Originally posted by steve500 Reading a review of the D60 on dpreview.com I came across a CON they wrote, they said that it did not come with a AF driveline on the lens mount for lenses that have no built in AF motor. I took my lens off and looked.. to realize, wow, yes there is a driveline shaft-dealio that connects from the camera to the lens to drive the lenses AF.
It's a "con" for Nikon D40/40X/60 cameras because there's a whole bucketload of lenses that don't autofocus on those cameras. Their cheap AF 50mm F1.8/F1.4 D doesn't AF on those bodies. as do any lens that isn't AF-I or AF-S. you have to pay the extra money for the AF-S 50mm F1.4G or the Sigma 50mm HSM
Makes no difference to Pentax as all but the Sigma HSM lenses, the DA17-70 F4 SDM and the 2 latest DA* lenses use the in-body screwdrive AF motor.. the other DA* lenses have both Screwdrive and in-lens SDM
(the
ME-F's 35-70 F2.8's lens doesn't count. it's MF on every other K-mount camera)
Originally posted by steve500 This must be why my k20d focuses my girlfriends lenses faster than her k200d, i thought it just shot more voltage into the AF motor of the lens.
your K20D focuses faster because it can acquire focus better.
Originally posted by steve500 What's the advantage/disadvantage?
Disadvantage: cost. if you're not going the whole hog and having an SDM motor in your lens, it's just going to increase the price of the lens. look at the same lenses by tamron/sigma for Nikon that have one variant without in-lens motor, and one with in-lens motor. the in-lens motor one is more expensive
Disadvantage: size. you're not getting DA40LTD sized lenses with in-lens AF motors
Advantage: Speed, but only with a Supersonic motor. as an example, the Tamron 18-250 with built-in motor for Nikon and Canon is no faster or quieter than the in-body lens drive of the Pentax.
Advantage: Full time Manual focusing, again, only with a supersonic motor. . sure, you can tweak with Quickshift (if your lens has it), but i can have my hand on the focus ring on the DA*50-135 while it focuses, and then tweak it. you can't do that with quickshift.
not every "in-lens AF motor" lens out there uses this funky Supersonic drive. it costs more, so it's only in the good lenses. Canon's 18-55 II and 18-55 VR have a standard micro-motor inside of the lens. it's no better than in-body screwdrive.
Originally posted by steve500 Which lenses that pentax offers have a built in AF motor?
any Pentax DA* lens.
the Pentax DA17-70 F4 SDM
Any Sigma with HSM, currently the 24-70 F2.8 HSM, 50mm F1.4 HSM, 50-150 F2.8 HSM II, 70-200 F2.8 HSM II