FOR LENS PROTECTION
When we buy a lens it is with a purpose in mind, with great expectations and with some effort. Surely we want to protect it from dust, dirt, moisture, fingerprints, scratches and even from a fall. From my own personal perspective, the best way to give our lens that protection -in addition to care- is to place a good multicoated filter and a hood on it and leave them both there at all times, except when using an also multi-coated polarizer.
Some Nikonians don't share this point of view; even react violently to the proposition, however with a valid reason: the introduction of more glass surfaces attracts flare and ghosting. However, you can always it take off when necessary. Plus, the ever present Murphy's law applies as shown in the image below. Keep your hood always on, even if reversed for storage.
FOR SHARPER IMAGES ON FILM
The UV, Haze and Skylight filters filter out UV (ultra-violet) light that caused a bluish haze on some of our color film pictures and loss of definition on distance objects.
However, a not so spread fact is that most modern color films -both slide and negative- and digital camera sensors are almost or not at all sensitive to UV light today, becasue they do have their own built-in filter, as pointed out by Nikonian Len Shepherd and later confirmed through exhaustive and exhausting research.
Thus, if only for protection, a clear filter like the Nikon NC clear would be better if less expensive where you live. Probably the main reason for UV filters continuing to be very popular is that they are recommended by store sellers or by those who either grew up with film or have been blesed with the joys of parenthood.
On the other hand, since B&W film continues to be not only sensitive to the visible light, but also to the UV light rays, we want to reduce it as much as possible or eliminate it.
Of course multi coating of the front elements of newer lenses reduce much of UV light rays coming in, but -as said- they reduce them, they don't eliminate them entirely.
So UV, Haze and Skylight filters continue to be most useful for B&W, especially when we are taking pictures in overcast days, or up in the mountains or by the sea or for aerial photography where there is plenty of UV light under "thin" atmosphere. They will filter out the blue haze that normally blurs the distant background of your images.
They may also turn out to be very useful when taking pictures in winter, when the atmosphere is cooler, but especially in the snow since it is an splendid UV rays reflector.
To further penetrate the haze that a UV filter can't do completely, some brands, like Tiffen, have Haze filters in two grades: A Haze 1 reduces excessive blue haze caused by UV light by absorbing 71% of it (transmitting 29%). A Haze 2 absorbs all of the UV light rays (transmitting 0%). These are best for the high altitude and marine scenes mentioned before. I frequently have to remind myself that haze can be dealt with the use of these filters, but not smog, fog, smoke or mist.
An interesting thing happened with the old color films: when the UV rays were filtered out, we noticed the sky in our color pictures was not as deep blue as it used to be. Of course, the UV component was missing, but our images looked sharper.
Today, modern DSLRs already have a UV filter over the sensor. Yet, try a few pictures with and without a filter and see what you like best under specific conditions.
if you shoot RAW (NEF) you may want to take the photo in such a fashion that the need for post processing is minimized. "Get it right" in the camera. So I use Nikon A2 warming filters on all of my lenses.
If you only shoot jpegs, the use of filters could help even further.
The skylight filter is typically a salmon colored UV filter, to add a slight 'warm' appearance, without so much blue. By having color, not only they absorb more UV than a UV clear filter, but also add a subtle and generally pleasing warm color tone to images. Skylight filters are usually designated 1A and 1B. The 1B being warmer than the 1A. For a less subtle warming effect, there are hybrid Warming Skylight or Warm-UV filters.
In degree of absorption of UV light under 400mu wavelengths -the industry standard- first are the UV filters, with "basic" reduction that varies across brands; then the Skylight (about 50%); then Haze 1 (about 70%), then Haze 2 (up to about 99.7%).
In order to reduce the flare that might be induced by additional glass surfaces on top of a lens, and also to suppress light reflected out, "bounced" away on a filter surface, it is important to insist on multi-coated filters, like the Nikon and Hoya S-HMC and Pro 1 series. Otherwise you are inviting flare to come into the scene.
So all of these filters absorb/transmit ultraviolet light rays in varying degrees and render cleaner, sharper images with less haze. And therefore it was highly recommended to leave a UV, Haze or Skylight filter on your camera lens at all times to protect it from dust, moisture, scratches and breakage. If you have small children around, all sort of foreign materials can land on your lens front element. If you have been denied the joys of children around, or will not encounter water, dust, sand, then by all means go "naked".
In consequence, before becoming aware of the improved characteristics of modern color film, I bought the now discontinued Nikon L37C filters for all my lenses, because they cut out UV light invisible to the naked eye, with no effect on visible light and had great coating.
My guess is that the L37C designation meant absorption of UV Light under 370mu wavelength, and C means coated. If this hypothesis is correct, the L37C was closer to a Haze than to a typical UV filter of other brands. This could also explain why the L39C was discontinued earlier as the absorption of UV light between 370mu and 390mu was probably found either unnecessary or the skies unpleasantly devoid of all blue.
However and again, today, when most modern digital camera sensors and color films -although not all- are insensitive the UV light, I have replaced all L37C filters with Nikon A2 ones or Hoya HMC 81A and looking into the Hoya Pro series that have the S-HMC coating. These, while continuing to cut some UV light if necessary, add a usually pleasing warming tone to images and don't induce flare.
NIKON AND HOYA
In 1996 Hoya introduced its line of Super Multi-Coated S-HMC filters. Consisting of the Skylight 1B, UV (0), ND 2X, ND4X, and a low profile circular polarizer. This line of filters has a 5+1 layering system on each side of the glass: 5 layers of anti-reflective coating and a transparent easy-clean top coat, making the filters 12 layer ones. This reduces light reflections off the filter surface to an average of just 0.3%. This seems to be the lowest reflective rate on the market from any filter manufacturer, except Nikon.
B+W and Heliopan filters, among others, look most attractive because its use of German Schott glass and their brass non-binding rings; but, if binding is a concern, the rubbing on the threads of filter with your finger tip with one drop of light oil (even edible will do) is most of the times enough to prevent two filters from locking together.
Field research has also confirmed that B+W and Heliopan filters on the stores shelves have less layers of multi-coating than the Nikon and recommended Hoya Pro series, both also made from glass bars.
As soon as feasible I will retreat into the mountains or the sea and will try to remember to illustrate the effects of
- Not using filters (like in the image at right)
- Using non-multicoated filters, not-so-multi-coated ones and
- Using the filters as recommended above
- With a digital camera and on film
In the meantime, whatever filter you choose ... or not ...
Have a great time
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