In terms of the development team at Kenko Tokina with their innovative Accu-ND Technology, creating a Neutral Density filter that precisely controls the amount of light entering the lens without affecting the color. A revolutionary filter that stabilizes the transmittance of color throughout the visible spectrum.
The Tokina PRO IRND filter is available in 2 styles, round and square/rectangular.The round PRO IRND filter has an ND vapor deposition coating on both sides of the glass creating a high precision, truly neutral filter. The square/rectangular type of filter has an ND vapor deposition coating sandwiched between two layers of glass so the filter can be re-polished again and again should it get scratched, extending the life of the filter.
There are generally two types of IRND filter manufacturing processes currently in the market today. One type cuts the near infrared from a particular wavelength and the other controls rather than cuts the infrared up to1200nm. The Tokina PRO IRND filter is of the latter category, using suppression rather than cutting to eliminate infrared pollution. Even though both methods can be equally effective, the former type of cutting is often prone to producing unwanted color shifts.