Eric wrote:Even with my new-as-of-last-year Nikon D5100 I can't capture some of the things I could on film, especially when dealing with low-light situations, trailing light, or fire. You get pixilation, whereas on slow film you wouldn't get any.
You probably know this stuff, so I apologize if this doesn't help or it's way below your expertise level:
There are some other differences too. For one, that camera has a cropped APS-C sensor, not a full-frame 35mm-equivalent that your film camera would, so you don't capture quite as much light per pixel, which means you need more sensitivity, and therefore more noise, to capture the same amount of light. The smaller sensor also affects the diffraction limitations
of the camera.
You can also mitigate some of the noise by resizing, as you've got a bit of resolution to play with on that 16.2MP sensor. Resizing the image down to something like 10MP will clear out a lot of the noise without notable loss of resolution, especially when that extra resolution does nothing for the photo when diffraction limited.
Also, you do remember to turn off auto-ISO and then set your ISO manually right? Even for manual mode auto-ISO will kick in; you need to manually turn it off to have full ISO control. I've had many long exposure shots ruined by the auto-ISO. I leave auto-ISO on so I can get "the shot" in most cases, but for longer exposures it's all about turning it off.
For capturing action and backgrounds, setting the flash to rear sync helps a bit. I found it produced some of the nicest night photos of people because it prevented the ever-present dust from obscuring the view, and captured the nice lights in the background.
Finally, there are other tricks if you're photographing very slow moving objects like stars, such as taking many single photos and summing them up in a program so that the sensor isn't operating constantly. Even more drastic, some people put the camera in a cold-box (dry ice, etc.) to cool down the sensor and reduce noise. It works quite well, especially for astronomy webcams.