|
|
SBIG ST-7XME&CWF8
You can see a gold shim plate between the two units (ST-7XME and CFW-8a).
This is a brass plate which has been placed
so that a thin filter can be inserted through a slit opened in this plate.
The combination of SBIG red filter plus this thin filter (Fuji SC64, optical
acetate film filter) enhances the red HII areas studded in galaxies effectively,
as well as vivid blue.
There has been a difficulty to use ST-7XME in such area with heavy@light
pollution: Some undulation tends to appear in background of theimages taken
by this CCD.
The undulation is usually weak and unnoticed,
but it becomes pronounced with high background and poor S/N ratio, i.e.,@with
the images taken in urban area.
In most of the cases, however, this@undulation can be reduced by Flat Flame
process.
|