I am wondering what is the optimal lens for Bird Photography? Also what is the best aperture to shoot at if using a long lens? for example f5.6 f8.0 to get good depth of field but keeping background out of focus. Would you sacrifice ISO for shutter speed? What do you think about 1.4X Coverters and 2X Converters?
The 100-400 is the lens I use the most. It does need a lot of light. I mostly try and shoot at f5.6. I have never used a converter so can't help you there.
You can go to my site at stevecreek.com and click on my bird photos and check them out.