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DPChallenge Forums >> Hardware and Software >> Why are fast lenses more expensive?
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12/10/2006 03:38:08 PM · #1
I know it sounds a silly question.
And therefore, there's probably a silly answer!
But what actually makes the lens more expensive.
Does more work have to go into making them, are there more parts, is the glass different?
What?
Somebody enlighten me with an ovbious answer.
Thanks.

12/10/2006 03:39:58 PM · #2
Here's the silly answer:

They cost more to make.

hehe.

Higher quality glass.. higher quality/more parts, labour is more intensive..

so yah, you nailed it.

However, I honestly don't belive that the extra cost in making them is as much as they actually charge... *THAT* is driven by the whole, "Because people will pay it." rule.
12/10/2006 03:42:54 PM · #3
Also, in order for a lens to gather more light, it needs larger glass elements. It's harder to machine larger pieces of glass.
12/10/2006 03:58:11 PM · #4
Just for thought...

If Canon, Nikon, Sigma, etc... produced a 80-200mm f/2.8 lens and sold it for $140, would anyone take the lens seriously and covet that lens? My guess is no.
12/10/2006 04:03:46 PM · #5
Remember that in order to make a lens 1 stop faster, you have to double the area of the front element. Double the area means more than double the glass (elements will also be thicker) and it all must be made to tolerances at least as tight as it's "slower" cousins. This is not a trivial matter. If you think fast lenses are expensive, price a fast refracting telescope (essentially a fast, APO telephoto but without aperture control or AF). High-quality units retail for thousands; prices are in fact pretty similar to super-telephotos of similar physical aperture (front objective size).
12/10/2006 04:09:48 PM · #6
One statistic that I have seen in the past is that cost of producing a lens increases as the cube of the diameter. i.e. doubling the diameter of a lens costs 8x more. It is just harder to produce high quality large optical glass.
12/10/2006 04:11:51 PM · #7
In my opinion it's because people are prepared to pay more for it.

I'm sure the production costs to produce a 'fast' lens are fairly minimally more than that of producing a normal lens.
But it people are willing to pay more, then manufacturers will certainly charge more.
12/10/2006 04:13:28 PM · #8
Originally posted by UNCLEBRO:


But what actually makes the lens more expensive.
Does more work have to go into making them, are there more parts, is the glass different?
What?
Somebody enlighten me with an ovbious answer.
Thanks.


because they is more gooder ;-)
12/10/2006 04:13:45 PM · #9
Generally faster=more expensive, but the cheapest cannon lens made (that I know of) the 50mm f 1.8 is practically as fast as it gets, and reasonably sharp, so I'm not sure what makes it different from other fast lenses (besides being prime, no USM, etc)
12/10/2006 04:23:59 PM · #10
Originally posted by Quickshutter:

Generally faster=more expensive, but the cheapest cannon lens made (that I know of) the 50mm f 1.8 is practically as fast as it gets, and reasonably sharp, so I'm not sure what makes it different from other fast lenses (besides being prime, no USM, etc)


The difference is that aperture is a ratio of shutter opening to focal length. In other words, it takes less glass to make a fast short lens than it takes to make a fast long lens. A prime is also much less costly than a zoom.

While you are correct that the 50mm/1.8 is less than $100, it's big brother the 50mm/1.4, just one stop faster, is over $300.

~Terry
12/10/2006 05:15:21 PM · #11
Originally posted by Kerm:

In my opinion it's because people are prepared to pay more for it.

I'm sure the production costs to produce a 'fast' lens are fairly minimally more than that of producing a normal lens.
But it people are willing to pay more, then manufacturers will certainly charge more.


Sounds like you need to set up a manufacturing plant building some cheap, high quality fast zoom lenses.
12/11/2006 02:23:41 PM · #12
The speed is one issue, but faster lenses are (in general) better quality lenses--they don't distort as much, have less barreling/pincushioning, have less chromatic abberation, have better build quality, faster A/F motors, etc. The front of the lens barrel doesn't rotate and sometimes doesn't move in and out. Sometimes the focus stays the same when you zoom a better lens (see parfocal lens).

So you do have more glass in the lens (as everyone has pointed out) and that glass is heavier (its taller, wider and thicker, so there's a cube relationship). The heavier glass needs heavier duty AF motors, which have to be faster. And these motors generally allow the user to manual focus in AF mode. The lenses' tolerance have to be more precise over a wider lens. And different elements have to be added to correct the chromatic abberation. L glass generally comes with lens hoods, and sometimes tripod mounts and lens cases.
12/11/2006 02:32:24 PM · #13
You can have good.
You can have cheap.
You can have fast.

Pick any two.
12/11/2006 02:34:04 PM · #14
Originally posted by ClubJuggle:

Originally posted by Quickshutter:

Generally faster=more expensive, but the cheapest cannon lens made (that I know of) the 50mm f 1.8 is practically as fast as it gets, and reasonably sharp, so I'm not sure what makes it different from other fast lenses (besides being prime, no USM, etc)


The difference is that aperture is a ratio of shutter opening to focal length. In other words, it takes less glass to make a fast short lens than it takes to make a fast long lens. A prime is also much less costly than a zoom.

While you are correct that the 50mm/1.8 is less than $100, it's big brother the 50mm/1.4, just one stop faster, is over $300.

~Terry


Also normal lenses require far fewer elements. Even the slower wide angle primes are more expensive, because they require more glass, gather more light and are just harder to get sharp focus across the whole focal plane.

The 50mm 1.8 is also made out of plastic while the 1.4 has much better build quality.

Message edited by author 2006-12-11 14:35:19.
12/11/2006 02:34:09 PM · #15
Originally posted by Gordon:

You can have good.
You can have cheap.
You can have fast.

Pick any two.


I've heard that before :-)
12/11/2006 02:36:44 PM · #16
Originally posted by fotomann_forever:

Originally posted by Gordon:

You can have good.
You can have cheap.
You can have fast.

Pick any two.


I've heard that before :-)


The twist with lenses is the double meaning of fast.

That canon 50 1.8 might be good, cheap and have a wide aperture, but it sure isn't 'fast' to focus ;)

So you get to pay for 'fast' twice, once with aperture, once with performance. I was really surprised with how much the camera has to do with AF speed though. I shot a 70-200 F4L on a 1DII, 20D and D60 a while ago. The focus speed of the same lens on each camera was very different. The 1DII blew away the 20D in how quickly it would lock on. I thought it would have been largely to do with the motors moving the lenses around.

Message edited by author 2006-12-11 14:38:38.
12/11/2006 02:43:07 PM · #17
i always wondered how people could spend $5000 on a Rolex-
it doesn't even take pictures.
12/11/2006 02:55:11 PM · #18
I'm not sure I buy the argument about diameter, at least in its relationship to speed (which was implied above). The 50/1.8 is only, what 52mm? Both the 17-40 and 24-105 are f/4.0 and are 77mm.

I think the cost comes from the tolerances required over a larger portion of the lens. It also comes from the generally improved workmanship in the build and the extras that come with it. Kirbic mentioned the 50mm/1.4 is $300 compared to the 50mm/1.8, but the 1.4 also comes with USM and a much better build.
12/11/2006 02:56:57 PM · #19
without hijacking the tread, i have another very silly question: could somebody please explain what constitutes a 'fast lens'? is it anything to do with apertures? also what are the advantages of a fast lens? sorry if this is very basic, its just that i've been wondering for a while
12/11/2006 02:59:02 PM · #20
becasue we are willing to pay for it, no other reason.
12/11/2006 02:59:33 PM · #21
Originally posted by andersbs:

without hijacking the tread, i have another very silly question: could somebody please explain what constitutes a 'fast lens'? is it anything to do with apertures? also what are the advantages of a fast lens? sorry if this is very basic, its just that i've been wondering for a while


Fast does mean a bigger aperture so as to allow you to shoot a faster shutter speed with the same amount of light compared to a "slow" lens. I think generally "fast" is associated with an aperture of 2.8 or lower.

One misconception that sometimes creeps up is that at the same aperture a "fast" lens can shoot at higher shutter speeds compared to slower lenses. This isn't true. At f/8 a 50mm/1.8 and a 50mm/4.0 (if there was such a thing) would shoot exactly the same.
12/11/2006 03:01:11 PM · #22
Originally posted by DrAchoo:

Originally posted by andersbs:

without hijacking the tread, i have another very silly question: could somebody please explain what constitutes a 'fast lens'? is it anything to do with apertures? also what are the advantages of a fast lens? sorry if this is very basic, its just that i've been wondering for a while


Fast does mean a bigger aperture so as to allow you to shoot a faster shutter speed with the same amount of light compared to a "slow" lens. I think generally "fast" is associated with an aperture of 2.8 or lower.

One misconception that sometimes creeps up is that at the same aperture a "fast" lens can shoot at higher shutter speeds compared to slower lenses. This isn't true. At f/8 a 50mm/1.8 and a 50mm/4.0 (if there was such a thing) would shoot exactly the same.


thanks for the quick reply! all is now clear
12/11/2006 03:02:28 PM · #23
Originally posted by PhantomEWO:

becasue we are willing to pay for it, no other reason.

Thank you.
12/11/2006 03:10:51 PM · #24
Originally posted by Kerm:

Originally posted by PhantomEWO:

becasue we are willing to pay for it, no other reason.

Thank you.


Only a fool really believes that.
12/11/2006 03:45:07 PM · #25
Originally posted by DrAchoo:

I'm not sure I buy the argument about diameter, at least in its relationship to speed (which was implied above). The 50/1.8 is only, what 52mm? Both the 17-40 and 24-105 are f/4.0 and are 77mm.

I think the cost comes from the tolerances required over a larger portion of the lens. It also comes from the generally improved workmanship in the build and the extras that come with it. Kirbic mentioned the 50mm/1.4 is $300 compared to the 50mm/1.8, but the 1.4 also comes with USM and a much better build.


That's the filter / front element size (though the 50mm 1.8 doesn't have a 52mm front element, because it doesn't need one other than 'air') but it is still the front filter size and the front element used to gather light.

The maximum aperture diameter for the 50mm is 27.8mm and the maximum aperture for the 17-40 is 10mm (interestingly the diaphragm has to change size to maintain that constant f4 - that's part of the reason why fixed maximum aperture zoom L lenses are so complex/ expensive too.)
10mm diameter at 40mm focal length, 4.25mm at 17mm focal length; both F4. Remember that f-stops are just the ratio of aperture diameter, to focal length. So if the lens zooms (changes focal length) and the f-stop stays the same, then the aperture has to change dynamically)

Cheaper zoom lenses don't do this, which is why you get things like f4/f5.6 - the aperture doesn't change, but the focal length does, so the maximum f-stop when zoomed in is lower, because of the changed focal length but constant aperture diameter. You pay more for constant f-stop lenses, so that your zooms don't slow down when you zoom in.

The uberexpensive 1200mm f5.6 has a wide open aperture diameter of 214mm

21cm. Over 8 inches that it focuses the light through. No wonder it has a front element that looks like a dinner plate.

Message edited by author 2006-12-11 15:50:42.
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