I use a push on lens hood, designed for the 35 Asph. Summicron, on my 50mm Summicron (latest, but non built-in lens hood version) as well-though I have to be careful to keep it aligned and not turn around. <p> I do so because of the convenience of a push on lens-cap, which saves me the trouble of taking off the hood everytime I have to close up. <p> Questions - What is the part number of the lens cap?
The 35/2 asph lens hood is part no. 12 526 and the lens hood cover is part no. 14 043. The original front lens cap for the 50/2 lens, without any hood, is 14 268. The original round vented 50/2 lens hood came in; metal, part no. 12 585 or, plastic, part no. 12 538, and reversed over the lens for storage. The reversed hood took a slip-on cap part no. 14 033.