This is my next lens and will be ordering in a week or two. My intended use is a bit different.
My plan is to put it on a 6D connected to a Ioptron SkyTracker and aim the rig at the Milky Way hoping to get some wide field nebula I can stack.....a rig that can go into the backpack. I've got astro mounts that can't go far from the car.
Next intended use-coupling with a cTC 1.4 iii and aiming toward the bird studio in the backyard.
Thoughts?
With the birds it will be all about the proximity, but I've used the 135 alone and had some good results. Get the feeders and perches close and you should get good results, perhaps look into using a remote release so the human behind the camera doesn't spook them. I don't have a Canon TC, but my only concern there would be AF speed, which can be overcome by setting a good perch and prefocus.
I'm yet to try out the 135 pointed toward the stars.




















