QUOTE(mingyuyu @ Aug 27 2013, 09:30 PM)
yeah i have read some articles about it, even with all tubes mounted, a 70-200 lens will still not achieve 1:1 magnification. Raynox and macro filters degrade the IQ quite much aren't they?
Top up a few more hundred and i can get a sp90 compared to extension tubes

Macro filters are single element lenses, uncorrected for optical defects so yes, they do degrade IQ alot. \
But raynox filters on the other hand are multi-element filters, hence the additional cost for them.
They're pretty darn sharp for what they do, but like a 40-60mm macro lens, the working distance is almost nil when used.
A tamron SP90 is still the best starting choice if you want to do serious macro work

or this if you're as into macro as I am

No barrel extension, VC, sharpness exceeding the older generation. Plus that massive price drop from RM2700 to RM1900 just makes the deal all the more sweeter for me.