Does anyone have any experience with either of these. I already have the 100-300 shown here.
PentaxForums.com Third-Party Lens Review Database - Quantaray 100-300mm F4.5-6.7 LDO
I can get the 70-300 cheap (if I act fast only).
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/2977-quantaray...-versions.html
I do not know which version it is (I suspect the tamron version but I do not know for sure).
I understand the quality is not pro but cheap glass Is all I can afford right now. My only major issue with the 100-300 that I already have is the autofocus sucks. I have a vision problem that makes manual focus an issue. The 100-300 has focus issues at higher magnification, even in daylight. Low light focus sucks and forget about using a teleconverter. Right now I have to take several shots in manual focus (at different focus points) and then find the in focus one later on the computer.
As best as I can tell the 70-300 is supposed to have a bit better AF. Of course its always hard finding info on quantaray stuff.
So does anyone know how they compare?
One a side note, I'm only concerned with its performance on the long end. I have several other lenses with less magnification including a 80-200m pentax brand lens.