OOUK's ODK 14 Optimized Dal Kirkham optical tube operates at a focal length of 2380mm with a Focal Ratio of F/6.8. The ODK 14 has an aperture of 350mm, or 13.8". The primary mirrors diameter is 350mm, and the secondary mirrors diameter is 136mm. Both the primary and secondary mirror use high quality optical glass which has been exhaustively tested for maximum quality control and optical clarity. All optical surfaces within this telescope are Hilux coated to ensure the greatest level of optical clarity and lifespan. Like all OOUK Telescopes, the carbon fiber making up the ODK 14 is of the same quality as that used in modern spacecraft and Formula One racecars. The ODK 14 does not come with a focuser- the focuser must be purchased separately. The compatible focuser that we offer is a Starlight Instruments Feathertouch- SI-FTF3235B-A.