Lens Cleaning, If You Must





Golden Bog, Madame Sherri Forest

It is difficult to believe that in over 300 blog articles I have never covered lens cleaning. It is an important topic and worthy of a short, hopefully, discussion.  Included in this articles are recent images from around Madame Sherri Forest in Chesterfield NH.  All captured with a less than  perfectly clean lens. 






Partridge Brook Gold : Dusty Filter

The camera lens or overlying filters are the part of a camera’s optics most exposed to the environment. They can be protected with a lens cap, but there is no escaping the dust and smudges that seem to have a magnetic attraction to the camera’s business end. A small amount of dust on the front of the lens may have surprisingly little effect on the quality of the pictures. I have always assumed that even a modest amount of grit could soften the image and may make it more susceptible to flare when shooting into the light, but how intrusive would be the effect?





A "Little" Dust
A Nightmare, but I lost a little of the crud when I aimed the camera.

　

Tests



Landscape Image

I compared images taken through a clean lens with the same scene shot through an intentionally filthy filter and found no perceivable difference. I presumed that there would be more evidence of a problem when shooting close-up with a small aperture, but the results were the same, no perceivable difference. I try to keep my lens clean but dust is everywhere and excessively frequent and vigorous cleaning can lead to scratches and damage to the delicate coatings that are applied to all modern lenses and filters. A little dust is probably better left alone.




Max Dust Effect: Close-up & Small Aperture

　

More critical is the dust that can collect on the rear element of the lens. Particles here are closer to the sensor and are not diffused by the multiple lens elements. Projected, unaltered, to the sensor they can have a much more visible effect on the image. The back element of the lens can't be protected by a filter and I am especially careful to keep this end pointed down during lens changes.



Prevention 

Center Squeezer Lens Cap

Dust is unavoidable but it can be reduced and the less cleaning required the better. The lens cap is my first line of defense. I try to remove it only when I am about to shoot. I can’t imagine how many caps I have lost over the years but a cheap lens cap keeper has saved me many times. For lenses with long lens hoods, I add a rubber band to allow me drop the cap inside and, to make them more easily accessible, I use caps with internal, "center squeeze", releases. Whatever else you do don’t place the cap in your pocket. You will be applying a generous dose of pocket lint every time you return the cap.




The Less Precious Filter


Lost a Polarizer, Saved a Lens!

My second line of defense is the lens filter. I know that there is resistance to placing a layer of glass in front of the costly optics, but I have averted too many disasters with a simple UV or clear filter and I am much more comfortable cleaning a replaceable filter than my expensive and delicately coated lens. I will always remember when I ground a Polarizing filter to splinters in my camera bag, but my precious 100-400mm Zoom was spared.


Cleaning
Despite your best efforts dust and smudges will happen and your first rule, like that for physicians is to "Do No Harm". The least invasive, effective, measure is always the best, and the least invasive approach is not to clean. It is worth repeating that a few dust specs will have little effect on your image and compulsive cleaning my do more harm than good. With all that in mind, let’s clean that lens.




"Clean" Air


Giottos Rocket Blower

I start with air. Whenever I remember to bring it, I use my Giottos Rocket Blaster blower. It creates a forceful blast of clean air that dislodges much of the loose dust. Compressed air is also effective, but it should be avoided, since the air can contain residue of the propellant. I am embarrassed to admit that I too often will use my mouth to blow across the filter, fully understanding the risk of depositing saliva or pieces of my salami sandwich in the process. I KNOW! ..., but now you understand why I keep a filter over my lens. Anyway, do what I say NOT what I do!






Gentle Brushing

Brush
To remove more persistent grit, my next step is to brush gently with a soft clean brush. I have seen how filthy camels get, but for some reason Camel Hair brushes seem to be the most favored. The secret is to keep the brushes clean and especially to avoid getting oils from your fingers on the bristles.


Note:  Because I lack a third hand the pictures here show the lens pointing upward, but, to enlist the help of gravity, in actual practice the blowing and brushing should be done with the lens pointing down.



Lens Cloths and Paper
Lens paper is cheap and can be effective, especially when 

Microfiber Cloth and Solution

moistened by a drop or two of lens cleaning fluid. Never apply the fluid directly to the lens since this could migrate to the edges and into the body of the lens. Lens paper is clean and lint free, but should only be used once. It can do a good job, but I have always felt nervous about rubbing with a scratchy piece of paper, especially when cleaning the actual lens. I generally feel more comfortable using a soft microfiber cloth. They are cheap and widely available? I get mine from 2Filter.com in Gilsum New Hampshire, which is a great on-line source for all varieties of filters. I typically cut the large cloths into smaller squares. The cloths are usable for more than one cleaning, but it is important to assure that they remain clean. It is critical not to grind dirt into the lens or filter. the cloths can be machine washed, but avoid fabric softeners that can leave residues.



Crabapple Bark: Dusty Lens

Cleaning Technique
Blowers and Brushes are great for removing dry dust, but liquid 


Sherri Cascade

will be required to dissolve oily smudges and luncheon residue. Whether using paper or cloth the cleaning technique is the same. A drop or two of cleaning fluid can be applied to the cloth and then the surface should be gently wiped with circular motions starting from the center and moving out to the edge. I have cleaning fluid (sometimes) but I must admit that I often use the moisture from my exhaled breath. From my previous career, I know that gently exhaled breath is clean and 100% saturated with moisture. I’m sure that cleaning fluid is better but, hey, I’m only breathing on my protective filter. You will develop your own approach. If you use a cleaning fluid make sure it is formulated for the purpose. PLEASE avoid materials such as window cleaner and acetone.



It is simple.
To summarize: 


Spectral Pool



• Protect your lens from dirt.
• Only Clean when you must.
• Try the least invasive
  techniques first.
• Keep you lens cloth clean.
• Enjoy a lovely and reasonably dust-free Spring!



Jeffrey Newcomer
partridgebrookreflections.com
603-363-8338