Originally posted by Blue Nikon does that with their full frame sensors to allow their DX lenses to be used on the D700. I know a lady here in T. allahassee that added the D700 to here Nikon aps-c set. She already had some ff compatible glass but also some very good DX glass as well.
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Yep. I use that feature all the time, mostly with my Sigma 50-150 2.8 on D700. It gives me about 6mp on the target, which is more than enough for an 8x10 print, and truthfully enough for much larger. I do that because that 50-150 HSM II is so lightning fast on the D700, is smaller than a 70-200 2.8, and is a pleasure to shoot.
I turn off auto-crop mode when I use the DX 35 1.8G and just accept some vignetting, which I can remove in post if I want (but rarely do.) That little 35 1.8 has incredible sharpness, allows remarkable subject isolation for the FOV, and really can give a 3-D look on FF.
I would never suggest buying a FF camera to shoot DX/aps-c glass on it, but you don't have to sell off your aps-c glass if you do - particularily if you still plan to shoot aps-c in addition, and especially if your DA lenses actually do cover the FF frame, with some slight vignetting.
But of course the K-1 would be really made for the FA lenses, new and old, and lenses like the DA* 200, DA* 300 and new 100mm macro, which is a FF lens.
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Quote: It won't require that much of a redesign on the optics, only the tube. However, Tokina has shown that it isn't that big a deal.
Granted this example is a DX lens, but it shows the addition of the focus motor in the Tokina version of the 12-24.
Tokina
It would work something like this: The plant manager walks into the mechanical engineers office one morning and hands him a FA* 24/2 and says, "motorize this and put it in a modern weather sealed tube." The next day he walks in and hands them a FA* 85/1.4, and says "motorize this and put it in a modern weather sealed tube."
That still could be considered a 'major redesign' from Pentax's perspective... But there are only positives to come from doing so. Imagine a 50-135 2.8 that snaps focus as fast as the Sigma HSM on Nikon, or the Nikon AF-S lenses, with added reliability to boot. Pentax zoom sales would increase, confidence would increase, and Pentax could even re-sell some lenses to current owners (Nikon enjoyed this benefit quite a bit.)
Downside is the 'SDM-II' lenses would probably cost a little bit more. Believe me, it would be worth it.
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