Why can't I remember how to use my camera?

I'm for some reason reminded of a part from John Holt's How Children Learn:On days when I have a lesson, I bring my cello to school, take it to a classroom, and give the children a turn at "playing" it. Except for the timid ones, who make a few halfhearted passes with the bow and quit, almost all little children attack the cello in the same way. They are really doing three things at once. They are making the machine go. They are enjoying the luxury of making sounds. And they are making scientific experiments. [...] But it is important to note that the first few times they do this, they do not seem to be doing it in the spirit of an experiment, to find out what will happen. They do it for the sake of doing it. [...] Then there is quite a change in their way of doing things. You can almost hear them thinking, "Ah, this string makes that kind of noise, and that string makes that kind of noise." But they have to do a good deal of what seems like random bowing, activity for its own sake, before they begin to think about what they are doing. They have to pile up quite a mass of raw sensory data before they begin trying to sort it out and make sense of it. [...] A scientist might say that, along with his useful data, the child has collected an enormous quantity of random, useless data. A trained scientist wants to cut all irrelevant data out of his experiment. He is asking nature a question, he wants to cut down the noise, the static, the random information, to a minimum, so he can hear the answer. But a child doesn't work that way. He is used to getting his answers out of the noise. He has, after all, grown up in a strange world where everything is noise, where he can only understand and make sense of a tiny part of what he experiences. [...] Where the young child, at least until his thinking has been spoiled by adults, has a great advantage is in situations—and many, even most real life situations are like this—where there is so much seemingly senseless data that it is impossible to tell what questions to ask. He is much better at taking in this kind of data; he is better able to tolerate its confusion; and he is much better at picking out the patterns, hearing the faint signal amid all the noise. Above all, he is much less likely than adults to make hard and fast conclusions on the basis of too little data, or having made such conclusions, to refuse to consider any new data that does not support them. And these are the vital skills of thought which, in our hurry to get him thinking the way we do, we may very well stunt or destroy in the process of "educating" him. But the greatest difference between children and adults is that most of the children to whom I offer a turn on the cello accept it, while most adults, particularly if they have never played any other instrument, refuse it.I think it's your association with the IKEA instruction booklet that reminded me of this, because those are so extremely concise, like choreography diagrams, and seem to leave no room for experimentation and failure. The steps are numbered and you are supposed to put them together like a programmed robot, and if you mess up it's embarrassing. It feels like a performance that you haven't been allowed to practice for. Maybe you could try doing more of this random experimentation? Like, you're not going to ruin the camera, just maybe get some terrible photos. Maybe your neural structures need a lot of input, and self-driven active exploration, in order to learn these kinds of things.

Might a pocket sized version of http://thephoblographer.wordpress.com/2010/12/13/how-iso-shutter-speed-and-aperture-all-relate-to-one-another/ help? As you mention you're happy using photoshop, it would be fairly easy to add some pictograms of the relevant camera buttons / controls needed to make changes at each corner.

I'd take it a step further and just get an old fashioned manual camera and some film, and then just play with it. An old Nikon isn't expensive, and it only has 3 settings or so that change at all, and they're all physical things on the camera... Not abstracted settings on a menu. I have a BFA in photography, and we all still had to learn on a manual camera first for this very reason... When you adjust the f-stop it is a physical dial, you can SEE the hole getting bigger and smaller and the depth of field getting deeper and shallower. Also, there is no real right and wrong.... Photographers manipulate all settings all the time to get the results they want. Just play.

The thing about photography is that nearly everything is interconnected in some way. This can make it tricky to break into. So, reduce the number of things you have to deal with at one time. This will help you learn everything else. For now, stick with aperture mode. Select an aperture, preferably a wide one (low number, like f2). Use Auto ISO if the D50 offers such a thing. Now, only ever adjust exposure compensation. Take an ordinary still life. Shoot it with no compensation, so that you're just getting what the camera determines is the proper exposure. Now use exposure compensation to shoot at +1. Now do the same thing, but in the other direction, shooting at -1. Fiddle around with this as much as you like. Compare all of your shots. Pay attention to what the exposure compensation is for each of these photos. Now, when you shoot, just stay in aperture mode. Don't change the aperture. Don't change anything else. Just change the exposure compensation, so that you can figure out how to expose on your own. After a while, try a different aperture, such as 5.6. What is different now? Pay attention to what happens to the depth of field when you change aperture. Pay attention to what happens to the depth of field when you use different focal lengths. Pay attention to what happens to the depth of field when you're closer or further away from the subject.

To use an SLR out of automatic mode, you have to know what you want the camera to do (ISO, exposure, f-stop, flash brightness/duration, focus stuff, etc), and how to make it do it (various buttons, menus, and knobs). It's not clear from your question which part of this keeps slipping out of your brain, but I think that'll be pretty important to specify to give a helpful answer.

I understand the concepts (e.g., relation of shutter speed to aperture width) but I can't remember how to actually change the settings on the camera to get what I want. So I know I want more depth of field but can't remember where the setting is it or whether it should go up or down...

How about writing a cheatsheet about how to do it or making a short video about it? You'll have a quick reminder when you need it, and possibly explaining it clearly will help it stick a bit more. Also, you can try the trick of focusing on one single thing to remember whenever you take the camera up again. Once you find yourself consistently remembering how to use the depth of field setting, for example, add one new setting to master. It's obviously a slow process, but maybe you don't really need to be in a hurry. It fits in well with mbrock's approach too: sometimes it's easier to learn a thing bit by bit at your own rate, without feeling like it's a big, high-stakes, impenetrable mess you have to tame.

Photography is difficult for you because the Nikon D50 was cost-reduced by combining dials and buttons so that you have to do two or more things at once to make it do what you want. I'm not surprised that you are frustrated - I would be too! I see two options for you: 1. Write down a list of functions that you feel you must memorize, and then memorize them. Ignore everything else. Shutter speed, F-stop, focus, and ISO might be a minimal set, though you could drop ISO and possibly focus. I don't know what sort of memorization works for you, but repetition of physical tasks helps me to develop muscle memory. It isn't much fun, but it works for me. Over time, you can learn more about your camera, but you need to commit the basic functions to memory so that you have a solid foundation. 2. Replace the d50 with something easier. Ironically, this would be a more "professional" camera, but not too professional. I think the d70s does everything that the d50 does, and is a little bit older, so you can probably get one cheap or maybe even trade your d50 for one (the d50 is lighter, so some people might prefer the d50). I think I opened my d70s' manual twice, and was disappointed that there was nothing new to learn. All of the controls either do obvious things or change values in the LCD or viewfinder that make them quickly obvious. I think "delete" is the only function that requires you to press two buttons.

I used to use an Olympus DSLR, and after a couple of years I became reasonably competent. It was just too bulky, though, and now I use a fairly compact camera, a Canon G12. It does about 90% of what the DSLR could do, and I'm more likely to have it with me when I need it. I always use Manual mode. One control sets the aperture and another one sets the shutter speed. It becomes intuitive after a while. I rarely have to use the menu system.