Originally posted by pleo
I have both lenses (and had the 60-300 too).
If I want the best optical results at 300 mm I use my manual/adaptall Tamron SP 5.6/300 macro....
I picked up an Adaptall CT-300 prime a few months ago as part of a bundle at a good price, but I have not yet got really good results from it - I think it needs a bit of imposed "flatness" to the colours to avoid saturating the reds or whites. I will try again soon, but I will probably sell it, and keep using the PLM zoom or the SP 60-300mm if I need 300mm. So Pleo is ahead of many of us in having the very good SP 300mm macro.