Hoya filters are "hard-coated", meaning the metals and chemicals that make up the coating are applied in a high temperature furnace to bond them to the surface of the glass.
To maintain their best optical performance, here is how we recommend cleaning HOYA filters as well as other multi-coated optics.
Each interchangeable camera lens has its own minimum focusing distance, which is the distance from the lens to the shooting subject. Its range value generally varies from 25cm to 50cm minimum.
In close-up photography, you can close up on the subject by simply moving closer to it, as by doing so the size of the subject projected onto the image sensor will appear larger.
When you cannot move closer, or when you would like to close up more on the subject, you need to further shorten the minimum focusing distance. This can be done by installing a close-up filter (also known as close-up lens) on the lens.
Close-up filters usually come in different magnifications. Choosing the appropriate magnification is fundamental and can be easily done by considering the minimum focusing distance value of the lens.
For example, if the minimum focusing distance value is more than 1m, you will need a +1 or +2 close-up filter. If it ranges from 30cm to 50 cm, you will need a +3 or +4 close-up filters, and so on.
HOYA close-up filters come in +1, +2, +3, +4 and +10 magnification powers.
When installing close-up filters, the minimum focusing distance of the lens at ∞ (infinity) will be reduced, its focusing range will change accordingly and can be calculated from the formula below:
+1 lens: minimum focusing distance at ∞ (infinity) ≒ 1m
+2 lens: minimum focusing distance at ∞ (infinity) ≒ 50cm
+3 lens: minimum focusing distance at ∞ (infinity) ≒ 33cm
+4 lens: minimum focusing distance at ∞ (infinity) ≒ 25cm
+10 lens: minimum focusing distance at ∞ (infinity) ≒ 10cm
The table below shows how the focus range value changes when installing a close-up filter:
|Close-up filter magnification||Minimum focusing distance value of the lens without||Focusing range with a close-up filter|
|+1||More than 1m||≒ 33cm – 100cm|
|+2||≒ 70cm – 80cm||≒ 24cm – 50cm|
|+3||≒ 30cm – 50cm||≒ 20cm – 33cm|
|+4||≒ 30cm – 50cm||≒ 17cm – 25cm|
|+10||Less than 30cm||≒ 8cm – 10cm|