![]() It also helps with regular observations - I use it almost every time I observe, it makes focusing so much easier. This will probably not help in your case, but it's just one way to remove another uncertainty. Then remove the mask - the scope is in perfect focus. Just make (or buy) one to match the scope's diameter, put it over the scope's mouth, point scope at a bright star, and tweak the focuser until all spikes intersect exactly in the center of the star. One way to be 100% sure that your scope is focused perfectly is to use a Bahtinov mask. It's always a good idea to let the scope "breathe" outside for an hour before you even begin to observe. At least you're removing one unknown from the equation. Being low contrast, your eye will not perceive a lot of detail anyway, so for these objects seeing doesn't matter.Ĭongratulations for being aware of, and following, the rule that says you need to acclimate the scope to ambient temperature. These are low-brightness, low-contrast objects, that are difficult to see from the city. Light pollution only matters for the "faint fuzzies": nebulae and galaxies. Also, it's important that the scope is in perfect collimation. These things are just too bright to care about it, so observing them from the city is fine. Light pollution is never a factor for: planets, the Moon, the Sun, most double stars. You'll use it a lot, probably more than the 10mm. You should probably get a 15mm eyepiece as well. But it's hard to diagnose things over the Internet. My bet is that it's either bad collimation, or you haven't compared the view at 200x with another scope, or both. When seeing is bad, Cassini starts to fade no matter what I do.ĭoes Saturn look equally soft in the center of the image, as well as near the edge? Good optics (mirrors, eyepieces) make a good image everywhere, cheap optics make an okay image in the center and a blurry image at the edge. This is in perfect collimation, perfect thermal equilibrium, high quality optics throughout the stack (primary and secondary mirrors, eyepieces), and good seeing typical of N. It looks super-sharp and high-contrast at 136x but it's kind of small. I have a very high quality reflector (self-made), similar aperture class to yours (a bit smaller), and Cassini is immediately visible at 180x and looks sharp it's also visible at 255x but the whole thing starts to look mushy and faded. The best scope in the world will look mushy and blurry if you push magnification up too much.Ĭan you easily see the Cassini division in Saturn's rings? If yes, then you're probably in okay shape (collimation and seeing), you're just not used to the softness at higher magnification. ![]() This is why there is always an optimal magnification for each view - sometimes higher, sometimes lower, depending on many factors. Also, the contrast always decreases as you increase magnification. Quality could be evaluated either on the test bench (which requires equipment), or via direct observation of stars (which requires a very experienced observer and takes time).įinally, have you compared views with another instrument of similar aperture? The image at higher magnification will always seem a bit more soft, compared to lower magnification - even in perfect seeing with a collimated instrument. There's nothing you can do about this, but the good news is - this problem is not very common nowadays optics quality, while not always great, tends to be at least passable in many cases. High quality optics produce a scope that is very "snappy" when achieving perfect focus, and make very sharp images when seeing is good. ![]() Optics with lots of aberrations cause "mushy" images and a difficulty to find the true focus. Are the rings perfectly circular? If not, it might be miscollimated.Īnother factor is optics quality. Point the scope at a bright star and defocus. Is there a collimation procedure you need to follow? (EDIT: yes, there is - page 20) A miscollimated scope indeed behaves as you described - seems "sharp" at low-ish magnification, but quickly becomes blurry if you push magnification up. If you get the exact same results all the time, and the image never improves even after many weeks of trying, then perhaps it's not seeing that's the culprit. But seeing changes with the seasons, or day to day, hour to hour, or indeed from one second to another. It is common in many places that less than great seeing means everything at 200x and over might start looking blurry. Several things could cause what you describe: With the 20 mm eyepiece, you get 100x magnification. Your telescope has a 2000 mm focal length, and 200 mm aperture. ![]()
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