I've got a great Tamron 17-50 (love this lens), and then a birding Sigma 150-500. I've found that the gap between these two is where of like to take photos of the kids and other family members.

I'm toying with finding a non Vc tamron 90mm. This would be useful for macro photography for local orchids and other flowers as well as the odd frog or two that my daughter lives finding.

It's there anything to watch for with this lens, or other similar lenses I should look at? My budget is $500 maximum, $300 preferred.

Also should add I use a d7100 which has the screw drive for auto focus.

Thanks for any tips.