Bino viewers

[TheThing]

Hopefully, just a quick query.  I've got a set of bino viewers and have picked up some pairs of eps now.  I'm intending to use them with a 127 mak for '3D' views of the moon.  Do I need to use a diagonal with them or will they reach focus without?  Also, I assume that I can put a Barlow in front of the bino viewers and not have to purchase pairs of barlows?

Thanks.

[Louis D]

3 minutes ago, TheThing said:

Hopefully, just a quick query.  I've got a set of bino viewers and have picked up some pairs of eps now.  I'm intending to use them with a 127 mak for '3D' views of the moon.  Do I need to use a diagonal with them or will they reach focus without?

It should reach focus either way, but you're going to end up with a stiff neck without a diagonal unless the moon is really low to the horizon.

 Also, I assume that I can put a Barlow in front of the bino viewers and not have to purchase pairs of barlows?

Correct.  It's best to use a single Barlow ahead of the binoviewer.  It will also keep the focus closer to the nominal design distance.  Even without the Barlow or a 1.25" diagonal, you'll be operating at a longer focal length to reach focus due to the BV's 100mm+ optical path length, but still a much lower FL than with the Barlow.

Thanks.

See inline comments.

[bosun21]

You should use a diagonal for the comfort factor alone. You only require one barlow and the 127 will have no problem reaching focus.

[TheThing]

Thank you kindly both.  That's exactly what I wanted to hear! Much appreciated.