Patent: Canon EF 100-400 f/4.5-5.6 DO

[rrcphoto]

So what is special about DO? I never really paid any attention to those lenses.

A DO lens element is able to bend light more sharply without introducing chromatic abberations. Canon's resin lens can do this, but it is apparently extremely expensive to build. They probably get a very small yield.
This equates to a very expensive lens, which is not going to sell, just to shave a little weight off.

it's not weight, it's size that it affects.

 

[Mt Spokane Photography]

So what is special about DO? I never really paid any attention to those lenses.

A DO lens element is able to bend light more sharply without introducing chromatic abberations. Canon's resin lens can do this, but it is apparently extremely expensive to build. They probably get a very small yield.
This equates to a very expensive lens, which is not going to sell, just to shave a little weight off.

it's not weight, it's size that it affects.

It affects length. That means less weight. The 400mm DO is shorter asnd much lighter, which makes it reasonable to handhold. The size and weight go together.

 

[mustafaakarsu]

So what is special about DO? I never really paid any attention to those lenses.

A DO lens element is able to bend light more sharply without introducing chromatic abberations. Canon's resin lens can do this, but it is apparently extremely expensive to build. They probably get a very small yield.
This equates to a very expensive lens, which is not going to sell, just to shave a little weight off.

it's not weight, it's size that it affects.

It affects length. That means less weight. The 400mm DO is shorter asnd much lighter, which makes it reasonable to handhold. The size and weight go together.

I just looked at Canon website,it says:

EF 400mm f/4 DO IS USM - 1,940g
EF 400mm f/5.6L USM - 1,250
EF 400mm f/2.8L IS II USM - 3850

It's significantly lighter than f/2.8 one, which is not a surprise when considering it's a f/4 lens, also its heavier than f/5.6 now I see no reason to buy DO lens unless its way too much cheaper.

 

[wsmith96]

So what is special about DO? I never really paid any attention to those lenses.

This is the idea behind diffractive optics, but at the moment it's more developed for sure.
http://en.wikipedia.org/wiki/Fresnel_lens

Thanks for the info!

 

[dufflover]

I just looked at Canon website,it says:

EF 400mm f/4 DO IS USM - 1,940g
EF 400mm f/5.6L USM - 1,250
EF 400mm f/2.8L IS II USM - 3850

It's significantly lighter than f/2.8 one, which is not a surprise when considering it's a f/4 lens, also its heavier than f/5.6 now I see no reason to buy DO lens unless its way too much cheaper.

No duh it's heavier (it can't defy basic physics like 400/4 = 100mm+ opening).
The better comparison is that it's a lot lighter than the aperture/light equivalent 300mm f/2.8L mk1 (2,550g).

The MkII is closer but I wonder what weight saving developments with these II's would make any DO lenses lighter too.

 

[AvTvM]

The MkII is closer but I wonder what weight saving developments with these II's would make any DO lenses lighter too.

I don't care for the DO stuff at all, I'd much rather Canon would come up with an excellent "regular optics" EF 400/4.0 L IS ... half the weight and a quarter of the price of the 400/2.8 L IS II.

 

[tron]

The MkII is closer but I wonder what weight saving developments with these II's would make any DO lenses lighter too.

I don't care for the DO stuff at all, I'd much rather Canon would come up with an excellent "regular optics" EF 400/4.0 L IS ... half the weight and a quarter of the price of the 400/2.8 L IS II.

The DO is half the weight of the 400/2.8 L IS II. A "regular optics" EF would be heavier. But yes, such a lens would be very popular.

 

[mustafaakarsu]

This video explains DO principles pretty good.
http://www.canon.com/v-square/movie.html?id=t005