Pre-war Aperture settings?

[Trawlerman]

I have a 1939 Leica III w/ Summar 50/f2.0 and have a question.

The shutter speeds and the apperture settings differ from the modern standards. I don't have a problem with the shutter speeds as they are not that different from modern standards but i'm having a little trouble in getting my head around the apaerture settings.


My Summar has the following aperture settings - 2, 2.2, 3.2, 4.5, 6.3, 9 and 12.5

How do these relate to the modern standards? I guess f2 is the same as that is wide open but what about the rest? Is 12.5 the new f11 f16 or f22?


I'm a bit puzzled by these? I was hoping to use the Sunny-16 rule with this camera but as there is no 16 what do I do?



Many thanks......

[pvdhaar]

With the f2 excepted, these settings are about 1/3 of a stop closed down from the current values (f2, f2, f2.8, f4, etc..)

This means the f12.5 is 2/3 stops wider than f16. So you'd select a shutter speed 2/3 stops faster that suggested by sunny16 there.

[sebastel]

maybe knowing what aperture numbers actually mean might help?

aperture numbers are the quotient of focus length and effective aperture diameter.
this is true for the old sequence of aperture numbers as well as for the current norm.

also see: http://en.wikipedia.org/wiki/F-number

cheers
sebastian

[richiedcruz]

According to an old copy of Graphic Graflex Photography I have these numbers correspond to the Continental Apeture System.

The modern equivalents are f12.5=f11, f9=f8, f6.3=f5.6, f4.5=f4, f3.2=f2.8, f2.2=f2 and I suppose that would make f2 slightly faster than the modern equivalent of f2.

Hope that helps,
Richie

[sebastel]

sorry richie, you are wrong.

f/11 is different from f/12.5.

look at the actual effective aperture diameter for a 50mm lens:

f/11 = 50mm/11 = 4.5454.. mm
f/12.5 = 50mm/12.5 = 4 mm

see what i want to say? 4mm is just a bit smaller than 4.545mm

regards
sebastian

[richiedcruz]

sorry richie, you are wrong.

f/11 is different from f/12.5.

look at the actual effective aperture diameter for a 50mm lens:

f/11 = 50mm/11 = 4.5454.. mm
f/12.5 = 50mm/12.5 = 4 mm

see what i want to say? 4mm is just a bit smaller than 4.545mm

regards
sebastian

Just reporting what I found in an old book.

Richie

[john neal]

Trawlerman,

There is a lot in the discussion above, but what I find on my old Leica lenses is that the practical difference between, say, 1/200 at f 12.5 on a pre-war camera and 1/250 at f11 on a post-war one is not worth worrying about - particularly if you are using print film. I guess that slide film may be different, in that it requires more accuracy.

In the UK, I find that "sunny f11" (or in this case sunny f12.5) works better than sunny 16 anyway, due to the quality of light we enjoy(?) here.

[sebastel]

please don't take it personal :-)

the book recommended to use the apertures as equivalent ... they only differ by about 1/3 EV, which is within the variation of sensibility of old-time film anyway. so, this recommendation is as good as the sunny-16 rule.

that's the difference between "exact" theory and practical use.

cheers
sebastian

[richiedcruz]

Trawlerman,

There is a lot in the discussion above, but what I find on my old Leica lenses is that the practical difference between, say, 1/200 at f 12.5 on a pre-war camera and 1/250 at f11 on a post-war one is not worth worrying about - particularly if you are using print film. I guess that slide film may be different, in that it requires more accuracy.

In the UK, I find that "sunny f11" (or in this case sunny f12.5) works better than sunny 16 anyway, due to the quality of light we enjoy(?) here.
Hi John,

I have found that here in California f12.5 with my Summar at 1/1000 is close enough to f16 at 1/500. So I figured that the conversion table I found and listed above is close enough to work from. It certainly works for me.

Richie

[richiedcruz]

please don't take it personal :-)

the book recommended to use the apertures as equivalent ... they only differ by about 1/3 EV, which is within the variation of sensibility of old-time film anyway. so, this recommendation is as good as the sunny-16 rule.

that's the difference between "exact" theory and practical use.

cheers
sebastian
Hi Sebastian,

No offense taken. I have a Summar, like Trawlerman, and the conversion table I found is the easiest way for me to remember what the f stops are close to.

Richie

[payasam]

While the stops on one scale do not have exact equivalents on the other scale, as others have said the differences are within the latitude of most films. A practical difficulty with fast film in bright light is that 12.5 may be the smallest stop on the Continental scale.

[jkelly]

Using 400 ASA film on a bright sunny day is no problem with a Summar. In full sunshine, just set aperture at 12.5 and speed at 1/1000. Here's an example; it doesn't get much brighter than this.

http://farm2.static.flickr.com/1294/543417226_b1daf20a54.jpg

Washington Monument, Leica IIIa + Summar

[John Shriver]

You can easily eyeball where the modern apertures are between the old European ones. f/11 is just a nudge before f/12.5, one third of the way to f/9.

Also, my Luna-Pro has 1/3 stop tick marks.

But, realize that the higher shutter speeds have a 1/2 stop tolerance at best...

[rbiemer]

I've only got one lens with the early f stop scale, a 9cm Elmar. Its scale is: 4, 4.5, 6.3, 9, 12.5, 18, 25, and 36. I spent some time worrying about this but two things helped me: since I mainly shoot C-41 BW print film, I have quite a bit of exposure latitude, and I had an older meter that (while it was working) read in those stops. Worked well enough for me and now I know what to expect from the different stops and treat them like this for Sunny-16:
4~4, 6.3~5.6, 9~8, 12.5~11, 18~16, 25~22, and 36 I don't use. I know that they are NOT equal but these are approximately close enough for me.
One of the reasons I regret selling my Bessa R is that since the Elmar(and most of my FSU lenses) is not click stopped, I could shoot "shutter priority" and let the f stop fall where it would with out sweating too much what the actual number was.
Rob

[VictorM.]

What you need is an old Weston Meter-and a pair of reading glasses! Each increment of the aperture and speed dials is ⅓ of a stop.

[Trawlerman]

Thanks for the replies fellas.
I feel much more confident on going out and shooting with the III and Summar now I understand what i'm dealing with.

Now if only the typically poor british weather would pass so that I can get out.