Im very challenged keeping low and high key elements into a shot - such as a moon with a sillhouetted surrounding (bit of an extreme example, but you get the idea).

Whats the best trick to keeping tonal range? Its the most challenging thing i encounter in the digital world. Im shooting with a KM maxxum 5D...

Welcome to the wonderful world of digital. :) I think the easiest thing to do in high contrast situations like this is to expose for the highlights, and them bring the shadows out in post processing. Graduated ND filters are another option. A third option is to bracket multiple shots of the same seen (use a tripod so they are exact) and then merge them in Photoshop, or whatever program you use. If you shoot RAW, you can do this with a single frame, by converting a few seperate exposures from the RAW image.

The moon is a pretty extreme example. Digital sensors (and film, for that matter) can only record a certain amount of contrast. When there's too much contrast for the medium, you'll have blown out highlights, blocked up shadows or both. Both of these "photo slang" phrases mean that there's no detail recorded in those areas.

You could shoot in lower contrast situations (sometimes), take multiple exposures and combine in Photoshop (shoot for the highlights and shadows separately) or try to lower the contrast at time of capture with fill flash, graduated ND filters, etc.

Im very challenged keeping low and high key elements into a shot - such as a moon with a sillhouetted surrounding (bit of an extreme example, but you get the idea).

Whats the best trick to keeping tonal range? Its the most challenging thing i encounter in the digital world. Im shooting with a KM maxxum 5D...

If you had a Nikon DSLR and you were shooting RAW and you had the latest version of Nikon Capture - then you can get the overexposed highlights back by using the Advanced RAW Exposure control which allows you to change the exposure by +/- 2 whole stops. Usually I use it to get back the detail in the highlights then I use the curves tool to put an S bend in the image so the mid tones come up without the highlights burning out again

Charles