At 300 mm, the same lens would appear different: 300/6.3 = 47.62 An example would be using a 70-300mm 4-5.6 lens, stopped down once to get sharper stars. If you are using a zoom/telephoto lens, this matters since zooming does change the diameter of view. You’ll want to round to the nearest hundredth.Īn example for the Rokinon 135mm lens: 135/ 2.8 = 48.20. To get an accurate diameter, you’ll want to use this formula: Focal Length / f-stop = Diameter. Telescopes and DSLR Lens: Diameter and Focal Length.įor DSLR Lenses: The diameter listed on most websites is related to the size of filter you need, if you plan on using a filter for daytime use, it is not the diameter needed for Stellarium. Specs You’ll NeedĮyepieces: Apparent Field of View (aFOV) and Focal Length It might take some digging if websites aren’t forthcoming with the specifications, but you can usually find them fairly easily. For example, the below Zhumell 30mm eyepiece is actually a GSO eyepiece with Zhumell branding. If you can’t find specifications for your brand, look for another that looks exactly like it. Tip: There are a small number of manufacturers of telescope components worldwide. Before adding your gear, go to the manufacturer’s website or a store website to look for the specifications for each item.
0 kommentar(er)
