My dad has a 20D and a 50mm 1.4L that hes been using for a while, and he is looking at the following two telephoto lenses for our trip to bermuda this summer.

http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=129188&is=USA&addedTroughType=search
http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=12129&is=USA&addedTroughType=search

We will be taking a cruise ship and he will be using the telephoto from the ship. His question is, should he get the 300mm f/4L IS or the 400mm f/5.6L non IS lens? We've never taken a cruise to bermuda before so we're not sure what the coast line will look like in terms of distance from the boat.

I figure he should get the 400mm, but the IS in the 300mm is tempting too.. with the 400, I could stitch the photos together to make a "more zoomed out shot", maybe something like a panoramic photo, but we're not sure about the zoom difference between the lenses...

How much of a difference does the IS make? What lens takes clearer photos? Has anyone ever been on a cruise to bermuda before?

thanks for taking the time to read this.. ;-)

***Edit**

How would a 1.4x teleconverter + 300mm IS f/4 be? it gives the option of 300mm f/4 or 420mm f/5.6, would it still be as sharp as the 400mm by itself?

so confused!

For what kind of images do you want a telephoto?

The short answer is... the 400F5.6L is a sharper lens UNDER OPTIMAL CONDITIONS. The 300 IS with a 1.4 TCII will be a great setup for wildlife, well lit sports, people from a distance and so on.

IS does help a great deal when you are handholding , but doesn't help stop action or freeze your subjects movement ;)

He said he wont be using it for a lot of action shots, but maybe every now and then he'll shoot some sports.

I may use it myself for bird shooting in the back yard, because we get a few interesting birds here. humming birds, cardinals, and some kind of hawk.

Probably the most this lens will be used for is shooting coast lines from the cruise ship, as we plan to be traveling a bit in the upcoming years.

I'm leaning towards the 400mm, but he's saying the 300+TCII because of the IS.

*double post, sorry

I dealt with this exact question about a month ago. I was having trouble deciding between the 300 f4 IS, the 400 5.6, and the 100-400 4.5-5.6 IS.

I shoot mostly sports, and so I analyzed the strengths of each lens for this purpose. The 100-400 would obviously great for the zoom, since its always better to get the shot even if its not as sharp as it could be. But I use a second body with a 70-200 on it so I've got it covered one way or another.

The 400 5.6 is supposed to be the sharpest of the bunch, but its not a very flexible solution.

I decided on going with the 300 f4 + 1.4x TC and I think I made the right desicion for me. I get a 300 f4 IS, and also a 420 5.6 IS with the extender. I find its plenty sharp for my purposes and don't notice any loss in quality with the extender. The IS is useful for me even in sports, because even though it won't help stop action, it helps me compose the shot better since I don't have the steadiest hands in the world.

I've been very happy with this lens.

Do you have pics of the same photo subject, but one with the TC, and one without? I need to see a rough estimate of the distance difference to determine what length we could use. that would be fantastic.

or if someone has both the 300 and 400 prime, which i doubt, if it wouldnt be of any trouble, to post pics with those?

Do yourself a favor and get the 300 and TCII :) That to me seems like too telephoto(300mm on a 20D) for coastlines from a distance anyway. Remember you will have all hinds of haze and heat shimmer to deal with at great distances ;)

I shoot a 100-400 IS with a TCII (rarely) on a 1D

Have you ever tried to shoot 400mm hand held before? It isn't hard for me usually, but alot of people have trouble without IS :) IS is worth it... believe me . A 400 deserves a sterady tripod to shine!