If you want a dedicated telescope for astrophotography, consider an astrograph. OPT offers a wide range of astrograph telescopes to fit different needs and budgets, all with the ideal focal ratios for imaging celestial objects. Featuring trusted brands such as AG Optical, iOptron, TPO, and more, our astrographs provide a wide field of view that makes them ideal for capturing deep-sky objects such as nebulae and galaxies.
All of our astrograph telescopes are alt-az mount and include the following types of designs:
We calculate the focal ratio as the focal length divided by the aperture. Because a telescope’s focal ratio determines the efficiency of its light gathering, we want fast (low) focal ratios for astrographs. Our astrograph telescopes feature optimized focal ratios that naturally excel at astrophotography but also allow for observing visually.
For beginners or those on a budget, consider a Petzval option like the William Optics RedCat71 APO. This bestselling refractor has a focal ratio of f/4.9, containing a 350mm focal length — perfect for capturing stunning wide-field sky images. A bit more functionality is available with an option like the Askar FRA600 4.3”, an f/5.6 Petzval that offers a completely flat field with minimal chromatic aberration and distortion. Like the RedCat71, this Petzval can capture fantastic images of galaxies, nebulae, and deep space objects. However, the FRA600 will counterbalance decreasing field illumination to keep stars sharp all the way to the edge of the frame.
At the higher end of the spectrum are telescopes like the Planewave CDK20. This Corrected Dall Kirkham astrograph allows for both observation and imaging with no compromises: a 20” aperture, an f/6.8 focal ratio, a Dawes Limit of 0.03 arcseconds, and enough light gathering power to match the power of large-format CCD cameras of today. Telescopes like this can eliminate problems due to field curvature, off-axis astigmatism, and coma — in other words, the field remains completely flat.
Keep in mind that you’ll need to be able to collimate your astrograph. Check out our video on how to collimate an astrograph telescope. If you have any questions about the relative capabilities and value of our astrograph telescopes, contact our knowledgeable and friendly sales team.