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I was cleaning my lenses when I suddenly realized... I had no idea how to clean the back element of the lens. I asked Google and it only talks about the front of the lens and how you can earn money by working at home. Kidding aside, I always cleaned the rear using a blower and lens pen but I have no idea if it's the right thing to do. With that in mind I ask; how do you properly clean the lens rear? Is it different from cleaning the front? Do you need specialized tools (butt cleaner, butt brush, butt blower, etc)? Does cleaning it using a pen or cloth damage the glass?

In addition (this is optional), kindly include ways to properly clean certain kinds of impurities commonly found on the rear element (smudges, dust, sand, slime, etc) and the tools you use.

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3 Answers 3

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Use the same careful techniques you use on the front element. Camera companies are very aware that the front and rear lenses get dirty and need to be cleaned. As such they won't but fragile coatings or soft glass compounds in those elements. What you're doing is perfectly good and safe to do. Here are a few tips per your request:

Tools of the trade:

  • Air blower
  • Lens brush
  • Microfiber cloth (nothing cheap or it will probably leave micro lint everywhere)
  • Methyl alcohol wipes

Smudges:

  1. Alcohol wipe - one to gently lay over and pick up any dirt/sand
  2. Alcohol wipe again to gently rub
  3. Microfiber cloth

Dust:

  1. Alcohol wipe - one to gently lay over and pick up any dirt/sand
  2. Air blower
  3. Lens brush
  4. Alcohol wipe
  5. Microfiber cloth

Sand:

  1. Alcohol wipe - one to gently lay over and pick up any dirt/sand
  2. Air blower
  3. Lens brush

"Slime": I tend not to slime my lenses, but if it's more like ectoplasm than pond scum I suggest the following:

  1. Soft silicone spatula to scrape the bulk of the slime off (careful not to scrape the lens)
  2. Microfiber cloth to remove what is left of the heavy slime
  3. Alcohol wipe to cleanse the fine remaining slime
  4. Air blower to dry out the slime
  5. Alcohol wipe again
  6. New microfiber to clean what's left
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  • \$\begingroup\$ I've heard some people swear that you should never use alcohol based fluids for lens cleaning, and that you should stick to purified water - I've even heard some say that the moisture in your breath can be better for the lens than alcohol. I seem to remember that the alcohol has the potential to dissolve some of the black coating surrounding the lens, spreading it over the lens. Can anyone confirm/deny this? Have I been fed lies? \$\endgroup\$ Jul 19, 2013 at 5:34
  • \$\begingroup\$ thomasrutter - you're absolutely right about alcohol causing rubber to degrade. Most lenses fortunately don't have rubber around the rear lens element. Usually they have rubber around the mount if they are considered weather sealed. All the same, it would be smart to inspect the lens elements for proximity to rubber and then proceed accordingly. The other consideration is strength of alcohol, most alcohol wipes have a very low concentration, but that doesn't mean you shouldn't be careful! \$\endgroup\$
    – kheric
    Jul 19, 2013 at 14:09
  • \$\begingroup\$ lol.. I included slime because a co-photographer of mine accidentally sneezed at his lens. hehe. \$\endgroup\$
    – ides
    Jul 22, 2013 at 7:02
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They are both coated glass, so there shouldn't be any serious difference. The only thing you might have to worry about is brushing things off the side of it into the lens if it isn't fully closed against the case of the lens. Otherwise, it should be the exact same as cleaning any other glass element. You want to avoid damaging the surface or the coatings.

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  • \$\begingroup\$ I would just add that I use LensPen and KimWipes. I kimwipe both the front and back lenses before using the lens pen, simply because I can do it lightly and avoid scratching. I particularly try to avoid blowing air on the back element, since the likelyhood that you'll just push particulate deeper into the lens is high. \$\endgroup\$
    – jrista
    Jul 18, 2013 at 19:27
  • \$\begingroup\$ It is of course different when cleaning an expensive lens, but my kit lens only has a tail of my T-shirt for cleaning. How fragile can the coatings be? \$\endgroup\$ Jul 31, 2013 at 0:16
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I had several times debris get into back of the lens. I use blower a lot. Is it possible it's caused by it? I always use a rear lens cap ( I change lenses about 5-10 times a day).

I noticed that in all my lenses, the front is sealed up pretty tight, but on the rear, there are gaping holes into the lens.

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