Birds are tiny creatures who are easily scared. So, if you want to catch them, you need a long telephoto lens. The thing is, which one? if we pull the 500mm+ out of the equation (too big / expensive), the choice most photographers have is between the 300 L f4 ISand the 400 L f5.6. Both are about the same price but target different market.

Ask any wildlife photographers and they will tell you that you need at least and equivalent focal length of 400mm to catch any good bird pictures. So if you are shooting with a full frame camera, only the 400 L f5.6 will fill that requirement so you are set.

On the other hand, if you use a cropped sensor, both doors are still open and interesting. Should you get the 400 L f5.6 with an EFL of 640mm to get extra close to your target or should you go with the shorter lens and make up with better light sensitivity and IS?

Having shot many times with both lenses in many circumstances, I have found the extra range to be more important than IS and wider aperture since both of these can be compensated with higher ISO. On the other hand, you can’t get any closer without cropping, which is generally a big nono.

NOTE 1: if you are thinking about using the lens to shoot other subjects than birds and other small animals, you will be better serve with the 300 L f4 IS. It is more flexible and can be used for portraits, landscape, etc.

NOTE 2: if you are thinking about doing video, get the 300 L f4 IS. At such a long focal length, IS makes a huge difference in the end results.

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chief astronomer at planet5D LLC
Mitch "planetMitch" Aunger is the creator and mastermind behind — which covers every aspect of HDSLR cameras (and a whole lot of other cameras as well). A lover of photography since his early days, he graduated to selling stock photos to make a little bit of spare cash. It wasn’t much, but it allowed him to upgrade to better cameras as well as computers, and it wasn’t taking money away from feeding his family.
He loves the stories that the still image can tell. In the summer of 2008, he read a story written by Arnold Kim called “I Quit My Job” — Arn is the owner of He started macrumors in 2000 as a hobby, and by 2008 he was making more money with the site than he was on his day job, so he quit. The surprise to the story is that he was a doctor making more than six figures! Right then and there, planetMitch dreamed about doing the same thing.
September 2008 rolled around, and Canon announced this new version of the incredible 5D — the Canon EOS 5D Mark II. It was the first Canon DSLR to shoot full HD video and the earth moved! (It really was a huge deal in the photography world.) planetMitch knew if there was ever a chance to ride a wave of something he was really passionate about, this was it — and the blog at was born. It is now one of the most popular HDSLR blogs on the planet, and he is making a full-time living from blogging. He couldn’t be happier!
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