The thing is, I think I understand the former, and then I try to go and figure out the latter, and discover that I really didn't understand the former in the first place.

Aperture is the amount of light reaching (in my case) the film. More light = less depth of field. Or, increasing the f-stop (e.g., from f/4 to f/16) gives you greater depth of field.

For most people's needs, you want to close down aperture as much as possible to increase depth of field. Because usually you want as much of your frame in focus as possible.

Film speed plays a big factor here too, because a lower film speed lets you close down aperture much more, which is what I don't get about how digital cameras work.

Digital cameras can adjust the sensor's sensitivity to light so it is a pretty good analogue to film speed. You generally have an ISO setting you can set the camera to. There is a trade off between sensitivity and noise.

Basically the more sensitive you make the sensor to light the more digital noise you'll get in the picture. It's similar to the way you see more grain in higher speed films. Anything film speed above 800 really tends to show the grain especially when you blow up the image. Digital behaves in a very similar way.

Do you already understand things like the relationship between aperture settings and depth of field

IIRC, the smaller you can get the aperture, the more depth of field.

I used to love the manual-ness of my Pentax K1000, I would manipulate shutter speed and aperture to widen or narrow the DOF.

I was really planning to get back into photography when I bought this house. I even picked up a used darkroom sink from the Associated Press.

However, my Pentax is mostly idle now, and if I save up for a dSLR, I hope I can be half as good as I thought I was at one time.

deleted duplicate.

The problem with copying large files from a dying HDD, is that it takes up a lot of processor time, and you end up finishing posts 20-30 minutes later.

So the sensor size Tom was asking about originally would relate to film speed, interesting.

Anything film speed above 800 really tends to show the grain especially when you blow up the image. Digital behaves in a very similar way.

This is why I hated when stores defaulted to 400, sometimes offering 200. Where's my 100 dammit! Not to mention Kodachrome 64. Sniff.

And looking at the previous post, it reads as a hot tranny mess.

Depth of field 101:

Depth of field is the amount of distance between the nearest and farthest objects that appear in focus. People usually want everything sharp, although there are reasons you might want surroundings to be blurry (up-close shots of flowers or birds for example).

Depth of field relates to aperture, lens focal length, and shooting distance.

Smaller aperture = deeper depth of field
Shorter lens (28mm vs. 70mm) = deeper depth of field
Greater shooting distance (from subject) = deeper the depth of field

So the sensor size Tom was asking about originally would relate to film speed, interesting.

Not exactly. Sensor size does not translate into sensitivity. Rather on most DSLR camers the sensor is smaller than a 35MM frame of film, so a 50mm lens behaves more like a 35mm lens. I believe my memory on that is correct. On the higher end cameras like the Canon 1D and 5D the sensor is the same size as the 35mm film.

So the sensor size Tom was asking about originally would relate to film speed, interesting.

The size doesn't matter, you can just set the sensor to whatever you want. One shot can be ISO 100 equivalent and the next can be ISO 1600 if you want.

The size of the sensor will change the effective focal length of the lens. A bigger sensor will also generally improve image quality.

Or, increasing the f-stop (e.g., from f/4 to f/16) gives you greater depth of field.

You see, this is exactly where I get confused. What exactly is an f-stop measuring? It's a ratio of what to what? Why can't they just measure the diameter of the hole?

I used to love the manual-ness of my Pentax K1000, I would manipulate shutter speed and aperture to widen or narrow the DOF.

That's certainly still possible in the SLR world. It's kinda the point.

Where's my 100 dammit! Not to mention Kodachrome 64. Sniff.

Because you can barely take pictures anywhere with those speeds! Or with any zoom lenses...