| Latest Review Posted | Promaster Spectrum7 AF 1.7x
I have been using this TC since December '08, primarily with my Pentax DA* 300mmF4. I bought this TC on a gamble, crossing my fingers that its twin Power Zoom contacts will allow AF on my SDM lens. Well, they do, partially. The lens begins hunting with AF on but doesn't lock focus. However, in time, I learnt to 'coax' it to lock by very gradually pressing the AF button until it locked- that allows me to keep track of not-so-fast moving birds now. Funny, but works, in most cases at least :lol: Taping the SDM contacts to try to 'fool' the DA* lens and my K 10D into thinking that a K 100D might be mounted and hence activate the screw drive AF failed to work.
That apart its very good value for money and auto focuses fine with screw-drive AF lenses like my Tamron Di 90mm f/2.8 macro. But the screw drive shaft is very noisy. Image quality is good and I don't think one can expect much more from a teleconverter of this price and age. It doesn't alter EXIF data correctly and the images still say '300mm, f/4' where they should be saying '510mm, f/6.8' causing the SR in the body to become less effective as the body still thinks that the focal length is only 300mm.
I like the 1.7X multiplication factor as it is a good compromise between reach and speed, i.e., 2X and 1.4X, but I think I'd definitely pick up a nice new SDM WR 1.4X TC if Pentax comes up with one. Also, I think I'd be tempted to pick up a Kenko 1.5X version that supports SDM AF. But at the same time, perhaps I would s... |
