Sekonic L-478D and Exposure Values question

[JohnM]

So I've managed to confuse myself or either read into this to much. Anyway I wanted to work within the dynamic range of my T2i and 7D camera. This L-478 light meter can be calibrated using an X-Rite color checker card and uploading the info via USB to the meter. To do this you're supposed to take a picture at standard exposure, one at +/- 4EV and another at +/- 8EV for a total of 5. Am I doing the calculation right regarding EV? At 1/15 shutter speed for a normal exposure, is -8EV 1/4000 and +8EV 15 seconds? Sorry if there is any confusion here. Just want to double check. Thanks