Phoenix 800mm f/8 Mirror
Manual Focus Telephoto Lens
This Phoenix 800mm f/8 Mirror Manual Focus Lens is an ultra-telephoto lens that is incredibly compact and lightweight for its focal length. This is achieved by using a reflex design. This lens is ideally suited for wildlife and sports photography. It has a fixed aperture of f/8. The lens is adaptable to fit almost any camera lens mount using a simple T-mount adapter.
This lens, at 4.37 x 5.69" and just over 2 pounds, has a broad diameter and stocky build. It is a bit easier to handle than a normal 800mm refractor lens, but it is still a super-telephoto in any case (you should use a tripod/monopod in any case for best results). It also has a much different rendering of out of focus areas than a normal lens; highlights will be doughnut-shaped rings with more saturation and contrast on the edge of the ring than on the center.
Catadioptric lenses have several drawbacks. The fact that they have a central obstruction means they cannot use an adjustable diaphragm to control light transmission. This means the lens's aperture value is fixed to the overall focal ratio of the optical system (typically f/8 for 500 mm designs, or f/11). Their modulation transfer function shows low contrast at low spatial frequencies. The folded optical path does reduce the length of the lens, but increases its width.
Their most salient characteristic is the annular shape of defocused areas of the image, giving a doughnut-shaped 'iris blur' or bokeh, caused by the shape of the entrance pupil.
Several companies made catadioptric lenses throughout the later part of the 20th century. Nikon (under the Mirror-Nikkor and later Reflex-Nikkor names) and Canon both offered several designs, such as 500 mm 1:8 and 1000 mm 1:11. Smaller companies such as Tamron also offered their own versions. Of the major manufacturers, currently only Sony (formerly Minolta) offers a 500 mm catadioptric
lens for their Alpha range of cameras.
Samyang offers a variety of uniquely priced optics, delivering a lot of optical
capability for very little money. These rebranded catadioptric lenses are
available under the names of Bower, Opteka,
Phoenix, Rokinon, Sakar,
Vivitar and others.
Mirror lenses can produce pictures and under carefully chosen conditions they
may even produce pretty good ones. However, these situations are rare and therefore
most will have unsteady background blur. Most mirror lenses suffer from a rather mediocre optical performance. This may all be fine for personal purposes and for documentation but most likely you'll not be able to sell such pictures. Therefore a classic (refractive) lens like a 400/5.6 fix-focal or even a xx-500mm zoom
or even a 70-300-f/4-5.6 with a 1.4 or 2x teleconverter is usually a better and more serious approach. Nonetheless mirrors are quite cheap
(but you get what you pay for).
(To rephrase the paragraph above: Mirror lenses are Junk!)
• Angle of view of 3°
• T-Mount (a T-Mount adapter is required and sold separately)
• F8 fixed aperture
• 8 elements 8 groups