Does anyone have any experience with using Canon 300 f4 with 2X iii teleconverter at f8 and comparing that with Canon f5.6 + 1.4X teleconverter at f8.
I am interested in knowing more about the following areas.
- sharpness of images comparatively
- impact on AF ability using a 1D Mk IV body, in good and low light
- weight and usability of the combo's.
- thoughts on effectiveness of the IS on the 300 mm when used with the TC
I am interested in having more reach for birds and wildlife, both while they are still and moving. Getting a 500 f4 and/or 300/400 f2.8 is out of the question budget wise.
That 2x TC will really slow down the autofocus.
Strictly from a focus speed standpoint, you will be better off with the 1.4x vs the 2x.
You will not have use of the better f2.8 focus points in the camera.
In "low light", the focus screen will be darker and you may not be able to see well enough to manually focus. The 1DIV is not known for "low light" AF capabilities.
I have a 300 f/4 and a 1.4x, and the focus speed is noticeably slower than using the same 1.4x on a 70-200 f2.8. AF lock with the 70-200 ISII is virtually instant with the 1DIV and it becomes "really fast" with the 1.4x attached. The 300 f4 does not focus as quickly.
I imagine that using a 1.4x on a f5.6 will be slower than a f4. I do not own the 400 f5.6 though.
If you do not own these lenses, I would suggest renting those combinations and trying them out first. I do not think that the keeper rate for moving subjects with either of those lenses + teleconverters will be very good if you are relying on the camera AF to get them.