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Message: <blockquote data-quote="Cosme" data-source="post: 2970992" data-attributes="member: 118064">Who's have never dream of look at 70x with both eyes? ok, neither is portable or cheap, but the experience should be amazing.<a href="http://www.birdforum.net/showthread.php?p=2970962#post2970962" target="_blank">http://www.birdforum.net/showthread.php?p=2970962#post2970962</a>Im gonna try to summarize this thread to see the options, performance, and prices.1. Binoscope:<img src="http://www.birdforum.net/attachment.php?attachmentid=84074&d=1178902830" alt="" class="fr-fic fr-dii fr-draggable " style="" /><a href="http://www.birdforum.net/showthread.php?t=85808" target="_blank">http://www.birdforum.net/showthread.php?t=85808</a>This is the best choice?: Is the one wich allow you not only to have the highs mags, but the lowers too. Its also, if you choose 80/85 scopes, the lightes combo. The bad thing is you need to collimate and mount, i dont think is hard, but has to be done. Another bad thing is the eyepieces. If you choose spotting scopes wich doesnt allow alternatives to the zoom or only the ones the brand sell, you will missing a great range of mags and fovs, not to say 60x with zoom is not the same than with a fixed one, and only the expensive scopes can reach at most 75x ... i dont know if all the brands offers fixed eyepieces for 70/80x too. Normally are 30x to 40x depend of the size of the scope. Its not possible with 45 dgree 80 mm and above scopes: not enough IPD. Maybe two 45 dgree 60mm or 65mm can reach enough IPD, but i dont know for sure and we are talkin of less "powerfull" binoscopes, but if you are to are satisfied with it, and want the truly most cheap and lighter this is the way to go. Be very carefull on the measuring or find a store to check it; dont you ever buy them like "im gonna have luck"There's a plan B: astro binoscope. The most complicated part ist to get straight through prism. The only one i know is a bushnell ... quality? seems to be too cheap so i think is correct, and no more ... there's the nikon prism unit, but i guess cant be attached to the 100% of the scopes. So you need to buy or find one to try it. And then is IPD ... my thoughs are it maybe can work on 80mm scopes, above that im afraid its risky to do the experiment with your own money.2. Binoviewers:Its hard to find a set that can go lower than 40x, impossible in maks, maybe in some refractors with a reducer ... BV worst thing is, there's no standar. I look at cloudy nights and some people achieve it with barlows, reducers, others with none ... then is the Binoviewers itselfs, depend on the clear aperture, than can go from 20 to 28mm, you can get more or less FOV, beacuse if the field stop of the eyepieces doesnt "fit" you find vignettin issues.There are normally, if you choose a refractor, heaviers than the binoscopes, but can go almost half the weight compared with chinese big binoculars, and with much, much better perfomance (normally big binos that are no APO are limited to 30/40x) ... with Maks the weight is more competitive. A binoscope made of 100 mm and a 150 bv mak, and a 127 bv mak and 80 mm binoscope,  in practicall terms, are the same loads (and the same apperture)So, lets take two examples that works:Celestron C6: <a href="http://www.cloudynights.com/ubbarchive/showflat.php?Cat=0&Number=1391967&page=0&view=collapsed&sb=5&o=all&fpart=1&vc=1&PHPSESSID=" target="_blank">http://www.cloudynights.com/ubbarchive/showflat.php?Cat=0&Number=1391967&page=0&view=collapsed&sb=5&o=all&fpart=1&vc=1&PHPSESSID=</a>A member forum who actually has done it:<a href="http://www.birdforum.net/showpost.php?p=1106438&postcount=25" target="_blank">http://www.birdforum.net/showpost.php?p=1106438&postcount=25</a><a href="http://www.birdforum.net/showpost.php?p=1111773&postcount=28" target="_blank">http://www.birdforum.net/showpost.php?p=1111773&postcount=28</a>Another example:Im thinking in a skywacther ED 120 :t:Here's a formula to calculate the result of a BV used in scopes: Its not the half of light, like i always though.Example: A 120 scope. 120x120= 11440/2= 7200.Then, take the apperture of a given binoculars, and multiply like this:85 binos: 85x85=7225There you have:120= Like 85 mm binoculars, keeping the resolution of the source.I take this formula from Edz, from cloudy nights. Trust me, is correct.3:BinocularsI say it before: forget those semi apo, half quater apo etc etc ... 40x max. Its no bad, but we are talking to raise the bar more. If you want it on binoculars, prepare 3000 the less for a brand new buy.My only hope are the vixen BT81 ... however i dont think they can reach 80x in good conditions, im betting 50x with luck. Wich is very good for 1000 euros and 4 kilos, and can go on low mags.Anythin else, avoid it for terrestrial use. Resume:Binoscope:Pros: Can be the lighter combo.Can works with low mags tooCons:Not so many models than can accept 1.25, from 80 to 100 mm straight through, for less than 1000. So the eyepieces versality could be limited. This combo could be the more expensive if you buy new. Maybe with luck you already have a straight and can buy another one. Find the same two models at the same time on second hand, its harder, but not imposible. However, do what you do, be way cheaper than a true APO binoculars.Need to be collimated and mounted. Remember, only straight through models on 80 mm, 60 or 65 mm need to be tested physically togheterBinoviewer:Pros: High mags performance works better on longer focal scopes and astro focuser made them easy. Can use a mirror diagonal.I think is easy to find one astro scope and all the stuff needed on the second hand market than two equals spotting scopes. So this could be really, really cheaper compared to a docters 40x80. You can get a beast like a C6 BV, even from new, for less than half any other true APO binoculars. Eyepieces of "any shape and colours" can be usedCons:You be missing the low mags ... if you already got a binos this is somehow, fixed.You need to made sure the set up you choose is work. Dont buy any scope, any BV, and join them like "ok here we go" ... im not saying this is what happen with this forum member, you to show you its not easy.<a href="http://www.birdforum.net/showthread.php?t=61124" target="_blank">http://www.birdforum.net/showthread.php?t=61124</a>Binoculars:Well, no pros and cons, those semi apos on terrestrial shows a fair amount of CA surpased the 40x and if already this binos combos are heavy, this is another dimension. True APOS: Heavy as well, 3000 euros min. Im keeping searching info of the Vixen BT81, my last hopeStop scrolling down :king:</blockquote>

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