| Latest Review Posted | Rear Converter-A 2x-S
There are teleconverters and then there are matching teleconverters. I bought my A 2X-S with the specific hope that it would work on my smc DA* 200mm f/2.8 lens because optically it is an FA-design from 1993 and the Pentax product litterature indicates that this rear converter should work on this type of lens (Pentax telephoto lens up to 300mm F.L.).
I have tested it extensively on my DA* 200 and I have not been dissapointed.
Of course, any teleconverter will be an add-on to a carefully optimized (one should hope) lens design and introduce some limitations such as lowering the fully open aperture f-ratio,and any (quality) teleconverter will magnify aberrations of the lens that it is sitting upon. But that's not the point. The point is: Does it work as a quality converter should work on a quality lens?
And it does. I have a hard time seeing the IQ degradation mentioned by others. What I do find, is that this TC unquestionably does help when a quality lens like the DA* 200 outresolves the sensor (the sensor under-samples the image produced by the lens). Images may sometimes at a casual glance look "sharper" without TC, but I have found that to be a matter of under-sampling and pixelation, as the following 100% comparison crops will hopefully demonstrate:
https://www.pentaxforums.com/forums/members/28516-stone-g-/albums/7288-pentax-rear-converter-2x-s-smc-pentax-da-1-2-8-200mm/picture64452.jpg
Downsized (approx. 30%) crops: The softness observed at f/2.8 is no worse that what the lens itself without TC would show.
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