Uh, never realized that gravitational lensing was stronger for higher frequencies ... is that a fact? Any reference? [EDIT]: the formula on page 4 of the book

Uh, never realized that gravitational lensing was stronger for higher frequencies ... is that a fact? Any reference? [EDIT]: the formula on page 4 of the book below does not seem to have a frequency parameter ... Also, they seem to consider that objects worth looking at are at infinity, which is why there is a well-defined focal distance from the sun. What seems to involve frequency is that the gain of the lens varies (same book, page 9). http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20Space%20Flight%20and%20Communications_%20Exploiting%20the%20Sun%20as%20a%20Gravitational%20Lens_%20Claudio%20Maccone_%202009.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20...