Pentax HD 1.4x convertar and Tamron 70-200/2.8

Since there's pretty much no information about this combo (I looked before buying the converter) I'll share my experience so other people could benefit from it.

I had Kenko 1.4x Pz-AF converter before and the biggest issue was autofocus. It would focus if it was in the ballpark already, but if it had to travel a bit it would just go to the extreme end of focus throw and stay there. So I had my reservations before buying Pentax one.
Happy to say that AF works fine, goes from close to far end and back without any issues. It's not as snappy or definite as lens itself, there's some micro movements just before it locks, but way better than with Kenko.

Image quality - still great. Wide open it makes the lens f4 but at that aperture there are green halos around sharp edges, by f5 they disappear and f5.6 is sharp with no fringing.

Quick and dirty test images from my garden:
https://www.flickr.com/photos/120246773@N07/26214488953/in/dateposted-public/

Slightly cropped, the strange out of focus line going across the image is washing line which I didn't see in viewfinder. It spoils the bird a little bit but you can see around it, eyes, legs and fence pretty sharp.

https://www.flickr.com/photos/120246773@N07/26725247802/in/dateposted-public/

This one was shot through the window, even with glare from it you can still see a lot of details in the feathers.

https://www.flickr.com/photos/120246773@N07/26725197162/in/dateposted-public/
No windows or washing lines in this, just a bit of cropping.


Overall the combo works fine, still a bit short for birds but I don't have 900 quid for DA 300 to put on the converter, so cropping will have to do for now.

On the side note:

It works quite well with DA 50/1.7 but not so much with Sigma 18-35/1.8. With Sigma AF just hunts without even trying to lock. Don't know why anyone would want to put those lenses on the converter though, bigger magnification at close distance possibly?