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Message: <blockquote data-quote="brocknroller" data-source="post: 2971089" data-attributes="member: 665">That is a monster! To use those oversized EPs, you must either use eyeglasses or have a Herbert Hoover bulldog face. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink    ;)" loading="lazy" data-shortname=";)" /> You didn't list the ER, but those huge EPs suggest it's probably long. If I stuck my high-bridged proboscis in between those giant orbs, it would get ground into sausage. I'd have to use the binoscope with eyeglasses, which I would need anyway to correct for astigmatism, which is a bigger deal at night than during the day when shrunken entrance pupils minimize the effects from the astigmatism. I've always liked the idea of using a binoscope for stargazing. Never tried one, but I have used telescopes with binoviewers, the best of which was the long discontinued Televue Bizarro. Markus from APM Telescopes in Germany offers some high end binoscopes, and there was an ATM in Japan who would customize a binoscope for you. It gets expensive quickly. You start out with two Televue 101 scopes or some other brand, I think he used Pentax scopes, too, and he makes the prism arm assemblies to fit the scopes.However, I'm not sure about the practicality of using a 70x binoscope for birding. The depth of focus is very shallow at high powers, which is okay for stargazing since you are focused at infinity, but for birding, it might be cumbersome. Once you have the bird sighted (and I don't see a 6x finderscope on the binoscope, which you would need for birding, it would also be useful for stargazing), you'd have to use a deft touch to focus on the bird without overshooting or undershooting. Also, birds usually don't stay very long in one place (neither do stars, in the sense that the earth is moving, but you just have to nudge the scope, the star is not going to fly away). Might work okay for shorebirds. Then you also have to deal with atmospheric disturbances, which are easily seen at 70x. During this spring transition from cold to warm, even a 10x bin can pick up instabilities in the air near the ground that cause the image to blur. I experienced this the other day with the 10x42 SLC-HD. And finally, even with a 120mm objective, @70x only gives you a 1.7mm exit pupil. You'd probably be getting blackouts galore during the day. On the night sky when your entrance pupils are dilated, the small exit pupils are less of an issue. But during the day when your entrance pupils are shrunken to 3mm or less, keeping your eyes centered on a 1.7mm exit pupil can be challenging. I tried this a couple days ago with the SLC. I used two different 2.5x "doublers" with it. The cheaper one was hard for me to use w/out blackouts, the more expensive one I could use with some care, but since it was cloudy the image was somewhat dim. To get a 2.85mm exit pupil, which would easier to use and let in more light, your binoscope would need to have a 200mm objective. Imagine carrying around two 200mm scopes for birding? You'd need arms like the Terminator. For biding, I'd also like a 45* angle prism. Getting high in the trees with a straight through scope would be rough on the neck or the knees, since you'd have to crank up the tripod head and get on your knees to view a bird high in a tree unless it was at a very long distance. I think binoscopes are better suited for stargazing than biding. A 15x56/60 seems about the practical limit for biding due to all the above mentioned factors. Brock</blockquote>

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