's viewfinder was 0.95x magnification then its brightness would therefore be at the same level as the K-3 but 1.25x larger than that of the 1D X. Since I haven't heard any complaints about the brightness of the K-3 viewfinder, I'm guessing that most people would be happy with this in a FF too - especially given the benefits of a larger view.
Originally posted by kadajawi I guess they could use the more sensitive AF sensors they have now and use a less translucent mirror (sacrificing low light AF capabilities).
This is an interesting point. I would like to know exactly how much light is lost through the mirror translucency required for AF. The option to reduce the translucency and therefore the AF sensitivity in return for a brighter finder may offer a good compromise for some, although this may be a difficult sell for many (rawr being one!).
Since having AF will always compromise the viewfinder to a greater or lesser degree, it becomes a matter of priorities as to where to set this compromise. I personally would like to see the priority moved towards the viewfinder, but I'm also interested in the possibility of having two FF cameras - one with AF and a good but more or less standard viewfinder, and one purely manual focus model with an exceptional viewfinder. That way it's more clearly defined in the marketplace.
---------- Post added 07-05-14 at 06:01 PM ----------
Originally posted by rawr On a conventional DSLR (eg the K-3 or the Canon 5D3 illustrated here) that's pretty much how it works now. Pic related:
My technical knowledge is limited here, but as I understand it, the rest of the mirror must be of reduced reflectance in order to avoid having a dark patch where the AF window is. Either that or there is something in the prism which achieves the same thing. Either way, since a portion of the light coming through the lens is clearly being directed to AF in the central portion of the image, the rest of the image must be reduced in brightness to compensate. Can anyone shed any light (!) on this?