# What happened to the DO lenses?



## NiceShotSteve (Feb 27, 2012)

If memory serves me correctly, Canon produced two DO (diffractive optics) lenses: 400/4 IS and 70-300/4.5-5.6 IS. The zoom is still current but no more DO lenses have been announced since those original two. The DO design was highly touted at the time, but seems to have been forgotten/shelved (?). Does anyone know why? Was it primarily IQ, manufacturing tolerances, slow sales, or-? (I'm new to the Forum, so apologies if this subject has been raised before.) Thanks in advance.


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## AvTvM (Feb 27, 2012)

NiceShotSteve said:


> If memory serves me correctly, Canon produced two DO (diffractive optics) lenses: 400/4 IS and 70-300/4.5-5.6 IS. The zoom is still current but no more DO lenses have been announced since those original two. The DO design was highly touted at the time, but seems to have been forgotten/shelved (?). Does anyone know why? Was it primarily IQ, manufacturing tolerances, slow sales, or-? (I'm new to the Forum, so apologies if this subject has been raised before.) Thanks in advance.



DO = sub-par IQ. Not enough resolution and rather poor Bokeh (onion structure in specular higlights). 
-> http://www.photozone.de/canon_eos_ff/540-canon70300f4556doisff?start=1

With the 70-300 IS both L and Non-L Canon themselves have proven "regular optical formulas" to be superior to exotic diffraction-elements will deliver far superior IQ at significantly lower prices (at least with the 70-300 IS Non L). In addition, the DO size advantage over regular lenses is not really huge. 

Unless they really improve DO-lenses a lot and slash their prices a lot, DO lenses will vanish from the face of earth and will not be missed.


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## Isurus (Feb 27, 2012)

Long-story-short, the trade off of image quality for smaller form factor isn't worth it. The form factor really isn't all that much smaller and the optical design results in weird bokeh and lower contrast. To top things off, they are expensive.

I've used the 70-300 DO lens and found it to have unacceptable image quality for the price. I wanted to like it, but couldn't.


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## Mt Spokane Photography (Feb 27, 2012)

DO lenses have not had much customer acceptance. They have given it a new name, radial refractive optics.

They have not gone away, just changed their name.

They vary the refractive index radially just as a DO element does, except they are resin (plastic) with nano particles in them and are custom designed for each lens. Expect to see them in many new lenses, they can allow a lens to be smaller with less CA.

http://www.canonrumors.com/2012/01/patents-24mm-f2-8-50mm-f1-2-300mm-f4/

Descriptionescription 

Title of Invention: OPTICAL SYSTEM AND IMAGE PICKUP APPARATUS USING THE SAME 

Technical Field 

[0001] The present invention relates to an optical element using a nanocomposite material and, particularly, to an optical system suitable for an image pickup system and an eyepiece system. Background Art 

[0002] It has heretofore been known that an effective aberration correction is attained by providing a lens with a desired refractive index distribution (gradient refractive index). Particularly, a radial-type refractive index distribution in which a refractive index is changed depending on a distance from an optical axis of the lens achieves a light collecting action by the refractive index distribution and exhibits a great effect on the aberration correction. 

[0003] U.S. Patent No. 4,457,590 discusses a single lens having the radial-type refractive index distribution. The refractive index of the single lens changes according to a fourth-order power series expansion formula depending on the distance in a radial direction from the optical axis, thus correcting spherical aberration and coma aberration well by maintaining coefficients of the power series expansion formula to desired values. 

[0004] U.S. Patent No. 5,359,456 discusses an example of using a lens having the radial- type refractive index distribution as a part of an endoscope objective lens. The lens includes, in order from the object side, a front group divergent system having a negative power and a rear group convergent system having a positive power, and at least one of the divergent system is a gradient index lens. 

[0005] U.S. Patent Application Publication No. 2008/0239510 discusses an optical element using a nanocomposite material obtainable by mixing an optical resin (base material) with minute particles (nanoparticles). It is discussed in U.S. Patent Application Publication No. 2008/0239510 that a nanocomposite resin material of which a refractive index is improved by the nanoparticles is suitable as a high refractive index material. 

[0006] In U.S. Patent No. 4,457,590, U.S. Patent No. 5,359,456, and U.S. Patent Application Publication No. 2008/0239510, although it is discussed that minute particles of metal or the like are mixed with the base material for attaining a distribution of refractive index or improving the refractive index, it is not discussed that the minute particles are mixed for the purpose of attaining a distribution of Abbe number. 

[0007] U.S. Patent No. 5,366,939 discusses an example of forming a distribution in which Abbe number is increased along with an increase in refractive index by distributing a first metal species with a gradient and distributing a second metal species substantially flatly in a medium. 

[0008] However, since Abbe number variation Dvd attained with the configuration discussed in U.S. Patent No. 5,366,939, which is 3.1, is small, a chromatic aberration correction effect thereof is not sufficient. Citation List


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## eos650 (Feb 27, 2012)

I have a friend that sold his 70-300L and purchased a 70-300 DO. I was shocked, when I heard that he had done this. I've been meaning to ask him why and if he is happy with the swap as I'm really curious.

I have the 70-300L and wouldn't consider the DO based on what I've heard, which basically mirrors what has already been posted above.

Another thing that has always bothered me about the DO lenses is that they are generally slower than their approximate L-Series counterpart. I would expect a slower lens to be smaller and lighter, DO or not.

Examples of how DO lenses are slower:
70-300 f4.0-5.6 L
70-300 f4.5-5.6 DO (1/3rd stop slower on the wide end)

400 f2.8 L
400 f4.0 DO (1 stop slower)


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## Michael_pfh (Feb 27, 2012)

Well, at least the 400 F4 DO has its justified place in the Canon lens set-up being a lightweight super telephoto lens. I tried it once at my local Canon dealer and was amazed how light it is compared to the 400 F2.8L which obviously is a stop faster. For a good price I would consider getting a used copy of the 400 F4 DO as a travel super tele well knowing that the IQ and contrast could not put up with its big L brother...


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## eos650 (Feb 27, 2012)

My point being how much does the DO, with all of it's short comings actually reduce the weight and cost? If Canon made a 400 F4.0L, it would be significantly lighter and less expensive than the 400 F2.8L, also.

Here is comparison of two L-Series (Non DO) lenses, one at f2.8 and one at f4.0:
EF 70-200 f2.8L IS II - weighs 1490g, ERP $2499
EF 70-200 f4.0L IS - weighs 760g (Almost half the weight of the f2.8), ERP $1349 (Almost half the cost)

Here is a comparison of the 400mm L vs the 400mm DO:
EF 400mm f/2.8L IS II - weighs 3850g, ERP $11,499
EF 400mm f/4 DO IS - weighs 1940g (Again, almost half the weight of the f2.8), ERP $6469 (Almost half the cost)

It seems to me that if Canon made an EF 400mm f4L IS, it shouldn't weigh or cost much more than the DO, but with out all of the short comings of the DO. So what is the benefit of DO?

*Estimated Retail Price (ERP) and weight were taken from the Canon USA site.


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## Kernuak (Feb 27, 2012)

But if you compare it to the original EF 400mm f/2.8, that was around 5360g, looking at some places that still have them for sale, so it was a significant weight saving then. The new teles are quite a bit lighter than the originals.


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## jwong (Feb 28, 2012)

eos650 said:


> My point being how much does the DO, with all of it's short comings actually reduce the weight and cost? If Canon made a 400 F4.0L, it would be significantly lighter and less expensive than the 400 F2.8L, also.
> 
> Here is comparison of two L-Series (Non DO) lenses, one at f2.8 and one at f4.0:
> EF 70-200 f2.8L IS II - weighs 1490g, ERP $2499
> ...



Perhaps the best direct comparison between DO and non-DO is the 70-300mm. The DO (f/4.5-5.6) version weighs about 25 oz and the non-DO L (f/4-5.6) is 37 oz. The DO elements allow them to bend the light at a steeper angle and allows the lens to be shorter. Unfortunately, the current generation of DO lenses result in IQ hits.


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## neuroanatomist (Feb 28, 2012)

jwong said:


> Perhaps the best direct comparison between DO and non-DO is the 70-300mm. The DO (f/4.5-5.6) version weighs about 25 oz and the non-DO L (f/4-5.6) is 37 oz.



I disagree. The 70-300mm DO lens isn't weather-sealed, has a narrower max aperture at the wide end, and a different zoom design. Rather, I suggest the best comparison is the 400mm f/4 DO to the 400mm f/4L. Canon never produced the latter lens, but they did make a prototype for comparison with the DO version. The DO lens is 26% shorter and 36% lighter. More details, including pics of the prototypes, can be found here.


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## noisejammer (Feb 28, 2012)

I own and enjoy using a 400/4DO... 

It's lighter than a 300/2.8, it's sharp, the bokeh is quite fine (imo it's better than the 70-200 / 2.8 Mk II) and it takes a 1.4x tc really well. Another plus is that inside or outside focus, it has absolutely zero chromatic aberration - you cannot do this with a conventional lens. 

Now it's not the equivalent of a 400/2.8 but neither is it $12k or whatever insane price is being asked. The IS is fairly rudimentary by current standards, so that could do with some work. It's also damn expensive - which is why I suspect it never really took off.

I did play with the 70-300 DO and was completely underwhelmed. The build quality is poor in comparison with the 70-300 L (which recently has sold for a similar price.) I've seen reports of inconsistent image quality over the zoom range - I observed this in the one I played with.

If memory serves, Canon recently was awarded patents for a 200/2 DO and maybe a 600/4. It strikes me that DO is one way to eliminate coloured bokeh in fast lenses... so one of these years they may be all we can buy.


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