# Why is a 50mm the easiest fast prime to produce?



## LFG530 (Apr 25, 2011)

Sorry for that "noob" question, but I can't seem to get an answer to that, I'm sure there's a quite simple physical explanation for that...

In other words, why is a 35mm/24mm 1.4 so more expensive/heavy/long than a 50mm 1.4 or 1.2 ? This seems counter intuitive since the aperture has to be about 24mm large on a 35 and 35mm large on a 50...


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## Admin US West (Apr 25, 2011)

LFG530 said:


> Sorry for that "noob" question, but I can't seem to get an answer to that, I'm sure there's a quite simple physical explanation for that...
> 
> In other words, why is a 35mm/24mm 1.4 so more expensive/heavy/long than a 50mm 1.4 or 1.2 ? This seems counter intuitive since the aperture has to be about 24mm large on a 35 and 35mm large on a 50...



I do not think your prices are quite, at least, not in the USA.

The simple answer is that the 50mmL costs more than the 35mm L, not less. They are both old designs, so the tooling and development costs are paid off long ago. The 24mmL is relatively new, so the tooling and development costs that must be paid for are still affecting the price. The special nanocoating on the glass is expensive as well. 

The 50mm f/1.2 has a MSRP of $1619 while the 35mm f/1.4 L has a MSRP of $1479. The 24mm L MSRP is $1749.
Presumably the MSRP is related to the cost of production. However, the street prices may be related to the law of supply and demand.

Street price for the 50mm f/1.2L is $1749, The 24mm L is 1749, and the 35mm L is $1579 all are listed as available on Amazon.com.

As for the 50mm f/1.4L, it is a much cheaper and simpler lens and does not have the heavy duty construction, a true USM focus motor or the exotic glass that the "L" lenses have. Its a bargain!


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## LFG530 (Apr 25, 2011)

- _ - Ok nice price lesson, but that doesn't answer why the 35 and 24 are still longer and why there's no 14 1.4 on the market for example...

And why are the fastest lens ever always 50mms. (ex: noctilux or the 0.7 zeiss (I think it was zeiss))


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## Admin US West (Apr 25, 2011)

LFG530 said:


> - _ - Ok nice price lesson, but that doesn't answer why the 35 and 24 are still longer and why there's no 14 1.4 on the market for example...
> 
> And why are the fastest lens ever always 50mms. (ex: noctilux or the 0.7 zeiss (I think it was zeiss))



35mm and 24mm still longer?? I do not understand the question.

BTW, I am assuming you mean lenses for full frame.

Wider lenses are indeed more difficult to design and build. A 14mm lens is much much wider than a 24 or 35mm lens, and is indeed difficult to build. It is also a specialty lens, one that will include your feet in the image unless you are very careful. I'm sure it could be built, but the existing lens is a expensive and slow seller, I doubt that Canon would invest the millions in development and tooling to make a slow selling lens. Super wide lenses seems to have never been something that Canon emphasied, they have always excelled at super telephotos. They get $10K plus for them, so they may have just made the right decision.


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## LFG530 (Apr 25, 2011)

By longer I mean PHYSICALLY longer, they are longer like a giraffe neck is longer than your, get it? And that still doesn't anwer to why a 50mm is easier to build than a telephoto or a wide (there's never been anything else than a 50mm that has reached an aperture under 1.2)... I know the stuff about investment, but the question is WHY is it more difficult and WHY is 50mm the focal lenght that appears to be easier to build.


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## HughHowey (Apr 25, 2011)

scalesusa said:


> LFG530 said:
> 
> 
> > Sorry for that "noob" question, but I can't seem to get an answer to that, I'm sure there's a quite simple physical explanation for that...
> ...



His question is a good one. And you're comparing a 1.2 to a 1.4. That's not a good comparison at all.

For some reason the 50mm focal range is the easiest to produce. This is evident not only by the lower price for the same f-stop prime, but the size not needing to be anywhere as large.

I'd love to know why as well.


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## bvukich (Apr 25, 2011)

Wider lenses must bend light to a much greater degree.

From my understanding, this results in much thicker and more curved lenses. This also makes it a lot more difficult to control CA and various forms of distortion because they are all more severe.


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## LFG530 (Apr 25, 2011)

bvukich said:


> Wider lenses must bend light to a much greater degree.
> 
> From my understanding, this results in much thicker and more curved lenses. This also makes it a lot more difficult to control CA and various forms of distortion because they are all more severe.



You mean it has to have more elements to "control light" so it makes it longer? If so, ok that's part of what I thought, but my question is more about what makes 50mm the "magic number"...


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## LFG530 (Apr 25, 2011)

Yes that helps, maybe if I fully understood I'd get what makes 50mm the "standart", but...

If it could remind the answer to someone: I've heard it's the "natural focal length and I know that if you put a pinhole cap (http://www.geeky-gadgets.com/wp-content/uploads/2010/10/SLR-Pinhole-Body-Cap_1.jpg) on your camera it has a 50mm equivalent length, so I guess it has something to do with the answer I'm searching...


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## Lawliet (Apr 25, 2011)

The thing with the pinhole is only partially causal. The hole happens to be (42mm due to the lens mount + a bit for the cap with the hole) from the sensor, giving it an effective focal length close to 50mm, and 50mm is the widest lens you can build without resorting to a retrofocus design, because the mirror enforces a minimum distance from mount to sensor. Remember the P&S/finder of the time? 35mm for the natural field of view. 

Natural fl is just a way to say the focal length is close to the diagonal of the film format you're using. That term was coined when 135 was among the small and cheap formats, with tons of medium and large formats in everyday use, making that 150mm lens everything from tele to wide angle depending on the body you attached it to, or the cassette you inserted - they needed a simple baseline. What FOV will x mm give me with this material?
Esotherics took over and gave it an unjustified importance.


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## LFG530 (Apr 25, 2011)

Lawliet said:


> The thing with the pinhole is only partially causal. The hole happens to be (42mm due to the lens mount + a bit for the cap with the hole) from the sensor, giving it an effective focal length close to 50mm, and 50mm is the widest lens you can build without resorting to a retrofocus design, because the mirror enforces a minimum distance from mount to sensor. Remember the P&S/finder of the time? 35mm for the natural field of view.
> 
> Natural fl is just a way to say the focal length is close to the diagonal of the film format you're using. That term was coined when 135 was among the small and cheap formats, with tons of medium and large formats in everyday use, making that 150mm lens everything from tele to wide angle depending on the body you attached it to, or the cassette you inserted - they needed a simple baseline. What FOV will x mm give me with this material?
> Esotherics took over and gave it an unjustified importance.



Thanks, it answers a big part of my question. So you're saying it's mainly a decision they took to "worship" the 50mm, but it's still weird that even with rangefinders the large aperture lenses are 50mm's, does that depend on technical difficulty or is it just on principle they don't want to invest on a 35 length since it won't suit the needs of as many people?


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## TexPhoto (Apr 25, 2011)

I think it's the sweet spot of two factors, then one economic one.

1. As seen above, wider lenses are more complex with more curvature to front and other elements, more coatings and aberration problems to deal with.

2. The longer the focal length, the narrower the the angle of light it takes in, thus you need a bigger and bigger front glass elements to bring in the light needed for a given aperture. Look at the size of a 400 2.8 compared to a 50 2.8, just like a telescope, it must bigger and bigger to gather that light.

The above 2 "rules" have a sweet spot around 50mm. I doubt 45mm, or 60mm is that different, but 14mm, and 400 are sure as heck way different. And if the true sweetest spot was 48.7mm, that just sounds awkward, while 50mm sounds right.

3. Economics. Canon probably sells 1000 50mm f1.8s for every 1 400mm f2.8, so economy of scale kicks in. Lowering the price of the 50mm dramatically. Actually i recently bought an 18-55mm IS for $88 brand new. That is probably Canons most common lens now.

Anyway there is probably way more "factors" at work, but I think those are the big 3.


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## Joaquox (Apr 25, 2011)

LFG530 said:


> Thanks, it answers a big part of my question. So you're saying it's mainly a decision they took to "worship" the 50mm, but it's still weird that even with rangefinders the large aperture lenses are 50mm's, does that depend on technical difficulty or is it just on principle they don't want to invest on a 35 length since it won't suit the needs of as many people?


 This does not answer your question, but for old rangefinders with a fixed lens 38-44mm seems to be the standard focal. I'm not talking about the ones with replaceable lenses like leica, but the cheap mass produced ones like the Minolta Hi-Matic.

So I'd say the focal suits the needs of many people - or at least it did, back in the days.

If you have a library nearby, I suggest you ask them to order the "EF Lens work III - The eyes of EOS", it's a great book by Canon on the subject.


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## NormanBates (Apr 25, 2011)

I also wondered why the 50mm f/1.4 could be so much cheaper than the 35mm f/1.4 or the 24mm f/1.4, and why there could be a 50mm f/1.2 and not a 35mm f/1.2 (and why that situation was the same in every brand's catalogue)

TexPhoto's answer totally satisfied my curiosity; thanks

another factor must be focal flange distance: leitz has 50mm f/0.95 for leica-M mounts, but only 50mm f/1.4 for leica-R


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## Cannon Man (Apr 25, 2011)

The reason why its called a standard lens is because 50mm is closest to what the human eye sees.. (Under 50mm makes Objects in the picture look far apart from each other and lenses with more than 50mm will compress everything in the picture so that it looks like everything is close to each other..)

And the other reason could be because in the old days almost all the cameras came with a 50mm prime..

The 50mm is really simple to build because you dont have to create a special effect with the lens.. Only what is natural and what the human eye sees.. Also because of the simple construction they have a wide aperture..

The reason why the wide angle lenses are longer than the 50 is because it creates the illusion that the distanses are further apart from each other.. So a different and more complex construction is nessecary..

Longer lenses than 50mm needs to be long because they need to be an x amount away from the sensor.. An 800mm lens is so darn long because it ( not sure what part of the lens) needs to be 800mm away from the sensor..youll see the focal plane mark on your camera where the distance is measured from..

You can go to http://web.canon.jp/imaging/l-lens/index.html
And you can see the construction of all the different lenses and see for your whats up..


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## NormanBates (Apr 25, 2011)

^ you didn't read passerby's links, did you?
http://www.lensrentals.com/blog/2011/02/who-invented-the-telephoto-lens
http://www.lensrentals.com/blog/2011/03/the-development-of-wide-angle-lenses

in the first one, under the section "What is a telephoto lens? (No, you donâ€™t know.)", it says:
"the actual definition of a telephoto lens is a lens with a physical length shorter than its focal length. So, for example, a Canon 100 f2.8 lens is not a telephoto (being 109mm long), while the Canon 100mm f2.0 lens is a telephoto (being 73mm long)"


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## kennykodak (Apr 25, 2011)

a telephoto is any lens whose focal length is Greater than the diagonal of the (film).


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## Lawliet (Apr 25, 2011)

That would be the definition of a long focus, telephoto is a lens with a shorter front to sensor distance then its actual focal length.


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## neuroanatomist (Apr 25, 2011)

The distance between the focal plane (sensor/film) and the mirror travel (not necessarily the mount flange) determines the threshold for when a retrofocus lens design is necessary. That's one reason EF-S lenses are cheaper to produce - the 's' in EF-S means short back focus, i.e. the rear element of the lens projects beyond the mount flange (the other main reason is a smaller image circle necessitates smaller diameter elements).


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