Why is aperture backwards??

The full range in thirds goes like this:-

i-XmXPsKg-O.jpg


The top line is the standard these days, highlighted in yellow. It's based on the sequence 1,2,4,8,16,32,64 etc and the f numbers are the square roots of the numbers in the sequence.

The second line uses the sequence based on 5,10.20,40,80 etc and the last line used 1½ as the base and doubles as the others do. Then we take the square root.

The middle row was used by Leica and others but I've yet to see a camera using the third row but I put it in so show the thirds and how the off scale ones fit.

It's just simple numbers theory...

There's also the confusing Universal Scale which was used by Kodak before the Great War. If you want to get really confused look at the scale around a VPK.

The camera people got together to sort all this out in the 30's and yet nothing came of it mainly due to patriotism. The off-scale ranges were seen as German...


Regards, David
 
The full range in thirds goes like this:-

The top line is the standard these days, highlighted in yellow. It's based on the sequence 1,2,4,8,16,32,64 etc and the f numbers are the square roots of the numbers in the sequence.

The second line uses the sequence based on 5,10.20,40,80 etc and the last line used 1½ as the base and doubles as the others do. Then we take the square root.

The middle row was used by Leica and others but I've yet to see a camera using the third row but I put it in so show the thirds and how the off scale ones fit.

It's just simple numbers theory...

There's also the confusing Universal Scale which was used by Kodak before the Great War. If you want to get really confused look at the scale around a VPK.

The camera people got together to sort all this out in the 30's and yet nothing came of it mainly due to patriotism. The off-scale ranges were seen as German...

Regards, David

Get an old enough lens and you can use that third line. :D

PF
 
On a far more basic level, it's convenient for one new to photography to remember that higher shutter speed numbers (as in 30, 60, 125, etc) and higher f-numbers both correspond to less light. :)

- Murray

I hope this bit helps, if you add it on to the end:

"...less light being allowed into the camera."
 
I'm glad someone said this.
Amps that go to 11 are very rare, and expensive. Every time an amp company makes a batch they sell out immediately, because they are just that bit louder than the "10" ones.

So, you're on 10 on your amp and you're on 10 on your guitar. Where can you go from this? Exactly, these go to 11.
 
I remember getting this question occasionally while working at camera stores in the early 70’s.
In the end, with a few folks it came down to, ‘I can explain it to you, but I can’t understand it for you.’
 
I find the easiest way to think about it is this.
We all know that as the f number gets bigger, the amount of light it allows in gets smaller. So think of it in terms of fractions (which most people who have a passing acquaintance with simple arithmetic will be familiar with).
Think of the series 1, 1/2, 1/4, 1/8, 1/16....................etc.
Each of the above numbers is half the preceding number in the series.
But the number below the line (the "denominator") gets "bigger" being double the denominator in the number before it. When expressed this way it is obvious why a "bigger" denominator represents a smaller size of each number in the series - each being half the preceding one.
It is basically the same concept with the f stop - each f stop number represents half the amount of light hitting the film plane as the previous one.
I think that people seem to find this confusing because the relationship between these numbers (f1, f1.4, f2, f2.8, f4, etc.) is not immediately obvious unless it is explained. This slightly unusual series of numbers occurs because the f stop can be thought of as being based on the area of the aperture "hole" (OK actually its a ratio but it amounts to the same thing in practice) and such numbers have a geometric progression not a linear one as in the first example I gave.
 
My attempt:

It's the series {1/√1, 1/√2, 1/√4, 1/√8, 1/√16 ...}

And for simplicity and because all know the context, we omit the inverse (1/) and provide the well-known 1, 1.4, 2, 2.8, 4, etc.

For those who don't like math much, I just say it's a progression 1, square root of 2, double the first term, double the second term, repeat.

For those who absolutely HATE math and their soul rebels at the mere mention, I say it's one, one "and a special half", two times one, two times one and a special half, repeat.

When asked, explain that a 'special half' is a math thing, and if they want more detail, I'm going to have to get the slide rule out.
 
My attempt:

It's the series {1/√1, 1/√2, 1/√4, 1/√8, 1/√16 ...}

And for simplicity and because all know the context, we omit the inverse (1/) and provide the well-known 1, 1.4, 2, 2.8, 4, etc.

For those who don't like math much, I just say it's a progression 1, square root of 2, double the first term, double the second term, repeat.

For those who absolutely HATE math and their soul rebels at the mere mention, I say it's one, one "and a special half", two times one, two times one and a special half, repeat.

When asked, explain that a 'special half' is a math thing, and if they want more detail, I'm going to have to get the slide rule out.

This might be correct mathematically but it obscures rather than reveals the idea that each successive closing of the aperture is 1/√2 times the previous diameter, giving a better idea of what is going on and why, halving the area each time. And don't you hover no vernier calipers over the front element of any of my lenses - I'd rather you showed me the slide rule. I rather like slide rules.
 
I doubt there's a good alternative. How it works has been explained plenty, so I'd like to point out some considerations and advantages of doing it this way rather than coming up with arbitrary, but more-intuitive-if-you-have-no-previous-knowledge numbers.

1. Shutter speeds are also a fraction, are we to also change these? How would we get the whole photographic industry to change it to the same system?
2. Flash exposure calculations with guide number are fairly easy this way.
3. It's not hard. If you can understand exposure well enough to gain anything from understanding aperture, you can understand aperture.

Perhaps because in the day, this language was invented by engineers. Day-to-day users just had to jump through their hoops.
 
Perhaps because in the day, this language was invented by engineers. Day-to-day users just had to jump through their hoops.

Quite right too...

Seriously, there were other systems but they just didn't last. And mostly they boiled down to the same thing because they had to.

Regards, David
 
Since the OP has failed to acknowledge any of the posts to this thread I'm beginning to think it was just a ploy to drive eyeballs to that YouTube video.


PF
 
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