Site Supporter Registered: November, 2012 Location: North Wales Posts: 2,870
1 user found this helpful
| | Review Date: September 20, 2016 | Not Recommended | Price: $90.00
| Rating: 6 |
| Pros: | 800mm, t-mount, close focus, cheap. | | Cons: | No iris, IQ inferior to alternatives. | | Sharpness: 5
Aberrations: 5
Bokeh: 6
Handling: 7
Value: 8
Camera Used: Samsung NX20
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I picked up one of these cheap just to satisfy my curiosity. It is the cheapest way to try ultra telephoto. Chinese made, marketed under numerous brands, Opteka seems to be the most common, mine was a Top-Max. There is also a 650-1300mm version (Opteka, Samyang, Walimex...).
These are t-mount lenses, so easy adapt to just about all DSLR's. It is not a preset lens however - there is NO iris to stop down, aperture is fixed. It's a slow lens too, only f8.3 at 420mm, slower than those long tube vintage 500mm f8's, dropping to a bright sunshine only, diffraction setting in, f16 at 800mm. Although it's a 62mm filter thread its front element is only ~ 50mm diameter - ~ 60% of the light gathering capability of eg a 67mm filter (~65mm element) soligor . A solidly made, metal lens however, no complaints there. Long (very) focus throw is helpful, closest focus distance of 1.6m is way better than eg the vintage 400mm I compared it to, zoom operates OK - not particularly smooth but works. This pic shows how it works - pretty simple actually, the cam slot in the sliding sleeve alters the separation of the 2 element rear telephoto group, changing the telephoto effect.
Test pics however were simply disappointing. Crop #1 is the Soligor 400mm f6.3 at f6.3. The Top-Max is soft at all focal lengths, best at 420mm, worst at 800mm, strong CA, poor contrast, halos/coma (samsung NX20, jpg's from RAW).
My test pics of the castle turret were no better, in fact they showed significant flare (?sensor reflections).
So there you go - you're better off with a shorter focal length and cropping. Already got rid of it. I dare say the 650-1300mm is no better. You want "800mm" or more? - try a good prime with a Pentax Q!
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