You have got to be kidding me!

[fer_fdi]

the correct hood for Summicron-C is 12518, thread is series 5.5 as 12517 for Elmar-C.
Hood for Rokkor 40/2 must be 40.5mm, not series 5.5!

 

[Ronald M]

Put a 39 mm in backwards.

 

[Graybeard]

Adapter

Adapter

There is a Chinese eBay vendor selling a 5.5 to 39mm adaptor for about USD12 if memory serves.

I have a couple - they are well made and fit just fine.

 

[hap]

I like the adapter solution....you can buy from DAG as well....but three times the price.