| Author: | | Pentaxian Registered: September, 2017 Location: South Wales Posts: 2,961 | | Review Date: January 12, 2022 | Not Recommended | Price: None indicated
| Rating: 5 |
| Pros: | Cheap, solidly made, lighter than an equivalent refracting lens | | Cons: | Soft-ish, small fixed aperture, T-2 mount, no camera body coupling | | Sharpness: 6
Aberrations: 7
Bokeh: 6
Handling: 4
Value: 8
Camera Used: K-1
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I have revised this review following a further chart test, replacing the test images. I managed to focus it more accurately than before - itself a comment on how difficult it is to focus, especially on a digital camera with no split prism or other aid except enlarging the live view.
My lens is branded Centon (they are quite common in the UK), but I believe it is yet another branding of this same lens, which someone said are all made by Samyang. The rubber focussing ring pattern is different, but I have seen variations in the pattern even with other Centons. The build quality is good.
Not the sharpest tool in the box, but inexpensive. It has a small fixed aperture, so the focussing is not easy in dimmer light. It fits on a K-1 without fouling the pentaprism housing. Despite the criticism it gets, I rather like the highlight dohnut bokeh.
Under 3 m the white focus scale changes to an orange macro scale. There is no particular change of internal configuration at this point and the maximum 1:2.7 macro ratio marking is accompanied by the minimum distance marking of 1.72 m. At the other end, the focus can be turned a little beyond infinity.
Mine was pre-used and cheap (can't remember the price) in a London shop some years ago. I did not then realise that it should come with a set of 30.5 mm filters that screw into the rear of the lens. It is also threaded for 72 mm at the front.
I have hardly ever used it. The atmosphere in the UK is too hazy for long range detail shots, and I'm not into wildlife or sport. Nevertheless I have just dusted it off, including taking it apart to clean fungus off the elements. I was relieved to find the mirror silvering is on the back of the glass (like a household mirror) rather than the front (like a SLR mirror) as I had assumed - so I could clean it safely. The big rear mirror drops out after unscrewing its retaining ring, but it is tricky to replace this ring as it has a large diameter and a very fine thread.
The A1 sized test chart shown below filled the frame at about 15 m, and the last picture is a 100% crop in a corner. I used a tripod and time delay. The shot is a bit soft, and vignetting is evident. At least there is no chromatic aberration; this is in the nature of mirror lenses where the principal focussing is by reflection rather than refraction.
I can get sharper extreme telephoto shots with my Sigma 70-300mm APO lens, and cropping to the same angle of view as the 500mm if I want. However, a mirror lens is interesting and this one is OK for not-too serious use
| | | | | | | Pentaxian Registered: February, 2014 Posts: 408 | | Review Date: August 10, 2019 | Recommended | Price: $30.00
| Rating: 8 |
| Pros: | very sharp lens, equal to the best mirror lenses I have ever used | | Cons: | none | | Sharpness: 8
Aberrations: 8
Bokeh: 4
Handling: 8
Value: 9
Camera Used: pentax K-S1
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Looking at the other reviews, it looks as though I got the only decent example ever made of this lens!
Picked it up from a local market, with a lens doubler, for very little-too cheap to leave on the stall. Popped it on my Pentax DSLR-and found it was far sharper than my Tamron 500mm that I have used for decades, plus fewer colour fringe issues. I then checked it against my Sigma 600mm, and a Pentax spotting scope just for fun. No comparison-blew them all out the water optically. Unfortunately I haven't had any chance to compare with my old, sharp, Russian MTO 500mm since I no longer have it and I only used that on film. Biggest advantage of this one over the MTO is that it weighs probably 80% less!
So if you see one going cheap, buy it. If its rubbish, not much lost. But if it works.....
Not had a chance to check with the doubler that came with it, but I doubt it will do anything other than degrade the image since I have never found any teleconverter that was satisfactory from a sharpness point of view ( although the Tamron 7-element used with the Tamron 500mm mirror came close, managing some decent eclipse of the sun photos a few years back when mounted on a solid tripod)
Update-this is most definitely NOT f8, more like f11 at best. Compared to my Tamron 500mm it gives a noticibly dimmer v/f image making focus in dim light a challenge.
| | | | | Pentaxian Registered: December, 2016 Location: London Posts: 1,079 | | Review Date: January 16, 2017 | Not Recommended | Price: $70.00
| Rating: 3 |
| Pros: | Small and light, reasonable macro capability | | Cons: | Poor contrast, lousy resolution | | Sharpness: 5
Aberrations: 6
Bokeh: 3
Handling: 8
Value: 4
Camera Used: Nikon D50
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Possibly the worst long lens I've ever owned, I never managed to get a good result from it. About the only positive thing I can say about it is that it is small and light, and would be useful for a travelling photographer who didn't want to carry a lot of weight. Even then it needs to be used on a tripod or high shutter speed. Unfortunately contrast and definition were lousy, I simply couldn't get good results. I'm also pretty sure that it's closer to f11 than f8
I should add that I got slightly BETTER results with another cheap 500mm mirror lens that was suffering from noticeable fungus, and considerably better with an old (and much larger) Soligor 500mm f8 mirror lens.
I forgot to mention the 2x teleconverter that was supplied with this lens, and fits between the mount and the lens. I think is part of the standard package. It's also dreadful, and I never understood why it was included, it just makes this lens's faults more obvious.
| | | | | Senior Member Registered: June, 2011 Posts: 160
1 user found this helpful
| | Review Date: October 24, 2011 | Not Recommended | Price: $99.00
| Rating: 5 |
| Pros: | long range, prime lens, manual focus | | Cons: | prime lens, manual focus only | | Sharpness: 6
Handling: 8
Value: 6
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Bought one that came with a t-mount adapter, and 2x teleconverter from ebay for $99.00. Put on the t-mount adapter and tried to unscrew it to put on the teleconverter but it never came off but wouldnt tighten back up either. Returned it and got a replacement and after a couple uses the same problem happened. Working on getting a refund now. But of the few pictures I got, they were decent and I really do love the range and price but it doesnt work/unreliable.
| | | | | | | Veteran Member Registered: October, 2009 Location: Texas Posts: 384 | | Review Date: July 7, 2011 | Recommended | Price: $54.00
| Rating: 6 |
| Pros: | Photos are fair, good price. | | Cons: | Not very sharp most of the time, needs tripod. | |
I got this lens New on ebay for $54 and thinking it's a great deal, most of them sell for $100 but guess it's not bad for a mirror lens.
Only thing I wish to get was shots of the moon, but you can forget that, this lens can never get the razor sharp image, but for somone that don't mind soft focus and slow lens it's great. Always need a tripod for best results.
This one of the best photos I ever taken with this lens.
But other times....
 | | | | | Veteran Member Registered: September, 2010 Location: Somewhere in the Southern US Posts: 12,285
1 user found this helpful
| | Review Date: June 20, 2011 | Recommended | Price: $95.00
| Rating: 8 |
| Pros: | Inexpensive, reach, lightweight | | Cons: | lower IQ than traditional lenses | | Sharpness: 7
Aberrations: 6
Handling: 8
Value: 8
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I listed the price as $95 because my copy came with a 2x telecoverter, T-Mount for Pentax, and a cleaning kit for $114.
The Opteka 500mm is a manual focus mirror lens that is incredibly compact and lightweight. It has a fixed aperture of f8. It comes with a soft pouch (very tight ft but the lens fits nicely in my Lowepro 1 lens bag) and three (3) rear mounted, 30.5mm filters, (ND-2X, ND-4X & Skylight). Mine came from Amazon and included the T-Mount (which is not optional and the M42 converters do NOT appear to be compatible), the Opteka 2x telecoverter, and some pretty low quality cleaning supplies.
The Opteka website claims that "Opteka mirror lenses incorporates advanced computer designed optics and the latest in multi-coating techniques. The process of multi-coating assures virtually flare free photographs even under adverse lighting conditions resulting in crisp high contrast pictures with full color fidelity."
Spec's are listed as:
• 8 Groups of 9 Elements • Diameter: 3" • Length: 3.4" • Weight: 360 grams • Filter Size Rear: 30.5mm • Filter Size Front: 72mm • Max Aperture: f:8 • Min Aperture: f:8 • Macro Magnification: 1:2.7 • Minimum Focus Distance: 5.5' • Manual Focus: Yes • Model - MF 500mm f:8 Mirror Lens • High quality crystal optics • Fully Multi-coated
Manual focus is smooth and throw is about 75 degrees. It has no tripod mount, which given the light weight is somewhat understandable but it is so light that being steady at 500mm is a bit tough even with SR on. Bokeh is interesting and as I understand it the standard doughnut shape. The f being fixed minimizes fiddling with settings under Manual on the K-x. Automatic metering seems to result in slightly underexposed images IMHO.
The only odd thing about mounting this lens, so far, is that live view results in constant thumping in the camera. Not good. Turned LV off and everything appears fine.
Will give more thoughts as I get to use the lens more.
UPDATE: 12/7/11 - I have found that this lens screams for a hood. The best option I could find was a 3-position rubber hood (72mm) which seems to help a great deal.
UPDATE: 3/3/12 - Still underexposes on the K-5 but with higher ISO performance it works better than expected even in lower light. A tripod helps a great deal even with SR on. The 72mm rubber 3-position hood also helps a great deal outside during bright daylight shooting. | | |
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