Binoculars vs Telescopes

I haven't been able to find any formal discussion of this subject -- I don't want to start a thread with speculation, but if anyone really knows the answer or where to find it, or has specific experience, please share.

Mathematically a 50 mm binocular gathers as much light as a 70 mm refractor, albeit spread over two eyes instead of one. But when our brains put together the two images from a binocular, would it not yield an effectively brighter image? Do 50 mm binos give an image similar to a 50 mm scope, a 70 mm scope, or somewhere in between?

Thanks very much to all of you for the comments -- great information.

It would be nice to see removeable eyepieces on lower-end binoculars -- not only to vary the magnification, but to be able to use diagonals as well. But I guess the cost of the accessories wouldn't make much sense with low-cost binoculars. I thought about zoom binoculars, but I guess they don't work so well for astronomy.

Hi Craig,

For me, binoculars seem to give a slightly dimmer image, than a similar aperture "monoscope". I suppose it might be due to all the extra surfaces of the prisms, or coatings etc. I did a side by side test of a ST120 and my Vixen 20x125 bino's at about the same power, and the the lowly ST120 actually gave just a slightly brighter image, with a hint of more stars. But the easthetic view in the bino's was a whole different story. The stars seem to come alive, star colors were more obvious, and nebula seem to stand out in front of the dimmer background stars. It was so dramatic, the ST120 was not used the rest of the night. The large open winter clusters really emphasized this effect. Orions nebula was ... well I could go on. : )



David Simons