Zoom Telescope Eyepiece
Tips On Buying A Spotting Scope
You may have been told that seeking out a spotting scope for birding, hunting, and other wildlife viewing and observing is your best bet if you truly want to maximize your outdoor experience. Spotting scopes are similar to both binoculars and telescopes, combining the convenient portability of the standard binoculars, with the longer-range viewing capabilities of the star-gazing telescope. Spotting scopes can give you the high definition magnification capabilities required from longer distances, and so are the perfect optical device for your birding or hunting adventure. However, sometimes it can be quite overwhelming trying to find the best spotting scope, sifting through technical jargon and industry terms. That's why we have outlined the most important aspects of the spotting scope, definitions of specifications, and recommendations on what to look for.
Magnification: Finding the best magnification in your prospective spotting scope relies on how large the objective lens is; i.e. the higher the magnification, the larger the objective lens should be for resolute image quality. The best magnification for birding/hunting endeavors should be between 20X and 40X. This range offers a good field of view, as well as necessary image brightness.
Objective Lens or Aperture: As previously discussed, the objective lens or aperture is directly related to the size of the magnification. The larger the diameter of the objective lens, the more light and subsequent clarity your object will receive. Depending on where you will be using your spotting scope, you'll want to find a scope with an aperture of 50mm-80mm.
Exit Pupil: The exit pupil is very similar to, and works in conjunction with, the objective lens. It is the diameter of light visible through the eyepiece. If these specs are not available at the time, just divide the objective lens specs by the magnification, and this will give you the exit pupil dimension. Make sure your new spotting scope has an exit pupil that isn't below 1.33mm, otherwise the light visible will be so minimal that seeing anything in any conditions will be almost impossible.
Eyepieces: Eyepieces help with your magnification depending on the type you prefer in any given situation. They come in two basic types: interchangeable fixed and single zoom or variable. The former is best applied for mountain and ocean panorama viewing, as the fixed will give you a wider field of view. The latter offers a varying magnification from low to high, which enables the viewer to both have a wider field of view but then also be able to focus in with higher magnification.
Field of View: The field of view is basically the width of the area visible 1000 yards from the viewer. It is inversely proportional to the magnification: the larger the magnification, the narrower the field of view. A fixed eyepiece will give you a wider field of view, and the variable eyepiece will give you both wide field of view and more intense magnification. Depending on your outdoor hobby, you should probably opt for a wider field of view (fixed eyepiece) if your scoping is predominantly deals with panorama; and a combination field of view/magnification (single zoom or variable eyepiece) for surveying both panorama and object detail.
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Tools for best visual observation through a Dobsonian telescope?
I bought an Orion Telescope XT 8 Dobsonian a few days back. I have had stunning views of planets but the galaxies and nebulas have been fuzzy. I could only make out a fuzzy cloud structure around them and the images are not clear. The eyepieces I have at this time are 25mm and 6mm. The town where I live is small but there are some streetlights around my house so the sky isnt that clear.I have been able to observe M42, M51 M81 & 82 and M64. Please recommend eyepieces and filters that can give me the best zoom, excellent field of view and sharpest visual views of DSO's with this telescope.
You probably have unrealistic expectations of how deep sky objects will appear, based on published images you have seen in books and magazines, and on the internet. Galaxies and nebulae look like faint wisps of smoke when observed visually through a medium sized telescope like yours. I have been observing for many years with some very large apertures, and can honestly say that only three times in my life have I seen _any_ colour in a deep sky object, and that took a much larger aperture than you are using. With 8" (or even 12") of aperture, all your eye is capable of seeing is shades of grey.
Some ways of improving your views: First of all, get away from those street lights. To see deep sky objects at their best you need to be in a totally dark location, with absolutely no light pollution. Wide field eyepieces will help. For nebulae like M42 a narrow band filter like an Orion UltraBlock will help improve contrast, but for galaxies, nothing much will help except dark skies and training your eye to see faint objects, using the technique called averted vision: looking slightly _away_ from the area of interest, so that it falls on the most sensitive part of your retina.
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