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bought an Arcturus Binoviewer & couldn’t be happier

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#176 StarAlert

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Posted 05 May 2020 - 06:46 PM

I tried the Arcturus in my Tak FC100DL, which has 223mm of back focus. The only EPs I could get to focus without a Barlow were the EPs that came with the unit. I think there was about 8mm of in-focus left (with a 2” Baader Amici prism). The Amici was fine as long as I didn’t point the scope at something very bright, like Sirius or Venus. If so, there was a bright horizontal line going through the object And entire FOV. I have since purchased a standard prism. 

 

When I did get the binoviewer to work, it was fabulous, but too much work trying to figure out what Barlow to use with what EP. I eventually sold that unit and bought a pair of APM 70mm 45s. Found that looking with two eyes is the only way to go, so now there is a Maxbright II binoviewer being deliver to my house today. I’m keeping my fingers crossed that this will work without a Barlow or GPC. I’ve read that it will, but I’ll believe it when I see it. 
 


Edited by StarAlert, 05 May 2020 - 10:04 PM.

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#177 Cali

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Posted 08 May 2020 - 01:15 PM

I eventually sold that unit and bought a pair of APM 70mm 45s. Found that looking with two eyes is the only way to go, so now there is a Maxbright II binoviewer being deliver to my house today. I’m keeping my fingers crossed that this will work without a Barlow or GPC. I’ve read that it will, but I’ll believe it when I see it. 

 

Please DO keep us informed.

 

- Cal


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#178 Binofrac

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Posted 28 May 2020 - 06:41 PM

I've since got my replacement BST (Arcturus) binoviewer and have been experimenting with it this evening. The optical quality is very good with no obvious dimming in either side. I tried a 1.25" prism diagonal to shorten the lightpath enough to see if it would negate the need for barlows. The only eyepieces to focus (just), were the supplied 32mm. There just isn't enough infocus for any others and so barlows it is. The supplied 3x nosepiece barlow works quite well although the magnification is too high. It's very similar to a Revelation 2x barlow element screwed into the normal nosepiece, showing the 2x is very near 3x in this setup. The supplied 1.85x nosepiece shows a bad coma from about 50% from the centre view and so I didn't bother with it.

 

The seeing tonight wasn't great but with good transparency in a cloudless sky. The only target tonight was the moon which was bright and clear. All stereo views were with the 32mm eyepieces as I don't have any other pairs. The field of view was roughly similar to my BST 8mm eyepiece in mono. Starting with the Revelation barlow the view was extremely good. The lunar surface was more crisp and had greater contrast than I've ever seen with mono viewing. There was a very slight colour which was comparable to normal mono viewing with the 8mm. I tried the 3x nosepiece barlow expecting the view to be reasonably inferior as it was a cheap bundled device, but was surprised to see the colour shown with the Revelation was almost non existant and better than the mono eyepiece. The whole view seemed to be cleaner, with the Revelation view looking ever so slightly ivory in comparison. It did show a flatter field though with the bundled 3x showing a little spherical error about 5% from the edge of field. Both barlows had the uncomfortable result of putting the eye position further out than normal. This meant I had to hover over the eyepieces holding a critical alignment until my muscles started to ache. I would much rather be able to rest my eye sockets on the eyepieces so that my relative movement would be less. Eye positioning and IPD is quite critical.

 

The collimation was ok and I could immediately merge the lunar images successfully. It did need further adjustment as shown by the misaligned field stops. This was easily achieved by shifting the eyepieces while looking at fairly dim star. I'll have to do this probably everytime I use the binoviewer but like the fact I can easily adjust it to be pretty much perfect.

 

The 32mm eyepieces seem very good value for bundled items although the necessary barlows affect them too much. To get an idea what eyepieces might work better I tried 3 other BST eyepieces, 18, 12 and 8mm. These were put in the left side of the binoviewer as I only have one of each. The 18 and 12mm worked very well with the 8mm greatly dimming the view and not working at all well with the current seeing conditions. The eye placement with each was a lot more comfortable though. My thoughts are that a pair of 25mm BST's would be a good purchase, and another 18mm to form a pair. Later in the year when I've had a chance to try some planetary viewing it might be worth getting another 12mm. One thing I noticed is that the plane of focus for the BST eyepieces in the binoviewer is very close to the surface of the bottom element. If this has any dust then it looks like your eye has suddenly gained a lot of floaters.

 

I generally use binoculars more than anything and so I'm very pleased to be able to use two eyes on my scope too. This will only be for high magnification lunar and planetary views though as the widest view so far only shows around 75-80% of the lunar disk. I can obviously get a better wider view straight through without a barlow and diagonal which for me is too tortuous for serious consideration. There is the ED version of my scope available which has a removable tube section. This would give better views and allow the binoviewer to be used without a barlow which would be a lot more user friendly. I may keep an eye out on the used market.

 

This is my first proper viewing with this binoviewer and like the title of this post I couldn't be happier either. It's hard to believe such an improvement in viewing from this price.


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#179 Binofrac

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Posted 19 June 2020 - 11:35 AM

This thread may now be heading out in the wilderness of time but I feel the need to complete my experience with this binoviewer. I returned the prism diagonal and spent the money on a pair of 25mm BST Starguiders. These work very well in the binoviewer and show almost the same as the bundled 32mm eyepieces but with a wider apparent field. They are more user friendly as the twist up eyecup means I don't have to hover uncomfortably to get the correct eye placement. I can rest my eye sockets on the eyepieces. It can be difficult otherwise to keep your eyes in the right place for any period of time. Before I ordered them I was looking to find some brass strip to fill in the undercuts. I needn't have worried as these come with a tapered barrel that fits in the binoviewer perfectly. I don't know if this is specific to the 25mm, or if this how all the BST's are now supplied. 

 

The only thing is that for me at the moment this whole binoviewer setup replaces just one eyepiece with regard to my scope. The long focal length shows too high a magnification, making this suitable only for lunar and planetary use. This is the slot currently occupied by my 8mm BST. I can't achieve lower magnifications and I'm not sure that higher ones will really be useful or worth the expense of more eyepieces.

 

The cost of the binoviewer, barlow and eyepieces comes to around £260. I can't think that I would get anywhere near the `wow` experience from one eyepiece at this (or any) price. Although for this scope it is not as flexible as I'd hoped, I'm still pleased enough that I would certainly buy it again. 

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#180 Larrythebrewer

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Posted 24 August 2020 - 12:06 PM

Since starting this thread, I have followed it, but I haven’t posted at much in it.
I’ve had diaster strike last night after observing. My Arcturus binoviewer & 2 inch diagonal fell out of my Bader 2 inch clicklock and of course hit the ground and now my binoviewers are toasted, chipped the prisms inside and won’t open to enough get the idp I need & collimation is gone.
Anyway just let everyone out there know, I ordered a new pair, that’s how happy I am with these.
It’s so good to see everybody’s posting & other people that bought them like them.
I hope my next pair are as good as my 1st


Edited by Larrythebrewer, 24 August 2020 - 05:17 PM.

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#181 Cali

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Posted 31 August 2020 - 02:24 PM

Ouch! So what was the point of failure? Loose screw? Too much beer ;>)

 

C'mon, C'mon ... confess.

 

- Cal


Edited by Cali, 31 August 2020 - 08:53 PM.



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