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UV or Skylight Filter: What’s the Difference?

UV or Skylight Filter

In the process of shopping for a UV filter, you may have come across something called a Skylight filter and wondered which one you should get: a UV or skylight filter.

The difference between a UV and skylight filter is subtle but notable: UV filters have no color cast to them. Skylight filters have a faint orangish-pink color cast. So UV filters are simply clear glass - that’s it. A skylight filter is just a UV filter dyed with a faint warm color tinge.

Why would you want a warm color tinge on a filter that will be on your camera all the time? Well, for the answer to that, we must go back. Way back. To the days of film! *gasp* Do they still even make film?!

UV or Skylight FilterSkylight Filter on the left, UV on the right
Notice the orangish-pink color cast on the skylight filter

Skylight filters were originally designed for use on traditional analog film and they really just don’t serve any purpose in digital photography. See, when shooting color transparency film like Fuji Velvia or Kodak Kodachrome, there is no adjusting color balance after snapping the shutter. In other words, it’s like the white balance was “baked in” to the film when it was manufactured. These films are usually manufactured with a “daylight” color balance - meaning they will get accurate colors in outdoor scenes in the sun, but not really under any other type of light source. Try using this “daylight” film indoors and you’ll get some seriously ugly yellow colors. Try to use it in the shade and your pictures will be too blue. There were also some films manufactured with an “incandescent” white balance for use indoors and those couldn’t be used outdoors without creating inaccurate colors.

So let’s say you have daylight film loaded in your camera, but you want to photograph someone in the shade. Well, that’s a bummer. Your film is designed for daylight, not shade. So if you take the photo, the picture will come out really blue.

What is a poor photographer to do?

Aha! What if we put yellowish-orange filter on the lens, then took the picture in the shade? The warm-tinged filter should cancel out the blue color cast from the shade, resulting in accurate colors.

Until digital photography hit the scene, this is how photographers would “adjust white balance” on color slide film before digital white balance existed. That’s why warming filters were so common. There was really no other way to adjust color balance than to use filters.

And this is why skylight filters were popular for shooters using color slide film. The faint warm color of the skylight filter helped to cancel out some of the blue created by an atmosphere rich in moisture. For example when photographing landscapes, often times distant subjects like a mountain range will turn out a little too blue on color slide film simply because there’s a lot of atmosphere between you and the mountains. But with a skylight filter, you’ll “cut through” that blue a little bit and get more accurate colors.

Plus, it just so happens that most (not all, but most) nature photography looks better if the colors are “warmed up” just a bit. Fall color, sunsets, sunrises - people tend to prefer warmer colors in these types of shots. So that’s another reason skylight filters were a common choice amongst outdoor photographers using slide film.

But with digital, it’s all replaced by white balance. There’s no need to use colored filters because a tweak to white balance creates the same effect. Rather than use a skylight filter or a warming filter, you could just use a “warmer” white balance setting, like cloudy instead of daylight, or shade instead of cloudy. Or better yet, just shoot RAW and tweak the WB in the computer. Want a little more warmth? No problem, just drag the slider.

So when it comes to digital, don’t bother with skylight filters. They will offer no benefit over UV filters. And besides, if your camera is set to auto white balance, the white balance will just cancel out the warm colors of the skylight filter anyway.

[youtube]http://youtu.be/y2c3bq_IB6Q[/youtube]

UV Filter Use: Does It Degrade Image Quality?

UV Filter Use: Do You Need One?Ah, to UV or not to UV, that is the question. This can be a heated topic amongst photographers. Some argue that UV filter use will degrade image quality, others argue that it’s the best insurance you can get for your expensive lenses. There are merits to each argument and we’ll get to that debate in just a second, but first things first - let’s talk about the purpose of a UV filter.

The best UV filter on the market will do nothing for your photos. That’s the whole point. UV filters are used simply to protect the front of your lens. It’s nothing more than a clear piece of glass that you screw on to the front of your lens and then forget about. You leave it on all the time as insurance. Drop your lens or smack it against a wall when it’s hanging around your neck, the filter will break instead of your lens.

If you get a good quality UV filter, it will protect the front of your lens without affecting the image one bit. If you get a bad one, it might degrade image quality or create more lens flare. And why are they called UV filters? Well, it sounds better than “clear piece of glass to protect the front of your lens.” True, they are supposed to block UV light - and most of them probably do - but it doesn’t matter because UV light doesn’t have any noticeable effect on your photos anyway.

Now the argument in favor of UV filter use is clear (ha! puns...). Put a UV filter on the front of your lens and you got yourself a $40 insurance policy. Replacing a shattered UV filter is much more affordable than replacing a shattered front lens element. And believe it or not, they actually do protect the lens. When I first heard about the purpose of UV filters, I thought, “Come on...like a single piece of glass is really going to do anything to protect the lens.” But they do. Of course it ain’t going to protect against a 5-story drop from a hotel balcony, but it’ll protect against those really frustrating “it just barely slipped out of my hands” kind of mistakes.

B&W UV MRC Filter

My UV Filter of Choice is the B&W UV MRC
Click Here to Purchase Yours from B&H

The argument against UV filters is, shall we say, untenable. Anti-UVers say, “Why would you put a $40 piece of glass in front of your $1,000 lens? A lens is only as good as the glass in front of it. You want to turn your $1,000 lens into a $40 lens? Huh? Do ya, punk?” Alright, maybe they’re not that hostile.

This argument is based in theory, not practice. Sure, it makes sense in theory that another piece of glass is just another chance for image degradation. But I’m betting the people spewing this logic have never actually done a side-by-side shot with and without the UV. This also sounds like the logic of someone who has never damaged a lens before. It’s easy to say “don’t get car insurance” if you’re never had a fender bender.

And by the way, I did do a side-by-side comparison with and without a UV filter. Can you tell which one had the UV filter and which one didn’t? Neither can I...

UV Filter Use: Do You Need One?

Below is a 100% magnification of the above image.
One of the samples below was taken with a UV, the other without a UV.
Can you tell which is which?

UV Filter Use: Do You Need One?

The bottom line is this: If you get a really poor quality UV filter, like the $10 Sunpak ones, then yeah, it might degrade the image a tiny, tiny bit when examined at 100% magnification on your computer screen (but still, I’m betting you won’t see a difference). Buy a good quality UV filter, like those made by B&W, and there is basically no chance of it degrading your photos.

So I generally recommend the use of UV filters to my students. If you want the protection, use one. I do.

Common Misconceptions: You Don’t Need Filters for Digital Photography

The Misconception:
Photoshop (and other image editing programs) have replaced traditional filters. I can do everything in Photoshop that photographers used to do with filters.

Why This is Wrong:
Whether you're talking about a digital sensor or a piece of emulsion, photography is all about recording light. The whole purpose of traditional filters is to alter the light on its way to the sensor or film so as to achieve an effect. Using Photoshop to mimic a filter is simply "pushing pixels." It's altering ones and zeros. It's trying to change the light after the fact.

Let's take graduated neutral density filters for instance. There are the real deal and there are imitations built into software like Lightroom. The way true graduated ND filters work is by darkening the light coming from the sky as it makes its way to the sensor. The way the "graduated ND filter" in Lightroom works is by darkening blown out pixels to make the sky appear darker. So with the real McCoy, the bright light is tamed down so that the sensor can actually record the sky in all its detail and color. With the cheap imitation, a blown out sky with no detail at all is artificially darkened without ever recovering much more detail.

Check out this side-by-side example. The image on the left was taken with no filters and the image received almost no post-production work. The image on the right is my attempt to digitally mimic a graduated ND filter on the exact same file. I used the dodge and burn tool in Photoshop along with gradients, layers and curves. It took about 10 minutes to do all that work to just one image.

Graduated ND ImitationYou'll see that the sky is a bit darker and there is a little bit more detail, but it's really no replacement for the real deal, as illustrated below. In the next comparison, take a look at how much better the image is when I utilized a simple traditional graduated ND filter. The image on the left is the same one as above - no filters with heavy post-processing. The image on the right is the picture taken correctly with proper filters with almost no post-processing work. Time spent on the computer for the image on the left: about 10 minutes. Time spent on the computer for the image on the right: about 10 seconds.

Digital Grad ND vs Read Grad NDLook at that...you can actually see detail in the sky! With a simple $40 filter and zero time spent in Photoshop, I went from a blown out sky with no detail to a beautiful sky with lots of detail.

No filters vs a Grad ND

So you can see that my Photoshop imitation of a grad ND doesn't even hold a candle to the real grad ND. It doesn't recover detail in the sky, it doesn't capture the color in the clouds and it doesn't preserve the quality of the original file. More work with worse results. I don't know about you, but I like to worker smarter, not harder.

Here's another variation on this picture that, again, utilizes true grad ND filters and received almost no post-processing.

Using Graduated ND Filters

Same goes for circular polarizers. Those filters cut through reflections on everything from water to windows to foliage. There is no replacement for that in the computer!

The Truth:
Filters are just as important today as they were with film!  There's no replacement for altering the light on its way to the sensor. And no matter how much money you spend on Photoshop and all its plugins, no piece of software can travel back in time to the moment you clicked the shutter and alter the light before it hits the sensor. Especially when it comes to blown out pixels, Photoshop just can't work miracles. If pixels are blown out, there is literally no detail to be recovered. And if you're thinking, "But Nick, what about HDR." Well...don't get me started.

My Thoughts and Rants:
I don't know where this idea started that just because everything's digital now, we don't need traditional filters anymore. I have a sneaking suspicion that it's all rooted in marketing from image-editing software companies. They want you to buy software, so they market their products as a replacement for filters. Just like diet pills trying to convince you it's a replacement for proper nutrition and exercise.

But regardless of where it came from, this mentality drives me nuts! To me, it's like using software to correct a horrible, pitchy musician who really has no business singing in the first place. Instead, let's ditch the software and just get someone who can actually sing. Is that really such a novel idea these days? What would the world be like if we never used Auto-Tune or Photoshop ever again? All the horrible musicians and photographers would drift out of sight like dregs at the bottom of a dirty bucket of water. Then all the actual talent would float to the top. Oh, also all of our supermodels and celebrities would suddenly look flawed and human. God forbid!

Bottom line is this: using software to mimic proper use of filters out in the field is the work of incompetent photographers. They can operate software, but they can't operate a camera. But don't fret if you fall into this category. We were all incompetent photographers at one point. But don't turn to software to fix your images - just become a better photographer through study and practice! Then you can save the $600 you would have spent on Photoshop for something really valuable, like filters and a tripod...or your mortgage.