Is this just a piece of junk? (1 Viewer)

Whilst searching on e-bay for second hand lenses for my new 400D (no luck ) I found this and this .

Are these just junk? I guess they must be at that price.

My Sigma cheapie 70-300mm has a 58mm thread so I could in theory attach these.

I may embarrass myself here. Excuse my extreme ignorance but are these teleconverters? I thought teleconverters went between the lens and the camera and not on the end of the lens.

Bet it's to good to be true! But for 24.95 I am almost tempted to try it!
My teleconverter on the 20D is between the lens and the camera, have to tape the pins in order for AF to work.
However, I get decent shots with my S3 and a 1.7 teleconverter that sits on top of the lens.

MOST VIDIO cameras take this in front type of converter and as said the s3 does so for the money it could be ok .
wonder if they do one for my 500f4
Rob

Your sensor will definitely outresolve this type of telephoto extender, so you are not going to get results any better than cropping images. Judging from the price point, it is likely these will also introduce significant amount of CA and loss of contrast.

I have tried to put the Canon 1.5x TC (DC-TC58N) which also has a 58mm thread in front of a 70-300 IS just for fun, and the results were sufficient to convince me that it is not worth it.