WaterLightGallery.com 11:59pm, 31 October 2010
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 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?

Is this correct?

Many thanks!! Best, James
jvconnors 8 years ago
I don't see how those could be full stops; we all know 2.2 is less than a full stop from f/2. So I don't trust the strange numbers. I just try to put the aperture close to where the standard number would be. For instance:

f2.8: between 2.2 and 3.2

f 4: between 3.2 and 4.5

and so on. I have only used ultra-forgiving tri-x so far, but I would suppose accurate exposure with these lenses comes from experience. Hope I could be of some help.

-also James
jvconnors Posted 8 years ago. Edited by jvconnors (member) 8 years ago
er, I realize now you wrote this almost 4 months ago, and it looks like you've gotten the hang of the lens by now :)
WaterLightGallery.com 8 years ago
Thanks, James! Yes, I discovered through some research and trial and error that the old markings are 2/3 stop from each other compared to the modern system of full stops. So, what I do is take a reading with a modern lightmeter and count how many stops my exposure will be from f2 (the widest aperture on the Summar). Once I know this, I just adjust the Summar by this many stops, but 2/3 stops instead of full stops. This archaic system seems to get me within acceptable range! And, you are quite right about using a forgiving film: it doesn't matter if we're off a bit on negative film, but I don't think I'd be using these old lenses on slide film as the tolerance is just too tight, and I'd be nervous every time about nailing exposure, and that would kill the whole experience for me!
CarloBambino 7 years ago
I understand the desire to get the exposure correct with slide film, but don't let the fear stop you from using it. I'm reckless enough to just use "the force" with my Leica IIIa and Summar lens. I will sometimes disregard the numbers on the aperture ring and just go by feel. I just rotate the ring to the left third, middle third, or right third of the travel range of the aperture ring. Shallow depth, medium depth, and deep.

I adjust the shutter speed similarly, and fire. I get excellent results (even with slide film). Basically I take the calculations out of it and go by feel.

It sounds like you may need the exact numbers in your shooting and might disregard this post, but not shooting slide films just because you need that level of control, is "paralysis by analysis".
WaterLightGallery.com 7 years ago
Well said!

Now that I've created a relationship with my Summar, I simply move the aperture settings to what is "close enough" to what I need; that is, if I need 5.6, I just approximate where that would be on the ring, and set it there.

I haven't missed an exposure yet.

And, no longer think about this.
thomas.78 6 years ago

these apertures are based on the old german aperture system which is also based at square root steps like the international system, but uses 100 as the basis:

100, 72, 50, 36, 25, 18, 12.5, 9, 6.3, 4.5, 3.2, 2.2, 1.6, 1.1

it is just 1/3 step shiftet to the modern system.

so you either use e.g. 4.5 as "1/3rd step less light than 4" or set your light meter for ISO 40 instead of ISO 50 and use 4.5 when the light meter reads 4.0.

There is no problem to work with this old style aperture system - for me it is a bit of the fun to work with pre-war lenses...

aehlen1 4 years ago
I'll echo what you've already said but I just estimate the distance between the numbers as well i shoot mostly ilford hp5 and haven't had any problems. Its a fun lens and its even more fun shooting on any of the leica iii's. most of my friends make fun of my slow pace but its more visceral.
aehlen1 4 years ago
wow ok you guys were posting these before i got into photography guess I should look at the dates.
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