Tips & Techniques

How to clean filters

Neglected dirt on your lens surface can ruin all the work behind your shots, making your final image awfully spotted or affecting its sharpness and beauty. Regular cleaning and correct maintaining of your lens is a good habit any photographer should have and get used to. However, unlike mere window glasses, the optical glass lenses are made of is a more delicate material. Therefore, the best solution will always be to choose a "lens protection filter (PROTECTOR, UV filter, etc.)" to attach on your lens.

The advantages are numerous: by cleaning the filter's surface instead, no cleaning product will ever make contact with your lens. Also, with the filter attached, the lens will be protected by accidental scratches, impacts or damages, and by simply replacing the filter with a new one, you can always shoot in the most desired and best conditions.

Filters, whatever type is used, need a correct cleaning and maintenance to preserve their good conditions over time. Here find some useful tips and easy-to-follow indications:

  • It is not recommended to use regular tissue paper or handkerchief to wipe dirt off your filter. Instead, better using a professional cleaning cloth and cleaning liquid specific for lenses. Other tools like a lens cleaning brush, air duster and air blower are also necessary for a flawless cleaning.
  • First of all, blow off dust form the filter's surface with the help of an air blower. By keeping the filter downward, you can prevent flying dust and dirt from settling on the filter's surface again.

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  • Next, spry air with an air duster on the filter's surface to make sure there is no dust left. When doing so, keep the air duster at the appropriate distance according to the product instructions.

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  • In case of persistent dirt, apply a small amount of cleaning liquid on a cleaning cloth and gently wipe the filter's surface. Refrain from applying the cleaning liquid directly on the filter's surface. Make circular movements from the center outwards when wiping the surface and make sure to use only clean clothes each time.

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  • Even after wiping the dust off the filter's surface, blow off again any remaining dust particles with an air blower.

These simple steps can be also applied for a correct cleaning of your lenses as well.

How to choose a CLOSE-UP filter

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.

How to calculate minimum focusing distance and focus range when CLOSE-UP filters are installed

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

Notes:

  • The above calculations are approximate and may vary depending on the lens.
  • Please take notice that, when installing a +10 close-up filter on lenses with less than 30cm minimum focusing distance, the focusing range will be extremely reduced to the value of around 8cm-10cm.
  • When combining with macro lenses, as the minimum focusing distance of these lenses is short by default, close-up filters will have little effect.