Upload & Sell: Off
The Contax Bellows are going back tomorrow for full refund. I got the 55mm F2.8 micro Nikkor but the adapter thickness with the bellows extension is just too great to allow 1:1 on the Contax Auto Bellows. (The Yashica 55mm F2.8 is also rated extremely highly and may have worked at 1:1 with the Contax bellows, but they are rare and the cheapest I located was £108, over twice what I paid for the Nikkor.)
Now I have the Micro Nikkor I will look out for the Nikon PB4/PS4 or PB5/PS5 Bellows/Copier combination at the right price.
My research in the interim has shown me that probably the cheapest and best (?) option at the outset would have been the Canon FL or FD bellows + copier with the FD 50mm F3.5 Micro. (Very hard to find a lot about this lens, but the litle I did find was that it was a winner, especially the later FD and FDn versions, (with a green "A" for AE)
Another option I looked at was the Olympus OM Auto Bellows/copier with Zuiko 80mm F4 bellows lens. Excellent reports, but more pricey than either the Nikon or Canon alternatives.
I also looked at the Novoflex Auto Bellows/copier with Noflexar 60mm F4, which is common on ebay.de for reasonable prices. However, very little info and what I could ascertain was that the lens wasn't all that brilliant and the bellows were rather short, 130mm as against Nikon's 185mm. Also the rear standard of the bellows is fixed and doesn't allow the camera to rotate.
Minolta systems are also available, but I didn't look.
At this rate, by the time I get the Nikon Bellows/copier I'll have forgotten what I wanted them for!
EDIT: I have since discovered that the Contax Auto Bellows were manufactured by Unitor and made for several makes, either rebranded or as Unitor. I've come across them in Konica, Nikon and Pentax mounts and generally cheaper than the Contax branded ones.