G'Day All

I have read with keen interest over the last month or so the discussion around the use of various types of zoom lenses. However, there has been little discussion over the use of various types of converters (1.4x; 2.0x and quality issues etc) in "stepping up" the zoom capabilities of lenses.

My questions therefore are:

(a) How effective is a converter in "stepping up" the capabilities of a zoom lens?
(b) Is a converter a "poor man's option" of wanting to have a bigger zoom lens?
(c) Should a converter be part of your camera kit regardless of the types of zoom lenses you have?
(d) I am currently using a Canon 300D with a 55-200mm Sigma lens and would like to know whether to invest in a converter (for now) or a bigger zoom lens?

I look forward to your replies.

Thanks,

Marc