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Old Oct 28, 2012, 11:24 AM   #1
nateo200
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Why are fast wide lenses so expensive vs long lenses

Why are fast wide lenses so expensive vs fast long lenses? I don't understand it...an 85mm f/1.8 has to capture more light on a reduced angle (hence the large front aperture) but a 24mm for example has a wider viewing angle to capture more light! Why doesn't Canon for example have cheap wider angle glass? I just dropped $290 for a brand new Canon EF 35mm f/2 but why is the 35mm 1.4 more expensive that some of the longer lenses just as fast?! Doesn't make sense to me...its also a pain trying to get wide shots on a crop sensor body...I mean yeah I can get wide shots but not wide shots at f/2!
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Old Oct 28, 2012, 11:40 AM   #2
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It's due in part to the design. The focal length being shorter than the distance from the back of that lens to the sensor causes the need to add extra elements for it to work. I believe it's a much more advanced design inside than a lot of the tele zooms. There are some key terms to use in this but I can't remember them. Regardless, it takes more to manufacture these wides because they're a little harder.

There are some extremely expensive fixed lenses with zooms greater than 300mm as well. In the wide range, the f/2 vs f/1.4 is actually a reduction of half the light. Something like (sq root of 2)*1.4 =2.0 I think. So basically, what seems like a small jump from 1.4 to 2.0 can make some difference when trying to focus in low light. Fact is, I don't think you'd need 1.4 as much for the price you pay. There are tons of other factors too, I'm sure.
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Old Oct 28, 2012, 12:09 PM   #3
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"Normal" lenses, 35-70mm for a full-sized "35mm" camera, are always going to be more for the money than either very wide-angle lenses or telephoto lenses. At any given focal length, faster lenses are going to be more expensive than slower lenses.

In my film days, the best thing I ever did was buy a high-quality normal (50mm) macro lens. It would make a picture of the ugliest bug on the planet look beautiful. Not to mention portraits and landscapes. You don't really notice all the flare, distortion, and chromatic aberration that your short, long, and zoom lenses are adding until you see photos missing these artifacts.
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Old Oct 28, 2012, 12:40 PM   #4
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With telephoto lenses, the engineers have lots of room to place the groups and elements to get the fast lens design that they aim for.
With wide angle lenses, not only do you have less space, but also you need more glass to bend the light further, squeezing up to 114° of view into a 24x36 area. So it's just plain harder to make a fast wide angle lens.
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Old Oct 28, 2012, 01:16 PM   #5
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Quote:
Originally Posted by nateo200 View Post
Why are fast wide lenses so expensive vs fast long lenses? I don't understand it...an 85mm f/1.8 has to capture more light on a reduced angle (hence the large front aperture) but a 24mm for example has a wider viewing angle to capture more light! Why doesn't Canon for example have cheap wider angle glass? I just dropped $290 for a brand new Canon EF 35mm f/2 but why is the 35mm 1.4 more expensive that some of the longer lenses just as fast?! Doesn't make sense to me...its also a pain trying to get wide shots on a crop sensor body...I mean yeah I can get wide shots but not wide shots at f/2!

50mm lenses and moderately longer can be made with a modified double gauss design, which is a simple symmetrical design that cancels out aberrations well at the cost of soft corners. But it's very simple and with good IQ and you don't need special glass.

I believe the 35mm f2 has a simple, relatively symmetrical, design and it's not a large lens. But most fast lenses wider than 50mm would bump up against the mirror in a dSLR if made with a symmetrical design (focal length is distance from optical center to the film plane when focused at infinity and I believe near-symmetrical designs put the optical center very near or at the physical center of the lens). Symmetrical designs lack a lot of aberrations and have good contrast because they are simple, but the corners can get soft. But when a lens gets too fast (the 50mm t0.7 lenses Kubrick used couldn't be used in a reflex film camera) or too wide (14mm f2.8) or a mixture of both (35mm f1.4) a special design must be employed so that the lens is longer between its optical center and the film plane than its stated focal length (otherwise the mirror would hit the rear element when focused at or near infinity!).

Telephoto lenses have a special optical group near the film plane that simulates a lens that is longer than the physical length of the lens (distance from optical center to film plane). Meanwhile, retrofocus (reverse telephoto lenses) have a similar element in front of the lens, and this is the design that is used for the 35mm f1.4, for instance. The downside of retrofocus lenses is that they have lots of aberrations relative to symmetrical designs: more distortion, CA, etc. But...by using very complex designs and rare glass (low dispersion or whatnot, aspherical elements, etc.) you can fix these aberrations. There are two problems: lots of large lens elements made of weird glass is incredibly expensive and difficult to design and you get so many air to glass surfaces that contrast is low. With advanced coatings and computer designs, the only real issue is cost. It's worth noting that Zeiss and Canon have 35mm f1.4 lenses that outperform their 50mm f1.4 lenses and Leica (rangefinders do not need retrofocus designs) makes a retrofocus 35mm Summilux. Zeiss is making a retrofocus 50mm f1.4 that will be thousands of dollars. So the IQ is better, too, in theory.

It's worth mentioning that Canon has a 22mm f2 for its mirrorless and Fuji has an 18mm f2 for its rangefinder... So when we all go mirrorless lens options should open up a bit!

If you need to go wide and fast for cheap, just buy a 5D (or 6D?) and a 24mm f1.4. There are great PL mount options (Master Primes, S4s, Superspeeds are my favorite and the least expensive...) but they're ridiculously expensive except to rent and they're all PL mount. Sadly, there's no market (in stills) for a 18mm f1.4 that's APS-C only and it's too hard to make that lens for FF. And the video market is still much smaller than stills and most videographers are tremendously ignorant. I'm hoping Samyang will make that lens (their cinema lenses are excellent except for breathing, but missing this focal length and 50mm f1.4), but there's so much misunderstanding about lenses and formats among young videographers and cinematographers (it's embarrassing that these people charge money) that few would appreciate how important it would be! Until then...the 17-55mm f2.8 IS is nice. Even the kit lens is nice at 18mm f3.5--better bokeh, too.

It's much more complicated than this, btw. Even if retrofocus vs symmetrical weren't an issue, coverage would be. And even symmetrical designs aren't truly fully symmetrical. Check out large format ultrawides (which have horrible vignetting) and see how expensive they are and how curved their front elements must be. And the vignetting is terrible! So even symmetrical ultrawides are tricky. I wouldn't chime in (I know nothing about lens design) except that a lot of the answers here are wrong or gross simplifications worse than my own.

Last edited by Policar; Oct 28, 2012 at 11:39 PM.
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Old Oct 28, 2012, 01:21 PM   #6
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Quote:
Originally Posted by nateo200 View Post
Why are fast wide lenses so expensive vs fast long lenses? ...
Quote:
Originally Posted by Prodo123 View Post
...
With wide angle lenses, not only do you have less space, but also you need more glass to bend the light further, squeezing up to 114° of view into a 24x36 area. So it's just plain harder to make a fast wide angle lens.
Just to expand on Prodo123's comments, wide angle lenses have two characteristics that make them more expensive to build, regardless. One is that they have to bend light more. Two is that the front element tends to have a greater diameter than telephotos (related to the angle of view).

When you bend light rays you get chromatic aberrations.... basically, the light wants to split like a rainbow. You add multicoating, use expensive glass, and add elements (other pieces of glass) to reform the light rays back into its proper form. Because wide angles lenses do more bending, you need to reform the light rays more aggressively. Because the front element is typically broader, you need more light reforming material.

For all lenses, a 'faster' lense has to have elements with an increased diameter (in order to handle the bigger apertures)... so you are doing more bending with bigger pieces of glass, and therefore you need much more 'reforming' of the light rays - which is expensive.

This is very basic - of course - but perhaps it helps.
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Old Oct 28, 2012, 01:34 PM   #7
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Originally Posted by Policar View Post
It's worth mentioning that Canon has a 22mm f2 for its mirrorless and Fuji has an 18mm f2 for its rangefinder... So when we all go mirrorless lens options should open up a bit!
Policar's response is absolutely correct.

Also, another example of how DSLRs can't have too fast or too wide a lens is the Noctilux 50mm f/0.95 for Leicas. Man, I'd kill to have that lens for DSLRs!
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Old Oct 29, 2012, 08:56 AM   #8
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Manual focus prime lenses can be bought at a fraction of auto-focus models. such as the Canon FD, or Pentax M42s.
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Old Oct 29, 2012, 12:03 PM   #9
rick d
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fast lenses expensive

Have you priced a 300--2.8, 500-- f4 much more than wide angle.
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Old Oct 29, 2012, 06:54 PM   #10
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Originally Posted by Prodo123 View Post
Also, another example of how DSLRs can't have too fast or too wide a lens is the Noctilux 50mm f/0.95 for Leicas. Man, I'd kill to have that lens for DSLRs!
Canon does have a 50mm f1 L from a while back, but apparently it's not so good optically. Both it and the Noctilux are modified double Gauss, of course, but the Noctilux likely takes advantage of the shorter flange focal length. But I don't know. It's also interesting that the M-mount 18-55mm IS outperforms the EF one.

Quote:
Originally Posted by rick d View Post
Have you priced a 300--2.8, 500-- f4 much more than wide angle.
Very true. Wide angle lenses can be very good, reasonably fast, and very cheap (11-16mm Tokina, 14mm Samyang although it has terrible distortion). Fast telephotos... not really.
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Old Oct 29, 2012, 09:08 PM   #11
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@Policar
Thanks a lot for your post, that was very interesting.
Quote:
Originally Posted by Policar View Post
Canon does have a 50mm f1 L from a while back, but apparently it's not so good optically. Both it and the Noctilux are modified double Gauss, of course, but the Noctilux likely takes advantage of the shorter flange focal length. But I don't know. It's also interesting that the M-mount 18-55mm IS outperforms the EF one.
Even the f/1.2 version they have now is optically a step down from its slower f/1.4 brethren, and it's really, really big and heavy. I wouldn't want to schlepp it around all day for that little extra in speed, although I can see why it's worth it for others.

The other trend I see is automated software correction when it comes to lenses: instead of compensating for things like vignetting and distortion in »hardware« (which possibly introduced more glass and other compromises as well as more expensive and heavier lenses), this is done in software. I think one of the more prominent recent examples is Fuji's new X-mount lenses. Photozone's reviews mention this and seem to grade the lens based on its »raw« (pun intended) distortion, in line with others who eschew this kind of correction of optical flaws (or rather, compromises).
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Old Oct 30, 2012, 09:36 AM   #12
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I'll add a (personal) historical component.

When I started using Nikon (1965), the fastest 35 mm was (I think) a 2.8. The fastest 28 was 3.5, the 24 didn't exist, and the 21 was only for the rangefinder.

At some point (I forget when) I got a 21 (maybe f/4?) that required me to lock up the F's mirror and use a viewfinder that mounted on the flash shoe. But I was crazy about that lens -- my first super-wide.

Then came the 35 f/2, which I bought, and then the amazing 35 f/1.4, which I also bought; the 28 f/2, the 24 f/2.8 and then the 20 f/3.5. I had all those lenses and only sold them in 2008.

My point, which is maybe getting lost, is that there was a time when looking for fast WA lenses didn't mean getting the money together as much as it meant waiting until they were released.

At the other end, I got an 85 f/1.8 early on (maybe 1968) and kept it until I got a modern 85 (the f/1.4, in 2004). Back in the day, the 180 f/2.8 was the one people lusted after but not many could afford (I couldn't either).

In 1969, the 1000 mirror (f/11) listed for something like $750. I had one, used it in fieldwork, then traded it for the 35 f/1.4 and the 20 and maybe another F body (which in those days listed for $220).

But going back to price differential -- note that the current 400 f/2.8 lists for a whopping $9K.
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Old Oct 30, 2012, 01:30 PM   #13
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Look up "fill in any lens name" + Section in Google Images. It will show you why.
The more elements, and the more curved they are, the more expensive.
If you check the 85mm, you will find it to be the simplest design of all. You cannot make a simpler lens for 35mm camera's than a 85mm.

Personally I would skip the super light wide angles. Since it is so hard to design one, the ones that capture more light have way worse images. For example, the corner of a 20-24mm image is almost always F4.0. No matter what the maximum aperture is. If you have a F1.4 lens, it will have 3 stops of vignetting in the corner, effectively making it an F4.
The 2.8's are often the best trade off. Super sharp, little corner problems and nice priced. And since the longest time you can hold your camera still is 1/focal distance, you can shoot wide angles at much longer shutter times than a tele. So there is less need for wide aperture.
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