Hoya 46mm W4 Umber Warming

Hoya 46mm W4 Umber Warming

The Hoya W4 Umber Warming filter prevents blue cast and adds a warm glow to your photos. This type of filter is ideal for shooting portraits, adding warmth to pale skin tones.

Hoya's Umber Warming series includes a W2, W4, W10 and W12 version. These provide a mired shift of +20, +40, +100 and +120 respectively. The higher the mired shift, the more warmth is added. Because differences in colour temperature (Kelvin) are not linear, this is expressed as a mired shift — an abbreviation of 'micro reciprocal degrees Kelvin'. The formula is as follows: mired (numerical value) = 1,000,000 / colour temperature. Taking a colour temperature of 6500K as an example: 1,000,000 / 6,500 = 153.8. If the desired colour temperature is 5500K, you also need to calculate its numerical value: 1,000,000 / 5,500 = 182. The difference to bridge — in other words, the mired shift you want to achieve — is +28.2. With this knowledge, you can choose the right filter.