1) the connection to the camera is very poor. It doesn't lock into place and can easy ...
Carol Moffatt, Amazon
29 November 2014
Summary: In addition to the filter adapter, I also purchased this tele-converter. I have the same issues with both items. 1) the connection to the camera is very poor. It doesn't lock into place and can easy turn and fall off the camera. 2) When using the tele-converter whether it in full zoom or not, the tele-converter blocks a large amount of the image you see through the viewfinder.
Excerpt: the standard G15 has a zoom ratio of 5x, from 28mm to 140 mm focal length (35mm film equivalent values). I don't have much use for the 28mm wide angle but would like a bit more telephoto. A 1.4x teleconverter sounded ideal - it should give a range of 39mm - 196mm. Sorry, it doesn't. You'd think that an expensive lens made by Canon specifically for this camera would be useable across the whole zoom range. It isn't.
Summary: The standard G15 has a 5:1 zoom range - 6.1mm to 30.5mm, or a 35mm film equivalent of 28mm-140mm. In this review below I give all focal lengths as 35mm film equivalent. A zoom ratio of 5:1 is about the lowest I can live with. For basketball pictures, for instance, that's about the range you need to zoom between someone on the near side of the court and on the far side.