I have a Canon 10D and I'm looking at different lenses and lens brands. Is there a significant quality difference between the Canon, Sigma or Tamron lenses, or does it depend on the lens category you're looking at? For example, the 24-70 f/2.8 (or something equivelent).

 

I tend to like the the canon lenses with my rebel. Im a label whore when it comes to the high end shit im gonna purchase. I have a sigma 10-20 instead of the canon 10-22....at the time i was short on cash but I accually just sold it to pick up the canon 10-22. With the canon glass you get the 'L' series wich is a better glass and has florite in it. Canon also features the IS option on most of its L glass and a few usm lenses.

As for the 24-70...I would say go with the canon. Its an L lens and its a quick (light gathering) lens. Im not sure what sigma or tamron has to offer in that focal length but i know they wont have the quality as the canon lenses. Dont forget, even tho the sigma or tamron might be the same focal length and possibly same f stop (or a stop or 2 slower) and be cheaper... you're not getting the same quality in the lens. I say save the few extra pennies and get the canon lens. Plus the resale values are better. Thats the next lens I get to replace my kit lens or i might go with the 18-55 f/2.8 is...we shall see

good luck!

 

there can be a significant quality difference. Consider that companies like Tamron and Sigma exist to sell cheaper zoom lenses than the OEM offerings. That doesn't mean every lens from Sigma and Tamron is crap. Some lenses from Canon are crap. Sigma and Tamron do make high quality lenses, but they are priced closer to the OEM models.

Like you stated, you really need to compare lenses by focal lengths. If the price disparity is large, there is probably a reason. One caveat is that really fast primes (non-zoom lenses) are really expensive, but the image quality is rarely as good as a slower and cheaper version. You are paying for the maximum aperture in that case, not image quality. The same probably holds true for zooms to a certain extent. If you want a fast lens or maximum image quality, you are better off with fixed focal lengths over zooms, anyway.

 

it does depend on the lens category (ultra wide, wide, telephoto... then you add in if it's a zoom or prime). for the most part, the Canon L lenses are superior to the third party glass but there are a few L lens that aren't worth the price tag.

If you use an L glass and a third party lens, you'll definately be able to tell the difference in build quality. Most who purchase L glass will rarely go back to a Sigma or Tamron lens. The USM AF mechanism on Canon lenses is much quieter, faster, and more accurate than the competition. 98% of the L lenses are also weather sealed, so when mated to a 1D series body, you can go play in the sand and not worry.

 

I agree with a lot of whats been said except the fact that own brand manufacturer lenses are always better. Look at the range you are going to buy and read up as much as possible, Sigma, Tamron etc. do better(and different) offerings sometimes. Sigma Tamron etc. don't have so much kudos so you do get better value generally.

One things to note when you do buy a third party lens is the quality seems to generally be more variable so test it to see if its a good sample and send it back if it isn't.

Personally I shoot a mixture of brands..

 

This is contradictory and wrong. Fast primes = Fixed focal length with large max aperture.

Fast Primes / Fixed focal length lenses can be some of the cheapest lenses you can buy 50mm f1.8 for example. These lenses are usually exceedingly sharp, contrasty and suffer little distortion. This is due to simple construction being of only fixed focal length.

Long Telephoto primes with large apertures are extremely expensive. Long telephotos zooms with large apertures are also extremely expensive and rarely offer the same aperture as the primes.

Primes usually offer better image quality than zooms and faster lenses usually offer better image quality over slower lenses.

Try reading www.photozone.de for lens reviews and look at ww.dpreview.com

 

this is typically wrong. In fact, the only case where it is widely considered true is the Zeiss Tessar 50mm/1.5 vs. the Tessar 50mm/2. The 1.5 version of the lens is considered perhaps the finest 50mm ever, which is saying alot as 50mm lenses are pretty much the best from any maker. Slower lenses offer better image quality with less distortion and more contrast. Increasing the maximum aperture typically increases the various kinds of distortion and reduces contrast.

The only thing faster lenses are typically better at is taking photos in lower light with acceptable shutter speeds, and reduced depth of field. What you pay for with faster glass is capability, not image quality. Companies like Canon hype their expensive lens series as "the best," but in reality, it is only because their slower glass is pretty crapppy build-wise. Most people would not be willing to shell out big bucks for Canon L glass if Canon told them the non-L lenses actually take better images.

I typically use sites like photo.net and rangefinderforum.com for lens info, as there is a wider knowledge base and discussion of lenses that weren't specifically designed to be mounted to a consumer DSLR (or any DSLR, for that matter). I particularly avoid "lens reviews," as they are not very useful, IMHO. Far more informative are examples of photographers' work. There's much more to a "good lens" than MTF charts and test shots. And a person sharing their experience with various lenses over time trumps the articles written by reviewers with only a few days in a lab with the lens, IMHO.