This les is very sharp and auto focus is very fast. I use this lens for bird photograph and get great results!

Fantastic lens. Very nice, stable focusing. Hand held in a canoe for bird pictures, no problem. I have been just blown away by the fine shots hand held. Super sharp, clear pictures. My first L lens, not going back. Problems Encountered: It is heavy...get over it. It is so worth it. A little slow to focus while bobbing around at times. Items I Recommend: sun screen, camouflage material for the lens

LANDSCAPES,WILDLIFE,PORTRAITS.

So, I have had 2 different 70/200f4 IS L Lens and felt like i was just not getting that L Lens clarity, So they where returned and i ordered this and was weary about weather i was going to be happy with a lens that i can not zoom in or out with. Will i got it yesterday and went out last night and at first i was not happy with it, Pictures where not clear and seemed very soft... so i came home and looked at my settings and went back out today. What a world of difference, the pictures are sharp and i could not be happier with this lens and the best part is that it is cheaper then the 70/200 f4. Also i am shooting outside and today was cloudy and the lens was still producing pin sharp pictures. As most people have stated is that it is very heavy, Might not be the heaviest but its not the lightest either... Would i recommend this? Yes with out a doubt...

This is a wonderful lens. I will go so far as to call it my favorite lens. It is extremely sharp, light weight and well balanced, even with the 1.4x tele-converter attached. If you travel or shoot mostly in the daytime, this is the lens. It's not really fair to compare this with the 300 f/2.8. That lens is probably the best lens Canon makes. It's super sharp and super fast and super bright. Here's what you need to consider. Does your living depend on the shot? Are you shooting NIGHT or low light indoor sports? Do you mind using a monopod and carrying a very heavy lens? (You can shoot the 300 f/2.8 hand-held, I do, but it's very heavy. These are really the questions to consider. If you don't really need any of the above, buy this lens. I owned and used the 300 f/2.8, generation I and II for over six years. It's top notch. But I now use this lens exclusively. I shoot night, high school football and day surfing and football on a EOS 1D Mark IIN. It focuses slower than the f/2.8 and even slower with a 1.4x tele-converter. I do get a greater percentage of out-of-focus shots at night and with the 5D especially. But, I love this lens. It is NEVER a burden to carry around and that is the biggest plus for me. It delivers professional results and sharpness, the IS is great and it's easy to carry around for hours. Expertise: Professional Photographer Previous Equivalent Item Owned: EF 300 f/2.8 USM IS Items I Recommend: 1.4x Teleconverter

For a number of years, I have been using a Canon EOS Rebel XTi with a 75-300 (Tamron) lens. My bird photos were never crisp and clear. I had to choose either a new camera or a new lens (can't afford to get both). I finally decided to go with the Telephoto EF 300mm f/4.0L IS Image Stabilizer USM Autofocus Lens. It doesn't quite have the reach as 75-400 lens, but the quality is SO much better!! It took a little getting used to at first, not being able to zoom in and out. For a closer photo, I just crop when I get home. The photo quality is excellent, even in a cropped photo. I have a cheap little monopod that I use with it, as the lens is quite heavy. I don't have any negative comments about this product.

For a number of years, I have been using a Canon EOS Rebel XTi with a 75-300 (Tamron) lens. My bird photos were never crisp and clear. I had to choose either a new camera or a new lens (can't afford to get both). I finally decided to go with the Telephoto EF 300mm f/4.0L IS Image Stabilizer USM Autofocus Lens. It doesn't quite have the reach as 75-400 lens, but the quality is SO much better!! It took a little getting used to at first, not being able to zoom in and out. For a closer photo, I just crop when I get home. The photo quality is excellent, even in a cropped photo. I have a cheap little monopod that I use with it, as the lens is quite heavy. I don't have any negative comments about this product.

I rented one of these lenses 2 years ago for a trip to Trinidad and was pleased with the results so I just purchased one. Although my dream lens is the 300mm f/2.8 L IS II (which I rented last year for a trip to Costa Rica -- can't say enough about it!), the f/4 L is much easier to hike with, more discreet, vastly more affordable, and is sharp, with comparatively pleasing bokeh. I also own a Canon 400mm f/5.6 L (for birding/wildlife) but realized that having IS often makes the difference in getting the shot. For the price the 300mm f/4 is a very solid lens.

I purchased this lens primarily for bird photography, and have been more than happy with its performance. It's a bit slow in low light, but sharpness and color are perfect. I find the auto-focus plenty fast enough.

This was a good investment for me. I have nearly 50 yearsexperience and learned a lot about photography from my dad.I've gone from Brownies to EOS. My L lenses helped take myshooting up to a new level.This the 135L, and 200L are my main short to midtelephoto lenses. I use this lens more than my 2.8. It's easier to carryduring long shoots and gives images that compare favorablyto the larger heavier lens. CA is very well controlled.Images are tack sharp and contrasty with well balanced colorand saturation. IS is a blessing for hand held and monopodshooting. Focus is fast enough to catch Indy cars at speedas well as the occasional humming bird.If I am going to be in a low light situation I bump up theISO to get shutter speeds fast enough to catch the action. 20D users with the lock up issue should download and installthe latest firmware. This takes care of most issues withthis model. It's not that hard to do if you read theinstructions and be patient. It takes some time to completethe process. The camera will let you know when it is readyto go again. Make sure you have a well charged battery anddon't touch anything during the upgrade. Problems Encountered: I don't know if I should sell the 2.8. Previous Equivalent Items Owned: EOS from 650 to 30D and 5D. Many lenses over the years Items I Recommend: 1.4X Extender