layerDefaults.marker.opacity Number (default: 1)

The the opacity of all marker layers.

Example - set marker layer default opacity

<div id="map"></div>
<script>
    $("#map").kendoMap({
        layerDefaults: {
            marker: {
                opacity: 0.5
            }
        },
        layers: [{
            type: "marker",

            locationField: "latlng",
            dataSource: {
                data: [{
                    latlng: [0, 0]
                }]
            }
        }]
    });
</script>