Advice please on two lens

I have narrowed my choice down to two lens

1/ EF 300mm f/4L IS USM

2/ EF 400mm f5.6 L USM Lens


I do mainly landscapes with a bit of steam traction ( details for construction of my 5 inch gauge miniatures live steam loco's ( coal fired )) with a fair bit of bird photography


would a 1.4 tele converter work with the above lens and with the one's in my sig


I cannot go much longer or heavier due to the fact I need wheels to get about

Note if you had not guessed I prefer Canon lenses particularly the smaller L variety

Neither of the lenses is long enough for (semi) serious birds photography. I tried with 400f5.6, but found myself too far and even too slow. If you add 1.4 on it, you'll get even slower... Hard to advice, hire first to see what works better for you.

The 300 f4 works reasonably well with a 1.4x extender, but even then it's grossly underpowered for small birds. Add a 1.4x to a 400 f5.6 and it'll only be useful in really bright light. I hate to say it, but if you want to get serious with birds you'll need some bigger guns. I know from experience. If you want casual snapshots and aren't concerned with quality and critical sharpness then anything can work.

Both work great with TCs. Both are great lenses. If you lean toward birds more, get the 400. If macro is also an interest, get the 300.

thanks for the info

Check out the 400 and 300 lens sample threads. I have a Tamron 1.4 TC and am pretty impressed with it on my 400.

thanks I have done that , I wanted some opinions before I pull the trigger so to speak , have to be a bit careful with the money as for me its just one of my hobbies and I have not had a job for the last 14 years

I haven't used the 400 f/5.6, but I'm very sure that the 300 f/4 IS is a much more versatile lens, esp when you add a TC. Even at 672mm AoV (50D w/300mm + 1.4x TC) you can get away with shutter speeds of 1/80s-1/125s, where as with the native 400 on a 1.6x crop you'll need 1/500s-1/1000s. Not to mention, you can trade a little length for an extra stop by removing the TC when you need the extra ight gathering ability. And, of course, if you put a TC on the 400, you'll lose AF with your 7D .

I shoot hummingbirds, larger bif and perched birds using the 300 f/.4 IS with and without a TC. Let me know if you want to see samples (100% crops).

Fwiw, I also use the 300mm for a lot of things, including large indoor events, large insects, plays, concerts, dance/theater, daytime field sports, etc, etc.