My attempts to shoot the moon last night got me looking around at teleconverter lenses. I know that there is no true teleconverter available for m4/3 right now. I'm talking about the ones that screw on the front. Yes, I know that they are optically inferior and will cause vignetting, but I thought one might be fun to play with. There is a cheapo one (from everybody's favorite Digital Concepts) that is 67mm and thus would fit in front of my 100-300mm. On the other hand, I found an old Canon TC-DC52 for just about the same price. The problem is that the TC-DC52 is 52mm rear thread, so I'd have to do some serious step-down ring action to mount it. So here is my question to you, dear friends. Would the (presumably) better optics of the Canon outweigh the light loss compared to the Digital Concepts version? Assuming that all I use this widget for is shooting the moon. Not too worried about vignetting because the moon takes up so little room in the frame anyway. Or, do you have other suggestions?