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How to Test LensA lens is the most important part of a camera. Here are some tips on how to test lens while purchasing. Lens is an engineering marvel, which is developed with advance optical design, mechanical movements, electrical and electronic components. This technology is further assist by refined chemistry, materialization and craftsmanship. However, it is a product for commercial sale. So it has to be manufactured in commercially viable manner, and that is where we find so many makes of lenses, which has same type of design and feature, but at different price.
For SLR and DSLR cameras, apart from original camera manufacturer, there are other lens manufacturing companies, which make lenses, which are compatible with the camera body. So whenever we are purchasing a new (or a used) lens, we must consider following parts for its quality and performance. By testing and understanding the lens and its limitations, we can take best out of it. All good lenses are made to perform best at all aperture settings, all focusing distance and if it is a zoom lens, then for all focal lengths. However, because of the limitations of physics and optical science, lens are bound to shift from optimum performance towards its average performance.
Lens testing is an experiment, which gives us experience and confidence on how to use a lens in most effective manner. Overall points, we must check, are: Aperture of lens: What we should check in aperture setting of a camera lens Built, finish and weight of a lens: Why finishing and weight of a lens is important Focusing mechanism of a lens: Different type of focusing mechanism of a camera lens Lens faults: Various types of faults a lens can have, and how to check it Other information on the lens: Indication and information given on a lens barrel Range of focal length: Range of zoom lens in terms of focal length Sharpness of lens: Resolution and lens contrast - how to test it Zoom ring: Ring on a lens barrel for zoom and focusing
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