Re: Bluedot Frustration...

At 25/01/2008, you wrote:

Possible reflection of the rear element on the sensor.
I had that problem with a 60mm Elmarit-R and the old Canon EF
35-350mm f/3.5-5.6 USM L.
This is now being addressed by various manufacturers with the
refiguring of ghost free coatings, or "Ghostless coating".
s.d.



Thanks, Slobodan... at least I'm not alone....
This explanation makes sense to me ... though it has only happened sporadically and, seemingly, with little consistency.... although it now seems to me that it has happened only with the 80~200/4 Vario. (I will search my archives, for other examples.)
Otherwise, it has occurred indoors (close up work) or outdoors (I shot Rose, at the third stage of the Eiffel Tower, in broad daylight, but on an overcast day, and got the "blue blotch" in the middle of her face).
Hmmm... today was overcast, though I was working with window light. Perhaps that's the key... though that makes little sense to me.
I will duplicate today's shots, tomorrow, with a different lens, and report back.
These "Ghostless coating"... is it applied to the rear element, or to the sensor? Available as a retrofit? 

Cheers!


---

David Young,
Logan Lake, CANADA

Wildlife Photographs: http://www.furnfeather.net
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