Tamron SP AF 2x Teleconverter
Pros:
High optical quality
Cons:
Auto focus gearing makes manual focus feel bad (Nikon mount version).
The Bottom Line:
For general use, you can't beat it at a sensible price.
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Overall Rating:
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Author's Review
The SP series of lenses appears to be reserved by Tamron for their best quality items. This appears to be true as well for the SP AF teleconverter as it does perform very well indeed.
Remember that a 2x TC doubles the image size details so of course it is also doubling the faults in the base lens that is why I did resolution chart tests using the Nikon AF 180/2.8D IF ED lens which is one of the best lenses around .
On general slides viewed normally on a screen with a great quality projection lens, the slides with the 2x seem perfectly OK. The differences in performance can be found by shooting resolution charts and then looking at detail using a 4,000 dpi film scanner. The results of those tests are at http://homepages.ihug.com.au/~parsog/Guy/testteleconverter.html for you to make your own evaluations. The 2x does obviously lower the image quality a bit (or enlarge the base lens faults) but in reality it is not a worry.
I would expect the very expensive Nikon TCs to be only maybe a normally non-detectable bit better, the Tamron is good enough for me for every day use.
The inbuilt AF gearing in the TC (Nikon version) causes the manual focus feel to be bad, but it works OK. The camera LCD as tested on N8008s(F801s) and F80(N80), reports the selected aperture of the lens itself and not the modified 2 stop less that is actually there, the exposures work out OK though. It is reputed that the newer Nikon S series of lenses do report the correct modified aperture, but that has not been tested by me.
The surprise was using the 2xTC with a Sigma 28-300 lens and the results were great, that's a cheap way of getting 600mm (at a small aperture of course) that's still portable. That combination on the N8008s had trouble with AF in daylight, but on the F80 it focused very well with no hunting. On the other hand I tried the 2X TC with a Nikon 75-240 zoom (cheapo Chinese thing) and the image was definitely bad, I was just "enlarging the faults".
This is the first time I have bought a 2x TC and been happy, all previous purchases of various brands (years ago) have been a disappointment. It is not "perfect" like the Tamron SP AF 1.4x appears to be - but it is very, very good.
