Kasai WideBino 2.3 x 40 mini review

[JTEC]

A short report on the Kasai WideBino 2.3 x 40 that came yesterday. The idea of sweeping the skies with superpower vision  is an appealing one, so I was looking forward to first light with these.  Remarkably, it was clear, though the skies here rarely get better than about mag 4 and typically only after some of the lights go out after 1 am.  Last night was a typical night.

The WideBino comes with a small case with shoulder strap. It has caps on all lenses. It looks and feels adequately robust and well made. The interpupillary adjustment is smooth and secure and has enough range, I’d have thought, for most users. The OTAs appear to be sufficiently well collimated for this design and I didn't notice any discomfort in needing to accommodate for inaccuracies. The eyepieces focus independently and, again, the action is smooth and neither too stiff not too sloppy.  

So, what are they like to use and how do they perform?  Well, they’re ‘opera glasses’ of Galilean design and the experience is not quite like using a ‘normal’ binocular that just happens to be wide-field and low power. For a start, they are small in the hand - paradoxically, I found this made them less easy to handhold than something bigger. The available headset looks interesting but is expensive.  The design requires that to experience the wide-field properly you need to get your eyes in as  close as possible to the eye lens. That’s not to say they don’t work if you hold them further away - they do. I found the focusing a little awkward at first but very soon got used to it, and it works well. There is considerable aberration towards the periphery of the fov, as you’d expect, but this doesn’t really detract from the value of the WideBino as a scanning around instrument.

In focus, the star images at centre and away from the edge were acceptable in terms of the Widebino’s intended use. Getting in close and with my no longer big exit pupil eyes, I thought I got about 18 degrees out of them. I concur with what others have said about magnitude gain. Scanning around Cygnus, Delphinus and the head of Aquila, a gain of at least 1.5 seemed about right.

Is it like having ‘superpower vision’? No more than using a Nagler or Ethos is like looking out of a porthole. Are they quite nice to have? Certainly. And it would be great to use them on a pristine sky when that opp arises!

They came with 2” filter adapters that screw into the front of the OTAs.  I’m still wondering what to try in those that’s affordable (i.e., in this context, ‘cheap’) as, given the constraints of aperture and design,I think filtered performance could be underwhelming. My UHC favourite in the big scopes is the DGM Optical NPB, but I’m not about to cough up for 2 of those just to find out ?. Does anyone have any suggestions, please?  Anyway, here are a couple of pics.

[LukeSkywatcher]

2 hours ago, JTEC said:

A short report on the Kasai WideBino 2.3 x 40 that came yesterday. The idea of sweeping the skies with superpower vision  is an appealing one, so I was looking forward to first light with these.  Remarkably, it was clear, though the skies here rarely get better than about mag 4 and typically only after some of the lights go out after 1 am.  Last night was a typical night.

The WideBino comes with a small case with shoulder strap. It has caps on all lenses. It looks and feels adequately robust and well made. The interpupillary adjustment is smooth and secure and has enough range, I’d have thought, for most users. The OTAs appear to be sufficiently well collimated for this design and I didn't notice any discomfort in needing to accommodate for inaccuracies. The eyepieces focus independently and, again, the action is smooth and neither too stiff not too sloppy.  

So, what are they like to use and how do they perform?  Well, they’re ‘opera glasses’ of Galilean design and the experience is not quite like using a ‘normal’ binocular that just happens to be wide-field and low power. For a start, they are small in the hand - paradoxically, I found this made them less easy to handhold than something bigger. The available headset looks interesting but is expensive.  The design requires that to experience the wide-field properly you need to get your eyes in as  close as possible to the eye lens. That’s not to say they don’t work if you hold them further away - they do. I found the focusing a little awkward at first but very soon got used to it, and it works well. There is considerable aberration towards the periphery of the fov, as you’d expect, but this doesn’t really detract from the value of the WideBino as a scanning around instrument.

In focus, the star images at centre and away from the edge were acceptable in terms of the Widebino’s intended use. Getting in close and with my no longer big exit pupil eyes, I thought I got about 18 degrees out of them. I concur with what others have said about magnitude gain. Scanning around Cygnus, Delphinus and the head of Aquila, a gain of at least 1.5 seemed about right.

Is it like having ‘superpower vision’? No more than using a Nagler or Ethos is like looking out of a porthole. Are they quite nice to have? Certainly. And it would be great to use them on a pristine sky when that opp arises!

They came with 2” filter adapters that screw into the front of the OTAs.  I’m still wondering what to try in those that’s affordable (i.e., in this context, ‘cheap’) as, given the constraints of aperture and design,I think filtered performance could be underwhelming. My UHC favourite in the big scopes is the DGM Optical NPB, but I’m not about to cough up for 2 of those just to find out ?. Does anyone have any suggestions, please?  Anyway, here are a couple of pics.

I have the Omegon 2.1x42. 

If i wrote a report on them, it would be very similar to yours. They are surprisingly tricky to hold at first for obvious reasons (shorter than normal bins).

[Stu]

@JTEC I had a pair of these for a while, with the filter holders too. I opted to mix and match Lumicon filters, using one OIII and one UHC as, like you I was going to buy a second UHC. It seemed to work quite successfully. I believe some people also try one filtered and one unfiltered channel which can also work well.

[Owmuchonomy]

What an interesting review and concept. I imagine a good dark sky would come alive using these.

[JTEC]

Thanks, Stu and others for your comments and advice.  With the exception of my venerable 22mm Nag, all my eyepieces and, consequently, filters are 1.25 fit. This is because I’ve suffered for years from OOD - Obsessive Orthoscopic Disorder and CBS - Compulsive Binoviewing Syndrome. An Ethos and a couple of Deloses have helped keep these issues under control but not effected a cure.  So I can either pick up a couple of cheap 2 inchers or, maybe better, following Stu’s thinking, one nice one - most likely the Omega NPB, which I like best of all the ‘UHC’ filters, including ... gasp! ... the Lumicon - and see how that goes. And it would go nicely with the Nag. 

John