B+W Filter 67mm F-Day Overview
This B+W Filter eliminates the green cast that occurs when daylight-type color
film is in fluorescent lighting. Examples are interior photographs made in offices,
reception areas, factory halls, subway stations and swimming pool halls, as well as
night-time photographs of office buildings whose windows would appear green because
their interiors are usually illuminated with fluorescent tubes. The abbreviation F-Day
stands for “Fluorescent Light - Daylight”, which reflects the fact that these filters are
designed for the most commonly used type of fluorescent tube, which emit light of a
color that, as mentioned above, resembles daylight. Because fluorescent tubes are not
“thermal radiators”, they do not produce a continuous spectrum like those of the sun
and incandescent bulbs. Instead, they emit a sharply defined line spectrum that has
high intensity spikes in the green region. Our eyes barely perceive this special green,
so the fluorescent light appears to us as nearly neutral in color. However, most color
films are especially sensitive to those wavelengths and they react with a strong pronounced
cast. Photographers using color temperature meters for three color metering
(simple meters that measure only two colors are not suitable for this purpose) can
also undertake the correct filtering with of a combination of LB- and CC filters.
With this method, they can also correct the light emitted by other types of fluorescent tubes,
such as Warm Tone, Standard Light, White Light, etc. But for hobby photographers
who do not wish to make a large investment in such an instrument and who do not care
to carry along a selection of LB- and CC filters, the B+W F-Day Filter is far less expensive
and much more practical. Its filter factor is approximately 2.
This B+W Filter eliminates the green cast that occurs when daylight-type color
film is in fluorescent lighting. Examples are interior photographs made in offices,
reception areas, factory halls, subway stations and swimming pool halls, as well as
night-time photographs of office buildings whose windows would appear green because
their interiors are usually illuminated with fluorescent tubes. The abbreviation F-Day
stands for “Fluorescent Light - Daylight”, which reflects the fact that these filters are
designed for the most commonly used type of fluorescent tube, which emit light of a
color that, as mentioned above, resembles daylight. Because fluorescent tubes are not
“thermal radiators”, they do not produce a continuous spectrum like those of the sun
and incandescent bulbs. Instead, they emit a sharply defined line spectrum that has
high intensity spikes in the green region. Our eyes barely perceive this special green,
so the fluorescent light appears to us as nearly neutral in color. However, most color
films are especially sensitive to those wavelengths and they react with a strong pronounced
cast. Photographers using color temperature meters for three color metering
(simple meters that measure only two colors are not suitable for this purpose) can
also undertake the correct filtering with of a combination of LB- and CC filters.
With this method, they can also correct the light emitted by other types of fluorescent tubes,
such as Warm Tone, Standard Light, White Light, etc. But for hobby photographers
who do not wish to make a large investment in such an instrument and who do not care
to carry along a selection of LB- and CC filters, the B+W F-Day Filter is far less expensive
and much more practical. Its filter factor is approximately 2.
