Wanted to say thanks for posting this. I just sent him some email to ask about the longer tube. Managed to get a B300 to use with my FZ20, but after looking at your image of how it would appear when mounted to the standard adapter I didn't feel all that comfortable with leaving it mounted that way for extended periods of time either. One question though. How much of a gap is at the end between the inside of the 72 mm tube and the outside of the B300?
A lot of members ask or talk about the Olympus Tcon-17 and or the legendary Olympus b-300 (tcon 17 took over that model) which are incredible high quality teleconverters for the price.
When I received my B-300 I had two minor setup challenges.
First, the B-300 is a very heavy lens and I do not want want to add stress to the camera or the UV/Haze lens protector by holding on to B-300 or by accidently hitting the camera at the end of the lens because its so long.
And second, it is always a must for me to keep a hood on during day shoots and the B-300 does not have front threads to screw on a hood.
I had Ron Jin the maker of Phayee tube adapter make me a custom made 72mm tube to accomdate the B-300 (probably would work fine with Tcon-17)
The original 72mm extension Phayee tube was only .75 inches and he made me one that is 2.25 inches.
This setup protects the teleconverters lens and essentially the whole camera by insulating the B-300.
And yes, i only take pictures in the nude, makes my FZ camera feel special.
The less the better. My adapter has a distance of 3.5mm between the extended front element and the front of the adapter.