So there's been a LOT of interest in the focusing tab I have on a lens for sale. More interest in the tab than the lens, in fact so I figured I'd start a thread here on how it was done.
I got the tab from Heavystar on ebay. The ad said it was a 35mm Summicron focus tab. When I first was looking for it, he had 14 of them. Supposedly i bought the "last" one but I'm not sure if this is just marketing.
I got the tab and it had two plastic prongs which fit into the focus barrel of the Summicron, I guess. I cut those prongs off then set the tab flush against the lens to see how much of the middle I'd have to remove to accommodate covering the Zeiss focusing bump.
Then I used a round file and carefully removed enough plastic to accommodate the bump.
After that I got a strip of 3M outdoor double sided tape (the kind used to put address placards on house exteriors) and stuck it to the plastic tab.
I trimmed off the excess before placing the new tab on the lens.
It has been great using this to focus the ZM.
If you can't find the one I have on this lens, you can easily make on of your own using 3/16"-1/4" plexiglass.
With the plexiglass, you have a lot more control over the shape and size of the new focus tab but the process is similar. You just need a dremel tool or something similar in order to sculpt the plexiglass tab.
I made a nice one for a Canon 35mm f/2 which worked fabulously.
This leads me to ask the question "are all or most ZM lens focusing barrels the same diameter?" 'Cause if they are, I can start taking orders on custom plexiglass focus tabs...
Have fun folks!