SC series C-mount adapters for older Nikon "chimney" style photoports, including Optiphot / Labophot trinocular F / T / UW heads. These C-mounts are adjustable for parfocality, and they will accept 21mm reticles. Available in 0.38x, 0.5x, 0.67x and 1x magnifications.
SC38NF 0.38x $750.00
SC50NF 0.5x $450.00
SC67NF 0.67x $450.00
SC10NF 1x $650.00