Take this example from the North American Sundial Society: a dial located at 78.15 degrees West longitude (near Buffalo, NY) is in a time zone fixed to the Eastern Time Zone meridian
of 75 West longitude.
For one thing, daylight-saving time pushes solar noon an hour past clock noon, and the fact that Eugene is west of the Pacific Time Zone meridian
adds about another 15 minutes.
To make sure you don't do it backward, use this formula: Standard time = LMT + Correction, where the correction is positive west of your time zone meridian
, negative east of it.
Otherwise, to get standard time add four minutes to times obtained from the chart for each degree of longitude that you are west of your time zone meridian
. Or subtract four minutes for each degree you are east of it.
Also, insert your local correction and, when necessary, add one hour for Daylight Saving Time; to get your standard time subtract 4 minutes for each degree you are east of your time zone meridian
or add 4 minutes for each degree you are west of it.