Early telescope makers compensated for chromatic aberration by: increasing focal length decreasing focal length increasing aperture decreasing aperture

increasing focal length

Explanation:

As we know that white light consist of seven colors of light which all have different wavelength. Since the focal length of lens also depends wavelength of light as as we increase the wavelength then the focal length will decrease for that color.

So here when while light incident on lens then its seven components will converge at different positions. This is known as chromatic aberration.

Now we can compensate the effect of chromatic aberration just by adjusting the focal length so that the colors will converge not near the lens after refraction.

So in Early telescope the focal length is increased so that the effect of chromatic aberration is minimized.