Quote: . . . to get a larger image of a subject that's too far away.
In the "good ol' days" with only MF prime lenses (35, 50, 135 & 200) my thinking was "
how can I position myself to format and frame the image with the len(es) I have available?" That was a composition-based mindset and sometimes the choice of vertical or landscape orientation to support final framing/cropping/printing was as controversial as the use of a TC today. (There was also that controversy over the "horrible" image degradation produced by those silly new zoom lenses despite the fact that some very good PJ work was being done with 'em.)
My transition to APS-C with a an Oly Pen-F kit and more recently the DSLR bodies included adopting some of those 'modern' zoom lenses and an unnoticed, subtle but significant shift in my thinking about lenses occurred. Focal length became a handle for
distance and zooms a lazy excuse to manipulate a scene by image size rather than perspective.
Thinking through some of the discussions in the earlier photo forums re-aligned my thinking to the field-of-view / angle-of-view and point-of-origin perspective again.
If you plant yourself in the position needed to get the desired composition
and perspective, lens choice including TC use becomes obvious and easy when restricted to what's available at the moment.
A TC then becomes a
force-multiplier rather than an
IQ-destroyer allowing you to make the best possible image
with what you have in hand. Unless you have a stack of test-bench comparison shots, you either like the TC results or you don't -- as with any other shot -- and the TC itself becomes a non-issue.
Just use the best tool you have at hand. If you don't know which one that is (yet?) then the whole point of arguing over IQ degradation is mute anyway.
An' don't forget to have fun too.
H2