>Personally, I would invest in the 5T and 6T close up supplementary
>lenses. They are very high quality and will work wonderfully with the
>70-210. In fact, if you need higher magnification you can stack the two;
>put the more powerful on first and then the less powerful. I recommend
>using the lenses with the 70-210 as you will get better working distance
>with it.
The accuracy of that last sentence is questionable.
Diopters will yield a fixed working distance, regardless of the focal length
they are used on. A 3x diopter (the 6T) will result in about one foot of
working distance whether mounted on a 50mm lens or a 300mm...
