Solar Imaging Tips:
Daystar recommends
MONOCHROME CCD
imaging whenever
possible for best results.
The recent availability of
CCD came ras and DSLR
cameras has o ffered a
simple op portunity for
solar ob servers t o imag e
the Sun in Hydroge
n
Alpha with a Digital SL R
camera. Ple ase b e advi sed, ho wever, that due to the nature of
monochromatic light and its effects on a CCD came ra, certain negative
effects are likely to occur.
The DSLR i mager mu st be a ware t hat mo st ca mera manufacturers
(Canon a nd Nikon) u se a n IR blocking filter which greatly re duces the
transmission of Hyd rogen Alpha light. DSL R cameras without this IR
blocking filter will have better sensitivity imaging in Hydrogen Alpha.
The imag er shoul d also app reciate that even after co nsidering IR
blocking filters, that the COLOR CCD chip is constructed in a way that
only 1 in 4 pi xels detect red light. The other 3 sensors only detect blue
and green b ecause the p ixels are a ctually perm anently covere d with a
colored dye for each corresponding color. So a co lor CCD chip (in a
DSLR o r a CCD camera) will only offer 1/4 the sensitivity and 1/2 the
resolution of a monochrome chip.
Another eff ect pre sent in CCD i
maging of
monochrome light of Hydroge
n Alp ha is the
interference pattern - or Ne wton's Rings. The
effect is similar to interference testing of an optical
surface b etween two flat surfa ces. The sen sor
and cover slip cause a small interferometer inside
the came ra and cau se a Newto n's Ring moire'
pattern. The CCD chip m ust be tilted to a mino r
degree to p revent this pa ttern. Recent advances
in afterm arket adapte rs of fer a si mplified solution f or th e i ssue. This
effect is a concern for both color and monochrome sensors.
An optional accessory is available from DayStar (MG-0408) which can be
used between the DSLR and Quark to adjust the lig ht angle and extinct
the interference pattern.
