The Fresnel or the Phase Fresnel lens is the technical name for the diffractive lens. It would appear alien to the high-quality stills photographers. What do you understand about the appearance using a diffractive lens? It would be pertinent to mention here that when you examine a refractive lens element, you would come across a smooth and polished surface. It would be precisely what you might expect in a lens. However, the Fresnel lens might come up with low-quality versions, such as in the rear-view magnifiers in commercial vehicles and cars. It could be seen in lighthouse projectors as well.
Rest assured that a diffractive lens would be manufactured of concentric rings having a saw-tooth profile. The Fresnel lenses have been used for high-quality precision optics inclusive of replacements for both natural lenses in cataract surgery and high quality, professional photographic camera lenses. The DSLR systems of the top companies use Fresnel optics. The lenses could be easily identified by the diffractive optics or DO designation or search for the description Phase Fresnel or PF. The approach has been based on the diffractive optics, despite using the Fresnel design.
Diffractive optics comes equipped with two major benefits.
- The foremost benefit would be the ability to reduce the weight and size of the camera lens. It would be pertinent to mention here that the diffractive elements in the lens have been relatively thin and lightweight. It would work by the refractive elements for reducing the physical size of the optical path.
- The second benefit would entail the Fresnel lens independently not eliminates chromatic aberration or CA. The phase of the aberration could be relatively different from that of the refractive elements. Therefore, it would be designed carefully to help cancel each other. It would be in your best interest to understand that the diffractive optics lenses would exhibit excellent control of chromatic aberration.
However, there have been certain disadvantages involved as well.
- The higher cost would be partly due to the increased challenges faced by the manufacturing procedure.
- The optical quality control has been deemed difficult as well.
- Contrast and light-transmission efficiency have also been deemed behind conventional refractive optics.
However, with the favorable trend of having a less bulky and lightweight photographic gear, diffractive optics have been highly likely to be the more popular accepted option for the contemporary photographer. It would be in your best interest to use the one suitable for your specific needs.