What Barlow do I need for the ASI678MM with an 8" f/10 SCT on Jupiter?
For planetary imaging, the ideal focal ratio is typically 5 to 7 times the camera's pixel size. With the ASI678MM's 2µm pixels, the target focal ratio is between f/10 and f/14. An 8" f/10 SCT is already perfectly matched to this camera for imaging Jupiter under average seeing conditions, so no Barlow is required. In moments of excellent seeing, a 1.5x Barlow could be used to push the focal ratio to f/15 for slightly more resolution.
Is the ZWO ASI678MM suitable for long-exposure deep-sky imaging?
No, the ASI678MM is an uncooled camera. While its high sensitivity and low read noise are excellent, it is not designed for multi-minute exposures of faint deep-sky objects like nebulae and galaxies. Thermal noise will build up over long exposures, degrading the image. It is optimized for high-frame-rate "lucky imaging" of bright targets like the Moon, Sun, and planets.
Can I use the ASI678MM for solar imaging with a dedicated H-alpha telescope?
Yes, the ASI678MM is an excellent choice for high-resolution solar imaging. Its monochrome sensor provides maximum detail and sensitivity for capturing features like surface granulation, filaments, and prominences. The high frame rate of 47.5 FPS is critical for overcoming atmospheric turbulence during daytime imaging.
How does the ASI678MM compare to the color ASI678MC?
The ASI678MM is the monochrome version of the ASI678MC. The primary differences are:
-
Sensitivity & Resolution: The ASI678MM (mono) is inherently more sensitive and captures finer detail because it does not have a Bayer color filter array covering the pixels. Every pixel contributes to the luminance image.
-
Workflow: The ASI678MC (color) provides a color image in a single shot, which is more convenient. The ASI678MM requires shooting through separate Red, Green, and Blue filters and combining them later to create a color image, but this method yields a much higher quality final result.
What does the "Zero Amp Glow" feature on the ASI678MM do?
Amplifier glow is a common artifact in CMOS sensors where a faint glow appears in the corner of images, especially on longer exposures. The Zero Amp Glow circuitry in the ASI678MM physically prevents this from occurring. This means you get cleaner raw data without needing to subtract dark frames to remove the glow, simplifying your image processing.
Do I need an IR Cut filter with the ZWO ASI678MM?
Yes, for most planetary imaging. As a monochrome camera, the ASI678MM is sensitive to both visible and infrared (IR) light. Different wavelengths focus at slightly different points, which can soften the image. Using an IR Cut filter ensures only visible light reaches the sensor, resulting in a sharper luminance (L) channel for LRGB imaging. Alternatively, an IR Pass filter can be used to capture data specifically in the infrared, which can help stabilize images in poor seeing.
