Observing Log 13/4/2019 @ 22:30-23:30, Lichfield

  • Orion Optics UK 10″ Dobsonian Telescope
  • Orion USA Premium Linear BinoViewer
  • APM Ultra Flat Field 18mm 65 degree FMC eyepiece pair
  • TeleVue Nagler 7mm 80 degree eyepiece pair
  • Bresser 14mm Plossl eyepiece pair

Predicted to be 50% or more cloudy tonight, I was surprised when the sky was clear – so I took the Orion 10″ and binoviewer outside to given them a spin. Once outside looking at the sky, I realised that the forecast was a lot more accurate than I have initially thought – although the sky appeared clear, transparency was poor due to thin high altitude cloud and a relatively bright Moon made the situation worse.

Nevertheless, the Moon gave a great opportunity to try out the binoviewer again – and I enjoyed some wonderful views of the roughly 60% illuminated disc and terminator.

I do not have a good history of being able to merge the two images in binoculars – tonight I found it easier than before to merge images particularly with the APM Ultra Flat Field 18mm 65 degree FMC eyepiece pair. The Nagler pair were the most difficult – I wonder if this is due to the large apparent field of view? I don’t know a great deal about how these things work but I have read that the field of view of a 1.25 inch binoviewer is limited…….is that relevant to my ability to merge images? Whatever the reason the APM pair seem ideally matched for this binoviewer.

I was also able to see single merged images of start fields in Auriga and Gemini with the APM pair.

This is the second time I have used the Premium Linear binoviewer – my ability to observe merged images was significantly improved tonight over the first time.

What I did notice tonight was a reflection of the secondary mirror which seemed to be coming from the central optics in the binoviewer which combine images from the two eyepieces. It only appeared with the bright Moon and not with the star fields. In addition, there was blue line along the edge on one side of the field of view with the bright Moon, although this did not seem to affect the image of the Moon itself nor detract from my enjoyment of the view. The Astronomy Now review of this binoviewer, although very positive, did mention reflections with bright objects, so I think this is what I am seeing.

Andy

 

2 Responses

  1. Nice report Andy- I’m also on a learning curve with binoviewers – they’re harder than they look, aren’t they! My experiences have been very similar to yours- when they work they’re stunning, but I’ve also had trouble with merging images and reflections. Have you tried a glob yet with them? That’s been my favourite so far.

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