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Though lacking the cachet of “original” lenses, third-party lenses can get high marks from reviewers. The Digital Photography Review website rates the Sigma 50mm f1.4 as better than the Canon 50mm f1.4 for image quality and build quality (8.5/10 versus 8/10).
This article describes the factors to look out for when considering a third-party lens.
Specialized Zoom and Prime Lenses
Back in the pre-digital 35mm film camera days, Tamron was the first, and for a while the only, manufacturer offering 28-200mm super zooms with a high zoom ratio. For anyone wanting a super zoom, Tamron was the only game in town.
It is still possible for third-party manufacturers to stake out pioneering positions in some niches. 50mm f1.4 prime lens with aspherical element for superior image quality? Sigma. The Sigma actually costs more than the Canon and Nikon 50mm f1.4 lenses.
Another example: neither Nikon nor Canon offer 20mm lenses brighter than f2.8. Who sells a 20mm f1.8? Also Sigma.
Each manufacturer will have their own conventions
- direction to turn the lens for zooming in and out
- direction to turn lens for manual focusing
- method of switching auto focus off and on
Adding a third-party lens into the mix can be confusing, and is a good reason to avoid them. While it may seem like a small issue, it can lead to frustration and missed shots.
Lens Filter Size
Third-party lenses can have lens filter sizes that are incompatible with those from the original manufacturer. Photographers who use special effects and correction filters may have to buy additional filters because of this.
One solution is to standardize on large filters (say, 77mm) and mount them on the different lenses using step up conversion filter rings.
Lens Sample Variation
Different copies of the same lens model can produce images of different quality. This is due to small variations from lens to lens.
Original manufacturers have a better reputation for low sample variation. Checking Internet bulletin boards will reveal how a particular lens model fares in this regard.
Professional Quality Lenses
Some third-party lens manufacturers started out by offering cheap alternatives to the “real thing” (others positioned themselves as quality producers targeting professionals, from the start).
These third-party manufacturers have since created a professional quality (optical and mechanical quality) line of lenses. These can be as good, and as expensive, as lenses from original manufacturers. They will be specially named and marked, similar to the way Canon differentiates its L Series professional lenses.
Lens Resale Value
The resale value of third-party lenses is lower. Though initially more expensive, original manufacturer lenses can actually cost less when this is taken into account.
Original Manufacturer Compared With Independent Third-party Lenses
Third-party lenses can be better, or worse, than original manufacturer lenses. For cautious photographers, original manufacturer lenses are the safe choice.
Savvy photographers looking for a bargain or for specialized lenses, can find good lenses from independent manufacturers. A little research can turn up some gems, and help avoid duds.