Optical lens

An optical lens having an optical axis, the optical lens comprising in order from an object side to an image side:

• a first lens element having a first surface and a second surface opposite to the first surface;
• a second lens element having a third surface and a fourth surface;
• a third lens element having a fifth surface and a sixth surface;
• a fourth lens element having a seventh surface and a eighth surface;
• a fifth lens element having a ninth surface and a tenth surface;
• a sixth lens element having a eleventh surface and a twelfth surface;
• and
• a sensor;
• and
• an optical filter, the optical filter being mounted between the sixth lens element and the sensor, and the optical filter being spaced from the sixth element and the sensor;
• wherein the optical lens also comprises an aperture mounted between the second lens element and the third lens element, the optical lens satisfies the following formulas:
• 0<T45< Wherein T45 is a center thickness of air space between the eighth surface and the ninth surface, T45M is maximal thickness of air space between the eighth surface parallel the optical axis to the ninth surface;
• wherein the optical lens satisfies the formula 0.77<f1/(f4*f5)<2.75, where f1 is the focal length of the first lens element, f4 is the focal length of the fourth lens element, and f5 is the focal length of the fifth lens element.