Hm, keine Highend-Vollformat-SLT mit A-Bajonett, keine spiegellose Vollformat-Kamera mit A-Bajonett? Was bleibt dann noch? Rückkehr zum klassischen DSLR-Prinzip mit optischem Sucher? Wiederaufgabe des Vollformats zugunsten APS-C?
Oder etwa eine Hybrid-Lösung wie die, für die ich vor einigen Monaten nochmal offen bei Dyxum geworben hatte (ihr kennt ähnliche Vorschläge hier aus dem Forum schon seit etlichen Jahren, aber der Resonanz nach zu urteilen scheinen sie in der englischsprachigen Welt relativ neu zu sein)?
http://www.dyxum.com/dforum/a99-features-c...84.html#1094984 (2012-10-28)
ZITATThe hybrid camera I envision and propose for several years now would have a traditional reflective mirror as in a normal DSLR. In fact, for as long as the mirror is down, it would work exactly like a normal DSLR with dedicated phase-detection AF and optical viewfinder. The AF module will be located in the bottom of the mirror box, and will receive light through a sub-mirror behind the main mirror - just as in any DSLR. Of course, the mirror will have to flip up during exposure, so the optical viewfinder will be dark and the dedicated phase-detection AF will not work during exposure. So far, no gain of features, but also no loss.
Now, in EVF mode, the mirror would flip up permanently. There are two possible options how to add an electronic viewfinder, in the first incarnation, it would be an optional electronic viewfinder to be mounted in the hotshoe - power and data would be fed through hotshoe contacts - the new Multi-Interface shoe already supports this (see FDA-EV1MK, although apparently not with the SLT-A99). The viewfinder would replicate the hotshoe at its top, so that a flash could still be mounted, just 20 mm higher.
In the second incarnation, the electronic viewfinder would be built into the camera and use the same eyepiece as the optical finder. The electronic image would have to be projected into the optical viewfinder while the optical viewfinder is dark, as the camera's mirror in the "up"-position ensures that no stray light reaches the viewfinder. It might be a challenge to project the electronic image into a solid glass prism, but certainly doable. In cheaper cameras with Porro mirror prisms, it is even almost trivial to do. The electronic viewfinder would receive its image from the live view image sensor (as in SLTs and mirrorless cameras). Even for a camera with built-in hybrid viewfinder, an optional external EVF should be available, and ideally it would be a tiltable one like the FDA-EV1MK.
Since we want to avoid the SLT semi-transparent mirror, in this mode autofocus would have to be based on the main image sensor, ideally by a combination of phase-detection AF (similar to what was introduced in the SLT-A99, but better - next generation perhaps) and contrast AF, so that we can combine the advantages of both focusing methods and eliminate their weaknesses at the same time. Phase-detection AF is good for fast focusing over large distances, but limited either in accuracy or usable aperture range, and the metering cells must be located near the center of the image. Phase-detection AF is prone to back/front focus issues, aperture-based focus shift errors and it cannot be used while the lens is stopped down. On the other hand, contrast AF does not have any of these limitations and errors, it can be used over the whole image sensor surface (with object tracking) with high accuracy (no front or back focus) even with slow lenses and stopped down, therefore aperture-based focus shift errors are eliminated as well. However, compared to phase-detection AF, contrast AF is slow and it does not provide any inherent direction information. The reason why contrast AF is slow is because finding focus is an iterative trial-and-error approach moving the focus forward and backward in micro-steps and comparing image contrast. While SSM and SAM lenses can cope with this (to some extent), as we all know, it is difficult to do this with screw-driven lenses (that's why the LA-EA1 does not support AF with screw-driven lenses). However, do we want to give up compatibility with screw-driven lenses? Of course, not!
The solution to this problem is not to try to alter the lens focusing but to move the image sensor forward and backward in micro-steps - after all, Sony is one of the companies who has the technology for sensor shifting: Anti-shake. If you move the image sensor forward, the focus will be moved towards infinity, and if you move the image sensor backwards, the focus will move towards the near end. Typically, the necessary amount of movement will be very small for the suggested type of fine-focusing, but it will certainly depend on the lens (can be calculated from lens data). It is extremely fast, almost silent, and it will work with any kind of lens, including all screw-driven lenses. Both contrast and phase-detection AF off the image sensor are supported. Since the moving part is the image sensor itself and the electronic viewfinder continues to receive its live signal even while the sensor moves, we can avoid complicated co-adjustments of AF sub-mirrors or optical viewfinders, as it would be necessary if we would want to support this in OVF mode as well.
Of course, we still need the normal focusing methods to focus over the lens' whole focus range, but since the "inner" fast fine-focusing is now done by the image sensor, the "outer" lens focusing can be changed to be less aggressive, and therefore, even screw-driven lenses could be focused with much reduced noise. Depending on the actual lens, moderate changes in the subject distance can now be followed by the AF in this combined system faster than ever before - without SLT mirror, and therefore without the corresponding light loss and image quality degradation, without a need to abandon a camera with a traditional OVF mode, compatible with contrast as well as with phase-detection AF, as well as with all existing lenses, including screw-driven ones.
So much for the basic configuration of this hybrid camera, as I propose it.
Depending on the available amount of image sensor shift (several millimeters in each direction should be possible), new types of glass-less lens mount adapters would become possible by moving the sensor slightly forward (for example to mount Minolta SR-mount, Leica R-mount or Nikon F-mount lenses). By shifting the sensor backwards a few millimeters it could be used as a small built-in extension tube as well.
There are several other potential extensions I propose for this camera, but they will not be limited to one mode, but work in both OVF and EVF modes.
Since this is getting off-topic I will just mention the introduction of flash TTL-OTS. It will combine the advantages of TTL-OTF with the advantages of P-TTL, similar to what P-TTL-OTF did in the lastest generation of film bodies (with and without ADI, which works on top of either TTL-OTF, P-TTL or P-TTL-OTF). This will give us back the much more reliable and sophisticated flash system as we knew it before the advent of digital, and it will not even require a pre-flash any more. Ambient light exposure metering is already carried out via the image sensor since some while, so adding TTL-OTS for real-time flash exposure metering is just one small further step. Technically it would be even possible to reuse the old Minolta TTL-OTF protocol for this, so that pre-digital flashes could be used as well.
Greetings,
Matthias[/quote]
Das Ganze war eigentlich ein Folgebeitrag auf eine noch sehr unvollständige und unsortierte ad-hoc-Liste von Punkten, die mir an der SLT-A99 nicht gefallen (als Antwort auf eine entsprechende Frage), die von Mladen prompt zum eigenen Thread erhoben wurde:
http://www.dyxum.com/dforum/a99-features-c...74.html#1086674
Viele Grüße,
Matthias