I am looking to purchase a telephoto lens and I'm torn between the two. They are both near equal in terms of cost. However, looking over the specifications of both I know the L is better optically than the non-L series lens(L is sharper wide open, and has better IQ). That aside, would the extra 100mm be worth it? Does anyone have both lenses, or have tried both? I have read nothing but good things for both so I am torn.

I plan on doing more nature photography and sports due to my son now joining soccer.

I have an APS-C camera(60D) and will be upgrading to the 5DMrk3 next year so both lenses I know will work.

Any thoughts or opinions?

I was thinking about the lenses, but also about your body choice.  Bill has a 5DIII, so I asked him about it to make sure I'm not off track.  He says if you're shooting sports with a telephoto, you probably don't want the 5D.  It's a full-frame camera, which cuts your telephoto range from 1.6 to 1.0.  That means with any telephoto lens you'll see farther with your 60D than you will with a 5D.  Instead of the 5DIII, you might want to think about moving to a higher-end crop frame body.  (I hear they're coming out with a new 7D and/or 70D in August, which will have the new high ISO chip.) 

If you decide on the 5DIII, you'll need a longer telephoto lens to compensate for the full frame format.

I've got the 70-200 L-series, and the thing I like about it over the 70-300 is that the f-stop range goes from 4.0 to ... whatever.  20?  I can't recall.  The 70-300 is limited to 4.0 to 5.6.  That doesn't give you a lot of latitude.  Also, the longer the telephoto, the softer your images are going to be, so you'll sacrafice a bit of sharpness to get that extra distance.

When we were at Bryce Canyon last month I was happy to have the 70-200 and the full f-stop range.  There are a lot of sunny spots, but also a lot of shady spots, and it was great to have a wider range of choices.

The 70-300 is a little bit lighter in weight than the 70-200.  On the surface that sounds like an advantage, but it means you've got less glass ... and less glass is the reason for the softness of the images.  Better glass equals better sharpness.

I hope that helps with your decision making process and doesn't muddy things up too much!  LOL!

Thank you so much for the feedback!

Yeah, I know I will be losing length when I switch to full frame. But I am only shooting sports for a short period of time, and trying to concentrate more on portraiture, and nature. I probably will buy the 2x extender when I switch so it adds to the focal length. I guess that's the added advantage of having a crop sensor compared to FF;I think it's what, 112-480mm for the 70-300mm on an APS-C body? . But, with the lens lineup I have now I want to switch due to what I am doing later on :D

I've considered some of the other L telephotos but they are so heavy in terms of price and weight lol. I would love the 70-200mm f/2.8 L but that is over my budget at the moment!!

Talking with a friend of mine he suggested I take my body to a shop and test them out or rent from borrowlenses. I think I'll go test them out and go from there.

Using borrowlenses is a terrific idea.  We rented some equipment before we made our final choices last time we bought new equipment.

Have fun!  :)

So, I went and tested both lenses today at a local camera shop. The extra 100mm was great, but the L was amazing. I got to test out the f/2.8L(non-IS) and was sad because it's soooo pricy but really really nice.

I bought the f/4 L because it just seems overall better quality than the non-L one. I'm a happy camper now lol!

I think thats a really good choice.  :)  Enjoy!