Comments on: Lens Patents

By: Heavybarrel

Heavybarrel — Thu, 14 Jan 2010 21:57:49 +0000

Why else would you blow all that money on lenses!? haha

By: Son of Daguerre

Son of Daguerre — Sun, 10 Jan 2010 19:49:20 +0000

Or if you are physically disabled and can’t lift such heavy lenses…

By: Paul

Paul — Sat, 09 Jan 2010 16:04:34 +0000

Hey, he’s got his priorities in the right place, regardless of the type of parties he goes to!

By: Carsten

Carsten — Sat, 09 Jan 2010 09:10:05 +0000

Yes, DO is just another name for a Fresnel lens – the same thing used in lighthouses since decades, but pushed to much better image quality. When you look at the cross section of a DO element (in the patents or in Canon’s description of the 400 f/4 DO), you see a sawtooth-like structure. The quality of the image will depend critically on the details of the “teeth”, in particular, on how sharp you can make the edge.

I would expect that DO elements are easier to make for long focal lengths – the shorter the focal length, the steeper the “teeth” become towards the outside of the lens. For the same reason, they are easier to make for moderate apertures, i.e. a 400 f/4 is much easer to make than a 400 f/2.8.

By: Fireice

Fireice — Sat, 09 Jan 2010 06:49:10 +0000

“To make a lens smaller and lighter, the spacing between the elements is shortened and the refractive properties of the front and rear lens groups are made more pronounced. This, however, results in increased chromatic aberration. To resolve this problem, the Multi-Layer Diffractive Optical Element is located within the lens to cancel out the occurrence of chromatic aberration. Compared with conventional super telephoto lenses, the prototype EF 400mm f/4 DO IS USM lens, measuring 233 mm in length, is about 26% shorter and, weighing 1,930 grams (including the 140 gram tripod collar), about 36% lighter. ”

It does help reduce the weight. As you grow older, lighter lenses are welcome.

By: Scalesusa

Scalesusa — Fri, 08 Jan 2010 23:39:12 +0000

Another rather nasty property of plastics is for it to darken with age and heat cycling. Some plastics last longer, but its always a tradeoff, you can’t have everything you want.

I have a large plastic lens from a B25, made in the 1940′s still in its original crate. Its absolutely beautiful, crystal clear with no darkening. As near as I can tell, searching parts lists and drawings, it was a test item and never went on production B25′s. It is a very interesting relic though. I hate to think what something like this cost in today’s dollars.

By: Victor

Victor — Fri, 08 Jan 2010 23:10:30 +0000

That 300mm f/2.8 diagram looks suspicious to me. The second element looks too strong (too short of focal length).

By: Jim Allen

Jim Allen — Fri, 08 Jan 2010 22:46:06 +0000

I have the current 400mm F/4.0 DO IS lens and love it. It is (relatively) short and light, and I’ve had excellent results with it. Seems to me that the bokeh complaints are from people who haven’t used the lens. As you go up in the higher telephoto ranges, the background bokeh is affected at least as much by atmospheric conditions as lens character, as your subjects are typically farther away. I shot this photo of a grizzly bear in Alaska last year with the DO lens and am very happy with it. Check it out – http://www.flickr.com/photos/26317521@N00/3726024358/sizes/l/

By: Freeze_XJ

Freeze_XJ — Fri, 08 Jan 2010 21:17:28 +0000

Why it’s so expensive? It’s new tech, Canon wants to get development costs back, while slowly trying to evolve production of these lenses. The first of these will be incredibly expensive, and then, when they get the hang of it, they can lower production cost (yields go up), and add more DO lenses. Until then, you’ll be paying through your nose for one.

By: Freeze_XJ

Freeze_XJ — Fri, 08 Jan 2010 21:14:36 +0000

DO lenses are harder to make i believe, and if they have so much trouble with a 400 f/4 DO, i think they just keep the technology in production to develop, but don’t expect to sell many lenses with it (explaining the incredibly high price). If i am correct, DO lenses look like a Fresnel lens, so they are grooved. Doing something like that to a 800 mm lens might result in too much disfigurement, and doing it for a 100 mm lens may not yield enough results. (if i look at Canons own site, it looks like it’s a triple lens, with the middle being the DO part. Making that in a 15cm wide plate of glass might be too much at the moment)

So far their choices have been defensive at least (400/4 is right between the cheap, and light 5.6 and the expensive, razor sharp, but heavy 2.8), and until Nikon or Sigma produces DO stuff, i think it’ll stay that way.

By: J

Fri, 08 Jan 2010 20:06:05 +0000

Lighter and smaller professional lenses are always nicer, especially if you do air travel at all.

Bring on the plastic!

By: ms

ms — Fri, 08 Jan 2010 19:44:49 +0000

well if they manage to make plastic elements perform as well as the fluorite then this is going to be a revolution (especially if they pass on the savings to the consumer). I’d love to see a 500/4 L IS plastic that at least matches the current lens… DO…meh, don’t mind the extra size as long as I get the bokeh and contrast of the traditional lens… if they can get DO lenses to match them then that could be cool though frankly if I had to choose between size and cost, Id go for cost as long as optical performance was identical (big hypothetical)

By: popo

popo — Fri, 08 Jan 2010 19:34:29 +0000

Good point. Everyone stuck an L on the end of this one and I got swept away by it too.

But we can still all dream of more affordable L lenses :)

By: Nick

Nick — Fri, 08 Jan 2010 19:17:11 +0000

what parties are you attending??? lol