300 F4IS or 400 5.6

[padi]

Hi Guys

Looking at buying my first prime lens and at a little bit of a crossroads. I bet this question has been asked many times.

Not being able to afford the 400 2.8 or 500 F4, I am looking at the 400 5.6 or the 300 F4.

Wildlife/birds are my passion (birds not necessarily in flight)and I have both the canon converters on a 5D Mk1 at my disposal, hopefully with a purchase of another body in the future maybe the 7D which, by the way I have access to now. So now full frame and 1.6 factor later. I also have the 70-200 2.8 IS lens which I never really thought about much to get me ino the 300is range with the 1.4.

So which way do I fall? Cost not a lot of bucks difference, but IS less reach on the 300 or more reach no IS and 1 stop less on the 400. I assume the converters with AF work on both? with reasonable image quality? giving me with 1.4 converter 420mm IS lens @ 5.6 or 560mm F8 is getting a bit slow I feel.

Image quality of these lenses are they comparable? Any sample would be great both with and without converters, heard lots of good reveiws on both. So there it is my dilema any input and experiance of these lenses in a similiar enviroment would be appreciated.

Regards

Padi

[RichardTaylor]

Personally I would go for the 300 F4 IS L mainly because of the F4, The IS and it focuses a lot closer than the 400 F5.6 . If you need more reach then add the 1.4 TC - Some reports say it is a good combination.
I feel the 300 F4 would also be a better general purpose long tele.

I have a friend who shoots motor sport with a 50D + the Canon 400 F5.6 and he loves it.

I don't own either lenses as I shoot with a Canon 100-400 F4.5-F5.6 IS L.

[inkista]

As Richard says, the 300/4L IS is a better general-solution lens, but only if you're primarily going to be using it as a 300mm lens and then occasionally adding the 1.4x tc to it. If you're planning on having a converter on it all the time (as with birding) then get the 400/5.6L. If you were shooting sports and birds, then I'd say the 300L.

And here's your one erroneous assumption:

Originally Posted by padi

I assume the converters with AF work on both?

Nope. They might work and the image quality might be OK for you, but your autofocus is going to stop when the max. aperture of the lens hits f/8. And the 1.4x adds one stop, while the 2x adds two. So, an f/4 lens can only use the f/1.4x tc, and the f/5.6 lens can't use either, if you want to autofocus. Which birds kind of make you want to do.

You can get around this by taping over the pins of the Canon TC, or using a non-reporting TC. I use a bargain-basement Tamron 1.4x tc on my 400/5.6L USM, and it works. The AF hunts and chatters a bit more (although a lot less on my 50D than it did on my 350D, and I still have some problems with backlit subjects), but overall, it's still usable.

Image quality of these lenses are they comparable?

From everything I've seen on the interwebz, yes. Telephoto L primes rock. No need to stop down for sharpness. I shoot wide open with the 400 all the time.

The third candidate to consider is the EF 100-400L IS USM. Reach of the 400, but with IS and zoom. Not quite as fast on the autofocus as the 400 prime, and possibly a little softer at 400mm, but also a much more general purpose supertele solution vs. the primes. I often wish I'd ponied up the extra dough for the 100-400L when I'm shooting at the zoo. When I'm birding, though, I'm never close enough, so having a 400mm prime isn't an issue. I'm still cropping with the 400mm.


Canon 350D/XT. EF 400mm f/5.6L USM. iso 400, f/5.6, 1/3200.


Canon 350D/XT. EF 400mm f/5.6L USM. iso 100, f/5.6, 1/640s


Canon 350D/XT. EF 400mm f/5.6L USM + Kenko 1.4x TC. iso 800, f/5.6, 1/2500s


Canon 350D/XT. EF 400mm f/5.6L USM. iso 1600. f/5.6, 1/200s. (handheld, supported on railing. Wild harbor seal at La Jolla Cove.