Apparently the Pentax DA* 50-135 f/2.8 IF ED SDM and the Tokina AT-X 535 PRO DX 50-135mm f/2.8 version won't be the same after all.



http://www.pentaximaging.com/files/product/DAStar_50-135mm.lg.jpg
Major features of the smc PENTAX-DA* 50-135mm F2.8ED [IF] SDM Lens
Mounted on a PENTAX digital SLR camera body, this 2.7X zoom lens covers angles of view from 76.5mm to 207mm (in the 35mm format). Coupled with a large maximum aperture of F2.8, it is a perfect telephoto zoom lens for applications such as portraiture featuring beautifully obscured, out-of-focus backgrounds and sports photography freezing split-second action at high shutter speeds. Incorporating three ED (extra-low dispersion) elements, this telephoto zoom lens effectively minimizes the chromatic aberrations which would be particularly detrimental to image-forming performance. This telephoto zoom lens is treated with PENTAX-original ghostless coating to effectively minimize internal reflections in the optical elements and greatly improve the image description of backlit subjects.

Lens Mount: PENTAX KAF2 Mount
Lens Construction: 18 elements in 14 groups
Angle of View: 31.5 - 11.9 degrees (when used with PENTAX Digital SLR camera body)
Aperture Control: Automatic
Minimum Aperture: F22
Number of Diaphragm Blades: 9
Metering System: TTL open-aperture metering
Minimum Focusing Distance: 1.0m
Filter Size: 67mm
Maximum Magnification: 0.17X Dimensions (diameter x length): 3.0" x 5.4" (76.5mm x 136mm)
Weight: 24.2 oz. (685g) without hood, 27.0 oz. (765g) with hood



http://www.bobatkins.com/photography/reviews/tokina_2006/50-135s.jpg

Tokina AT-X 535 PRO DX 50-135mm f/2.8

Mount availability: Canon EOS, Nikon-D
Focal length: 50 to 135mm
Maximum aperture: f/2.8
Minimum aperture: f/32
Optical construction: 18 elements in 14 groups
SD glass: One elements
Coatings: "Water Proof” optical coating
Angle of view: 31° 3’ ~ 11° 8’
Minimum focus distance: 39.3 in. (1.0m)
Reproduction ratio: 1:5.89
Zooming system: Rotary type
Number of diaphragm blades: 9
Filter size: 67mm
Maximum outer diameter: 3.07 in. (78.2mm)
Dimensions: 3.07 in. (78.2mm) X L 5.32 in. (135.2mm)
Weight: 29.8 oz. (845g)
Lens Hood BH-671
Availability: November 2006

Aside from the 3 vs 1 ED elements, the Tokina version is heavier and won't have Pentax's smc coating.

:Grin:

SMC coating makes shooting with a pentax all the more worth it. SMC has been proven time and time again as the best multi-coating on the planet. (just in case you havent heard)

do both have a silent motor?

I forgot, the Tokina version won't have a Supersonic Drive Motor nor will it be weather/dust sealed. All the niceties are reserved for Pentax. :)

third party lens kasi so there are some trade offs

Manufacturers does reserve certain technologies to themselves so some trade offs will be there. Pentax collaborated with third party lens maker more than once before, the last one I know is with Tamron around 1999 when they made the 28-105, 28-200 (also 28-80 though I'm not sure) series of FA lenses. So Pentax has these lenses that looks suspiciously like the Tamron made ones. Only that the lenses received Pentax' super multi-coating and electronics. Theorectically they should be better than the Tamron version although they did not win accolades. Pentax eventually went on to design their own lenses along those focal ranges (at least the 28-80 & the 28-105). It seems the later version of the 28-105 did get a lot of positive reviews.

pero kung.. ang price ang half compared sa DA*.. why not! :-)