I wanted to try out the Kenko Teleplus PRO 300 DG 2x teleconverter - anybody know how long it is? Wondering if I can stack my ext rings to fit it. I've got a D80 w/ the 105 macro (non-VR). Already have the 105 ext ring, along with the 18-70 ext ring and one for the 10-17.

It's been a long time since I used the Kenko, but you should be OK using one or more of the other extensions. Just leave yourself room for the lens to rack out. If you use all 3 extensions and it's a little too long, it won't hurt you.

Rack out the lens, then switch to MF. Try o mount the port with 2 extensions. If it doesn't fit, add the 3rd.

Tip: Take a white or metallic sharpie and mark a line on all extensions so they line up when turned and locked properly. Very important when using multiple extensions. Easy for one to get bumped out of place.

Thanks for the tip. I actually found a length on B&H, looks like it's around 43mm, which is just longer than the 18453 (41mm). Depending on how much room the 18462 gives me in front of the lens, it might work. I'll give it a try.

I think it is the same ring as the 200mm extention ring. I cannot say with someplete certainty though.