I picked up a DA 200mm Pentax lens last month to give myself a faster (2.8) telescopic option than my Tamron 70-300 zoom (F5.6 at 300). Really happy with the 200mm in low light situations (i.e. shooting sports in stadium lighting ) and the smoother AF is very nice as well.
But sometimes I yearn for just a little more reach so I thought I’d try the 200 with a 2X teleconverter (knowing full well the sacrifices that entails.) I picked up a Kenko MC7 model based upon some positive reviews I found.
However I ran into an interesting problem and am curious if anyone has any insight:
I can attach the TC with the 200 lens to my *ist and everything works fine. By that I mean the AF works and I can take a clear picture. The AF process seems a bit slower and it does hunt a bit more with the TC on.
When I try the same TC & 200 on my K20, however, I can't get the combination to work. Not only won't AF or Live View work, I can’t even use the lens in MF as the shutter won’t engage. When it's fully connected, the MF displays (despite all the appropriate settings on camera and lens) and blinks. If I try to push the shutter release, the viewfinder just goes black.
I took the TC and lens down to the local camera store and tried them together on a K7 and got the exact same (non-) results as the K20.
However, both my Sigma 17-70 & Tamron 70-300 work (and very nicely) with the K20 & TC. Again, I mean, AF, Live View, and picture taking ability.
My first thoughts were that something isn’t seating correctly. But I’ve repeatedly experimented with it enough to convince myself that isn’t the issue. Since the TC/lens work on the *ist, it’s clear they can play nice together and that the TC-to-lens interface isn’t the issue. Ditto regarding the camera body-to-TC contacts since the K20 and TC play nice with the other lenses.
I’m wondering if there’s something in the K20 (and K7?) firmware that can’t recognize the DA lens when the TC is in the middle.
Just a little disappointing that it works on the *ist but not the others, newer models. Wish I had my old K10 to give it a try but I've already given that away to my nephew.
Anyone have any thoughts on what's going on? Appreciate any thoughts you might have.
Regards,
-tom
Last edited by tpeace; 10-07-2009 at 01:53 PM.
Reason: spelling/lens type correction