[KorHaan]

http://cgi.ebay.ca/Olympus-TCON-17F-...54461251067081

Here's a picture of the Olympus TCON-17F 1.7x 58mm thread.

It looks like this might fit the Canon bin's objective thread.
The TC thread does look to go all the way down.

[KorHaan]

http://www.amazon.com/Sony-VCL-DH175.../dp/B0009OAFJ8

The Sony VCL-DH1758 1.7x 58mm thread. Click "see larger picture".

Not decisive, but there's a hint it threads all the way down. Can't see it properly.

Regards, Ronald

Best thing to do is try them out myself in a shop.

[wanderer55]

Originally Posted by KorHaan

http://www.amazon.com/Sony-VCL-DH175.../dp/B0009OAFJ8

The Sony VCL-DH1758 1.7x 58mm thread. Click "see larger picture".

Not decisive, but there's a hint it threads all the way down. Can't see it properly.

Regards, Ronald

Best thing to do is try them out myself in a shop.

Yes, the best thing is to try it in a shop.
I use the Sony and it has threads all the way to the bottom. It's a good choice and has good quality optics.

From the looks of your Canon, there's very little room to spare. Weight may be an issue. The weight of the TC compared to how much thread you get. If you can find a shop with the Sony TC, try it out. I think it will work.

I would get a couple of cheap 58mm filters and remove the glass from them. Then thread the filters into the Canon and the TC's into the filters.

With the filter retainer & glass removed from the filters, you will have more threads for the TC and the filter (naturally) fits well in the Canon. (I've done this stuff before..........).

[statestat]

Glad to see you are keeping at it, frustrating as it may be. Sounds like using the filters as a coupler would work as the Wander suggests. You are breaking new ground so as a trailblazer you pave the way for others so hang in there.