Patent ID: 6870687

Claim:
An optical system with a wavelength selecting device comprising, in order from an object along an optical axis: an objective optical system composed of optical elements having refractive power and an aperture stop; a no-power optical group composed of optical elements having no refractive power; and an imaging device; the no-power optical group including a wavelength selecting device having a light transmittance spectrum with a short wavelength portion and a long wavelength portion, the wavelength selecting device transmitting substantially only visible light and being selectively substantially non-transparent with respect to light in part of said short wavelength portion and light in part of said long wavelength portion, said wavelength selecting device including an absorption filter; wherein the following conditional expressions are satisfied: 390<λ V50 <430 where λ V50 denotes a wavelength in nm of short wavelength light whose transmittance of the wavelength selecting device is 50%, 10<λ V80 −λ V10 <40 where λ V10 denotes a wavelength in nm of short wavelength light whose transmittance of the wavelength reflecting device is 10%, and λ V80 denotes a wavelength in nm of short wavelength light whose transmittance of the wavelength selecting device is 80%, and 650<λ R10 <750 where λ R10 denotes a wavelength in nm of long wavelength light whose transmittance of the wavelength selecting device is 10%.