Combining images from different telescopes with different cameras.
The telescope/camera combinations were:
- William Optics Super Zenithstar 81mm ED Doublet APO refractor at f/5.5 with x0.8 reducer/flattener, (F=445.5mm) and an SVBONY SV605MC mono camera fitted with an Altair quadband filter. The field of view of this setup is FOV: 1.45° x 1.45° Resolution, 2.12 sq°.
- ALTAIR STARWAVE 60 ED f/6 Imaging Refractor with field flattener (F=360mm) and an SVBONY SV605CC OSC colour camera fitted with an Optolong LeNhance triband filter. The field of view of this setup is FOV: 1.80° x 1.80° Resolution, 3.24 sq°.
Both cameras use a Sony IMX533 CMOS sensor. The SV605CC uses the colour sensor and the SV605MC uses the monochrome version of the sensor. The pixels in these cameras are 3.76µm x 3.76µm in size.
AstroDMx Capture was used to capture data from the two systems described above.
One reason for combining data from a monochrome camera and a colour camera is to increase the detail in the final image by incorporating the extra detail from the monochrome image. One shot colour cameras lose some spatial detail during the debayering process, although with small pixels, this is not usually serious. Due to the different focal lengths of the two systems, images are at different scales and this must be corrected for when combining the colour image captured with the Altair system and the monochrome image captured with the William Optics system.
Picture Window Pro 2.5 running in Wine was used to combine the two images. Picture Window Pro 8.0 will also do the job, but I prefer the interface and modus operandi of 2.5.
Colour image of the Rosette nebula with the Altair 60mm scope
Monochrome image of the Rosette nebula with the William Optics 81mm scope
It can be seen that the monochrome image scale is larger than the colour image scale
Picture Window Pro 2.5 running in Wine was used to combine the two images. Picture Window Pro 8.0 will also do the job, but I prefer the interface and modus operandi of 2.5.
Picture Window Pro 2.5 combining the images using 2 points, shift, rotate and scale
The difference in image scale can be seen nicely in this screenshot
The colour data have been overlaid on the monochrome data to combine the images into one with less saturation.
The saturation can be increased as required in Picture Window Pro or another application such as the Gimp 2.10.
By mixing channels and varying the colour components of Curves, it is possible to render the image in a variety of ways, including a palette resembling the Hubble palette.
Pleasing and valuable results can be obtained by manipulating the colour channels from images produced by OSC narrowband filters. OSC narrowband filters can also be used with monochrome cameras to produce luminance data and the high resolution monochrome data can profitably be combined with colour data to produce high resolution colour images.
