What is the M Lens Focus tab?

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Greetings!

I was fully into the always state-of-the-optical-art Leitz rangefinder photography from 1954-1988 (IIf, M2-3-4), when the need to cope with school sports forced me into SLR (Nikon) which was ideal and very successful for the job and for which I have great affection and respect. But I disposed of all my Leica gear. What a fool!

The reason for this self-indulgent autobiography is to enable me to establish some credentials for chipping in to this forum, which I have followed silently for some time and find refreshingly civilised, useful, and mature.

I have several questions on which I should welcome advice later, but for starters I would like to learn why so many correpondents stress the value of the focus tab on the M lenses which have it e.g. the penultimate F2 50mm Summicron. Having retired, I have now returned like an expatriate to his native land to the Leica rangefinder and its consistently unbeatable lenses, and its requirement to converse with the user.

I had never heard tell of the focus tab before. It is possible that I may have enjoyed one on various 35,50,90,135 lenses without realising my luck. It seems that I shall not have one on the new F2 50mm Summicron which I have ordered but not yet received to go on my M6(non-TTL). Presumably if I had it on my earlier lenses and do not have it on the new F2 Summicron I will be unhappy and frustrated and in need of counselling. But what is it? If it is some sort of prominence which lets you know by feel exactly where the focus ring has moved to, could I replicate that by sticking a bit of velcro or similar on the focussing ring? But it may be more subtle than that.

This is not meant to be a facetious question.

And thank you for being such a friendly lot of people. I am most impressed.

James Harper

-- Dr James Harper (drjh@btinternet.com), June 20, 2001

Answers

No big secret here, the tab is simply an extrusion on the focus ring that you can quickly rack back and forth with your finger and allows for faster focusing once mastered. The last series 50's that had the tab were also more compact than the current lens-another nbenefit tocompact equipment lovers. That said, I have actually noticed that WHEN I have time to focus critically, I have a better success rate at wider apertures with the current style lens without the tab. I can fine tune the focus better using the knurled ring than I could with the tab-at least with a 50. So what is more important, speed or accuracy?

-- Andrew Schank (aschank@flash.net), June 20, 2001.

The tabs have only been found on lenses up to 50mm. The 75, 90 and 135 lenses have never been tabbed. They do make focussing faster, but I think the main reason they're put on is that the focus rings on these lenses are inherently too narrow to grip with your fingers.

there's always an underground movement afoot to create add-on tabs for lenses that don't have them. This ususally involves the use of plastic cable ties (especially for the 90/2.8 Elmarit or the current 50/2.0). Only the truly demented drill and tap the focus ring so they can crew on something more permanent.

The only lens on which this is an issue is the 50/2.0, where optically identical models exist with and without the tab. On all other lenses, you either get one or you don't.

I hear from my scientist friends that the human body contains only a certain number of "worries", and when they're all used up, you die. It's kind of like the Hayflick limit, for any biologists in the crowd. The moral of the story is, spend your worries wisely...

-- Paul Chefurka (paul_chefurka@pmc-sierra.com), June 20, 2001.


Jim: It is my understanding that the focussing tab on 35 and 50 lenses enables the photographer to manually focus the lens without looking thru the view finder. This of course takes a bit of practice which can be obtained by first focussing on a subject, say 10ft away using the rangefinder within the view finder and noting with your finger the position of the tab. Then move the tab and try to return it to the same position as before. With repeated practice at various subject distances you will develop a kinesthetic sense and you will move the tab with more and more accuracy. If you get good at this all you will have to do is lift the camera to your eye and compose the shot without having to spend time focussing. This is a great aid in street photography, and takes advantage of the Leica's quickness etc.I believe that the tab is not available on longer focal length lenses because the shallow depth of field on these lenses.

-- Lewis Lauring (eyeye@tampabay.rr.com), June 20, 2001.

Poor Dr. Hayflick! his limit didn't even outlast his academic career and now Geron Corp. has made it possible for human cells, like human worries, to replicate themselves, not a reasonable 50-80 times, but endlessly. Immortality? maybe. Sounds like a mighty close cousin of cancer to me. But a member of this estimable group has given us all a focusing tab for ten cents, so that's one worry gone:

http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=005HY9... .....................................................(

-- david kelly (dmkedit@aol.com), June 20, 2001.


I understand the need for the tab on the lenses whose focus rings are too narrow to grip, but I am happy to have 2 tab-less 50's (the 11817 of early-70's and the current model)and also my 3E is tab-less. The camera hold and focus motion are more similar to other cameras I own so the transition is instinctive.

-- Jay (infinitydt@aol.com), June 20, 2001.


As far as I'm concerned the focus tabs are the most unreliable part of the Leica M system. The problem is that on the older M lenses before the current ASPH series (where the tabs have been "beefed up") the cheap and nasty plastic tabs are prone to crack up and fall off.Not good for a pro spec camera. Presently my 21 Elmarit, 28 Elmarit and 35 Summicron tabs are all cracked and about to break off.This has happened twice before to these lenses and I'm going to fit cable ties and dispense with the Leica repair bill to yet again sort this out. I do not abuse my gear but do use it a lot. I had no problems with the well engineered 35 F1.4 that I used to own with a proper metal tab that was virtually bomb proof.I'd be interested to know if anybody else has had this problem.

-- Paul Macnamara (paul@pmacnamara.freeserve.co.uk), June 20, 2001.

Dr.Jim; So still you havenīt put your hands on your new summicron; I had the oportunity to use a tab one and I own a latest without it, both are great I admit, and hadnīt thougth before but as said by Andrew tab focusingīs faster but barrelīs more acurrated; on the other hand it can be mastered so you prefocus with your focusing finger; the problem for here is that having diferent tabbed lenses, 21,28 and 35, it is very confused to master them all; even my three 35īs tab diferently; so to realy master it I would have to use only one; or become supertabmasterman.Being honest I feel comfortable to have a 50 lens without tab, at least something diferent to focus from. What Iīm sure is that with or without tab you will enjoy your new lens a lot, and thatīs my wish.

-- r watson (AL1231234@HOTMAIL.COM), June 20, 2001.

I've owned and used a tabbed 50 for 10 years. When the tab-less 50 came out I flirted with the idea, encouraged also by the retractable lens hood. The curiosity passed, and I moved on to other things. But, I do find close-focussing with the tab to be difficult. Vertical framing is also difficult. I'd better stop thinking about this. The bottom line is that you get used to these things. And, when you're doing your job right, the pictures are great.

-- Jim Shields (jim.shields@tasis.ch), June 20, 2001.

I’ll toss this out again, even though I am the only one that seems to think this is a good idea: Leica should knurl the focusing ring on all lenses regardless of the size of the focus ring and then supply all lenses with a tab that can be added or removed by the consumer. A single, small allen head screw would hold the tab on the ring. The tab would have small locator nubs that fit into very small, shallow indentations in the focus ring. The nubs would also keep the tab from twisting.

-- Bob (robljones@home.com), June 20, 2001.

Bob: Your solution is much too simple and elegant to even be considered ;)

-- Tim (tjkamke@excelimaging.com), June 20, 2001.


I'm surprised none of the Barnackmen pointed out that the DEFAULT for Leica is tabbed lenses (going back through the Elmars and Summars to the original Achromat). All the lenses 50mm and shorter were so small that there wasn't even room for a focusing scale on the lens barrel, let alone a focusing ring - the scale had to be on the screw-mount base and the lenses had a infinity-locking "ziggurat" knob to swing the focus with.

-- Andy Piper (apidens@denver.infi.net), June 20, 2001.

Here's another vote for Bob's simple solution. While I understand the reasoning behind the focus tab (as explained by Mr. Lauring, for example), I think the 1 on the current 35/2 Summicron ASPH is too big. I also agree w/Mssrs. Schank & Watson that focusing w/a standard ring is significantly more precise. As a Leica newbie who's accustomed to the Zeiss Ikon Contax RFs, the focus throw on Leica wide-angle feels way too short to me, @ least right now, It's indeed faster for street photography, per Leica's design philosophy, but I think I could do just as well w/a bigger, knurled focus ring (like on the Nikon RF 35/1.8).

-- Christopher Chen (furcafe@cris.com), June 21, 2001.

I wish they hadn't put a convex rounded shape on the tabbed 50mm. My 35's and my 28 all have a concave shape, which feels more right. I often use the non-tabbed 1969-79 Summicron instead, because the tab on the later one feels wrong. I wonder if I should grind it into the more traditional shape? It seems like it might be plastic, rather than metal. If so, the color should go all the way through. If it's metal, I would have bright aluminum showing through the ground area. Does anyone know?

-- Bob Fleischman (RFXMAIL@prodigy.net), June 21, 2001.

Many thanks for the interesting and helpful replies to my enquiry. Best wishes.

-- James Harper (drjh@btinternet.com), June 22, 2001.

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