50mm f2 Summicron Rigid " Secret number"

[Dominique Pierre-Nina]

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Hi Guys hope every one is well and in good health.

I know that the "Secret  Number "on the barrel relates to the Actual focal length mine says 19 so the actual focal length is 51.9.

But I have two 50mm Summicron Rigid and one of then does not have the " Secret Number" 

My question is why some of them have and some don't have the number, does any one know?

Thanks you,

Dominique.

Dominique Pierre-Nina
Film Photographer and Dark Room Printing

Phone: +61410471375

Website: www.pierreninaphotography.com
Email: pierreninaphotography@gmail.com
IG: @pierreninaphotography (www.instagram.com/pierreninaphotography)

 

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[a.noctilux]

Interesting.

 

Not "secret number", just two things in "not so secret code" : as you wrote real focal length measured and inscribed in 0.1mm to match the focus unit (mine also "19" ) made

somewhere ( by another person ) else in the factory, with a signature on the optical unit.

Just had a look on mine Rigid, optical unit unscrewed from the focus unit, engravings at three places: on a ring "19N", around the optical block "60", at opposite "D".

...

SOMNI variations :

Another mystery is on my SOMNI (DR Summicron) optical block, which we know that only real "51.9" focal length be used on every DR,

on the ring ( same as where the "19N" found on former Rigid), I see engraving "B" and 2cm at right "21/19" very strange.

Nothing around the optical block in this particular DR.

All of my SOMNI optical blocks have engravings, one has "42"  "51,9N", another "44" "51,9N" (N engraving kind of gothic style)

[Michael Geschlecht]

Hello Dominique,

Welcome to the Forum.

Engraving the actual length of the lens in 1/10ths of a millimeter, at a right angle to the other numbers, outside on the focusing barrel, began around 1960. If your lens without the engraving is from that earlier time period that may be the reason that the number is not there..

best Regards,

Michael

Edited May 16, 2020 by Michael Geschlecht