Steve... isn't the meter that you are using the same meter as in the manual link (post #7)? Luna Lux SBC with nulling LEDs? If so, it appears that you need to offset the exposure correction dial by 1 1/3EV when using 15deg or 3 EV when using 7.5 deg readings. The normal offset is 1 (or no offset). Described on pages 28 and 11 of the manual. Then you meter "normally" to null. It seems VERY important to remember to re-set the exposure compensation before and after using the spot attachment or subsequent reading will be all wrong.
The "automatically adapts" is misleading. The meter only adapts after you specify the proper offset of the meter for the amount of light it is being provided: 30 deg reading acceptance angle = offset of 1; 15 deg acceptance angle = offset 1 1/3; and 7.5 deg acceptance angle = offset 3.
If you haven't done so already, look closely at the attachment and you will see that it creates the smaller acceptance angles by restricting the amount of light reaching the meter. Smaller hole for 15 deg and even smaller hole for 7.5 deg. It is ingenious, but by it's very design must involve some compensation at the meter for the smaller amount of light hitting the sensor.
Last edited by BrianShaw; 11-28-2013 at 04:11 PM. Click to view previous post history.