Canon EF 300mm f/4L IS USM Telephoto Lens for Canon SLR Cameras: Customer Reviews & Product Details

This is a wonderful lens. I'm using it on a Canon 30D alone or with a Tamron 1.4x extender taking pictures of moving birds in dark conditions or close-ups of insects when I don't have time to change lenses. I can zoom in on the computer 3-4 times and still see a crisp picture. The auto-focus is crisp and it's very pleasurable to hear it snap onto a subject. With a tiny subject surrounded by large objects, it gets very close, and it's easy to switch to manual focus and finish focusing even with my not so great eyesight. It's relatively light weight is a help and I'm amazed at what I can take hand-held in difficult conditions no doubt thanks to the image stabilization. Now I wish I'd gotten the Canon 1.4x.

I recently purchased this lens and have been extremely impressed with the results it produces. The "IS" works extremely well.

I was a little concerned at first because the "IS" makes a little humming noise when in operation. I thought it was an issue at first due to the fact that my other "IS" lenses don't make the same noise, but found out it is completely normal for it to make the little humming noise that it does. I tested it out by turning off the "IS" and focusing in on a subject while hand holding my Canon 30D and I was moving around all over the place. Then I turned on the "IS" and it immediately made the image through the viewfinder much more steady and controled. It's nothing short of amazing.

The focus is quiet and quick, what more could you ask for? It provides crystal clear shots as long as your shutter speed is over 1/30th (hand held with IS on). If you combine a tripod and this lens in "IS" mode, you will lose image quality, so ensure you turn off the "IS" if you are using a tripod.

With the 1.4x teleconverter, it works great. Taking the 300mm and converting it to 420mm gives you a serious amount of "reach" for under $300 for the 1.4x teleconverter. The IS and the Autofocus work great with the 1.4x teleconverter, but I did notice the focus seemed to take just a touch longer, but it's so minor that most individuals probably wouldn't even notice. Combined with the 1.4x teleconverter, your F4 lens will convert to a F5.6 lens.

With the 2.0x teleconverter, you get range that you wouldn't be able to get unless you paid huge $$$ for a 600mm prime. The IS works well with the 2.0x but you lose the option for Autofocus. So if you stack this 300mm lens with a 2.0x teleconverter you will be manually focusing all your shots. Combined with the 2.0x teleconverter, your F4 lens will convert to F8.

Overall, this is a great lens at a great price, especially when you compare it to it's big brother the 300mm F2.8 that sells for nearly double the price of this lens. If you purchase this lens, you won't be disappointed.

I am very satisfied with this lens. I have not tried it with the 1.4 extender yet,but if it is as good with the extender as the reviews, I will be more satisfied than I am now.
The quality of sharpness is better than any lens I have purchased before. For the price it is probably the best in class. I have to have IS because of my age I have a slite shake when taking photos handheld. The lens takes very sharp photos even with my shaking hands.
I have taken some test shots on a tripod with the 2x extender with quite a bit of quality. It does take a solid built tripod to hold it. There is no allowance for any movement with the 2x extender,and it takes me awhile to ajust and focus in. So I would not recommend using it for action photography. Also you lose auto focus.
The 1.4x is suppose to work a lot better . Will update when I receive my 1.4x
So far I am satisfied completely,with the sharpness and build quality.
4/25/2007 I purchased a 1.4 extender and have tried it with the 300 prime,even in very cloudy weather I have taken very sharp photos. It does work as I had hoped it would,even dropping to F 5.6.

Over seven years I've found the 300 f/4 IS to be a solid performer. I still recall how amazed I was at the brightness of the image in the viewfinder when I first purchased this lens. Autofocus is quick and sure; if you have trouble with autofocus check the camera settings to see if you are in single shot mode, as the AI focus modes yield different behavior. The contrast and sharpness are excellent, and fall off a bit toward the corners of the frame. Resolution improves somewhat when the lens is stopped down to f/8. If you shoot wildlife and want to take the edge off of the white finish, some camoflage tape on the built in lens hood will help.

I own the EF 2x II teleconverter, which provides better performance than one might expect for a 300mm lens in this price range. With my 300 f/4, I get noticeably better resolution stopped down to f/16 than I do wide open, though the falloff toward the image corners is still sometimes unacceptable. Knowing this has not caused me to remove the teleconverter to photograph a bull elk in rut, so obviously I can live with this.

I tried mating the 300mm f/4 with various Kenko extension tubes to increase close focusing performance, but here the lens fell flat: both contrast and resolution were awful. I am unable to explain why. My solution was to buy the incredible Canon EF 180mm Macro lens for chasing insects, and I am happy I did.

While I appreciate the availability of the image stabilizer system in this camera, I still use (and recommend) a tripod whenever possible. If you plan to use Arca-Swiss style plates with your tripod, it is worth considering the Really Right Stuff double-dovetailed plates that accomodate a quick-release flash bracket. Kirk Enterprises has a less efficient system for lens-based flash brackets. While most of my plates are from Kirk, for this lens I grabbed the Really Right Stuff.

This is the sharpest telephoto lens I have ever owned. For wildlife photography there is nothing even close to it for the price.