I just bought an "0.43x Super Wide Angle" converter. The converter consist of two separate parts, a wide angle (W) part and a macro (M) part. The full converter screws on the filter thread of my Sigma DC 18-50mm f2.8-f4.5 HSM lens (L) and the lens is attached to the camera (C) as is shown in the schematic drawing below.
--- \ ¯¯ |¯ ¯ ¯ |||||
--- / __ |_ _ _ |||||
The problem I have now is as follows:
If I put the wide+macro on my lens I do get a wide angle image, but it's not very wide. When I set my Sigma lens to 24mm I roughly get the same image as when I have my lens without converter at 18mm. This means I only get an 0.75x conversion.
If I only screw on the wide part (W) I do get a very wide image with roughly 0.45x magnification but my lens can not get anything in focus. I have tried manual focus but it seems as if the image falls out of the focussing range of my lens.
It seems as if I have to use the wide part with the macro part, but then I loose the 0.45x magnification. Is there a fix for this, did I fall for some false advertising, or haven't I thought this true very well?