6/29/2023 0 Comments G494 vivitar telescope![]() ![]() This will boost the focal length of the telescope by x3 so giving you a focal length of 900mm x 3 = 2700 and that is then divided by the eyepice focal length to give you 2700/4 = 675 which would be totally unusable. To boost magnification you add the Barlow between the eyepiece and the telescope. The focal length of your scope is 900mm which means when you plug the lens 4mm lens in you will get x175 magnification because magnification is the focal length of a telescope (in your case 900mm) divided by the eyepiece focal length (in this case 4mm) so 900/4=175. Your telescope has a lens siamter of 76mm which will mean your maximum magnification would be x152 - ignore the blurb that came with your scope theres no way you will get x350 magnification and in any event most astronomy is done at about x200 anyway. ![]() A 4mm lens is pretty useless son almost any telescope. Your telescope specs I looked at suggest that there should be TWO lenses. the lens goes into that hole, you look through that and focus by turning the wheels round. This should plug in to the side of the telescope (there will be a hole with a couple of wheels either side of it - the wheels are your focus control). SR4mm Lens - this is the bit you look through and is called an eyepiece. 3X Barlow Lens - this goes between the lens (see below) and the telescope to provide 3x power for the lens,ģ. 1.5X Erecting Eyepiece - this turns the image inside the scope the right way up for terrestrial viewing.Ģ. All finder scopes (and generally speaking all astronomical telescopes do this as there is no real value in correcting an image in space - simply put if you are looking at the Moon or a Galaxy it doesn't really make much difference which way up it is and in fact the idea of up and down is meaningless in space).ġ. Observing the sun without the correct filter can result in permanent damage to your eyes.įirst off the finder scope - the small one on the outside of the telescope will show things upside down. If your telscope was supplied with one I strongly suggest that you throw it away and also never point the telescope at the sun. The insertion of the eyepieces is discussed around page 6 (assembling yout telescope). This is a link to the Vivitar 76700 manual. The barlow lens is used in conjunction with the other eyepiece to increase the magnification. A high magnification one (4mm in your case) and another of lower power. I am surprised that only one eyepiece is supplied with the telescope, normally two are supplied. The SR4mm eyepiece will be the eyepiece to use at night. The erecting eyepiece flips the image the correct way up for terrestrial viewing (for astronomical observing you don't need this). ![]() Without them you wiil just see a reflection of your eye. The items you have described are put into the focuser to draw tube so allowing you to use the telescope. Im really confused how to use this unit - any help would be appreciated, thanks! When I look thru the main scope all I see is a reflection of my eye - when i used the 3X barlow lens I dont see anything except three lines (like a cross hair setup) and a middle circle - which is a smaller version of what I see when I look at the front of the scope. SR4mm Lens - where does this go and what is it used for? ![]() 3X Barlow Lens - what is this - does it go in the side scope?ģ. 1.5X Erecting Eyepiece - what is this and what is it used for - where does it go?Ģ. There are a couple different items in the pack and im not too sure what they are or what they are used for.ġ. I have no issues looking thru things on the sighting scope (but its upside down) - but I cant view anything from the main scope. The instructions only deal with assembly of the unit - doesn't tell you how to use it.įrom what I have learnt so far this is a "Newtonian" telescope so has the scope on the side. I have always wanted to purchase a telescope and the above unit was on special so I decided to take a plunge. ![]()
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