"scientific" vs "geometric" shutter speed designations

David Lyga · Aug 31, 2020

I am old (REALLY OLD) enough to have witnessed cameras whose shutter speed designations were routinely stated non-geometrically. What I never could understand was WHY it was somehow 'better' to state shutter speeds in that way, since transferring data, via EV values, would then be very difficult. In other words, being able to fluidly change shutter speeds and aperture values while still maintaining the same overall exposure amount would then be hard to do with any real accuracy.

Also, what I had not known was that those 'skewed' shutter speed designations had a special, uplifting name. This intellectual generosity confused me even more. Ken Rockwell (kenrockwell.com) makes the following point in his Buyer's Guide to the Leica M3 with this statement:

"The earliest M3s had click-stops at the scientific speeds of 1, 2, 5, 10, 25, 50 and 100, while newer models use the geometric speeds of 1, 2, 4, 8, 15, 30, 60 and 125 (with a red bolt at 1/50)."

This conundrum also applies to aperture values which were also stated (may I presume?) "scientifically', like f4.5, f6.3, f9, etc.

What is so 'scientific' about stating shutter speeds in non-geometrical terms? I fall to see the value here, although other things in photography have also been done 'wrong', but persisted due to some factors which were maybe a bit hidden from view, such as Hollywood's transition to safety film long after it was developed for use because the nitrate film proved to be physically stronger and hold up better with continued projection. - David Lyga

DWThomas · Aug 31, 2020

Enh -- I suspect those old mechanical shutter speeds are +/- 10 to 20 % to begin with, so one could assume either series is geometric and probably not be able to tell from the photographic results. That's my theory. My recently exercised Argus C-3 has 10, 25, 50, 100, 300 but earlier revs had more (7?) speeds that made even less sense in their arrangement.

ic-racer · Aug 31, 2020

Not sure about that, I'm still trying to find out why they went from Spade Mashie, Mashie-Niblick and Pitching Niblick to the geometric 6 Iron, 7 Iron and 8 Iron...

David Lyga · Aug 31, 2020

DWThomas said:
Enh -- I suspect those old mechanical shutter speeds are +/- 10 to 20 % to begin with, so one could assume either series is geometric and probably not be able to tell from the photographic results. That's my theory. My recently exercised Argus C-3 has 10, 25, 50, 100, 300 but earlier revs had more (7?) speeds that made even less sense in their arrangement.

Yes, stated speeds ACTUALLY fluctuate, but the Argus progression which you have presented does not ultimately end its progression with a doubling (or halving) of the preceding. In other words, if you wish to present the 1/10th as 1/8th, then the next should be 1/15th, then 1/30th, then 1/60th, then 1/125th ...1/300 is a long way from 1/125.

In other words, within your skewed arrangement that Argus adopted, we find that, suddenly, there is a jump to the fast speed of 1/300! This makes knowing how to change shutter speeds and aperture values in order to obtain the same overall exposure, VERY difficult. I don't know why this craziness was adopted in the first place.

In other words, even though shutter speeds, especially with clockwork mechanisms, are usually even considerably 'off', they still have to have some basis in making theoretical sense and practicality. The 'goal' should have been for manufacturers to adhere, in both shutter and aperture, to a doubling (or halving). Why does this prerequisite make so much logical sense to me and not to the original manufacturers? Was there ANY advantage with being so crazy? - David Lyga

DWThomas · Aug 31, 2020

All of the speeds for the Argus, except for the slowest which has a bunch of gears whirring, are set by a follower on a cam, continuous, not stepped. It strikes me that they produced a mechanism and then picked speeds to allow the markers to be spaced relatively evenly and pronounced it "good!" Hell, back in the day some cameras had a choice of two 'I' and 'B' !!!

David Lyga · Aug 31, 2020

DWThomas said:
All of the speeds for the Argus, except for the slowest which has a bunch of gears whirring, are set by a follower on a cam, continuous, not stepped. It strikes me that they produced a mechanism and then picked speeds to allow the markers to be spaced relatively evenly and pronounced it "good!" Hell, back in the day some cameras had a choice of two 'I' and 'B' !!!

Yes, but the whole purpose here is to dissect just WHY manufacturers chose to make such odd arrangements. This question is a bit similar as to why SLR lens manufacturers had a '50', then the cheapest tele was '135', almost three times as long. Their in between choices were always far more expensive.

There are many things within this photographic genre which, with the advantage of hindsight, seem ill-planned. - David Lyga

BrianShaw · Aug 31, 2020

I’ve never heard that terminology distinction of “scientific “ Vs “geometric “. Is that something Rockwell concocted or is it common lingo that is just new to me? I use shutters with both (different shutters, of course) and always thought of it as older and newer sped progressions. But beyond that I never really worried about the difference or really wondered.

David Lyga · Aug 31, 2020

BrianShaw said:
I’ve never heard that terminology distinction of “scientific “ Vs “geometric “. Is that something Rockwell concocted or is it common lingo that is just new to me? I use shutters with both (different shutters, of course) and always thought of it as older and newer sped progressions. But beyond that I never really worried about the difference or really wondered.

Why Rockwell said that I do not know, but it is currently within his Buyer's Guide for the M3. I did not dispute his 'scientific' modifier because he is very knowledgeable about these things. But now, I wonder why. - David Lyga

Vaughn · Aug 31, 2020

IMO, knowledgeable or not, he's tossing words around. Nothing scientific using numbers divisable by five.

BrianShaw · Aug 31, 2020

This offers a potential explanation: Standardation.

https://en.wikipedia.org/wiki/Shutter_speed

DWThomas · Aug 31, 2020

BrianShaw said:
But beyond that I never really worried about the difference or really wondered.

That's pretty much where I have been -- but I think the forced isolation for Covid-19 safety is resulting in a lot of picking of nits!

David Lyga · Aug 31, 2020

DWThomas said:
That's pretty much where I have been -- but I think the forced isolation for Covid-19 safety is resulting in a lot of picking of nits!

But I don't have any nits to pick!

But, I will be the first to admit that this discussion was a bit of a strain, essentially unnecessary, but, at the same time, curious, because it really makes little sense to introduce a continuum like the 'scientific' one.. - David Lyga

Chan Tran · Aug 31, 2020

Modern cameras shutter speed are labelled 1,2,4,8,15,30,60,125,250,500,1000,2000,4000,8000 while they are actually calibrated for 1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192. I think with the old cameras they can label them either way as the speeds are not that accurate. The 1/50 and either be 1/50 or 1/60.

Alan Edward Klein · Aug 31, 2020

Are we confusing fractional designations such as 1/8 or 1/125 that old standard cameras used with continuous decimal fractions that are express in some cameras with in between points such as f/8.3 or similar shutter deisginations?

AgX · Aug 31, 2020

there are several speed ranges:

the old one:
1 - 2 - 5 -10 - 25 - 50 - 100 -200 - 400

the current one
1 – 2 – 4 – 8 – 15 – 30 – 60 – 125 – 250 – 500 – 1000 – 2000 – 4000

the correct one
1 – 2 – 4 – 8 – 16 – 32 – 64 – 128 – 256 – 512 – 1024 – 2048 – 4096

The issue with the common, actually applied versions (late and current) is just that they are intended to avoid crooked mumbers. That is all. No idea what "scientific" has to to with that.

I rather wonder that those numbers are reason for discussion, but not the terminlogy "shutter speed", when actually times or more correct time-periods are given (by means of nominator of a fraction).

awty · Aug 31, 2020

Im confused why most modernish meters work in 1/3 stops and my enlarger timer works in 1/4 stops, why cant they just be that some.

More importantly, why do f stop numbers have to get bigger when the hole gets smaller?

AgX · Aug 31, 2020

awty, in German and other languages we do not have it about speeds but times. Thus large numbers, short times, large speeds.

Where you have it about shutter-priority AE, we have it about aperture AE. Same thing...

David Lyga · Aug 31, 2020

AgX said:
awty, in German and other languages we do not have it about speeds but times. Thus large numbers, short times, large speeds.

Where you have it about shutter-priority AE, we have it about aperture AE. Same thing...

Yes, aperture AE is identical to shutter priority AE. In fact the German method leaves out what should be inferred. Likewise, I do not like 'exposure' meter, but I like 'light' meter. The latter is more rightly specific as to what it is, just like aperture AE properly leaves out the dross.

As AgX stated, there really are THREE different shutter ranges: the old one, the current one, and the correct one. However, there is no essential difference between the current and correct. The 'current' one IS the 'correct' one ... unimportant numerical 'remainders' are simply left out of the current range. However, the 'old' one is 'wrong' in that it ends up with 1/400 when it 'should' end up with 1/250 (or, precisely, 1/256). This is nor a simple 'rounding' error, but a substantive one, which makes transferring EVs very difficult. There is next to NO difference between 1/250 and 1/256. However, using the precise range as an anchor, there IS a troubling difference between 1/256 and 1/400.

And, can't we all say that the Germans are MORE correct with calling shutter 'speeds', instead and more intuitively, shutter 'times'? - David Lyga

Dan Fromm · Aug 31, 2020

David, if you can't think simultaneously in shutter speeds and apertures, get a broken Weston Master IV exposure meter. The meter's calculator dial will help you solve your problems. Broken ones cost less than ones that work but their calculator dials work as well.

David Lyga · Aug 31, 2020

Dan Fromm said:
David, if you can't think simultaneously in shutter speeds and apertures, get a broken Weston Master IV exposure meter. The meter's calculator dial will help you solve your problems. Broken ones cost less than ones that work but their calculator dials work as well.

NO, I KNOW, instantly, how to convert both shutter speeds (times?) and aperture values into 'instant' EV values. in fact, I rate films not on ISO or EI, but, rather, on sunlight EVs. For example, for me, Tri-X is not a '400' (or '250') film but, rather, a 17 EV film. I find doing this to be much easier to deal with exposures and, even more importantly, make immediate changes to both shutter and aperture. That is how I think. It works well for me.

In other words, Dan, because I CAN think simultaneously with both, I do this to give myself a clearer mind. - David Lyga

BrianShaw · Aug 31, 2020

After all these years we are finally finding out how wrong everything we’ve ever known about photography has been. Incredible!

David Lyga · Aug 31, 2020

BrianShaw said:
After all these years we are finally finding out how wrong everything we’ve ever known about photography has been. Incredible!

But, without due fret, David Lyga is here to correct all which dared to rear its ugly face within the historical photo continuum. - David Lyga

BrianShaw · Aug 31, 2020

Gee thanks David. I’m struggling, though, to figure out what’s useful photographic information and what’s basically mental masturbation. Whatever you can do to help me with that will always be appreciated!

David Lyga · Aug 31, 2020

BrianShaw said:
Gee thanks David. I’m struggling, though, to figure out what’s useful photographic information and what’s basically mental masturbation. Whatever you can do to help me with that will always be appreciated!

Brian, in most cases what we are talking about is not 'wrong' but subject to a more refined, concise interpretation. You know, thinking about this, concerning what AgX said about "shutter speeds" vs (his German way of thinking) "shutter times", the 'times' is far better intuitively. Or, again, take his German 'aperture AE' instead of the English 'shutter priority AE': again, the German thinking takes pre-eminence I think because ours states what should be obvious and his states what is actually happening.

And my insistence on 'light meter', as opposed to the foolishly acculturated 'exposure meter', well, here I think that I am more correct.

Hindsight allows us to explore these anomalies, especially during COVID-19. - David Lyga

BrianShaw · Aug 31, 2020

Okay... I’ll play. After a 10-hour workday I’m feisty!

A light meter measures light in scientific terms - lumen or lux or candelas - not a “LV”. The presence of an exposure calculator (or direct exposure readout) makes the photographic meter, indeed, an exposure meter.

Shutter time vs shutter speed is classic mental masturbation...

There are some things that are really wrong, like calling a tomato a vegetable instead of a fruit. But then there are some things not worth making more precise, like hoagie vs submarine. Now “grinder”... THAT’S something totally different.

"scientific" vs "geometric" shutter speed designations

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