Archive for the ‘filters’ Tag

Friday Foto Talk: Using a Circular Polarizer, Part II   11 comments

Recently-flooded wash in Death Valley, California.

Recently-flooded wash in Death Valley, California.

Last week I got all technical about how circular polarizers (CPLs) work.  Of course you don’t necessarily need to know all that to shoot with them.  But it certainly doesn’t hurt.  The more you know about how CPLs work the better able you are to extend the situations in which you use them.  You can more competently go beyond landscape photography, which is where they’re primarily used (and where I’ll focus this tutorial).

Now let’s get into the meat of things and learn how to employ these great filters in your photography.  As usual it’s a good news/bad news story.  We’ll start with the bad.

Staying in Death Valley, this dramatic side-light didn't really need a CPL.  I used one but dialed down the strength a bit.

Staying in Death Valley, this dramatic side-light didn’t really need a CPL. I used one but dialed down the strength a bit.

DOWNSIDES & HOW TO MINIMIZE THEM

  • First off, it’s a filter, the kind you screw on to the end of the lens.  This adds another layer of glass between your subject and your sensor or film.  That introduces a chance for flaws in the way light is transmitted, at least in theory.

 

  • But as long as the filter isn’t cheap and you keep it fairly clean, it should yield perfectly sharp images just as when you’re not using a filter.  I’m not the type of photographer who puts a lot of stock in the idea of an imperfect image.  If I can’t detect any fall-off in quality then it’s simple: the benefits of using the filter outweigh any theoretical considerations.

Arches National Park, Utah. I used a CPL, maximizing “punch”, mostly in the sky.

  • Again because it’s a filter, a CPL will increase the possibility of flaring: those often annoying but sometimes interesting bright colorful spots that show up in your pictures when you shoot toward a strong light source like the sun.  But you can control flares by keeping your filter and lens clean, by using a hood, and of course by not pointing directly toward the light source.

 

  • Sometimes you have no choice, your photo demands pointing it toward the sun.  Then you simply roll the dice and keep shooting until you get flares that are easy enough to remove on the computer.
Washington's Olympic Peninsula at Lake Quinalt. These are the kinds of flares that aren't too hard to clone out on the computer.

Washington’s Olympic Peninsula at Lake Quinalt. These are the kinds of flares that aren’t too hard to clone out on the computer.

UPSIDES & HOW TO MAXIMIZE THEM

  • So you know a CPL filter reduces reflections.  But this may or may not be what you want.  In the case of mountains reflected in a lake, you’ll want to be careful to rotate it just the right amount to maximize the color and light in your reflection.  If you rotate it fully you’ll begin to see what is underneath the water, if it’s shallow enough.  In the case of wet rocks or plants, you may want to use it fully to help bring out the color of the rocks or greenery.
For this hot spring, I wanted to see the subtle colors of the algae growing along the little falls, plus I wanted smooth water. Cutting reflections and lengthening exposures is a great two for one when using a CPL.

For this hot spring, I wanted to see the subtle colors of the algae growing along the little falls, plus I wanted smooth water. Cutting reflections and lengthening exposures is a great two for one when using a CPL.

 

  • A CPL also reduces the total amount of light reaching your lens.  Some models reduce the light only slightly (called “high-transmission” CPLs), but most block between one and two stops of light.  In a way this is a downside because it can hurt you when you’re hand-holding the camera and need a fast shutter speed.  You may need to raise ISO.  But it can help too.  For example when you’re on a tripod and want to lengthen shutter speed, say to blur a waterfall (see above photo), a CPL can provide just the right light-blocking strength.

 

 

Without a circular polarizer.

Without a circular polarizer.

  • A circular polarizer will darken and tend to saturate colors a little, especially the blues in a sky.  When there are white clouds it increases the contrast between blue sky and cloud, quite a lot if you’re shooting at a right angle to the sun.  A typical landscape shot with a CPL has more “punch”, or mid-tone contrast.  The photos above and below, which are deliberately sort of “average”, show the difference.
Same scene as above with a CPL.

Same scene as above with a CPL.

  • As the pair of shots above show, a CPL can do nice things for colors, especially when you consider that when shooting RAW your images often come out looking flatter and more washed out than the real scene was.  But as you can also see, contrast is increased over the RAW image as well.  That’s why a CPL can often be used to great effect when you’re shooting for black and white.  Try it.

 

A polarizer can lend black and white images a little more drama: Panamint Valley dune field, Death Valley N.P., California.

Okay that’s it for now.  Next time we’ll conclude with more guidance on using CPLs, along with tips on maintaining them.  Happy weekend everyone!

_MG_6879-Edit

Advertisements

Friday Foto Talk: Using a Circular Polarizer, Part I   2 comments

Soap-tree yucca growing on the dunes of White Sands National Monument, New Mexico glow in the bright morning sun

The circular polarizer (or CPL) is a must-have for any landscape photographer.  This handy filter can be used in many different situations, but like any piece of photo gear it helps greatly to know exactly what it does and what its benefits and downsides are.  This is the first of two parts.

WHAT A CPL IS & HOW TO USE IT

  • A circular polarizer is a filter that screws on to the threaded front end of your lens.  It has two pieces of glass sandwiched together.  So it also has two rings for you to grip.  If you grip the ring closest to the threads you will be able to screw the filter on and back off your lens.
  • Once it’s on (not too tight!), grasp the ring furthest from the threads to rotate the front piece of glass relative to the other (now fixed in place).  This is the way you adjust the filter’s strength.  It goes from minimum to maximum effect with 90 degrees of rotation, then back to minimum if you continue rotating all the way to 180 degrees.
I used a polarizer for this shot in Death Valley recently because I wanted to maximize the effects of the side-light and show the texture in the land.

I used a polarizer for this shot in Death Valley recently because I wanted to maximize the effects of side-light to show the texture in this awesome alluvial fan, visible in the lower part of the image.

HOW A CPL WORKS

  • The CPL filter works by polarizing light in a couple different ways.  When light is reflected it becomes polarized to one degree or another.  Light rays can be thought of as vibrating waves.  When emitted by some source (like the sun), the light waves vibrate in all directions.  When light hits a reflective surface and bounces off it, the waves vibrate mostly in one direction, parallel to the reflecting surface.  The light has become linearly (or plane-) polarized.

 

 

Light reflected from a lake becomes polarized.

Light reflected from a lake becomes polarized.

 

  • A circular polarizer works by first polarizing the light linearly, then turning it into circularly polarized light.  In the case of the plane-polarized reflected light above, the front glass element of the CPL acts as if it has slits, either allowing the polarized rays through or (partly or fully) blocking them.
  • The rear glass element, the 2nd one the light passes through, takes that linearly polarized light and polarizes it further, but this time circularly.  If you think of the linearly polarized light as a line on a graph, with both horizontal and vertical (X and Y) components, the CPL is blocking one component (vertical, for example) more than the other.  It turns it into a vibrating wave that sort of spirals.  The light that finally reaches your lens is now circularly polarized!

 

Diagram of a circular polarizer in action. Click on image to go to source website.

Diagram of a circular polarizer in action. Click on image to go to source website.

  • As described above, you adjust a CPL by rotating the front glass element.  This increases or decreases the degree of circular polarization.  And if you have reflected light, off a lake or river for example, rotating the filter also changes how much of that plane-polarized light you’re blocking.  Again, think of that front glass element as having ‘slits’, which when crossed at an angle to reflected light will prevent some of that naturally polarized light from getting through.

Yellowstone’s Lone Star geyser erupts.

  • By the way, that crossing of the slits to plane-polarized light is called cross-polarization, and it’s how polarized sunglasses work.  Their “slits” are fixed in a vertical position, enabling them to block the plane-polarized light reflected off of water, roadways and other horizontal surfaces.  Look at the reflection off a vertical store window  with your sunglasses on and you’ll see they allow that light right on through.

I used a polarizing filter at this pool in Ash Meadows Wildlife Refuge, Nevada in order to show some of the detail under the water.

BASIC FIELD USE

  • Again the effect increases as you rotate the moveable (outer) ring.  In the case of light reflected off water or glass, rotating the filter to its max. position (90 degrees from minimum) will cut the reflection dramatically.
  • And for similar reasons, as you point the camera close to right angles (90 degrees) with the sun or other light source, the polarization effect increase dramatically as you rotate the filter to its max. position.

Those are just the two basic ways to use a circular polarizer in the field.  There are quite a number of other, more subtle ways to use a CPL in photography.  And next time we’ll look at using the filter to improve your images, all the while emphasizing its strengths and dodging the inevitable drawbacks.  Have a great weekend and happy shooting!

The barren, channeled nature of a Death Valley alluvial fan is highlighted by strong side-light. I used a CPL but not set to its max setting.

Friday Foto Talk: Shooting at Sunrise & Sunset – Part II   5 comments

Sunrise from a campsite deep in the Okavango Delta, Botswana.

Sunrise from a campsite deep in the Okavango Delta, Botswana.

This is the second part of three dealing with photography at sunrise and sunset.  It will focus on how and what to shoot.  See Part I for some general info., equipment and tips.

Now what to shoot?  As I mentioned above, water should probably be near the top of your list.  But you can find beautiful bodies of water in the mountains, broad valleys, cities, even deserts.  And of course seascapes by definition include a very big body of water.  While including the sun in your shots is the classic composition, photography at these times of day is so much more than that.  Start to think and plan along the following lines:

The Bridge of the Gods spans the Columbia River at Cascade Locks, Oregon.

The Bridge of the Gods spans the Columbia River at Cascade Locks, Oregon.

I. Shoot toward the Sun

You will face the strongest contrasts when doing this, so looking at your image on the LCD right after you take it is important.  Turn on your highlight warning (blinkies) and also take a look at the histogram.  Make sure you don’t have too much dark area (which will just look noisy when you lighten it) and definitely avoid letting areas get blown out (climb up the right edge of your histogram).  You can let things like the sun, headlights or streetlights, and a few other things blow out to white of course.

Springtime means that the sunflower-like balsamroot blooms at Rowena Plateau above the Columbia River in Oregon.

Springtime means that the sunflower-like balsamroot is in bloom at Rowena Plateau above the Columbia River in Oregon.

Using a graduated neutral density filter is nearly always key when shooting into the sun.  Although Photoshop, Lightroom and other software have graduated filters, you cannot expect to use these programs to darken a blown-out sky.  So you might need to use a grad. filter in the field just to tame the bright sky enough to be able to use another grad. in post-processing.  If you have trouble seeing in your viewfinder the line where dark goes to light on the filter, use the depth of field preview button (if your camera has one).  Also try using live view.  I hand-hold the filter in place, but you can also get the dedicated filter-holding kit.  I also will often move the filter up and down to effectively soften the transition.  You can buy a hard-transition filter and then use this technique to turn it into a soft transition.

We often don't think about macro photography at sunrise, but this is in my opinion the best time.  Here a windless morning pairs with beautiful dew to make this balsamroot shine.

We often don’t think about macro photography at sunrise, but this is in my opinion the best time. Here a windless morning pairs with beautiful dew to make this balsamroot shine.

Also watch for flare.  Use your lens hood, and consider wearing a cap just so you can use it to help block the sun.  Avoid using any screw-in filter unless you have to.  For example, use a polarizer to tame that reflection on the lake surface (so you can see the pretty rocks beneath the surface) but take off your protective UV filter.  A little flaring is easy to remove later on the computer, and flaring sometimes adds something to the shot.  Simply be aware of it when you’re shooting toward the sun or any bright light.

Natural channels along the rocky Oregon Coast often serve to funnel waves inshore, soaking unwary photographers in the process.

Natural channels along the rocky Oregon Coast often serve to funnel waves inshore, soaking unwary photographers in the process.

It’s usually best to take your meter reading off of the bright part of the sky near the sun (not the sun itself).  You can also take it off of the bright part of a reflection in water.  In aperture-priority mode, point the center of your frame at this bright area.  Press and hold the exposure lock button before recomposing and also before sliding the grad. neutral density filter over your lens.  In manual mode, you set your aperture, point the middle of the frame at the area you’re metering from, and then adjust shutter speed so the light meter is more or less centered.  I like to bias  my exposure a little to the right, which refers to the histogram bulging to the right (slightly overexposed).  Remember to use the highlight warning to make sure important detail isn’t lost by making it too bright.

A lone man walks the beach on the remote Andamon Sea island of Tarutao off southern Thailand's coast.

A lone man walks the beach on the remote Andamon Sea island of Tarutao off southern Thailand’s coast.

II. Shoot at an Angle to the Sun

This is often what you want to do when the sky is decorated with colorful clouds at sunrise or sunset.  Shadows of things like rock formations, trees, even people or animals, can really help to set off the photo and give it depth.  Same principles apply as with other images: meter off of the brighter areas of the landscape or better yet, a medium-bright part of the blue sky.  Or you can simply frame and shoot, then check the LCD, including the histogram.

There is plenty of shadow and depth in this image shot at an angle to the sun.  Sand dunes and the Totem Poles in Monument Valley as the sun sets and the moon rises.

There is plenty of shadow and depth in this image shot at an angle to the sun. Sand dunes and the Totem Poles in Monument Valley.

This is also when a circular polarizer comes in most handy.  Realize that when the sun is low and you are shooting in a direction that is near 90-degrees from the sun, the polarizer will have its maximum effect.  What this means in practice is that you need to be careful; don’t necessarily rotate the filter to its maximum.  Less can sometimes be more here, so try a partial polarizing effect.  If you need to tame large contrast between land and sky use a graduated neutral density filter over top of the polarizer.

Photographed at an angle to the setting sun, a lone farmstead in the Khumbu region of Nepal's HImalayan Mountains lies in spectacularly rugged country.

Photographed at an angle to the setting sun, a lone farmstead in the Khumbu region of Nepal’s HImalayan Mountains lies in spectacularly rugged country.

If you are using a very wide angle lens, be careful of two things regarding the polarizer:  (1) the filter might show up in the corners, forming a vignette.  Zoom in a bit or go buy a polarizer built for wide-angles (they’re thin); and (2) the polarizing effect will vary across the sky, since the angle of view is so large.  This can result in some weird effects, especially if you have a lot of blue sky.  Don’t use the filter at maximum effect, or use a graduated ND filter to darken the lighter area in the sky.

The desert sun sets over the ubiquitous sandstone outcrops that surround Page, Arizona.

The desert sun sets over the ubiquitous sandstone outcrops that surround Page, Arizona.

Hope you’re enjoying these posts.  Stay tuned next Friday for the final part.  Note that these images are copyrighted and not available for free download, sorry.  If you’re interested in purchase of any of them, as fine-art prints or as high-resolution downloads, simply click on the image.  Once you are at the screen-filling image, click “add this image to cart”.  It won’t be added to your cart right away; just click the appropriate tab to be shown pricing for the image.  Please contact me if you have any questions.  Thanks for looking!

Shooting at an angle to the sun lends texture and shadows to this view of the Namib Desert near Sossusvlei, Namibia.

Shooting at an angle to the sun lends texture and shadows to this view of the Namib Desert near Sossusvlei, Namibia.

%d bloggers like this: