30x80 / 25x100? Too much Mag?

[Stargazer_00]

Hi,

I currently have a pair of 20x80 and am craving a little more detail.

I have seen that 30x80 exist and 25x100 both at just-about-affordable prices.

I naturally use mounted bins as handheld doesnt give a nice stable view.. I am wondering if the bins, even on a mount, start to become difficult to use after 20x mag?

I am guessing that a 30x80, compared to my current 20x80, will show objects at a greater size but dimmer and that the 25x100 will present a slightly larger image than the 20x80 and possibly a fraction brighter too.

Is that about right?

Does anyonethink that it's worthwhile upgrading from 20x80 to either of these? I'm happy to spend £200 - £250 on a good set of slightly more powerful/larger bins.

to be honest I'm finding im using my scope less and less since I got big bins! May even fleabay the scope and get a decent set of astro bins

[Peter Drew]

As you are already using your binocular on a mount, then used in a similar manner the higher magnification alternatives would not be too high. In fact they still represent the lower end of the magnification scale for the aperture. I don't think you would gain much from upgrading to 30X80 but 25X100 would be a noticeable improvement over your 20X50's

[michael.h.f.wilkinson]

25x100 has the same exit pupil as the 20x80, so the surface brightness stays the same, but the integrated or total brightness of extended sources, and the brightness of point sources (stars) goes up. 30x80 would not be my choice, although a good 30x80 might be better than a so-so 25x100.