Old shutter speeds and exposure.

I probably already know the answer to this question, but I wanted to ask anyway, in case I'm wrong.

I've got a zenit c from 1957 and it's speeds go: 1/25, 1/50, 1/100, 1/250, 1/500.

I was wondering if I would need to use very slightly smaller apertures when using any of the 3 slower speeds to compensate for the slightly longer speeds than my lightmeter can work with?

Probably not for the 1/25 instead of 1/30, maybe not for the 1/50 instead of 1/60, but what about the 1/100 instead of 1/125? How much of a 'stop' is the difference between those 2 speeds?

Any help would be much appreciated.

Hello Sean

I think it will not make big differences for all the speeds. The variation will be much less than 1 EV (without calculating but only estimating: around 0.2 EV) and this will be compensated by modern labs in developpment and print without any difficulty. Even variations of more than 1 EV will be compensated there depending the film used. I remember the Ilford XP2 had something like 4 EV, but I used it many years ago. More than a decade ago I switched to digital.

Hope this helps.

Best wishes - Guido

unless you shoot diapositives, it doesn't matter a lot. one speed step is one aperture value. the old speed values are 20-25% longer, so it's only 1/5 or 1/4 of an aperture value. modern film can cope with that.

but I bet that the speeds of your camera are slower than the given values. so you have 2 choices: get yourself a shutter tester or shoot a roll for test. there is a roumanian guy on ebay who sells quite sophisticated testers for less than 100€. I have one of these (and some older ones) and I'm fond of it.

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Thanks for the replies and the information, guido and xya.

Tempest in a teapot... There is no perfect exposure which means that -0.5/+0.5 EV gets unnoticed. More, I would say that in general -1/+2 EV is fully acceptable (for BW negative, don't shoot color or inversible). No reason to stress when shooting at 1/25 instead of the standard 1/30 (assuming that your shutter really yields 1/25...).

Gelios, that's what I was thinking too, but I wanted to check, just in case.

The situation is a little trickier when on top of that you use a lens with the 'old" aperture scale... But here again, films are generally forgiving enough so a slight underexposure or overexposure is without consequence.

I imagine that would be the case, Gelios. I've no idea when the 'old' aperture scale fell out of use, nor indeed, if there were more than one 'old' scale in use at the same time. I suppose that could be possible with cameras from the 19th century..

Not so old. My prewar Fed lens has the old aperture serie.

Rellay? What is the range of apertures on that lens?

f/3.5 to f/18.

All prewar FED lenses have old apertures. Than after WW 2 old apertures for some time were used too.
The same with Leica lenses.

as far as I know the new shutter speeds and apertures were introduced to come nearer to an easier handling.
one aperture stop more is half the light. one speed shorter is half the light as well. no correction factor needed.
I found this on the web:


..new...........old.......correction factor
..1,4...........1,6.........1,4 + 1/3
..2,0...........2,2.........2,0 + 1/3
..2,8...........3,2.........2,8 + 1/3
..4,0...........4,5.........4,0 + 1/3
..5,6...........6,3.........5,6 + 1/3
..8,0...........9,0.........8,0 + 1/3
..11............12,5........11 + 1/3
..16............18..........16 + 1/3
..22............25..........22 + 1/3
..32............36..........32 + 1/3


1/500.........1/400.........1/500 + 1/3
1/250.........1/200.........1/250 + 1/3
1/125.........1/100.........1/125 + 1/3
1/60...........1/50...........1/60 + 1/3
1/30...........1/25...........1/30 + 1/3
1/15...........1/10...........1/15 + 2/3
1/8.............1/5............1/8 + 2/3
1/2.............1/2............1/2
1................1...............1

sorryfor the dots, but this site doesn't allow multiple [space].

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@Gelios, thanks for the info. Looking at the tables that xya posted, your lens with f3.5 seems a little odd as xya lists f3.2, but yours has f18 and so does xya's list. Could your lens have a hybrid aperture range? I dubt it, but it would be fun to find out that it does have.

@Alfa, thanks for the info.

@xya, thanks for the info and the effort you put into writing the tables out. Don't worry about the dots, I had to do the same thing with a post I did on a different forum.

I am a little confused though (It doesn't ake much to confuse me). I fully understand the 'half as much/twice as much' witht he next setting up or down, but I'm not sure about the '1/3 and 2/3 correction factor' bit. Is that something photographers had to do in those days, or something modern photographers have to these days when using cameras with the old settings?

Nothing odd with my lens. All FED 50mm have f/3.5 as max aperture. Between us, f3.2 or f/3.5 does not make ANY difference as many other factors can have a much greater influence (shutter accuracy, development, etc...).

Seany65, problem of how many light goes through an old lens is more complicated than you expect.
Numbers given on lens scale is not equal to "real" numbers which are not visible. "Real" ones depends on many other factors e.g. how many groups you have in a lens and thickness of groups.
Nowadays the best to use is Aperture Priority.

Really, this discussion is purely theorical.
On a 24 exposure film, I always have 22 or 23 photos which are correctly exposed. I don't talk about my qualities as a shooter!

Actual films are much more forgiving than the Kodachrome 25 of my childhood. They even allow not to use any lightmeter when one correctly knows the material. Right to say I always use the same body (Fed S) with the same lenses.

Jacques.

Yes, todays films forgive a lot so we don't need to care about old/new scale.
There was rather something like consideration or philosophising. [;)]

<blockquote id="quote"><font size="1" face="MS Trebuchet, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jacques M.</i>
<br />
Actual films are much more forgiving than the Kodachrome 25 of my childhood. They even allow not to use any lightmeter when one correctly knows the material.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

I don't trust my eyes so it is lightmeter all the time unless I am in a Sunny16 situation.

I understand that films have a lot of latitude these days, I was just wondering what the correction factor was for, and what it was 1/3 or 2/3 of.

<blockquote id="quote"><font size="1" face="MS Trebuchet, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by seany65</i>
<br />I understand that films have a lot of latitude these days, I was just wondering what the correction factor was for, and what it was 1/3 or 2/3 of.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
it's 1/3 or 2/3 of a diaphragm. so if your meter reading says 1/60 (and let's say F8) and your camera has 1/50, you have to close the diaphragm to F8 + 1/3 toward F11 to be exact. but as everybody says: modern film doesn't care about 1/3 of a diaphragm.

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@xya, Ah, I see. Thanks for the info.