Lens choice for photographing birds in flight

Silver

I’m going to purchase my first decent lens for birds to go with my 60D. I have the kit lens, an 18-200mm and a 50mm lens.
I have narrowed my choices down to these two: Canon EF 300mm f/4.0L IS USM or the EF 400mm f/5.6L USM.

As I really enjoy shooting birds in flight, I’m leaning towards the 400mm. However, from what I read the 300mm is very sharp.
Much of my waterfowl shooting is on cloudy days (I may end up renting these two, but really don't want to do that). Suggestions or comments appreciated.

Auston

@Silver - I wish you the best and would like to see some of your work. To get to your question, I recommend renting both lenses and see which one works best for you.

With lensrentals.com, the cost of renting for a weekend is a lot cheaper than buying either lens and not liking the results.

I think you should also look at the 300mm f/2.8L. It also comes with IS and a lower F/stop, giving you the ability to add an extender and keep your shutter speed up and ISO down. The Canon 2x extender (teleconverter) would give you the zoom power of a 600mm f/5.6 lens, which would be nice on those cloudy overcast days the waterfowl like.

Also, don't forget to account for the 1.6x crop factor with the 60D, which would give you an effective field of view comparable to 480mm when using the 300mm lens.

I hope this helped. Have a Great Day! - Auston

lamson

I have the Canon 100-400mm and I highly recommend it. It is slightly more expensive than the 400mm that you're considering and probably not as sharp. But, it is more versatile with the zoom and the IS is great.

withns

With the 18-200mm I got this shot
http://img403.imageshack.us/img403/3265/201205282496.jpg

With the 100-400mm I got this one.
http://img266.imageshack.us/img266/6788/201204220419.jpg

As you can see it's not necessarily the lens, just pure dumb luck!

This is coming from someone with serious lens lust! I'm always on eBay having a dream.

wessyfiesta

Have a look at the sigma 120-400mm f/4.5 lens. This is a very good lens for wildlife.
Take a look at the photos I took with this lens:

http://www.flickr.com/photos/wessyfiesta/7222634006/

http://www.flickr.com/photos/wessyfiesta/6992706204/