Newbie question: What makes a quality high end lens?

[robscomputer]

Hi,

I'm still new to the high end lens and wanted to know what really makes a Canon L lens high quality. I have heard they have better dust seals for professional use, also higher quality coatings on the glass. Anything else I am missing? I also read they weigh much more than regular lens, is there more elements in a L lens?

What brought up this is my friend picked up a Nikon lens, I think 17-35 f/2.8 that is very heavy and big, I think with a 77mm filter? The lens is about twice as heavy as the regular 17-35 zoom and wonder how they differ in construction.

Guess i'm trying to justify spending money on them when the time comes. :)

Thanks,
Rob

[ubergeek]

Relative to non-L Canon lenses, the L's have




Ultra-low Dispersion (UD) glass and/or Flourite elements
more rugged, sealed construction
generally larger apertures
a pretty red ring around the barrel :D
The reason that L's are generally heavier than non-L's of similar focal lengths is partly because of the more rugged construction, but probably mostly due to the larger apertures. An f/2.8 lens lets in twice as much light as an f/4, which doesn't necessarily mean twice as much glass, but it definitely means more glass, and consequently more weight.

Note again that the differences mentioned above are relative to non-L Canon lenses. Other manufacturers produce lenses with similar (more or less) specifications, usually at a lower cost--whether the L's are worth the premium is often the subject of much debate. :D There is no question, however, that the L lenses are at the top of their class. If cost is no object, you can't go wrong with an L lens; if you're on a budget, you might get more bang for your buck with one of the alternatives.

Cheers,
Jeremy

[robscomputer]

Thanks for the great write up.

I tested out a few lens in the shops and the more expensive glass always impressed me with the focus speed. When photographing a motorcycle race I was having so many problems with my 100-300mm f/5.6 lens not keeping up with the motorcycles. Kept thinking my EOS 3 was not focusing correctly or the AI servo was having a problem. It was so bad I had to keep the focusing on single and then lock onto a point where the motorcycle would travel over.

Then I talked about this to a local shop and they let me test out the 70-200mm IR, it was a huge improvement in focus speed!

Thanks again,
Rob

[ubergeek]

Ahh yes, there's also the focus speed. I believe all (or almost all) Canon L's have the USM focus motor, offering some of the fastest focusing around. But some non-L's have USM as well, so it's not exclusive to the top-tier lenses. Sigma also offers a similar technology, which goes by the name HSM, in some of their lenses. (So far I think Sigma is the only third-party lens manufacturer that offers such technology.) Finally, it's worth noting that there are some reasonably fast-focusing non-USM lenses out there, but all else being equal, a USM lens will focus faster than a non-USM one.

Cheers,
Jeremy

I tested out a few lens in the shops and the more expensive glass always impressed me with the focus speed.

[Khaos]

Yep the Canon 100 macro has USM and I would recommend it. Very sharp and a lot cheaper than the 180 L.

It does need a lot of light though. If it doesn't get it, the focusing hunts forever.

[pathfinder]

Canon's website lists UD ( Ultradispersion ) glass and Flourite lenses as two of the criteria to be called an L lens. Many of the lens barrels are of Magnesium also. And most have USM motors. L lenses all have the famous Red ring around the business end of the lens.
Interestingly the 24mm T&S is an L lens, but the 45mm T&S and 90mm T&S are not.

http://consumer.usa.canon.com/ir/controller?act=CanonAdvantageCatIndexAct&fcategoryid=156

Lots of interesting information here about Canon lens construction and what goes into their L lenses. Makes me appreciate them even more. :):

[Haifidelity]

The same reasons Toyota labels some of their cars "Lexus", Honda's "Acuras", BMW's Mx's, Mercedes AMG's...etc. ad infinum.