Tuesday, 1 June 2021 | Tommaso
The m48 ring is almost a mockery because you will hardly gain anything in vignetting. The flattener's output light passes from 39mm to 42mm in the transition from the m42 thread (originally supplied with the flattener) to the m48 one. If you want to buy this ring to increase the output light, DON'T DO IT.
If you only want to change the thread, it is worth buying a simple M42-M48 adapter.
This adapter cost me 42 euros due to postage and customs fees.
Thursday, 29 April 2021 | Jason
as discribed ... great product!!