Couldn't agree more.
Sometimes it's well nigh impossible to predict actions of the subject (if cleaning itself or moving its prey around etc) and the only practical way (imo) to ensure getting everything in frame is to back off a little, knowing that you can crop afterwards.
Yes, it's great to fill the frame in the intended manner, but I'd rather get the reduced pixel sized frame I want (after cropping) than no pic at all - or one with bits missing that I wanted to be in the frame.
Rotated crops can also help - here's an old one.
(Also worth considering blurring the background a bit to get rid of distracting items)
Edit
<< I'll put the teleconverter on my 'must do' list for sometime in the future >>
If you're interested in preserving as much image quality as possible, buy the best you can afford.
To many ppl, 2x ones are a step / stop too far ... 1.4x doesn't sound very much, but you're doubling the No of pixels (that cover the main subject) in the image.
If possible, try both (and view test shots on pc) before handing over cash
pp
http://www.photomacrography.net/forum/v ... highlight=