I recently bought a used Soligor 2X Macro Tele-Converter. I didn't expect much but it was inexpensive, so thought I'd give it a shot. I'd read that Tele-Converters were a bad idea because you loose 2 full stops of light, and the 4 element optics in most of the cheap used ones were fairly crummy. I checked around and indeed the 7 element ones were nearly impossible to find and priced out of my "I'm just experimenting with this" range. I then discovered that some versions had removable lens sections so they could become simple extension tubes, so now I had two features to experiment with. If the 2x lens ended up being worthless at least I'd have an extension tube. When it came it took me a little bit to figure out how the take the lens tube out (it's spring loaded so push in and turn), but then I was ready to do some testing. I tried all the >50mm focal length lenses that these Tele-Converters were intended for with okay results (took a nice 1000mm equivalent focal length picture of the moon with it), but then I thought I'd try it on the 28mm Macro lens that it wasn't supposed to work at all with. Subscribe to see EXIF info for this image (if available) Sirius Macro 28mm f2.8 at f4, 1/160 sec, ISO 200 Subscribe to see EXIF info for this image (if available) Sirius Macro 28mm f2.8 at f4, 1/100 sec, ISO 500 with Soligor 2X Tele-Converter With Lens Inserted Subscribe to see EXIF info for this image (if available) Sirius Macro 28mm f2.8 at f4, 1/125 sec, ISO 400 with Soligor 2X Tele-Converter As Macro Extension Tube Only I may never use this much but it does just what it's designed to do, and the results are somewhat better than I expected for a $10 investment.