Canon 70-300 IS USM vs 70-300 L IS USM

I have a few comments regarding the 70-300 L IS USM which may prove very important to you. I purchased the lens a couple of months ago so I do not have too much experience with it but so far am happy.

You say you use a small tripod. Do you also use a ball head? A lightweight ball head? Adding the lens to the camera body shifts the center of gravity forward. Can your tripod and head support the weight, and without movement? Canon sells a tripod mount ring (Type C) but it is outrageously priced. $170 is about as cheap as you will find it. There are generic brands that are much cheaper but the comments/reviews have in general not been good. If you use a tripod mount ring then you can't use a battery grip at the same time.

Do you use an extender? The Canon extenders are not compatible with the L lens. You can use them if the lens is extended to 300 mm, but you have to make sure you do not turn the zoom ring or the rear element of the lens will bang into the front lens of the extender; this is not good. Non-Canon extenders from what I understand will work, however.

If you look at the lens in person at a dealer, make sure you take your tripod with you for evaluation. And make sure you extend the lens to 300 mm, as this is the worst case for inducing camera movement, both tripod mounted and hand held. Hope this helps you to make a decision.

Ron