Where does the 24/35/50/85mm standard originate? Is it arbitrary?

[preppyak]

Like apertures, common focal lengths tend to follow multiples of the square root of two.

So, 24 (close to 25), 35, 50, 70 (OK, that's not a good example as 85 is used instead), 100, 135 (close to 141), 200, 300 (close to 283), 400 etc.

I think a useful thing to remember is that a 50mm lens is rarely actually exactly 50.00 on the patent. Just like a 70-300 zoom is usually actually a 71.89 to 292.35 lens, but, they round it to make it simpler. Note that, 24mm aside, all those numbers land on a 0 or a 5. Just makes the numbers simpler. It's actually interesting to me that 14mm and 24mm are standard instead of 15mm and 25mm, because you could market it the same.

An example of this are the 100-400 patents. Technically the lens should be marketed as a 104 to 391, but they round it off to keep it simpler

So, to answer the OP, it's a combo of science and BS. The lenses all match a certain field of view and preferred look, but, the number that represents them is not always accurate

 

[luciolepri]

It's actually interesting to me that 14mm and 24mm are standard instead of 15mm and 25mm, because you could market it the same.

Actually, with such short focal lenghts, 1mm makes quite a difference. For example, many years ago, Zeiss and Pentax produced the great and famous 15mm f/3.5 Aspherical (fow 86°). After that, Canon produced a 14mm f/2.8 (fow 90°) probably to show off a wider ad faster lens. The same thing most likely happend after Leica produced the first 25mm for a 35mm camera. So, I suppose that current standard focal lenses became standard for various reasons and technical improvements are definitely one of them.

 

[privatebydesign]

Classic film before 35mm was 72mm but 35mm (which is actually 36mm) rapidly became the dominant film standard.

I'd dispute the first claim, after all what do you mean with the term "classic film"? But anyway, regarding 35mm film "which is actually 36mm" you couldn't be more wrong, roll film is measured by its film gauge, that is, it is 35mm wide, hence 35mm film, it has nothing to do with the arbitrary dimensions of the film we expose. Look at the Hasselblad X-Pan with a 24mm x 65mm exposure area on 135 format film. Don't forget we, as still photographers, are actually using film in the "wrong" orientation to its primary original purpose, running through movie cameras and theater projectors.

As for "standard" lenses being the diagonal of the format, yes that holds up across formats.

 

[ahsanford]

Awesome thread. I've always wanted to know this. I understand fully well why certain lengths in general are used, but I've never understood how they landed on the specific focal length values.

- A

 

[Etienne]

it seems that we just naturally gravitate towards certain focal lengths; even with a zoom, we tend to choose prime focal lengths more so than we choose non prime.

I always find it interesting to look at the focal lengths of my photoshoots, I find it amazing just how often they do gravitate towards primal focal lengths. But then again, there are lies, damned lies, and statistics!

Few would debate that there are certain focal lengths that work well for certain types of shots. But my original question was really about why the standard focal lengths are PRECISELY 24/35/50/85mm, and not +/- 5mm off of those lengths.

They are not precisely 24/35/50/85 .... they are just labelled that way by the manufacturer for easy marketing I suspect. They are all off by a bit. Zoom ranges can be quite a bit off.

 

[Vossie]

"Normal" focal length for 35mm film is 43mm, which got rounded up to 50 by Oskar Barnack. The idea behind the progression of primes is this:

A 75mm lens will give you roughly the same framing from top to bottom when used in portrait orientation as a 50mm would when used in landscape. Put another way, if you took a photo take at 50mm in landscape orientation and cropped away the left 1/3 and right 1/3 of the frame, you'd get roughly the same image as if you used a 75mm lens in portrait orientation. Kind of awkward to describe so I hope that makes sense.

So, it's not completely arbitrary. All primes are multiples of 43mm or 50mm (1.4x, roughly the square root of 2, much like f-stops). "Normal" focal lengths for larger formats are also familiar numbers: 85mm (medium format), 200mm (large format) etc.

+1

nice to learn about this part of photography history. Thanks!

 

[dirtcastle]

it seems that we just naturally gravitate towards certain focal lengths; even with a zoom, we tend to choose prime focal lengths more so than we choose non prime.

I always find it interesting to look at the focal lengths of my photoshoots, I find it amazing just how often they do gravitate towards primal focal lengths. But then again, there are lies, damned lies, and statistics!

Few would debate that there are certain focal lengths that work well for certain types of shots. But my original question was really about why the standard focal lengths are PRECISELY 24/35/50/85mm, and not +/- 5mm off of those lengths.

They are not precisely 24/35/50/85 .... they are just labelled that way by the manufacturer for easy marketing I suspect. They are all off by a bit. Zoom ranges can be quite a bit off.

Good point! And that begs the question even further. A few possible scenarios...

1. There are true "standard" focal ranges (e.g. +/- 2mm) around the 24/35/50/85 marks; and, for marketing purposes they have always rounded to a number that sounds good.

2. There are no inherent or intrinsic "standards" and everything is just a product of arbitrary historical precedent.

Personally, I think the standards are arbitrary. Great shots can be had at any focal length.

I think the reason why people accept the standards (and some believe they are baked into the fabric of life) is that they do serve successfully as guides for choosing lenses and composing shots. But it would seem to me that in a parallel universe (or by quirk of history)... 22/32/46/80 could just as easily be the standard focal lengths.

On a side note, I should point out that the most commonly used focal lengths (35mm equivalent) are probably...

Samsung Galaxy S III: 26mm
iPhone 5: 33mm
iPhone 4s: 33mm
iPhone 4: 29mm
HTC One: 27.54mm

From this we can see how marketing departments might be tempted to round up or down to 28mm and 35mm. Certainly "27.54" has a bad ring to it. And if rounding up or down by 0.5 is no sin, then surely rounding by .75 or even 1.75 is no sin either! ;-)

 

[ahsanford]

it seems that we just naturally gravitate towards certain focal lengths; even with a zoom, we tend to choose prime focal lengths more so than we choose non prime.

I always find it interesting to look at the focal lengths of my photoshoots, I find it amazing just how often they do gravitate towards primal focal lengths. But then again, there are lies, damned lies, and statistics!

Few would debate that there are certain focal lengths that work well for certain types of shots. But my original question was really about why the standard focal lengths are PRECISELY 24/35/50/85mm, and not +/- 5mm off of those lengths.

They are not precisely 24/35/50/85 .... they are just labelled that way by the manufacturer for easy marketing I suspect. They are all off by a bit. Zoom ranges can be quite a bit off.

Good point! And that begs the question even further. A few possible scenarios...

1. There are true "standard" focal ranges (e.g. +/- 2mm) around the 24/35/50/85 marks; and, for marketing purposes they have always rounded to a number that sounds good.

2. There are no inherent or intrinsic "standards" and everything is just a product of arbitrary historical precedent.

Personally, I think the standards are arbitrary. Great shots can be had at any focal length.

I think the reason why people accept the standards (and some believe they are baked into the fabric of life) is that they do serve successfully as guides for choosing lenses and composing shots. But it would seem to me that in a parallel universe (or by quirk of history)... 22/32/46/80 could just as easily be the standard focal lengths.

On a side note, I should point out that the most commonly used focal lengths (35mm equivalent) are probably...

Samsung Galaxy S III: 26mm
iPhone 5: 33mm
iPhone 4s: 33mm
iPhone 4: 29mm
HTC One: 27.54mm

From this we can see how marketing departments might be tempted to round up or down to 28mm and 35mm. Certainly "27.54" has a bad ring to it. And if rounding up or down by 0.5 is no sin, then surely rounding by .75 or even 1.75 is no sin either! ;-)

+1

Super insightful comment -- great thinking. Smartphone makers don't have to satisfy the 1% of the population that appreciates 'standard' focal lengths. Instead, I'd imagine Apple, Samsung, etc. mined what focal length people tended to shoot and built their 'standard' around that.

And it should be no surprise where they landed, really. Most people aren't shooting tightly cropped headshots with their phones. So lenses in the 24-35 neighborhood play very well with users.

-A

 

[rcarca]

But anyway, regarding 35mm film "which is actually 36mm" you couldn't be more wrong, roll film is measured by its film gauge, that is, it is 35mm wide, hence 35mm film, it has nothing to do with the arbitrary dimensions of the film we expose.

Let me be more precise. The gauge (from edge to edge of the film including the sprocket holes) is 35mm. The area we exposed on a 35mm film was 24 x 36mm. That is the relationship that drives the "standard" lens.

I will research further on the relationship with cinema film.

Richard

 

[Rocky]

The diagonal of the 36 X24 mm film is 43. 27mm. It was rounder up to 45mm. A lot of fixed lens 35mm film cameras from the 40's to the 60's are 45mm lens. It also happens that is about the same"clear viewing " angle of the human vision. Leica further round it up to be 50mm. Here comes the film SLR in the 30's. Due to the mirror, it is hard (expensive) to make a 50mm standard lens. Therefore 55mm became the standrd SLR lens until the 50's or even early 60's. So the 50mm standrad focal length is semi arbitrary. For the "portrait lens", Leica arbitrarily assign the 90mm focal length, while others are using 85, 100 or 105mm. 135mm is the longest focal length that Leica feel comfortable with their range finder camera without additional attachment. Leica does make longer focal length for their visoflex reflex housing. Since Leica is the premium and propular range finder camera in the 50's, the 135 mm beomes a "standard". 35mm (0.7X of 50 mm) is the comfortable "wider' angle of view to have a easily controllable perpective distortion. It became a standrad also. 24 mm is 0.7X of 35mm and becomes another standard with large perspective distortion that is not that easy to control. Then 28mm is right between the 35mm and 24mm in terms of viewing angle to be wider than 35mm and more controllable perpective distortion than the 24mm.

 

[Mt Spokane Photography]

Those standard focal lengths have been around for a long time

 

[privatebydesign]

Due to the mirror, it is hard (expensive) to make a 50mm standard lens. Therefore 55mm became the standrd SLR lens until the 50's or even early 60's.

It is very easy and cheap to make 50mm lenses, even for 135 format reflex cameras, thought 135 format was adopted long before the SLR became a standard and rangefinders are even easier to design lenses for, 50mm lenses have no technical hurdles to overcome, no retrofocus or similar issues. That is why, even today, you can buy new auto focus 50mm lenses for $100!

Canon and Nikon were selling 55mm lenses well into the '70's, often alongside 50mm versions.

 

[Rocky]

Due to the mirror, it is hard (expensive) to make a 50mm standard lens. Therefore 55mm became the standrd SLR lens until the 50's or even early 60's.

It is very easy and cheap to make 50mm lenses, even for 135 format reflex cameras, thought 135 format was adopted long before the SLR became a standard and rangefinders are even easier to design lenses for, 50mm lenses have no technical hurdles to overcome, no retrofocus or similar issues. That is why, even today, you can buy new auto focus 50mm lenses for $100!

Canon and Nikon were selling 55mm lenses well into the '70's, often alongside 50mm versions.

Now it is cheap and easy to make 50mm lens for SLR due to the new technology in glass making and grinding process. In the 40's and the 50's it is entirely different story. 55mm was use to avoid retrofocus and keep the price reasonable. I would suggest you to look into the history a little bit more, pay attention to the price of lens and camera in the 40's and 50's also.

 

[privatebydesign]

Now it is cheap and easy to make 50mm lens for SLR due to the new technology in glass making and grinding process. In the 40's and the 50's it is entirely different story. 55mm was use to avoid retrofocus and keep the price reasonable. I would suggest you to look into the history a little bit more, pay attention to the price of lens and camera in the 40's and 50's also.

Leica's first lens was a 50mm, the 135 format and the 50mm "standard", became popular long before slr's. There is zero retrofocus issue with a 50mm multi element lens on an 18mm- 38mm flange distance, common rangefinder interchangeable lens flange distances. Even with slr's requirement for larger flange distances closer to 42mm-48mm there is still no retrofocus issue with multi element 50mm lenses.

For the Canon FL system, their first interchangeable slr system, from 1964-1971 that morphed into the FD system and shared mount and flange distance, they made six 50mm lenses and one 55mm lens and two 58mm lenses, the later three being the more complex f1.2 version of their standard lens.


I love it when people say stuff like "suggest you to look into the history a little bit more" without having the slightest idea of who they are talking to, nor give references for their own education.

As a primer, read this.

http://www.lensrentals.com/blog/2011/08/lens-geneology-part-1

 

[Sporgon]

Now it is cheap and easy to make 50mm lens for SLR due to the new technology in glass making and grinding process. In the 40's and the 50's it is entirely different story. 55mm was use to avoid retrofocus and keep the price reasonable. I would suggest you to look into the history a little bit more, pay attention to the price of lens and camera in the 40's and 50's also.

I love it when people say stuff like "suggest you to look into the history a little bit more" without having the slightest idea of who they are talking to, nor give references for their own

;D

Maybe a little history lesson from CR archives would be a good start !

 

[dirtcastle]

As a primer, read this.

http://www.lensrentals.com/blog/2011/08/lens-geneology-part-1

Good call! I recognized my 50mm f/1.4 in those configurations!

The lens configuration diagrams beg the question of whether there are inherent "sweet spots" in the lens configurations. Obviously it is easier to make a 50 f/0.95, than it is to make a 500mm f/0.95.

What I'm talking about is shifting the entire prime intervals up or down by +/- 5mm. Would it pose a challenge to engineers? And, obviously, I'm talking actual focal length... not the focal length put on the box by the marketing department. ;-)

I'm assuming that, in the 24-85mm range, lens engineers can create a comparable IQ lens at ANY length in that range. I'm assuming there aren't difficult lengths in that range that engineers struggle with. Please correct me if I'm wrong.

 

[Rocky]

Leica's first lens was a 50mm, the 135 format and the 50mm "standard", became popular long before slr's. There is zero retrofocus issue with a 50mm multi element lens on an 18mm- 38mm flange distance, common rangefinder interchangeable lens flange distances. Even with slr's requirement for larger flange distances closer to 42mm-48mm there is still no retrofocus issue with multi element 50mm lenses.

For the Canon FL system, their first interchangeable slr system, from 1964-1971 that morphed into the FD system and shared mount and flange distance, they made six 50mm lenses and one 55mm lens and two 58mm lenses, the later three being the more complex f1.2 version of their standard lens.


I love it when people say stuff like "suggest you to look into the history a little bit more" without having the slightest idea of who they are talking to, nor give references for their own education.

As a primer, read this.

http://www.lensrentals.com/blog/2011/08/lens-geneology-part-1

All the example that you have quoted are either Range finder lens (Leica) or post 50's SLR lenses
Ziess Biotar is from the 30's till early 50's It is even at 58mm. if you can spend time to look at ebay, you will find a lot old 55mm lens.
The reason that I mention 55mm (or 58 mm) for early SLR to to show how arbitrary the standard lens can be. I have not yet mention the 40mm for the fully auto 35mm film camera in the 80's t0 90's and Canon's 'shorty forty" yet.
But if you think that you are right and know them enough, then you are right. Let us not to waste any more time on this pointless discussion.

 

[dirtcastle]

Lots of good information from everyone here. No need to get hung up on a few details.

 

[gtog]

For the Canon FL system, their first interchangeable slr system, from 1964-1971 that morphed into the FD system and shared mount and flange distance, they made six 50mm lenses and one 55mm lens and two 58mm lenses, the later three being the more complex f1.2 version of their standard lens.

Actually, a visit to the Canon Camera Museum would show the Canon Flex http://www.canon.com/camera-museum/camera/film/data/1956-1965/1959_flex.html?lang=us&categ=srs&page=r&p=1 to have been Canon's first SLR in May 1959, with one 58mm f/1.2 and three 50mm f/1.8 lenses in the R lens mount line-up.

I would also note that even the older S mount series lenses shows the "standard" focal lengths, supporting the notion that those focal lengths are not reflex oriented or constrained.

I would certainly add the Canon Camera Museum to the list of sources commended to readers attention for further historical research.

 

[privatebydesign]

gtog,

You are right, how could I have forgotten the little R mount? I hang my head in shame....

Having said that, as you point out, history, as evidenced by the lenses available at the time, doesn't actually support the problematic 50mm theory, and it is worth noting the R mount had the same 42mm flange distance the FL mount did, and that was the same as the FD and FDn.

I'd hardly lump the 1950's into "modern lenses" but each to their own.

But back to more interesting stuff, didn't Olympus push for shorter "standard" lenses in the '70's, I remember seeing kits with the 40mm and OM-? Though even they had a proliferation of 50's from a 1.2 to a 3.5 macro and the one 55mm 1.2.