The Bower 500mm f/8.0 Manual Focus Lens is a
catadioptric mirror T-mount lens, precision manufactured in South Korea.
When combined with the T-mount to fit your camera system, this mirror lens mounts to camera and works on both "full frame" cameras as well as the
"APS-C" style digital SLR cameras. T-Mounts are available for all the
digital SLR systems, as well as for C-mount systems. However, in every case the fixed f/8 aperture is not communicated to the camera body. As such, you can use the lens in "M" manual exposure mode or "A" aperture-priority mode only.
Despite this lens' long 500mm focal length, it has a compact 3 x 3.5" size and weighs under 1 pound, making it a bit easier to handle than normal 500mm refractor lenses (it should be used with a
tripod or monopod in any case). 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.
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!)
Features
Economical 30.5mm rear filter system
Compact and light-weight
This lens is an ideal candidate for astrophotography use when mounted to a Vixen GP2 Photo Guider (or other motorized equatorial telescope mount).
Fixed-aperture 500mm f/8 mirror lens in T-mount
Multicoated optics
Distinct out-of-focus highlight characterization
Excellent close focusing capacity
Accepts 30.5mm filters at rear of lens barrel
Made in South Korea
