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I read that in a 90 degrees prism diagonal. Chromatic aberrations
are almost cancelled. I'd like to know to what extend it is true and what is the rule. For the entering light cone, it encounters flat surface via the air-glass interface, and since there is an angle of the incident light, chromatic deviation occurs from the splitting of the white light into the different wavelength inside the glass, But when the light cone exits on the other flat surface of the prism diagonal, the chromatic aberrations are cancelled from the opposite glass-to-air interface and the light cone returns to its original unchromatic aberrated form (this is assuming of course that the objective lens of the telescope is an apo or sct where chromatic aberrations are a nil compared to an achromat). Now what is the rule, like does shorter focal ratio or steeper light cone make the prism diagonal ineffective in cancelling the chromatic aberrations inside the prism diagonal? In long focal ratio scope or light cone entering and exiting a prism diagonal with parallel entry and exit surface (remembering that there is no chromatic aberrations from the internal reflections). How many percentage approximately of the light cone returns to its original unchromatic aberrated form after it exits the prism diagonal. If anyone has any site or articles about this in details. Let me know. Thanks. (Note: Some may say that a prism diagonal is obsolete and just buy a mirror diagonal. Well, the above inquiry is to understand better the behavior of chromatic aberrations in parallel entering and exiting surfaces such as a prism diagonal and novelty item like binoviewer (which has almost zero chromatic aberration when I observe thru one) and also to get some idea like how some products such as the chromacorr (which removes spherical aberrations) work. optidud |
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Thread | Thread Starter | Forum | Replies | Last Post |
Prism Diagonal Anti Chromatic Aberration Effect? | optidud | Amateur Astronomy | 12 | July 18th 03 04:25 AM |