[Guest]

I think Joseph Wisniewski at DPReview gives a pretty good explanation why back reflection from lenses is nowhere as bad as ghosting from Sony's partial mirror. Allow me to quote from:

[url="http://forums.dpreview.com/forums/read.asp?forum=1000&message=36225053"]http://forums.dprevi...essage=36225053[/url]



"Lens surfaces are generally

• curved - which means that any rays that are converging on the sensor (and therefore, capable of generating a sharply defined image) will have their point of convergence changed by reflecting from a curved surface. The curved surface will either increase convergence and make the ghost image focus in front of the sensor and then diverge again before it hits the sensor, or decrease convergence and make the ghost image not converge before it hits the sensor.
• reasonably perpendicular to the optic path - so anything that does converge will do so pretty well aligned with the original image.

The pellicle mirror reflections are from a

• flat surface - that doesn't really affect converging rays: so the ghosts converge as sharply focused images.
• at 45 degrees to the optic path - to displace the ghost by the thickness fo the mirror (less some effects due to refraction).

This is why Canon used a much thinner mirror in their Pellix and EOS RT cameras, and why Oly used solid cube beam splitters in the E-10 and E-20"



This agrees with what Brightcolors has been trying to convey here.



Sigh, such a pity that partial mirrors in DSLRs have suddenly dropped off my radar screen.