The argument against using lens filters for lens protection is that when you put any extra optical glass between your lens and film or digital sensor, it's likely to degrade your camera/lens IQ (image quality). Yet photographers compromise image quality regularly for all sorts of reasons. For example, to increase the reach of a lens many photographers regularly use teleconverters that most definitely diminish lens IQ.
If you use a lens filter for lens protection, since there is some likelihood you'll reduce the IQ of your camera/lens, it behooves photographers to be circumspect when making a choice to use a lens filter solely for lens protection.
There are a number of lens filter characteristics which photographers must consider when deciding about their use for lens protection:
- With film cameras it was often necessary to use a UV filter, because most film is extremely sensitive to UV light. For this reason, UV filters became ubiquitous as lens protectors for film photography. Digital sensors are generally insensitive to UV light, so for DSLRs, general use of UV lens filters isn't warranted. As a result, I don't recommend the general use of a UV lens filter on a lens attached to a digital camera.
In digital photography, if a photographer wants to use a lens filter for lens protection, it should be a clear lens filter, such as a clear NC glass filter. In this way, it won't alter the color spectrum of the light passing through it, from the scene being photographed, to the sensor of a digital camera.
- Any filter used on a lens should be of high quality to maintain the maximum lens IQ possible. In my opinion, a high quality lens filter will make such a minimal reduction in IQ that it can be successfully used when needed for a variety of purposes.
- Lens filters can cause flaring and ghosting in addition to potentially reducing lens IQ, so they need to be multi-coated to minimize reflection at the filter surfaces which will reduce flaring and ghosting.
- Any lens filter should be made of high quality glass to ensure minimal lens IQ reduction. Do not use polyester or resin based filters even if touted as high quality filters. They won't be as good as high quality optical glass.
I've found that lens filters for lens protection are helpful, and make sense in the following situations:
- In crowds where significant jostling of equipment may occur,
- Storms with high winds,
- Industrial sites with significant dirt particles being blown at velocity such as in some construction sites,
- Refineries and chemical plant sites, etc. with significant emissions which can damage photographic equipment,
- At sea or along sea coast with significant salt spray,
- Other site conditions similar to those above.
I've had lenses saved from terrible front end scratches while shooting in the Sinai, Sahara and Mohave. How do I know? My NC clear filters were damaged by pitting. I had to throw them out. That was far less expensive than repairing or replacing the lenses they protected.
I've had lenses saved from damage when in a crowd twice, once in Paris, and once in New York. In each case, I was pushed and the lenses smashed into building appurtenances. In each case, the filter was destroyed, but not the lens.
These examples of the benefit of using lens filters for protection, show me that when you need them their use is worth it.
I use Nikon Clear NC Glass Filters for lens protection. They're made from high quality glass, are multi-coated and don't alter the spectrum of light passing through them. Other excellent lens filter brands making clear filters which I've tried are: B+W, Schneider and Hoya.
Only clean your filters and lenses with high quality optical cleaners meant specifically for photographic filters and lenses, plus lens cloths meant for today's modern filters and lenses with extensive use of special coatings.
I use an optical cleaning product called Purosol to clean my filters and lenses. It's alcohol free and superior to every other lens and filter cleaner I've found.
Lens cleaning cloths can't be abrasive as they could scratch the coatings on your lenses and filters, or the glass itself. While scratching lenses and high quality filters isn't particularly easy, it's far from impossible. I use non-woven cloths manufactured specifically for the purpose of cleaning lenses and lens filters.
Each photographer will have to weigh the benefit of protection versus the potential loss of IQ when deciding if and when they will use lens filters to protect their lenses.