Coma, also known as “comatic aberration”, is a type of optical aberration that results in off-axis points of light appearing comet-shaped. As light rays from the edges of the frame pass through various parts of a spherical surface, they vary in magnification, creating a series of asymmetr...
In the past, I have written about my thoughts on using a refractor for astrophotography and that I think it is the best choice to get started in deep-sky astrophotography. Modern refractor/refracting telescopes come in two styles: achromatic and apochromatic. Each of these styles is designed ...
A good 90mm refractor is worth your consideration, depending on the light pollution in your area. My AT92 is my most commonly used scope. A C5 or C6 with a focal reducer would be my second recommendation. A 6 inch collapsible dob would be another option, if you can find a coma correct...
With reflectors (especially those under F/5) your issue is coma. Coma will make the outer parts of the field unusable and won't be corrected by a flattener. I've never used a reflector for EAA so not sure, but you will likely have some curvature as well. Any sort of reducer that ...
For example, let's say that f/1.4 actually gives you all the DOF you need (e.g. astrophotography) -- you'll still stop down to get more sharpness and/or less coma in many circumstances. The same applies for scenes with movement but depending on the slowest shutter speed you need to ...
Thanks to SIGMA's latest technology, the lens combines an ultra-wide angle of 14mm with a maximum aperture of F1.4. In addition, SIGMA's lens technology has achieved high optical performance with thorough correction of sagittal coma flare, specialized functions to support starry landscape ...
“This is looking awesome! Now all we have to do it get it into space!” As the comet is warmed by the sun, some of the components of the comet start to liven up, vaporize and vent out into a cloud (coma) around the core of the comet (nucleus), which can then be blasted away...
Initially, he believed it to be a comet, but ongoing observations showed that it had no coma. This led Piazzi to consider that the object he had found – which he named “Ceres” after the Roman goddess of the harvest and patron of Sicily – could, in fact, be a planet. Fifteen mont...
One thing to remember here is that in order to take an image where all the stars appear flat across the field of view, you will need to purchase a coma corrector like this one here.This scope in turn can be put on to a HEQ5 Goto mount here which will not only help you image ...
so now I worry that I might've somehow reduced the efficiency of my filter by making those "rubbing movements"; did I rub out some sort of coating? is it alright? c'mon, I was very gentle! tonight, if it's clear, I'm going to see what effect this has on nebulae; if it's ca...