Buying a DSLR lens based on brand image ignores the range of quality levels often found within a brands range. Most lens manufactures offer range of quality levels from their premium lenses ignoring cost and convenience in search of optical and mechanical performance.
Then there are the budget class lenses aimed at more occasional photographers who put greater emphasis on price and convenience. This results in smaller, lighter lenses with greater zoom ranges and smaller maximum apertures.
There is a perception of the superiority of camera manufacturer’s lenses over specialist lens manufacturers. Often the specialists offer advantages to DSLR lens buyers in the form of price, smaller size, or better quality. Their budget offerings that compete on price often reinforce the belief that they only offer low quality products. However, many also offer premium interchangeable lenses with quality suitable for professional use.
Manufacturers Clues to Quality
Most but not all manufacturers give a clue where a particular lens sits in their quality hierarchy, these are some indicators of premium lenses;
- Olympus: offer two levels of premium quality High Grade and Super High Grade
- Canon: L series
- Sigma: EX
- Tamron: SP
- Pentax: * and Limited ranges
- Sony: G series and Carl Ziess designed
Nikon is the notable exception but price and specifications are a good guide to differentiate their budget from premium lenses.
Price – You Get What You Pay For.
The quality of lenses differs not only between manufacturers but also within their own lens ranges. This reflects the compromise between quality, convenience, and price.
Sometimes photographers base their lens buying decisions based on poor performance of the budget lens of one brand. They compare the budget lens with the professional image of the cameras manufacturer branded premium lenses and then buy a budget lens from the camera manufacturer. This ignores the spread of quality levels within a manufacturers range. If photographers want professional level quality then they need to pay a professional level price whatever brand of lens they choose.
Very often, the names of lenses consist of strings of strange letters and number. Some are reasonably self-explanatory and others require more explanation of what they are and why they could be important in your lens buying decision.
Remember the basic premise of this article is no single factor should be the only consideration in any lens buying decision. These specifications have varying importance to prospective lens buyers depending upon their individual photographic requirements.
APO (Aprochromatic )
This is when the lens elements produce the same amount of refraction on the different wavelengths, or colors, of visible light.
These letters are different lens manufacturers way of referring to low dispersion glass used in the elements of the lens. This relates to the sharpness of the resultant image.
A number follows this symbol indicating the maximum aperture size of the lens. The smaller the number the larger the aperture and the more light the lens can gather. It is only one number for a prime lens but some zooms have two, for example; f3.5-5.6 indicating the effective aperture becomes smaller as the focal length of the lens increases. Generally, the lower the f number the better the image quality of the lens. Zooms with the same effective aperture over their zoom range are usually better quality lenses.
USM, HSM, SWM
These refer to lenses with inbuilt autofocus motors. They usually operate faster and quieter than lenses where the autofocus system uses the motor in the camera body via a drive shaft.
Weight and Size
Maximizing the performance indicators in premium lenses usually results in larger and heavier lenses. In price conscious consumer grade lenses often the goal is to make them smaller and lighter without sacrificing too much image quality.