Why 200F2.8L cheaper than 135f2L?

[Vince Ecosse]

Any idea to justify the huge price difference, at least in Europe?

[Michaelmjc]

The 135 is f2, the 200 is 2.8. There is always a huge price difference with lower apertures. Especially in the L series.

[Big Hands]

f/2 - close to a full stop of light faster

Image quality is from what I have seen, among the best offered by Canon although the 200L is in the same ballpark.

Also consider that if you add a 1.4x TC to the 135mm f/2L that you also have an effective 189mm f/2.8.

[KevC]

You can also crop that 135L to get 200mm FOV... but it's much harder to get that one more stop of light if you DESPERATELY need it =)

[genewch]

Aperture means $$$.

The 200mm is one of the lenses in my wish list. It's really a bargain in L glass. However a 200mm can't turn into a 135mm, while you can always crop a 135mm picture to imitate a 200mm FOV. If you need a slightly longer than 135mm, the 200mm is a very fine choice.

[Vince Ecosse]

I don't really follow here, because if we apply the argument aperture=$$$ (or £££ or anything else!), then 85 f1.8 should be more expensive, 50 f1.4 as well, etc etc.

[KevC]

I don't really follow here, because if we apply the argument aperture=$$$ (or £££ or anything else!), then 85 f1.8 should be more expensive, 50 f1.4 as well, etc etc.

Of course focal length comes into play. The further you deviate from 50mm, the more difficult it is to make the lens. That's why the 14mm f/2.8L and the 1200mm f/5.6L (or even anything longer than 200mm) are *ridiculously* expensive even though they are not that "fast".

[PaulB]

Of course focal length comes into play. The further you deviate from 50mm, the more difficult it is to make the lens. That's why the 14mm f/2.8L and the 1200mm f/5.6L (or even anything longer than 200mm) are *ridiculously* expensive even though they are not that "fast".

The 135mm focal length became so popular BECAUSE in the early days (sic - think 1930s to 70s) it was easier to make a good lens at that focal length but harder to make good longer ones and shorter ones were not really considered to be telephotos (rather they were long-focus ones - like 85mm based on a stretched 50mm design). Every manufacturer had a good 135mm in the range.
For the record, I have a Pentax A* 135/1.8 which seems the equal of my 135/2 Canon - pity it doesn't fit, isn't AF......................

[genewch]

Of course focal length comes into play. The further you deviate from 50mm, the more difficult it is to make the lens. That's why the 14mm f/2.8L and the 1200mm f/5.6L (or even anything longer than 200mm) are *ridiculously* expensive even though they are not that "fast".Well said.

For the same focal length, aperture does mean $$. Aperture is linked to focal length since f = FL/d where d is the diameter of a lens. The longer or shorter the focal length, the more difficult to make good glass, the even more difficult to make fast lenses. The 135mm is a traditional limit of telephoto lenses in the old days. Anything longer than that cannot be made at f/2 or faster. That's why 200 f/1.8 is much much more expensive and bigger than the f/2.8.

[prep]

Of course focal length comes into play. The further you deviate from 50mm, the more difficult it is to make the lens. That's why the 14mm f/2.8L and the 1200mm f/5.6L (or even anything longer than 200mm) are *ridiculously* expensive even though they are not that "fast".

The 1200 5.6 cost is mostly the front CaFl element. It is the full diameter, and quite thick. A rough and ready price reconer for Optical blanks of CaFl is that they are about the same price as an equivalent sized piece of gold.. [Schott]

The very small number built also adds a load to the cost.

[Lester Wareham]

It's an interesting question they are both very sharp, the speed difference asside, when you acount for the focal length the element sizes are similar as are the masses and size.

Both have two UD elements, the only obvious difference is the 135 has slightly more complex construction with 10 elements in 8 groups compared to 9 in 7 groups for the 200, doesn't seem to justify the cost difference so it may be down to sales numbers or what the market will accept.

[basroil]

The very small number built also adds a load to the cost.

the ef 1200 f5.6 is a custom order only lens. all hand crafted, so the price can be explained in materials and labor costs. the main reason why the 200mmL is quite inexpensive (for a fast telephoto prime) is the availability of the 70-200 f2.8L. since the zoom lens has the same speed as the prime, the need for a prime is diminished quite a bit. when the 70-200IS came about, the 200 prime was pushed further back. if the 200L was a higher cost than the 135L, it would begin to encroach on the 70-200's price range, and for a few hundred dollar difference, most would get the zoom instead of the prime. if you want to compare prices, compare the 135 f/2 with the 200mm f/1.8 (discontinued). roughly the same speed, but 65mm difference. that difference cost over 3k more (when it came out)

[kevbailey]

I have to throw in my 2 cents. Being in optics, I have a slight different understanding of glass and the characteristcs of refraction through a lens. In order to achieve these crystal clear images, the light is doing all sorts of things inside of that tunnel we call the lens. Light, when refracted has a tendency to split, as the ends of the light ray, red & Violet like to drift away from the rest of the pack, so to speak. If you're moving light and bending it 18 times, through different refractive indexes, your slowing it down considerably, and literally changing the direction of it's travel with every lens. While the very center of every lens has an optical center (point where light passes through without bending, the edges of the lens are moving light aggresively. Take a standard magnification lens and hold it up over a grid and you will see the center in proper proportion, however as you move towards the edge of the lens, that grid starts to deform, or take a different shape. Now do this through a series of different lenses at different refractive strenghts and you are going to have some really distorted images. The R&D of these lenses are pretty amazing in that they can offer the quality and full image refraction without distortion and with no percievable chromatic abberation.

Now adding twice as much light at the end of tube, which is 1 stop, a 2.0 instead of 2.8, becomes a major challenge in that all of the problems they face with a smaller diameter lens becomes increased exponentially. In order to make a lens bigger diameter, you now increase the thickness of the lenses inside the system, which slows down the light more and causes more C.A.. Also the different types of glass used have different abbe values which creates an entirely different set of problems in term of both CA and IQ.

To get that red line on a lens like the 135/2.0 took millions of dollars, and i'm sure much more time to develop than the 200/2.8

Magnification is not difficult to acheive. It's the requirements of that magnification that cost the money. Lots of light, high contrast, Perfect I.Q. from edge to edge and no color loss or seperation, and oh yeah lots of light.

[ed rader]

The 135mm focal length became so popular BECAUSE in the early days (sic - think 1930s to 70s) it was easier to make a good lens at that focal length but harder to make good longer ones and shorter ones were not really considered to be telephotos (rather they were long-focus ones - like 85mm based on a stretched 50mm design). Every manufacturer had a good 135mm in the range.
For the record, I have a Pentax A* 135/1.8 which seems the equal of my 135/2 Canon - pity it doesn't fit, isn't AF......................


135mm was the standard short sports prime/portrait lens back in the day.

ed rader

[drbenjamin]

OK, since this thread is continuing, I'd be interested in people's comments. I've also been confused about the price diff between these two lenses. As we all know, the f stop of a lens is (in principle) the ratio of the diameter of its front element to its focal length. Given that 135*1.4-189mm it has always seemed to me that the 135 f/2 and the 200 f/2.8 are almost the same lens, in that the front elements should be the same size. I would have thought that all the geometric problems (i.e. the light path + fraction of the lens elements through which light passes) would be the same, and if anything slightly tougher for the 200mm.
I can see that for a fixed focal length it will be harder to make a lens that is brighter by one f stop, but in this case the gain in f stop (f/2. -> f/2.0) is compensated by a reduction in focal length (200mm -> 135mm). Am I thinking about this incorrectly? Is it easier to make a longer lens than a brighter one, given the same front element diameter?

[kevbailey]

The f/stop is a fraction to be divided, so on a 135 your aperture at 2.0=67.5mm, where a 2.8 aperture for a 200mm lens would = 71.4mm, close indeed, but your only talking about one aspect of the lens being similar. If you look inside of these two lenses you will find they are entirely different.
135:
Focal Length & Maximum Aperture : 135mm 1:2.0
Lens Construction : 10 elements in 8 groups
Diagonal Angle of View: 18°
Focus Adjustment: Rear focusing system with USM
Closest Focusing Distance: 0.9m / 3 ft.
Filter Size: 72mm
Max. Diameter x Length, Weight: 3.2" x 4.4", 1.7 lbs. / 82.5 x 112.0mm, 750g

200:
Focal Length & Maximum Aperture: 200mm 1:2.8
Lens Construction: 9 elements in 7 groups
Diagonal Angle of View: 12°
Focus Adjustment: Rear focusing system with USM
Closest Focusing Distance: 1.5m / 4.9ft.
Filter Size: 72mm
Max. Diameter x Length, Weight: 3.3" x 5.4", 1.7 lbs. / 83.2 x 136.2mm, 765g

[Jon]

Yes, it's easier to make a longer lens than a brighter one. As the aperture gets larger for any given focal length, the light rays have to be bent more to achieve a single point of focus. This requires more curvature of the lens, and thicker glass. Managing all this without introducing chromatic aberration, spherical aberration, and all the other possible nasties is what makes a fast lens of physical diameter X more expensive than a longer lens with the same physical diameter X. It's also why shorter focal length primes (and zooms as well, but they have other complications) get bigger - they need more, and bigger, lens elements to correct for these aberrations.

[cwphoto]

I would suggest that the price has more to do with market forces and less to do with engineering difficulties.

With a lens as superb as the 70-200mm f/2.8 L in the range the demand for 200mm f/2.8 must be pretty low - look at the choices I have made as an example.

I would only consider a non-zoom 200mm lens if it was faster (like if they brought back the f/1.8 L) or if the equivalent zoom wasn't up to par.

[genewch]

Yes, it's easier to make a longer lens than a brighter one. As the aperture gets larger for any given focal length, the light rays have to be bent more to achieve a single point of focus. This requires more curvature of the lens, and thicker glass. Managing all this without introducing chromatic aberration, spherical aberration, and all the other possible nasties is what makes a fast lens of physical diameter X more expensive than a longer lens with the same physical diameter X. It's also why shorter focal length primes (and zooms as well, but they have other complications) get bigger - they need more, and bigger, lens elements to correct for these aberrations.Good explanation. Could you explain more on the complications of short primes and zooms? Why a 24-70 f/2.8 is so big like a bull?

Marketing strategies may also contribute to the higher price of 135mm. Since the 70-200mm f/2.8 has the same aperture as the 200mm f/2.8, a more expensive prime would push consumers to go for the zoom instead.

[Jon]

In SLRs especially, short focal length lenses need to be what's called "retrofocus" designs. The opposite of telephotos (which are shorter than their actual focal length), they have to be this way because a true wide angle would need to protrude well inside the mirror box. They achieve this by starting with a diverging lens (or lens group) in the front, and converging lens (or group) further in. This extra lens group adds more aberrations which will need to be nullified somewhere along the way. Lenses like the 50 and 85 mm primes are basically what I'll call "native" lenses, they' don't rely on a diverging lens to achieve their final focal length. As a result they're a very straightforward design which is easily corrected, and can be offered relatively inexpensvely. The 24-70 needs to provide an f/2.8 aperture at 70 mm, which defines the maximum diameter, but it needs to accomplish this with a front lens group that can act as a strong negative element when you're at 24 mm, so you have to correct aberrations introduced by that group.