Can someone please refresh my memory? What does the engraved number adjacent to the infinity mark on M lens barrels mean? Thank you. Regards, Richard Fulco

-- RICHARD FULCO (CALCINC@MN.RR.COM), July 12, 2001

Answers

Richard,

This came up a couple of weeks ago. You can access the thread at the link below. Basically, it is Leica being totally honest in that the actual focal length may deviate from the standard, 50mm, 90mm, etc... The small numbers are laid over the focal length to give the real length. A small 22 would indicate that the 50mm lens is actually 52.2mm.

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

-- Al Smith (smith58@msn.com), July 12, 2001.

I think it's nitpickier than that. I believe that actually a 50 with 22 engraved on it has a focal length of 50.22mm. My 80mm Summilux-R has a 95 engraved on it; no way that pup is an 89.5mm f/1.4 lens. But I would believe 80.95mm. My 75 Summilux-M is engraved 50. So, 75.5mm? Most likely.

-- Robert Schneider (rolopix@yahoo.com), July 12, 2001.

Robert,

This comes right out of several books, including the latest lens book from Erwin Puts. Your 80mm lens is 79.5. The level of deviation is said to be up to 5%, so you go down for your number. There is a detailed table in some of the books, and just the formula in others, but 52.2 is common, as well as telephotos that are a bit less than marked, in every book I have from the 1960's up to Erwin's brand new book.

-- Al Smith (smith58@msn.com), July 12, 2001.

Makes sense to me. Thanks for the info.

-- Robert Schneider (rolopix@yahoo.com), July 14, 2001.

My late 50 Summicron doesn't have a mark. Does that mean that it's actually a 50.000 mm focal length?

-- Bill Mitchell (bmitch@home.com), July 14, 2001.

I have a 50/2 latest version with a 22 mark, it seems that 52.2 are quite common, does super wides like 21's have the same caracteristic?; it can make a diference at that focal length.

-- r watson (al1231234@hotmail.com), July 14, 2001.

Bill,

I don't know about your particular lens. Both Erwin Puts' and Andrew Matheson's books list a marked double zero (00) as meaning 50.0mm. No mark???? Don't you have one of those limited edition LTM Summicrons? Maybe they don't conform.

Roberto,

The same books say that only lens at or over 50mm have these marks.

-- Al Smith (smith58@msn.com), July 14, 2001.

No, it's one of those next to the last Summicrons (with the tab and that damn self-removable lens hood).

-- Bill Mitchell (bmitch@home.com), July 14, 2001.

it is kind of logic, imagine a 21 that is actualy a 22.2, it begins to make a diference, for sure there are diferences on those focal lengths but not so evident.

-- r watson (al1231234@hotmail.com), July 14, 2001.