Hoya Filters, 80A Blue for Indoor Photo Colour Balance in
I have three of these blue filters, which the Hoya website describes as: - These are color conversion filters for use with artificial light sources. 80A increases the color temperature from °K to °K for the use with °K lamps. 80B increases the color temperature from °K to °K for the use of photoflood lamps. 80C increases the color temperature from °K to °K for the use of clear flash bulbs. I have two of 52mm diameter and one of 49mm. One of the 52mm filters appears to be perfect, but the other two have very slight blemishes which can be seen at an acute angle to the light, hence the price differences. One of these is fixed to a 49mm adaptor ring, see third photo. The best price I have found is a special offer of £20 for the 52mm filter. 52mm perfect filter £10 in box 52mm imperfect on 49mm adaptor£3, no box 49mm imperfect £3, no box Buyer collects, or could be posted for 73p