Aperture markings on Summar

[waterlightgallery]

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My Summar aperture reads: 2, 2.2, 3.2, 4.5, 6.3, 9, 12.5

 

I assume every Summar reads the same?

 

I am trying to coordinate these markings with my light meter which, of course, is marked in modern stops.

 

1) I assume each marking on the Summar is one-full stop from the next, therefore, halving the light as you close down?

 

2) since the markings don't match our modern system, I assume that I find the correct reading off the light meter for f2, and then simply count how many stops I need to go for my intended reading off the light meter, then correspond my Summar to that same number of stops from f2?

 

Is this correct?

 

 

Many thanks!! Best, James

[Michael Geschlecht]

Hello James,

 

Welcome to the Forum.

 

Actually no.

 

2.2 thru 12.5 are the old system used before the Second World War.

 

The numbers following 2 on your lens are actually each 1/3d of a stop smaller (therefore allowing a little less light) than 2 thru 11 on your modern meter dial.

 

2.2 thru 12.5 being the progression in one stop intervals w/ each other.

 

Best Regards,

 

Michael

[waterlightgallery]

Thank you, Michael!

 

Is there a way to correspond the Summar's aperture settings to modern settings, something simple like a conversion table or chart as an easy reference?

[lars_bergquist]

Just compensate by 1/3 of an f-stop. (As is the case in with many lenses, the largest stop does often fall out of the logarithmic progression).

 

With the abbreviated ISO value (e.g. ISO100, 200, 400 ...) there is no fixed value you can add. In this example, you would have to add 25 to ISO100, 50 to ISO200, and 100 to ISO400. But to the right of the slash there is a logarithmic value, e.g ISO160/23° or ISO 320/26°. Here, you just add 1 to the logarithmic value in both cases.

 

What you are seeing on your Summar is the old "continental" or "German" aperture scale. Some German companies, like Carl Zeiss, adopted the present "international" scale already before WW2. Leica did so fairly immediately after the war's end. Before that, manufacturers of exposure meters often marketed special models "for Leica", with the old scale.

 

The old man from the Age Nearly Before Exposure Meters

[giordano]

Wikipedia's F-number article includes a scale that shows how all the numbers fit together.

[earleygallery]

I just use the nearest approx stop i.e. if it was going to be f5.6 I'll set the Summar to between 4.5 and 6.3. The fact that there are no detents on the aperture ring make it very easy to do so.

 

As I use B&W or colour neg film there's plenty of latitude to allow for it.

[luigi bertolotti]

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I just use the nearest approx stop i.e. if it was going to be f5.6 I'll set the Summar to between 4.5 and 6.3. The fact that there are no detents on the aperture ring make it very easy to do so.

 

As I use B&W or colour neg film there's plenty of latitude to allow for it.

 

Yep... is the best way... I made like this for years with old lenses... even with my Leica IIIc, its "odd" times, an old Elmar and a modern meter with International scales only, it wasn't such a hard mind-gimnyck... 60/f8 wasn't so far from 40/f9 etc...