ZM lens focusing tab

[Phil_F_NM]

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!
Phil Forrest

[MCTuomey]

brilliant, phil! thanks for sharing.

[robbeiflex]

Looks like a great idea. I would imagine that there are as many barrel diameters as there are filter diameters. Meaning that two sizes, one each for lenses that take the 43mm and 46mm filters, would cover most of your target market.

Cheers,
Rob

[Phil_F_NM]

Originally Posted by robbeiflex

Looks like a great idea. I would imagine that there are as many barrel diameters as there are filter diameters. Meaning that two sizes, one each for lenses that take the 43mm and 46mm filters, would cover most of your target market.

Thanks for the technical info. I figured that Zeiss had only one or two common barrel sizes but only own one ZM lens. Maybe I'll do an imprint before this one sells and fab up a few of the plexiglass ones for RFF members.

Phil Forrest

[bennyng]

Phil,

That is really a neat solution to the tiny tab, which I've always felt was a weaker part of the total barrel design ergonomics.

Cheers,

[back alley]

i wonder if this would work on the older cv lenses with the screw in focusing lever?

[Phil_F_NM]

Sure it would, you just need to make sure the contour of the focus tab is close to the curvature of the lens. If I'm not mistaken, the screw-in tabs were on lenses where the focus ring was a conical section. you could even go so far as to make one out of wood even, drill a hole through it and affix it to the lens with a countersunk machine screw of the same thread pitch.
I thought about doing this with my 28mm f/1.9 but then sold it before the idea came to fruition.

Phil Forrest

[back alley]

can't find them at heavystar...

[Phil_F_NM]

I guess one could always borrow a "friend's" pre-ASPH 35 'Cron and "accidentally knock it off". I'm just kidding!
I guess I actually may have been the buyer of the last available one.
I'm going to ask if they plan on ever getting any more in and will let RFF know.

Phil Forrest

[Chriscrawfordphoto]

I'd definately be interested in buying one if you start making them!

[fbf]

Item id: 360331969572

[Phil_F_NM]

There it is folks! Get them while they are hot!

Phil Forrest

[Chriscrawfordphoto]

Originally Posted by fbf

Item id: 360331969572

Gracias! Tabs bought

[akk2]

I hope someone will CNC some with alloy

[back alley]

great, just ordered one.

[myM8yogi]

I just ordered a couple too. Funny, I was looking at this exact product a couple of months ago, thinking I could add one to my J3. Never did it though - I guess I needed someone else to take the plunge and show me how it was done!
I plan to follow your suggestions for my ZM21/2.8. In my opinion the useless focus bumb is a complete waste of time on the ZM.
I hope to then use the second focus tab on my J3, but I modified the sonnar for close-focus and it now has one hell of a long focus throw, so even if the Leica focus tab is the same arc/diammeter and can be fitted to the lens, I will have a tricky decision to make in terms of it's precise location on the focus ring. I will try to locate it so that it will be most comfortable in the near focus range, which is the range in which I will need fastest focus.
Thanks for posting this Phil!

[sepiareverb]

My tab arrived in the mail today. Will be a nice project one stormy night.

[sahe69]

Originally Posted by fbf

Item id: 360331969572

Thanks for the id, got one for my 21/4.5.

[myM8yogi]

Tabs arrived in the post. The second tab looks like a perfect fit for my Jupiter 3. I'm not really sure how I'm going to attach it because I have no idea where I can find that 3M double-sided outdoor tape in Denmark. Do any Danes have any suggestions?

[back alley]

mine arrived but it does not fit on any of the cv lenses i have.
i would have to shave the sides...

[ZeissFan]

That was a very novel and excellent approach, although I am not a fan of tabbed lenses.

[sepiareverb]

I'll be shaving the sides for my 50mm Elmar-M...

[semilog]

I hollowed out the tab portion of one of the Heavystar ones, and it fits perfectly on my 35/2.8 Biogon-C... and matches perfectly the feel of my 50/2 Summicron-M. Joy.

[back alley]

the small cv lenses have the focussing lever so the area that they are in can be very narrow.
i could shave the sides of the tab but it would likely look like crap by the time that i am done with it. (not very handy)

[sepiareverb]

Originally Posted by back alley

but it would likely look like crap by the time that i am done with it.

I expect my Elmar may fall into this category too, I intend to use a removable adhesive.