RU99107027A - TV FOCUS WITH INTERNAL FOCUS - Google Patents

Claims (1)

A telephoto lens with internal focusing, consisting of the first and second optical components with positive refractive power, arranged successively in the direction of the optical beam propagation, consisting of positive and negative lenses, the first component containing glued positive and negative lenses, and the second has the ability to move along the optical axis of the device , characterized in that the second component is glued from a negative meniscus facing its convex surface to nstvu object, and a positive lens, the focal length f of the entire system, the focal length f ₁₁ of the second component, the interval d ₃ between the first and second components _{ν I +, ν I-, ν} II-, ν II + - Abbe materials respectively first positive and the second negative lens of the first component, the negative meniscus and the positive lens of the second component satisfy the following conditions:
1.0 ≅ f ₁₁ / f ≅ 3.0 (1)
0.3 ≅ d3 / f ≅ 0.8 (2)
ν _{I +} > 50 (3)
ν _{I +} - ν _I- > 23
ν _II- > 27 (4)
ν _{II +} > 50