In Jan 2003 bought the Williams-Optics DCL4337 40 mm plossl with which I take most of the videos after Jan 2003. This eyepiece is sharper than my previous 40mm plossl. However, it produces significant vignetting near the higher end of the camcoder zoom. 

I have also bought the Surplus Shed 50 mm military surplus plossl which comes in 2" barrel. Cheang Kum Seng had been able to remove the lens assembly and remount it into a 1.25" barrel. He also trimmed the excess length to reduce eyepiece-camcorder distance. This eyepiece is sharper than my old 40mm plossl but not as sharp as the DCL4337. It constitutes a good compromise between sharpness and vignet-free video. A mild degree of vignetting is apparent when shooting against the sky with the camcorder near the telephoto zoom end. With a darker background, vignetting becomes inapparent. Some of the videos and pictures after May 2003 are taken with this eyepiece. 

Since Jul 2003, Cheang had also modified and remounted the Surplus Shed 80mm eyepiece into 1.25" barrel. Vignetting with this eyepiece is even less than that of the 50mm but the useable zoom range is not much more. The combined zoom is sometimes relatively inadequate when small birds are videoed from a distance. In addition, this eyepiece is very long, making it difficult to mount the camcorder or change eyepiece in the field. Hence, I am reserving this eyepiece mainly for shooting birds in flight.