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Hi Bert, thank you for the explanation, i did not know this. So my maximum magnification is 80-90x or 180-225x if assuming perfect optical/weather conditions. Does using a bigger lense (for example a 12.5 mm (= 80x mag) in combination with a 3x Barlow lense (result = 225x mag) give a better result than for example using a 5 (200x) or 4 (250x) mm lense when it comes to sharpness (focus) of the image? or does that make no difference either? Thank you, Joel Bert Katzung wrote: Hi Mango: All of the things you mention can contribute to a fuzzy image, but probably the most important is the focal length of your eyepiece. Unless you have superb optics (both eyepeice and mirror), a 5 mm eyepiece is pushing the magnification too high in this scope. Your 1000 mm focal length with a 5 mm EP gives 200x and that's asking a lot! A reasonable rule of thumb is 20x per inch of aperture, so with your 114 mm aperture, about 80-90 x is the maximum magnification you should expect to give nice clear images. I know that the books claim a maximum of 40 to 50x per inch of aperture, but that's assuming perfect optics and perfect seeing conditions. Hope this helps, Bert Bert Katzung katzung1@comcast.net www.astronomy-images.com ----- Original Message ----- From: "mango" <j.kolling@chello.nl> To: <astro-photo@seds.org>; <videoastro@yahoogroups.com> Sent: Monday, November 10, 2003 9:11 PM Subject: [APML] sharp image with 5 mm lenseI have a new telescope, a newtonian 114/1000 and when i used it to watch the moon yesterday when i put in a 5 mm lense the image wasn't clear, could this be because of the quality of the 5 mm lense, the weather (it was not very clear and a little misty, but just a little), the mirrorsize, the focal length, or something else? _______________________________________________ Astro-Photo mailing list Astro-Photo@seds.org http://seds.org/mailman/listinfo/astro-photo_______________________________________________ Astro-Photo mailing list Astro-Photo@seds.org http://seds.org/mailman/listinfo/astro-photo |
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