These Takahashi eyepieces use a proprietary five and six lens designs to combine relatively long eye relief with exceptional sharpness and contrast. They do it at a price less than that of other premium eyepieces.
While the Takahashi eye relief is not as long as it is with some specialized eyepieces designed solely for long eye relief (often at the expense of image clarity and contrast), it is typically twice as long as similar focal length eyepieces that are invariably of lesser optical quality.
These Takahashi eyepieces are optically corrected for very low to very high power use at focal ratios from f/15 down to a fast f/4. They are usable with all telescope types, for all types of observing. The shortest focal lengths use an ED (extra low dispersion glass) element for exceptional contrast and color correction. All are fully multicoated, threaded for standard filters, with soft fold down rubber eyecups. All focal lengths are parfocal. Each has a rubber grip ring for secure handling in cold weather when wearing gloves.
Optically, they have very little ghosting and very good sharpness and contrast. It’s an optical combination that is particularly well suited for lunar and planetary use. The fields are quite flat and aberrations are held to a minimum. Optically, they are worth their not-inconsiderable cost. Add in the extra measure of eye relief, however, and you have high end eyepieces that many observers consider to be absolute bargains.