Bower 800mm f/8 Manual Focus Lens

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Bower 800mm f/8 Manual Focus Telephoto T-Mount Lens

review The Bower 800mm f/8 Manual Focus Lens is a catadioptric mirror T-mount lens, precision manufactured in South Korea.

Bower 800mm f/8 Manual Focus Telephoto T-Mount Lens Top ViewWhen 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 or for nearly any film camera. However, in every case the fixed f/8.0 aperture is not communicated to the camera body. As such, you can use the camera in the "M" manual exposure mode or the "A" aperture-priority mode (if your camera is so equipped).

This lens, at 4.4 x 5.2" 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.

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!)


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 800mm f/8.0 mirror lens in T-mount
Multicoated optics
Distinct out-of-focus highlight characterization
White lens barrel helps prevent heat retention
Accepts small, less-costly 30.5mm filters upon rear of barrel (also accepts 105mm filters)
Made in South Korea

Lens styleMirror
Max Format Size 35mm  
Lens focal length800mm  
Stabilization type No
Camera mount T-mount
Angle of view 2.6 x 1.7 (WxH)
1.7 x 1.1 (WxH) w/ APS-C (15 x 22mm) cameras 
Largest aperture opening Fixed f/8
Smallest aperture opening Fixed f/8  
Includes aperture ring Yes  
Total diaphragm blades  
Total Elements 8  
Number of Groups 8  
Coatings / special elements Multi-coating  
Minimum focus distance 11.5' (3.5 m)  
Autofocus type N/A
Motor No  
Full time manual focus Yes  
Focusing method    
Lens distance scale No  
Depth of field scale No  
Magnification 1:3  
Overall weight0.79 lb (360 g)  
Lens diameter 4.4" (111mm)  
Overall length 5.2" (132mm)  
Construction materials Composite / glass  
class="label">Lens ColorBlack  
Zooming method N/A  
Filter thread size Rear-mounted screw-in 30.5mm / Front 72mm  
Lens hood included No  

Lens Includes
Bower 800mm f/8 Manual Focus Telephoto T-Mount Lens
Front Cap
1-Year Warranty


Better than I expected

By Jeff from Ithaca on 3/3/2010

The lens has a much sharper focus than I expected and I've even been able to get some nice wildlife shots with it. Obviously there is no controlling the aperture with this lens, so make sure you want a F/8.

Not impressed at all

By Constantine from Cyprus on 2/10/2010

To begin with, I didn't expect a lot from a catadioptric 800mm lens at this price range. I don't usually shoot this kind of photo and I was looking for an occasional compact alternative to the 80-400mm with the teleconverter.

This lens is extremely soft. Comparing it to the 80-400mm at 400mm with a 2x teleconverter it's considerably softer. I find that its quality is about the same as a crop of a refractive lens at 400mm (that is resizing 2x an image made with a 400mm lens) and even worse.

To make things worse there is no tripod collar on the lens and even with a pro body the center of weight of the system is somewhere on the lens, thus becoming really unstable on a tripod.

I would pick any of the superzooms instead of this lens any day and either crop and resize or use a teleconverter.


Bower 800mm f/8 Manual Focus Telephoto T-Mount Lens

Bower 800mm f/8 Manual Focus Telephoto T-Mount Lens - Front Angle View

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