[Prickly]

Evening all,

I am considering getting some binoviewers and was interested in feedback about what would be a good choice of eyepiece / barlow combinations for planetary observation (approx 250 - 350x mag) for my telescope. My scope is a 140mm f5.8 refractor 800mm focal length.

Some points I have gleamed from reading other points.

-Most binoviewers allow a max usable field of 60 degrees
-Mostly binoviewers need a barlow (around 1.6x seems common) to enable focus to be met
-Barlows used in front of the star diagonal (say a 2x barlow) may end up resulting in closer to a 3x barlow effect [maybe not the case with the powermates]
-The effect of using the barlow increases the eyerelief so that 20mm eye relief eyepieces may end up more like 30-40mm depending on barlow used I guess
- The preferred eyepiece range is 10-20mm and less than 10mm can be hard to fuse.
- I dont want to get too heavy with the diagonal, eyepieces and binoviewers which may cause focussing problems.

One thought has been a 8-24 zoom eyepiece with around 12-15mm eye relief (post barlow maybe around 24mm?). Allowing for the barlow effect it might be possible to have a nice range to dial in the right focal length.

Another though would be just a nice high quality fixed focal length eyepiece eg. 5mm ortho or similar with short eye relief that barlowed might increase to around 10-15mm. At present Im thinking this may be the way to go.

So over to everyone. What do you find works well. Appreciate feedback from those of you who have experimented with binoviewers/eyepiece/barlow combos. Im thinking the williams optics unit looks quite a good binoviewer.

Thanks in anticipation.

David