How to Clean Camera Lenses
Removing dust, dirt, and stains
By K David in Tutorial Videos on Jun 23, 2014
We use our lenses and demand much of them. The front elements, especially, can be splashed with rain, mud, and sweat; bumped by hands, elbows, and dog noses; or dirtied by a myriad of other terrible and creative destructive forces. Addressed when you return home or to your on-assignment home, correctly cleaning your lens of dirt and detritus can prolog the coatings' lifetime, improve image quality, and protect your lens's value. Performed incorrectly, however, and lens cleaning can damage your lens. Searching the Internet for a tutorial on lens cleaning will return tens of thousands of results. Some present sound and proven methods. Some are the work of crackpots. The technique described herein is my approach for lens element cleaning. Of course, clean your lens element at your own risk.
For this procedure, you'll need the following equipment:
- A lens, preferably dirty
- Rocket-type air blower
- Lens brush, preferably camel hair
- Lint-free lens tissues (preferably disposable)
- Lens cleaning fluid (no brand is given preference here, but there are differences and some are good while others are not) or 70% isopropyl alcohol
Here is some optional equipment:
- A small flashlight
- Cotton swabs
Also, you'll want to avoid these items:
- Compressed air dusters
- Cotton t-shirts, no matter how old
- Reusable leans cleaning cloths (unless you use them only for cleaning the outside of the lens body and they never touch the glass)
- WD-40, acetone, and other liquids and solvents
- Zeiss Ikon Lens Care Kit
- Gittos Lens Cleaning Kit with Air Blower
- Trijicon Lens Pen
- Tiffen Lens Cleaning Tissue, Pack of 50 Sheets
- Zeiss Lens Tissues
First Step: Analysis
Using your LED flashlight, evaluate the lens element's surface with the light at different angles. This will help identify dirt that can only be seen when light hits it at a certain angle. Ascertain if the lens has surface dust or grease. Whether the problem is dust because you carried your camera into a grain silo or hand oil or sweat because you took it into a crowded concert, the process below is similar. With simple dust, a full wet cleaning may not be required. If you have to remove something like sweat or rain water stains, follow the earlier steps as they will remove physical surface debris that could scratch your lens during fluid-based cleaning.
Second Step: Rocket Blower
Begin the cleaning process by removing surface dust with a rocket blower. Hold the lens so the element faces downward or at an angle downward. This helps the blown-off dust fall away from the lens. Holding a lens with the element upright can cause an air vortex when the rocket blower is used that traps debris inside the lens indent. This is more significant on lenses with large indents such as some macro lenses.
With the rocket blowing complete, check the lens to see if dirt remains. If not, then the cleaning is done. For this process, it's recommended that you use a small LED flashlight and move it around the lens at different angles. This will reveal dirt that is only visible when light hits it at a certain angle.
Third Step: Brush
If you have a cotton swab and the lens has visible dirt, it is a good idea to use the swab to remove individual large pieces of dirt. Simply touch the swab to the dirt and lift. Do not move a cotton swab across the lens' surface. It should only move onto the dirt and be lifted straight off of it again.
Using a camel hair lipstick brush or similar tool, prep the brush by shaking it. This creates a static charge that will help remove dust particle like a magnet. Use the brush to lightly brush the lens element's surface from the inside outward. Angle the bristles into the crevice where the lens retaining ring meets the glass. This will remove dirt that is lodged there. If needed, perform this step multiple times. Physical dirt on your lens for the following steps can have detrimental effects. Again use your flashlight at different angles to verify cleanliness and determine if the next step is required.
Fourth Step: Fluid-based cleaning.
Remove two lint-free tissues and set them where you can reach them easily. Next, put a few drops of lens cleaning fluid or rubbing alcohol on the lens. Put a tissue on your finger and put two drops on the tissue.
Using a single-use tissue is preferable here as reusable tissues can retain grease and dirt from previous cleanings. This risks grease reintroduction to lens surfaces and lens element scratches if a reusable tissue removed a piece of sand or other sharp detritus in a previous cleaning.
Place the wetted area of the tissue into the drops on the lens and clean from the center outward. The pressure used here should be enough to push on your keyboard keys without depressing the button that registers a keystroke. Also, try as much as possible to prevent fluid from seeping into the crevice where the lens meets the body. If lens fluid dries on the rear of a lens element, the lens will need to be disassembled to be cleaned.
After an initial cleaning, use dry areas of the same tissue to remove excess cleaning fluid. After this step, a thin fluid sheen will remain on the lens. Lightly use the second tissue, the dry tissue, to remove this sheen, again from the inside out. The amount of pressure used in this step should be so light that if you were running your finger over a razor you would not receive a cut. You can also wad the dry tissue and perform this step that way, with your fingers slightly away from the lens element. This will prevent any downward pressure from pushing the tissue into the lens' surface.
Fifth Step: Drying
Leave the lens cap off but rest the lens on its side. The lens cap can be used a chock to prevent your lens from rolling onto the floor. Resting your lens on the side helps prevent errant fluid from drying on the back of the lens. Side drying causes any errant fluid to dry in the crevice where the lens meets the housing or within the internal lens mechanisms where the fluid cannot harm any optical components.
The lens should dry for one to two hours in a typical climate (less if you're in an arid area, more if you're in the rain forest) before the lens cap is re-placed. Placing the lens cap on too soon will trap moisture inside the lens. This can result in moisture marks on lens elements as moisture condenses and dries or, if left long enough, fungus.
Using 70% witch hazel in lieu of lens cleaner presents no risk to your lens and can dramatically reduce drying time.
Sixth Step: Preparedness
There are many pre-assembled lens cleaning kits available for purchase. To assemble one yourself, pick up a 50-pack (or larger) or lint-free single-use lens tissues, a small bottle of lens fluid (or reuse and empty one by filling it with 70% isopropyl alcohol), a camel hair lipstick brush, and an optional reusable cloth to wipe dust off the lens housing (this is the only use a reusable cloth should have for lens cleaning.) These can be stored in an inexpensive plastic clamshell case obtained from a hardware or sporting goods store. Alternately, an unused travel case for hand soap can provide a suitable case. You can also place a few cotton swabs in the case to use for removing visible pieces of dirt or cleaning crevices on the lens' housing.
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