Hi, just took another shoot with 2 lens at same time:
300mm + 50mm macro with an inversion ring.
http://olhares.sapo.pt/buraco-da-agu...to6641839.html
Very hard to focus as you need to do it with 2 lens. You have an area to work about 3 mm. The object has to be at a certain distance to the last lens. 3 mm far away and you will no t see anything.
This is a photo of a niddle hole. It has +/- 3 to 4 mm.
Hope you like it.