Topic: The Atlantic: How the 50mm lens became "normal"

[EarlJam]

An interesting, albeit somewhat inaccurate, article on the history of camera lens design and how the 50mm focal length came to be considered "normal". The author errs in his description of lens choice for 35mm motion picture production, somehow missing the fact that the standard 35mm motion frame is 4-perforations tall with a diagonal of roughly 27mm, calling for a 25mm "normal" lens.

For 35-mm motion-picture production, the 50-mm lens provided the clear, crisp definition necessary for later projection at a larger scale in theaters. A 50-mm lens was an effective approximation of the focal length necessary to fill the diagonal dimensions of the 35-mm celluloid frame (43 mm) fully and consistently.

https://www.theatlantic.com/technology/archive/2018/05/how-the-50-mm-lens-became-normal/560276/

[hookstrapped]

Also disappointed no mention of the desire for fast lenses and the marketing and popularity of 50mm lenses. Always wondered about that

[Francois]

I too was wondering how he managed to make a 50mm the normal lens on a vertically traveling piece of 35mm film...
But it would make a decent sized mini telephoto that has a long enough registration distance to work with bulky movie cameras of the era.

[Sandeha Lynch]

While 43mm is the actual diagonal such that a 43mm lens provides a 'normal' perspective for the eye (or so the argument runs), I read many years ago that the 50mm was simply a cheaper lens to make.  Many SLR makers started out with 55mm or 58mm as their standard, but more efficient manufacturing left us with the ubiquitous 50.

[cs1]

First of all: I like 50mm lenses. ducks to dodge 50mm lenses thrown at him

The Olympus 35RC has a 42mm lens which is very close to "normal" and it's a wonderful focal length.

[Sandeha Lynch]

I like them, too.  I have a 1.4, 1.7, and a 2.0.  But for choice I mostly use my 43/1.9 ... Pentax, obvs.

[Francois]

The cheapness of the 50mm probably has mostly to do with the flange to film distance, especially when it comes down to reflex cameras. The nifty fifty doesn't need a lot of additional glass and the complex design of a reverse telephoto design like is required for wider angles.

As for me, my favorite 50's are the Industar-61 (mine happens to be a 53mm for some reason) and the Yashica f/1.7...
Wish I had one with a bigger aperture but these things get to be expensive.

[cs1]

I've always been wondering why there're so many fast 50mm lenses compared to other lenses North and South of 50mm. E. g. it's easy to get an f/1.4 50mm lens, however, getting a fast 28mm or 35mm is really difficult, same goes for 70mm. In the 85mm range things look better again. Is it so much easier to construct a fast 50mm? Or have lens makers just put more effort into making fast 50mm lenses because everybody buys them?

[Francois]

It actually is easier.
Thing is that the f/stop is in relation to both focal length and max aperture size. While it would be possible to make any telephoto a wide aperture, the glass would quickly end-up being so heavy that you'd need a fork lift to carry it.
If we look at a simple meniscus lens, a 50mm F.L. would need glass that is only 70mm in diameter to achieve an f/1.4 value. Adding more glass of high quality can shrink the whole thing down to a moderate size.

When it comes to wide angle lenses, they inherently need more glass to accommodate the mirror housing and shutter mechanism. This makes the construction of a lens more complicated.

The big winners in this field are strangely the new mirrorless cameras. Since their flange to sensor distance is so small, it's easy to design a lens that comes very close to the sensor. That's why their lenses often have bigger aperture than expected.

One thing I could never quite figure out though is why hasn't any manufacturer ever made a fixed lens super luminous optics camera that uses an in the lens shutter and an external viewfinder or point 'n shoot like autofocus system?

[johnha]

I've preferred something around 40mm (firstly a Pentax 40/2.8 'pancake' but more recently the 43/1.9) for their slightly wider view. On my Pentax 6x7 I've gone for the 90 (roughly 45mm equivalent) rather than the 105 (although partly on cost grounds - the 105 is much more expensive). 55 & 58s just seem un-natural focal lengths (not wide or long enough). When I was shooting APSC d*****l, 28mm was my preference (about 42 equivalent).

There seem to be a lot of 40mm pancakes available - there must be a reason for this as it's an odd length on formats smaller than 135?