I need an afforable macro lens - Advice Please

[Daniel Browning]

I have thought about the Tammy 90mm but this statement on Photozone is what stops me from purchasing it ...

"[...] Beyond f/8 diffraction is the limiting factor - a physical barrier where no smart lens design can help. Generally you should avoid stopping down beyond f/16."

Many times for macro shots, I stop down to f/8 and beyond. So, I always thought this lens wouldn't be a good choice.

You understood photozone to say "Generally, you should avoid stopping down beyond f/16 *on this particular lens*". But they didn't mean that particular lens -- they meant every lens from every manufacturer. For whatever reason, they don't mention the same thing on other lens reviews, but it's not because of anything specific to the Tamron lens. In any case, as you already know, you can get perfectly acceptable results from f/22 and beyond, so ignore that particular bit of advice.