For the 7D, as with all digital cameras, are likely to embed the info within the image file itself. There is no need for this gadget.

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Yea right!! I forgot about the EXIF data that accompanies each shot.... can't blame me... ever used a DSLR only once....
If you are using slide film and are still learning, bracket. That allows you to see the effect of different exposures. If you are not learning, bracket anyway. Different exposure gives different mood.
For negatives, you can be very casual about exposure. When in doubt, overexpose to capture shadow details, unless limited by shutter speed (not too slow to avoid camera shake).
Hmm.... I seem to be always over exposing my 200 or 400 Fuji film eveytime I use it, day or night.... makes the shot better but just makes me wonder if the light meter can be made to default to read a brighter value.... it's still very hit and miss for me... and I have a grand dinner to cover.... very sianz..... thought I can go there and relax but kenna "arrowed"...