Originally posted by kenafein
I can attach almost every lens ever made to my NEX, but they don't spend a lot of time mentioning that in their reviews. I think they're reviewing native products/applications, not adapted ones. I bought my Q specifically for super-tele, but I don't think that's their market. Adam gave a great review of the Q as a cheap telephoto option. There is room for niche articles on enthusiast sites, but DPReview isn't so adventurous.
Hi kenafein,
This is true, but with the Nex, the resulting image is the same as you can get with any APS-C camera with the obvious differences in sensors and processing engines. It does not enhance or change the capabilities of the photographer in any way, except for differences in technique to achieve essentially the same results.
With the Q series, the crop factor changes the nature of any SLR lens so drastically from what we're used to that this should be mentioned more than in passing. This is a "feature" that most novices and many experienced photographers miss when they look at the Q system only from a size and IQ perspective. As an ILC, the Q can do things that other cameras in this sensor format cannot dream of achieving, and it can do things that cameras in any other ILC system cannot do. Comparing it with other cameras in the same format or other MILC systems from strictly a size or IQ perspective cannot do the system justice because the other cameras cannot go where the Q system cameras can.
I shoot candids at parties and family get-togethers with a Q and a 50 f1.4. This gives me a very unintimidating and totally silent (if I use a 3rd party adapter) camera that shoots at 180mm FOV at f1.4 so I can get the the head shots I like to take from across the room. Sure, I can sacrifice the 2 stops in aperture and shoot my K-5 at higher ISO with a 200mm f2.8, but I'm no longer inconspicuous, and the "candid" nature is much more difficult to get when everyone knows there's a photographer in the room. I don't consider this "niche" photography. . .
This is the lack of vision that I talked about in my first post in this thread.
RE: your first post to this thread -- A Q mount 100-300 f4.5 would have to be at least as large as an FA* 300/4.5. The front element would have to be 67mm like the FA*300 (FL/fstop = Aperture (entrance pupil or front element diameter) -- 300mm/4.5= 66.67mm -- you can't change the nature of optics, even if it's for a smaller format sensor), and the zoom would add size and weight. It could conceivably be made lighter than the 3lbs 4oz of the 100-300 f4 Sigma, but not by that much without sacrificing material stability needed for the optics. Of course the price would be similar, if not more than the Sigma (if it were still made), but I'd say it would be easily well over $1K, and the weight of the focusing elements would require a larger motor, so battery drain would be a problem with the Q. This is an unrealistic suggestion, IMO.
AF for adapted lenses -- at least limited AF, just for critical focus, is another matter. If they used the design philosophy behind the F 1.7x AFA, it seems possible to make a TC that would fit between the K to Q adapter and the body that incorporates focusing elements and a standard Q system in-lens AF motor. It would necessarily have some magnification because of the added registration distance it would cause, and it would not AF over the entire range of the original lens, so the user would need to prefocus manually to get the lens into the focusing range of the AFA. You'd also lose some light due to the mag factor. It would not need to be as deep as sthe 1.7x AFA since there would not be the same design goal -- the 1.7x AFA was meant to be a transitional unit that allowed full focus range AF with an MF 50mm lens (the kit lens of the MF film era) to introduce users to AF. It would just need to have enough focusing range to get critical focus from a set parameter of what would be considered "close" to in-focus my most people. In use, a person would actuate AF, manually focus the lens, then when this got close enough, the AFA would take over and lock critical focus. It would be similar to using CIF (trap focusing) on Pentax DSLR bodies, but would allow better timing for triggering the shutter.
Of course, they could implement CIF in the Q bodies for adapted lenses, and this would probably satisfy most people, I would think. . .
They probably could have offered AF with adapted AF K mount lenses, but the great majority of these are screw drive, and that would mean incorporating a motor and a different AF feedback system into the Q. SDM would probably be easier, but either would mean a significant increase in battery drain from a battery that's already marginal. I suspect that the AF would be very slow also, and not really satisfactory for most, so they probably deemed it not worth the effort (or added expense for that matter). It would have been groundbreaking, but it's proving hard enough to convince even dedicated Q users that the Pentax adapter is worth the price (I think it is) -- add AF and $200-300 to the price for slow AF that cut the battery life to 100 shots, and I would even balk at the cost/benefit.
Scott