Here it goes on the upgrade of firmware on A1.
Subject: Re: Anyone use the new accessory lens for A-2
I got the teleconvector ACT-100 friday. It works fine on my A1 (it
works on the 7hi and the 7i too). You get a cd to update the
software of the camera. It is a fabulous lens. Be aware of the fact
that you get a fixed 300 mm lens. Zooming is not recommanded because
of the heavy weight (almost 500 gramms). I can still shoot by hand
and still at F3.5. There is almost no loss of light and there is no
loss of quality of the picture. A great piece. But heavy and you get
only a fixed 300 mm. I use is for portrait, candid en animal
photography.