Quote:
Originally Posted by bojan
Thank you for the offer, I will PM you when I am ready  |
OK sure.
Quote:
Originally Posted by bojan
As for comparison....
the attached images below were taken with the same lens, left one is with unmodified 60D (last year), right one is with 450D FSM + L_pro (last night).
Some stars (with L-Pro) have halo, some others (of same or even higher magnitude) don't.
There are no halos on corresponding star images taken with unmodified 60D.
The difference is most likely in spectral type and excess of IR (most likely) or UV (I don't know yet what L-Pro filter does compared to Canon filter in 60D)
So, it seems more filtering will be needed to fix this (IR? I will know when replacement UVIR-cut from Rocolax arrives).
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If you use a normal camera lens you could possibly rule out the 450D haloes as being caused by excessive L_pro UV bandwidth, by also stacking a lens mounted UV filter on to your lens, which should remove most of the UV and then check again for haloes against another non-UV filtered image, preferably taken at same time with same exposure.
In a round about way you could do something similar for the Infra Red end of the spectrum as well if you have some sort of photographic IR filter (like an R72 or the like). Except that this time you'd be looking to possibly find the halo in the Infra Red image. If you find the halo in the IR image then bingo.
Another possibility for the haloes, relates to the 450D's Full Spectrum Mod - When the UV/IR filter was removed was it replaced with clear glass of some type or left empty? My thoughts would be that if left empty or if the replacement glass is not of the right refractive index, it could cause a tiny deviation in the intended focus of infra red (if enough IR is coming through to be apparent) , in that it may not focus soon enough, which one would probably see as a sort of chromatic aberration (except not Red, Green, Blue, Magenta..., as IR is not represented by the sensor in that way, but mostly as deep deep brown/red or grey and would represent as a halo.
Or maybe there's just too much Infra red bandwidth picked up by the sensor, which the lens is not able to focus closely enough to the visible light focus, either way I could certainly see it would represent as a halo of some sort (and a slightly defocused image) - see below... (coming soon ....
)
EDIT: .... Now added as diagram below (that was fun !!!)
