The making of a lens involves numerous steps, the first of which is the basic design. Determining the target users for any lens is the starting point in the basic design approach. Will the lens be used by working professionals and advanced amateur photographers or is the lens targeted for use by the general consumer? This criterion defines the level of performance necessary in various categories: optical performance; durability factors based on usage; and environmental changes due to typical areas where used.

Once the target market is determined it then becomes a matter of determining:

• Optical design approach
• Materials to be used (both optical and mechanical)
• How to process the mechanical components, i.e. by machining or by molding
• What type of AF interface to be employed in the case of auto focus lenses  

In approaching the optical design, there are certain basic patterns in lens design technique that have been established as a sort of "template" for conventional lens design separated by category of wide-angle, telephoto, and macro.

The optical glass materials used in lenses are available from a few manufacturers and quite often these companies supply the glass in the form of a "pressed plate", a sort of sliced glass plate. The glass elements are then sent through the initial grinding process using a machine called a "curve generator". Here the rough contour of the element is shaped which is either concave or convex.

As the grinding progresses and the elements are shaped closer to their final specifications, the polishing particles contained in the water to process the element surface get finer and finer toward the final stage. The speed of the curve generation and grinding can vary depending on the characteristics of the glass material itself and the diameter and contour of the lens element. Materials typically called LD (Low Dispersion) or AD (Anomalous Dispersion) glass require a longer processing duration due to the softness, fragility and oxidization of the materials. This explains the relatively high cost of lenses using LD or AD glass which is not only attributable to these factors but also to the higher initial cost of these materials. The higher price for these materials is justified, in any case, because the use of such high tech glass materials effectively reduces chromatic aberration.

Once the final polishing is done, the elements go through a centering process, which ensures perfect eccentricity of the individual elements. In other words, the circumference part of the elements is evenly ground to the optical axis. Another type of optical element used in the production of  lenses is called "Hybrid Aspherics" which is used to compensate spherical aberration, a form of optical noise resulting when light rays are broken by spherical elements and do not focus at the same point on the image plane. This loss of image quality can be eliminated to a great extent by means of aspherical elements (meaning elements which cannot be derived from a spherical form). The use of aspherical elements also effectively reduces the image distortion of a lens.

This is a compound method of bonding glass and resin materials to produce a lens element with a non-spherical surface. The formation of the aspherical surface onto the completed element is accomplished through the centering process.

After the elements are formed, the next stage is the coating process. This is one of the critical factors in lens production for which each company has developed its own proprietary technique. Coatings on the lens element serve the purpose of protecting the element itself from oxidization and preventing unwanted reflection.

Reflections not only reduce the light transmission of a lens (in every lens surface apx. 4% of the light is lost due to reflection), they are also largely responsible for decreased image contrast, diminishing the image quality of a lens considerably.

A multiple-layer coating technique is applied for optimum color rendition and maximum light transmission. In the meantime, Tamron has developed new "Internal Surface Coatings" (i.e., multiple-layer coatings on cemented surfaces of plural elements) to further reduce reflections and guarantee a higher image quality.

The barrel components and cosmetic parts are produced by a die cast method and/or machining process. Parts with carn grooves and helicoid are some of the most critical components of all since their accuracy largely influences the final quality and performance of the lens. Today, more and more of these parts are manufactured by an engineering plastic, ultra-high precision injection mold technique that yields high production efficiency.