Using the new DS, I was able to test the Pentax mount lenses which we have.
We have a light board, and I took a piece of aluminum foil and poked holes in it with a thumbtack, as well as a few slices with a pocket knife. With the foil on the light board, and the exposure set for massive overexposure of the lightboard, you can see pinholes of light coming through the lens. At a wide open aperture, you can see ghosting around the pinholes. All the SMC lenses were good, except a 35-105 f3.5 which is old enough that it has slack in the zoom and its focus changes considerably while zooming. This lens had a blue flare around the pinholes of light. We also have some old generic brand lenses. A 28mm f2.8 was ok until you got down to 2.8, at which point it was pathetic. I tested it with a church service a few days ago and people under the spot light ended up blurry. Two different 135 f2.8s were also useless at 2.8. They're fine at f4. When you sit in a dark room and shine a flashlight through the 28mm at f2.8, you can see the flashlight beam ghosting all over inside the lens. I decided to open up the lens and try cleaning the glass. It helped a little bit but not much. The lens is easily 20+ years old ( CPC brand, I read somewhere it was a Pentax 'generic' label?? ), with worn aperture notches ( you almost have to hold it on 2.8 ), so it was no loss if something went wrong. The most fascinating thing about it was the element in the middle, which is almost a hemispherical piece of glass. Too bad these old primes are no good at 2.8. Another disappointment was the Tokina 28-70 f2.8 ATX Pro SV, a used lens from KEH in beautiful condition. It was only useful at f4 and up. We have the 16-45 f4 DA, a 75-150 f4 M SMC, a 50 f1.7 A SMC, and a 50 f2.0 M SMC. These are all great. There is also a Tokina 60-300 f4-5.6 SZ-X which does not mount on the DS or the ZX-M due to an extra large shield around the aperture lever. Was there a reason they added this? Can it be cut down to size safely? We'll probably end up buying a Sigma 24-70 f2.8, which has good results at 2.8 on the brand C camera, and a Sigma 80-200 f2.8 which has good reviews at 2.8 as well. It'd be neat if someone made an APC sensor sized equivalent to the 80-200 f2.8, which would be around a 50-150 f2.8 DA. Something a little lighter to carry around all day long. Brian
