Kristy mentioned over on her blog that we’re trying to purge ourselves of some of our excess stuff. Part of that means finding things that have been in boxes for a long time and getting rid of them, either by donating them, or, if they seem salable, by putting them up on eBay.

One thing that I do, when buying from eBay, is try to find an auction with a crappy cell-phone looking picture, or, better, no picture, and as little descriptive text as possible. These ones get missed by more searches and overlooked by more bidders, and as a result, I spend less money. So of course, to maximize our take from the items that we’re going to try to sell ourselves, we’re trying to do the opposite. And part of that means getting *nice* pictures of everything we want to sell.

What is a photographer with little equipment to do? Worse, what is a photographer who has pledged to forego discretionary spending to do? Why, construct a lightbox-alike for cheap, of course!

We had a white sheet that we’d purchased to project on (unfortunately, the day we wanted to project on our patio, it was quite windy, so the sheet was in pristine condition). Fortunately, among my equipment, I do include a few un-substitutable essentials: a tripod, a reasonably advanced digital camera (I am overqualified in this area). I also have a nice fast lens, which helps get rid of pesky backgrounds, and a totally-overpriced gray card. A word about gray cards–they cost so much because they’re supposed to last. But if you have a decent color printer and don’t mind reprinting one every month or so, you can use this handy one I threw together in Photoshop (more details about what it is, what it’s for, and how you use it later on).

1. Controlled lighting
2. White sheet
3. Tripod and camera
4. Gray card

Setup

Even with a tripod to help you out, you still want a reasonably bright light source; however, to save time, try to make sure that the light source isn’t going to change while you are shooting (light from a window is bad for this). To make it easy to reach your work surface, I recommend working up on a table. To give yourself enough room to work, the table needs to be relatively deep. Finally, you need to be able to attach a white sheet behind your work area, and the sheet needs to be long enough to drape down to your table surface and cover it. The sheet should be draped loosely, not forming a sharp angle where it meets your work surface–otherwise you’ll get strangely shaped shadows. Pictured at right (or above, depending on how this text lays out) is the arrangement I used. If you can arrange for your light to be coming in at a 45 degree angle, it will produce some nice shadows for you. I know that in a real lightbox, you try to completely eliminate shadows, but that isn’t going to happen for us.

1. Work table at comfortable height
2. Hang sheet behind, curved gently from vertical to horizontal
3. Light at 45 degree angle

Getting Started

Turn on your light source and walk away for at least five minutes. This is especially important if your light source is a CF bulb or (ugh) a fluorescent tube. The light will change as the source warms up, so just let it sit for a few minutes. Before we start shooting and every so often while we’re shooting, we’ll be metering to make sure we take the best pictures we can.

Before we start shooting, there are a couple of steps to get your camera ready. The first thing you should do, whatever camera you are using, is set the ISO value as low as your camera will permit. Higher sensitivity lets you shoot in lower light at faster speeds, but it adds a lot of noise to the picture; and we’ll have a tripod, so shutter speed is immaterial for our purposes. Once your light source has warmed up, take your camera off the tripod, bring it over to your work surface, and haul out your gray card. Almost all cameras have a feature that lets you adjust the “white balance”–this is how the camera compensates for the fact that most light sources are not pure white. The first thing you’re going to do with your gray card is set this white balance. The process varies from camera to camera. With my D70, I hold down the WB button and roll the primary selector until PRE is selected. While holding down the PRE button, I press the shutter release. On my SD400 point-and shoot, I press Func/Set, choose “CUSTOM” white balance, and then press the menu button. Check your manual for details. For this part of the process, you want to be pointing only at the gray portion of the card. Your camera may have a hard time focusing at close range; if manual focus is available, use it. If you have a viewscreen, you should see the colors of things around you abruptly change; if you have an SLR, snapping a few shots should show you quite a difference.

The next thing we’re going to use the gray card for is to figure out the best exposure for our photos. Sadly, many point-and-shoot cameras aren’t flexible enough to let you perform this adjustment on the camera. If you’re using one of them, instead place the gray card in the middle of your workspace and shoot a couple pictures of it. Try to make it take up about 1/4 of the frame in at least one of the shots and about 1/2 of the frame in another. We’ll use these later in Photoshop to correct your images. If you have an SLR, however, we can actually figure out the correct exposure settings using your card. Put your camera in aperture priority mode; after selecting the aperture you want to shoot at (I recommend f2.5 if you can), shoot a frame containing only the gray card, again probably using manual focus. Note the shutter speed the camera uses; then abandon aperture priority mode, and put the camera in full manual mode with the aperture and shutter speed from the previous step. The metering logic in SLRs will try to perfectly expose this “18% gray” value. A final note about exposure: when shooting photos in this style, I prefer to overexpose by about “one stop” of light, to help blow out any background details that may escape our shallow f2.5 depth of field. On my SD400, I do this by setting the “Exp” value to +1; on an SLR, you would do it by setting the shutter length to twice the value obtained from the previous step (so, for example, 1/40s -> 1/20s).

Please note that if you’re shooting on an SLR, I highly recommend that you use RAW mode. If you should overexpose an image too greatly, it can usually pull back at least half a stop of detail more than if you had been shooting JPG.

Place your camera back on your tripod and start shooting. If you are using a point-and-shoot that doesn’t let you manually adjust aperture and shutter, try to make the object you’re shooting fill as much of the frame as one of your test shots with the gray card; that will make color correction easier. In either case, remember to repeat the procedure above every hour or so to make sure that the light has not changed too much on you.

1. Let the light warm up
2. Use the lowest ISO setting available
3. Set the white balance on your camera using the gray card
4. SLR shooters, use aperture priority to figure out correct exposure with the gray card, then MAKE SURE to switch to manual
5. If you can’t adjust the aperture and shutter independently, take several test shots with the gray card to help with correction later
6. It might be a good idea to overexpose slightly, especially if you shoot RAW anyways. If you are unable to shoot in full-manual mode, you must overexpose

Shooting

Because we are working with (probably) an artificial light source from around the house, and because we’re actively trying to overexpose the image we produce, the shutter time is likely to be rather long; at anything longer than 1/60s, hand shake is likely to be visible in the image, and even if you are using a tripod, pressing the shutter release will likely cause some jitter. If you have a remote release, you should use that; and if not, you should use the self-timer feature. Set it to the minimum value (2s on my SD400), and use the 2s it provides after pressing the shutter release to gently let go of the camera.

Work as quickly as you can to prevent the light from changing too much on you. I recommend a brush to dust your work surface off if you are photographing items that have been in storage; if the bristles are soft enough, you can use them on the item itself. Keep in mind that if you attach any additional filters, such as a polarizer to cut reflections or a close-up lens to capture details, you should repeat the white-balance and metering steps; anything in the light path will change the light received at the sensor.

When you are done shooting, drink a beer.

1. Use a tripod
2. Use a remote / cable release if you have one
3. Use the self-timer feature if you don’t have any better option
4. Redo the metering and white balance whenever the light changes
5. I like a nice weiss beer

Post-Processing

If you are fortunate enough to be shooting with an SLR, you should have very little in the way of post-processing to do. Congratulations–the extra $374189 that you spent on your camera is paying off today The image at left came directly from my camera with no color correction whatsoever–just the RAW processing, but that’s a part of my workflow by now. What’s great is that if I’d followed my own directions (I didn’t–I left the camera in aperture priority mode, a big mistake) all I’d need to do at this point is crop. Because I left some of the exposure decision up to the camera, quite a few actually needed the kind of adjustments that the exposure section is meant to avoid.

If you’re shooting with a point-and-shoot or if your camera otherwise restricts your ability to control exposure, you still have some work cut out for you. The white balance should have removed any color casts, a particularly difficult problem to solve in image processing software, but there’s still the question of making sure your levels are where they should be. Because cameras try to expose “18% gray” correctly, photos that are mostly white tend to get underexposed–it thinks the white should be gray, see?–so you’re going to have to do what you can to correct that.

An important tool in post-processing is the histogram. You might remember histograms from that stats unit that sometimes happened toward the end of the year in math cla–WAKE UP BACK THERE–class. Histograms show the frequency of each of a discrete set of values. In image processing, the values are usually luminance values, and the histogram is to show you how much of your image has a particular brightness. At right is the luminance histogram of our sample gray card image, as I produced it on my computer. Notice the small spike at far left to show the region of the image that’s pure black, the small spike at right for pure white, and the large spike for “mid gray.”

The goal here is to, using the levels tool, find the adjustments that restore your photo of the gray card to the correct brightess.  Once you’ve done that, write down the levels settings that you used, and apply them to subsequent images.  This should resolve any brightness problems you may have.

I just bought gray cards.  I had a gift certificate, I needed them, and it’s probably good to buy gray cards if you’re going to be using them a lot.  They’re low-reflectivity, they’re sturdy, and they hold their color.  But it hurts me to pay money for carefully colored cardboard, and I probably wouldn’t have purchased any without a gift certificate.  But not white-balancing will hurt your photography.  What to do?  You could always hack your own… the results will almost certainly not be as good as a professional gray card, but they will be free.  This is a photochop tutorial, so here goes.

Now, I know that gray cards are usually called 18% gray cards.  And I know that they are 18% gray because, when you take a scene that is equal parts 0% black and 100% white, the 18% gray is the resulting color.  I don’t know why that is–ask a physicist.  And I don’t know enough about how printing works to do anything useful with that 18% number, so I’m going to cheat.

1. Make a new file, 2px by 2px.  May as well set the background color to be white.

2. Zoom in to the maximum extent allowed (do this automatically by double-clicking the hand tool).  You’re going to need to see what you’re doing.

3. Using the Rectangular Marquee tool, mask off the top left pixel and fill it with black.  Repeat for the bottom right pixel.

4. Select the entire image (Edit > Select All) and turn your image into a pattern (Edit > Define Pattern).  Name it whatever you’d like.

5. Create a new file, the actual dimensions you want to make your gray card.  I find that it’s helpful to switch to “inches” here from pixels… for example, 4″ x 6″

6. Select your entire new image (Edit > Select All); we’re going to fill it (Edit > Fill…) with the pattern that you defined in step 4.  Select “Pattern” from the “Use” drop-down list, and then choose your pattern from the “Custom Pattern” drop-down list. Note!  If you are using an analog monitor, the resulting image may exhibit frightening moire effects.

7. We have cleverly constructed an image that consists of equal parts 0% black and 100% white.  If only there were some way to average the two… (Filter > Blur > Gaussian Blur…) Oh look! 18% gray… see what I mean by cheating?

8. For added utility, I like to add strips of white and black at the ends of the card.

9. Our histogram shows we’re ready to go out and kick some butt!  Just make sure to print this on a printer configured for ColorSync (if you can) and on the least glossy paper you can find (important!).

Some day soon I’ll have a tutorial about what to do with a gray card.

Well, like I said, I never let acute guilt about the role of the US in world politics keep me from a barbecue. We had our friends John and Lindz over for a really nice barbecue yesterday to celebrate the holiday in style. They brought their dog Chai, whom Sybil and Ruby were really glad to see, and we had a nice time; first hanging out inside and then moving out to the patio to grill and relax. Unlike our last cookout, it wasn’t too windy to talk; however, we almost missed the wind, since there were swarms of gnats instead. A light dusting of DEET-enabled bug spray and a citronella candle later, we were in business. Brats, burgers, corn, cheap beer–the All-American summer meal, amirite?

Afterwards we retired to our building’s sundeck, a really nice facility whose location had been a mystery to Kristy and I until last night. We got a nice late-afternoon / early-evening view of the city as the sun sank. We played a few rounds of Uno, but of the three hands we played, I was the only one not to win. Dick bastards.

As dusk gathered about us, we gathered our possessions and headed out to an “underground” fireworks show in Ukrainian Village, whose organizers/performers we are to varying degrees acquainted with. He’s a really cool guy, and in the image at left, he’s demonstrating why I describe the event as an underground show. Yes, that’s a real 6″ shell; it made a pretty impressive skyburst. There were literally hundreds of these, and it went on for at least 45 minutes. It was quite honestly better than I remember the 4th of July fireworks in my hometown being, and it was put on by a bunch of well-connected amateurs. The show has apparently been going for years now, and the whole neighborhood turned out to watch. The cop cruisers circled, but seemed to be looking for trouble at the fringes of the crowd, ignoring the pyrotechnics in the parking lot. Had we not eaten first, there were plenty of tasty-smelling kebabs making the rounds, and the smell of cooked brats mingled with the sulfuric tang of the display all night. Needless to say, I was there with my camera set up to try to capture the air show.

So, photography. I checked with the guy who had invited us all to make sure that photography was permitted. You know, “underground show” and all. It was enthusiastically encouraged, so I hauled out my tripod and set it up pointing at the sky. It’s amazing how unselfconscious I’m getting about it by now–at long last! Since it was going to be right over us, I swapped out the 50mm prime that I’d used to excellent effect on the 3rd for my 18-55mm zoom, so as to cover the greatest possible area of sky; I could use it wide-open without fear of vignetting, because a) I wanted to stop it down anyways so I could leave the lens open and b) I was taking pictures of a dark sky! Everything was looking great on the screen when I occasionally checked it for proper exposure. Not only were the histograms showing that I was “doing it right,” but the photos were good too. Of course, you might guess that I wouldn’t elaborate on this unless something were actually going wrong…

Fig. 1: Looking good on-camera…
Fig. 2: Oh fuck.

Heartbreak. This is what I forgot, when I switched lenses: the 18-55mm zoom is a piece of absolute shit when it comes to manual focus. First of all, distances are unmarked, making any manual focus dodgy. But that’s ok, right? because I’m shooting with a fairly deep aperture at stuff that’s far away–I can just set focus to infinity, and the depth of field will sweep in anything more than 50 feet away. Sadly, unlike any other lens I’ve used, turning the manual focus all the way to the end is not “infinity”; instead, it’s “nothing.” Perhaps that is why this lens had to be refurbed, perhaps it’s just a bad design, but you can actually place the manual focus adjuster so that literally nothing is in focus. Which is what I cleverly did, so that I could shoot more shots because I wouldn’t have to wait for autofocus on each one. About 2/3 of the way through the evening, I realized my horrible mistake, but by then we were on to the finale, and smoke obscured a lot of the effects, leaving a tantalizing glimpse of what might have been.

Fig. 3: Even looks better at this distance
Fig. 4: Aha, focused correctly

What I should have done: first, I shouldn’t have assumed infinity focus would work. I could have sacrificed a few of the effects, not taking pictures in order to use them for finding focus–this is what I ended up doing later. Alternatively, I could have let autofocus handle the first one, and then switched the camera to manual focus after I’d found the right distance. I could have bought a lens, like the Tokina 11-16mm that I’m lusting after right now, that actually has proper infinity focus. Finally, I could just relax, as Kristy suggests, and realize that although a lot of my pictures aren’t as focused as I’d like them, they still turned out really well. And there’s always next year, right?

Disappointment aside, I did add a few decent tricks to my arsenal. Using manual focus DID allow me to snap freely–with no focus time, the shutter opened immediately when I asked it to. I tried using my remote for a shutter release, so that my hand wouldn’t jitter the camera, but the mechanics of bulb mode with the remote (press to open, press to close) ended up being too difficult to be practical for high-speed use. I left the camera in bulb mode, but I used the shutter release button instead (press to open, release to close). This let me open the shutter right when I knew the shell was going to explode and release as soon as I thought it had made the effect I wanted. I figured out that there was a reason my tripod’s panning release has a variety of degrees of tension, too–by tightening it halfway, I could still pan the camera up, but it offered enough resistance that I could pan to where a firework was and snap a .5s - 1.5s exposure without my hand on the unlocked tripod causing any visible jitter. I worked most of the night that way, panning up to the shell, holding the shutter, releasing.

Between the new things that I picked up and the hard reminder that I got, I’m going to take some amazing pictures next time I’m near fireworks.

I’m not much for celebrating the 4th of July. Far be it for me to turn down a chance to barbecue, or to see fireworks (I got some great pictures last night that I put in my flickr account here), but more and more these days the US seems like a blight on the world. Here’s hoping that by next July 4th, the Democrats will have solid majorities in the House and Senate, Obama will be in the White House beginning to repair our international reputation, troops will be on the way home from Iraq, and liberal nominees will be waiting to replace aging Justice John Paul Stephens. In the meantime, I can at least take solace in this news item.

NP: MC Hawking, Why Won’t Jesse Helms Just Hurry Up and Die?

Why no, I don’t believe in the ridiculous taboo about speaking ill of the dead.  While I’m at it, fuck Tim Russert too.

Today was the 15th annual “Chicago Cares” Serv-a-Thon. I’m proud to say that my company put a group together to volunteer, and that, although I signed up rather late, I was able to participate. We painted four classrooms at Cook Elementary, near 81st and Loomis. Now I’m sitting on our couch at home, with ice on my knee, a beer in my hand, my laptop on my leg, the dogs at my side, and the new episode of Battlestar Galactica on my TV. And yet, the work I did this morning was even more satisfying. If you have a chance, please find time to volunteer for something. It’ll be even better for you than I can possibly describe.

The wifi connection here at the hotel leaves a lot to be desired, so updates are not going t be forthcoming, but Kristy and I are still alive and well in the Dominican Republic.

Today’s post title is attributable to me.  We went snorkelling today, and not only did I avoid losing my snorkel in terror, I actually did pretty well at it.  I’ll give more details later because the trip deserves its own post, but during the past week I taught myself not just to snorkel properly, but even how to “free dive” by sealing the snorkel with my tongue while underwater.  On our third of three snorkels today, a school of bright blue and purple fish about the size of my hand swam below us, and I couldn’t resist giving it a shot.  Tongue in the snorkel, bend in half, kick, and I had joined the school!  Kristy hung above watching, and when I surfaced (after some spluttering) the best I could do to express my astonishment was to exclaim, as above, “I was a fish!”

So exciting.  Snorkelling today was one of the most exciting things I’ve done in quite a while.

Yesterday Kristy and I were having a really interesting discussion with one of her coworkers and that coworker’s partner about campus shootings and the appropriate response to them. My contention was that campus violence is simply a manifestation of our national inability to respond to mental illness in a mature fashion, and that the correct responses were to increase the availability of mental health treatment and to, most importantly, combat the stigma attached to mental illness that keeps so many people from seeking the treatment that they need. Perhaps the vehemence of my argument would surprise people who are not aware that I have an iron in this fire…

I was thinking about the stigma and silence surrounding mental illness, and decided that while I can’t do much individually about the stigma, I can at least break my own personal silence on the topic and hope that in some way it will do some good. So, because I don’t know how to do things halfway, I’m going to use my blog to “come out” as someone who is mentally ill. I have been in treatment for some time now for what I would vaguely describe as a major depressive disorder. This problem has been a daily fact for most of my conscious life; this is my second stint in psychotherapy, and the first one that shows any sign of sticking. In the time between round one and round two, I spent the better part of a decade self-diagnosing as anything from bipolar to borderline personality disorder to seasonal affective disorder, all because I was too intimidated by the prospect of therapy to actually get help.

But putting a label on a set of symptoms is not treatment, and many problems are simply impossible to sort out on your own, without the aid of an objective voice.  In my new treatment, I have not even asked for a clinical description of my set of symptoms.  The only lay use for a label is to help pigeonhole a person’s unique, unsharable, unreproducible, indescribable psychic distress, a game that I’m no longer interested in.

While the events that finally led me to re-enter therapy late last year are of a personal nature that I won’t discuss, suffice it to say that therapy has so dramatically changed my inner life that I had to write this post.  And that I had to use it to make this point: if you are wavering, wondering if feeling sad almost every minute of every day is just normal (it isn’t), doubting if your problems are “bad enough” or “matter enough” (they are and they do, if you ever think so–it isn’t a contest), afraid to go into therapy because of what people will say or think when they find out, please please do yourself and the world a favor and go anyways.  And if you need someone to talk to about it, please email me.

I’m in therapy and it’s ok.  I have a mental illness, and it’s not great, but it’s not my fault and it doesn’t make me less of a person.  And now I’m taking a very deep breath, counting to ten, and pressing “publish”…

…in which I pick up the title theme from my last post to wish Kristy and I a happy first anniversary. As Kristy says at her place, it’s been an interesting year, but we’re both still here and happier than ever.  Here’s to many many more. *mwah*!

We have fun things planned, as she says, and we had a great weekend, thanks in part to Kristy surprising me with Cubs tickets for us.  Thank you!  Tonight we get to find out how year-old unfrozen cake tastes

Aside from the game, some tasty sukiyaki tonight, and a new purse I bought Kristy that should arrive this week, we’ve booked a vacation in the beautiful Dominican Republic at the beginning of next month, and are finally replacing a 9-year old TV in our living room.  Huzzah!

Anyways, I have a lot of practice remembering our anniversary, because we’ve been celebrating it together for seven years (for varying reasons).  Those seven years have been some of the best of my life.  I love you Kristy!

Five years ago now, George W. Bush launched an elective, “preemptive” war of aggression against the sovereign nation of Iraq. It’s not necessary to paint Saddam Hussein as some sort of false saint to note that this is a war crime, and one need not be a leftist to point out that Sen. McCain and Sen. Clinton are both tarred with their support of that decision. In a similar period of time, the United States and its allies fought the Axis powers to a complete standstill; but thanks to the ineptitude of this administration, we are still mired in Iraq and figure to be for some time. Five years is too many, and thousands of Chicagoans took to the streets (as they have every anniversary of this invasion) to protest. This year, I was one of them.


The protest convened in Federal Plaza, which filled up quickly as the start time of 6:00pm passed. There were people of all ages, races, and ethnic backgrounds. Many young parents came with their children, a wonderful experience for both, I imagine. We assembled peaceably and listened to speakers while waiting for the rest of our brethren to arrive. During this time, some of the more outspoken protesters donned the familiar orange jumpsuit of the hapless souls that disappear into the CIA’s own Gulag Archipelago of classified detention facilities. Kristy noted what a dramatic suggestion the Federal building behind them provided.


After some minutes had passed and the crowd fully assembled, we began to march. Our route took us through the heart of the loop, up Clark to Wacker, then through the Magnificent Mile up Michigan to Oak St. The temperature being relatively comfortable, the majority of the crowd seemed to have little difficulty with the mile-and-a-half route. Chicago’s finest saw to it that we did not interrupt the important consumption-related program activities of tourists and yuppies on Mag Mile, lining our route ominously, sometimes in riot gear.


At right, what the Chicago Police Department thinks of your right to freedom of assembly. At far right, what I think of their presence–it can be hard to separate my resentment at the powers that put them there from the officers individually.


Our permitted route ended at Washington Square Park, near Oak St. and Dearborn. Although the crowd became rowdy, huge numbers of police showed up and were able to successfully disperse us, though not without some histrionics. Although I can admit to a side of me that was spoiling for a fight, ultimately I agree with some of the more veteran protesters that thought this behavior was unfortunate.


One thing that was unfortunate: Kristy was laid low by a cold and could not join me. Still I’m very glad she encouraged me to go. Not only was it a remarkable experience, but it also felt really good to step away from the sideline a little bit. I’ve been blogging about politics for nearly as long as our troops have been killing Iraqis, but, aside from voting and internet demagoguery, this is my first foray into activism. What an important cause to be able to support.

More images in my Flickr account or at my gallery.

One of the most remarkable discoveries I’ve made in the past few months is the proper usage of my circular polarizer. I had one on my wishlist for a long time because I’d heard near-miraculous descriptions of its capabilities: deeper, bluer skies, more vivid colors, and, even more supernatural, the ability to kill reflections. The first two are easy to realize. Point your camera at the sky, or something bright. Hooray, aren’t you glad you have a polarizer? But using a polarizer to cancel reflections was something I only began to understand recently. Consider the two pictures below, both properly exposed, identically white-balanced, and taken on the same stretch of the Chicago River (during the St. Patrick’s Day dyeing) less than thirty seconds apart:

The difference is that the second one (on the bottom right) was taken with my polarizer properly aligned. Let’s examine the results in a little more detail.

1. The polarizer greatly reduces the amount of reflected light passing through the lens. This causes areas of the water where I was getting a lot of glare from the clouds to become “darker”
2. Because there is less reflected light, I can keep the shutter open longer (or aperature smaller, your choice) resulting in areas of the water that don’t reflect light getting more exposure
3. This is especially evident in areas like the edge of a reflection. Note how much lower the contrast is in the image on the right, and the resulting difference in saturation.
4. However, the orientation of the polarizer has little-to-no effect on the color rendition of other areas of the image.

This is pretty cool stuff. But what did I do differently? The key is to understand how a polarizer works. In all cases, it reduces the light coming through the lens by about two stops, which means that you need to be careful about deciding to use it indoors. But the way it accomplishes this is by only letting certain kinds of light through. There is a great deal of physics here, but the essential idea is that rays of light (or photons, depending on how you prefer to think about it) can be polarized in two different ways, and those ways are at right angles to each other. Circular polarizers are actually two pieces, the first of which screws onto your lens, and the second of which rotates freely. By rotating the polarizer, you change the polarization of light that it lets pass.  Light reflecting from water or from glass apparently tends to end up polarized mostly the same way, so what you’re trying to do is align your polarizer so that it filters out light with that polarization, while letting normal light pass through.  So:

1. Try to be at least 45 degrees away from a right angle with the surface that is reflecting at you.  This is important and was the major obstacle in my early efforts to understand polarizing.
2. Focus first.  This lets you see more easily the effect you are having, but is even more important for lenses (like my zoom) whose front element rotates as it focuses–this would completely throw you off if you had set the polarization first
3. Look for areas of highlights that you want to cut
4. Slowly rotate the polarizer, watching the highlights.  You are hoping to see them fade in comparison to the rest of the picture.
5. Don’t give up too soon–before assuming that your polarizer can’t help you, make sure to take the time to rotate it through a full 180 degrees.

That’s about all I have time to write, but I think it’s a good introduction.  Any questions or corrections in the comments, I will try to answer.