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bought an Arcturus Binoviewer & couldn’t be happier

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#126 Joe1950

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Posted 15 January 2020 - 08:16 PM

True, most seem to have units that are collimated to the point where are quite usable. And, for the relatively low cost, it’s a good deal, especially for those first trying binoviewing. The world of low cost, mass produced goods does have some lemons get out the door, as to be expected.

 

But I glad you found the reason some units just don’t work. There is a possible cause other than the eyepieces not being aligned.



#127 Zwick

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Posted 01 February 2020 - 07:06 PM

The Arcturus and Astromania units do appear identical. However the eyepieces (which also appear identical from the available pictures) are listed as 30mm on the Arcturus and 32mm on the Astromania units. Does anyone know if they are actually different, or is it just sloppy ad copy? I'd also be interested in the FOV. Arcturus clams 48degrees, while Astromania makes no claims that I can find.


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#128 Joe1950

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Posted 01 February 2020 - 08:37 PM

I would wager they are the same exact unit. Things get lost in translation, however, making it seem there are minor differences. But economics says they are exact save for the brand name.


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#129 StarAlert

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Posted 05 February 2020 - 01:32 AM

So tonight I had a short window to try out the Arcturus binoviewer with my Obsession UC18.   Results were not as nice as with the C11 EDGEHD.   With or without a paracorr, only the 1.85x Barlow came to focus.  Surprisingly the 3x Barlow did not.  With the paracorr and the 1.85x, although I could get to focus, the paracorr was not at the correct position to remove the coma.   

 

So for now I will stick to the C11 when using the binoviewer.

 

John

I posted something related to this a couple months ago. The 1.85x Barlow comes to focus with more backfocus than the 3x Barlow. Which makes no sense to me. Native should require the most  in-focus and the 3x should use the most backfocus. I haven’t been able to figure out why, yet. 



#130 StarAlert

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Posted 07 February 2020 - 02:49 PM

I bought a pair of 20mm Meade 4000 super plossls to try out in my Arcturus. Has anyone tried these in a binoviewer? Everything outside the middle 30% FOV looked like a comet racing towards the center. What is going on? The 30mm's that came with the bino are far better. I was looking for a little more power. hmmmm


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#131 Joe1950

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Posted 07 February 2020 - 04:11 PM

I used several Meade Series Super Plossls with the Arcturus BVr and they worked great. I got them since they had no undercut and seemed better in the eyepiece holders. But no noticeable aberrations at all. I had pairs of the 15, 20 and 26mm Super Plossls.  

 

I don't know what to tell you.  I recently bought a different well known single eyepiece that should have been a decent quality and the pincushion distortion was terrible.  Many times worse than even cheap eyepieces.  All I can think is that some of these are arriving with inside lens elements reversed.

 

Also, try a different nosepiece Barlow.  The first binoviewer I got had a bad performing 3x Barlow.  I was able to get it replaced with another that worked better. The 1.8x one was always better.  Or use a separate Barlow and see what you get.


Edited by Joe1950, 07 February 2020 - 04:17 PM.


#132 StarAlert

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Posted 07 February 2020 - 04:22 PM

I used several Meade Series Super Plossls with the Arcturus BVr and they worked great. I got them since they had no undercut and seemed better in the eyepiece holders. But no noticeable aberrations at all. I had pairs of the 15, 20 and 26mm Super Plossls.  

 

I don't know what to tell you.  I recently bought a different well known single eyepiece that should have been a decent quality and the pincushion distortion was terrible.  Many times worse than even cheap eyepieces.  All I can think is that some of these are arriving with inside lens elements reversed.

 

Also, try a different nosepiece Barlow.  The first binoviewer I got had a bad performing 3x Barlow.  I was able to get it replaced with another that worked better. The 1.8x one was always better.  Or use a separate Barlow and see what you get.

Good to hear. I bought them for the same reason. They fit very nicely in the EP holders. I tried a DeLite, but with the undercuts it sits very sloppy in the holders.

I'm going to try your suggestions tonight.


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#133 sonny.barile

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Posted 07 February 2020 - 06:26 PM

I bought a pair of 20mm Meade 4000 super plossls to try out in my Arcturus. Has anyone tried these in a binoviewer? Everything outside the middle 30% FOV looked like a comet racing towards the center. What is going on? The 30mm's that came with the bino are far better. I was looking for a little more power. hmmmm

Did you try them without the binoviewer? Could be the ep’s. 


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#134 StarAlert

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Posted 07 February 2020 - 10:58 PM

I did. They were very sharp without the BV.

#135 Joe1950

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Posted 07 February 2020 - 11:20 PM

Can’t think of anything in the binoviewer itself that would cause that kind of distortion. I’d have to guess one of the Barlow-like nosepieces is causing it.  If you see it with both nosepieces, I’d try it with an external 2x Barlow if you have one.

 

It was a while back, but I recall the faulty 3x nosepiece gave a similar view to what you describe. But the 1.8x was fine. The replacement 3x was much better but still fell off right near the edge of field. 



#136 Zwick

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Posted 08 February 2020 - 02:58 PM

I finally had a relatively clear night and a little time to try out my new binoviewers (Astromania, but just like Arcturus as far as I can tell). I was inspired to get them after trying a friends WO binoviewers briefly on my 12' collapsible dob. The WOs are supposedly optically virtually the same, but I was surprised to find a big difference in achieving focus. The collapsible dob has detent stops about 4.5 inches short of full extension for use with binoviewers. This shortened position worked perfectly with the WO units with the uncorrected nosepiece. With my Astromania set, that position was way too short. I was reaching good focus with the tubes set at only an inch or so short of full extension. I guess this should mean that I am losing less aperture to secondary mirror obstruction? The supplied 1.85x and 3x nosepieces came to good focus at full extension. So far I am very happy with the binos, and with the adaptability of the collapsible truss rig on the Dob. Loved the two eye viewing and had no trouble with image merging.

 

I am still very much a newb here and would be interested in thoughts about what is going on or implications of these differences in tube extension and reaching clear focus.



#137 StarAlert

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Posted 08 February 2020 - 09:08 PM

I used several Meade Series Super Plossls with the Arcturus BVr and they worked great. I got them since they had no undercut and seemed better in the eyepiece holders. But no noticeable aberrations at all. I had pairs of the 15, 20 and 26mm Super Plossls.  

 

I don't know what to tell you.  I recently bought a different well known single eyepiece that should have been a decent quality and the pincushion distortion was terrible.  Many times worse than even cheap eyepieces.  All I can think is that some of these are arriving with inside lens elements reversed.

 

Also, try a different nosepiece Barlow.  The first binoviewer I got had a bad performing 3x Barlow.  I was able to get it replaced with another that worked better. The 1.8x one was always better.  Or use a separate Barlow and see what you get.

I spent a couple hours this afternoon testing the Arcturus BV with my new 20mm Meade 4000 super Plossls. I brought my Televue 2x Barlow and my 2.5x Power-mate. This is what I discovered. 

 

When I put the Meades in the BV with the 1.85x nosepiece Barlow, there is extreme distortion in the outer half of FOV. Someone told me it’s called coma, when I explained it to them. The Meades are very sharp without the BVer.

 

First, I replaced the 1.85x with the native nosepiece and used my 2x Barlow. The Meades were sharp to the edge. Yay! But get this. The 2x Barlow resulted in much more power and less FOV relative to the 1.85x nosepiece Barlow. If I had to guess, it was perhaps twice the power and half the FOV. 
 

Next up was trying the 2.5x Power-mate. The Meades looked great! But this is where it gets weird. The 2.5x Power-Mate resulted in lower power and a larger FOV relative to the 2x Barlow. In fact, the power-mate was very similar to the 1.85x nosepiece. How is this possible?

 

i was so perplexed, so I had to try the Barlow and Power-mate without the BVer to make sure they are labeled correctly. Yes, they are! Without the BVer, the 2.5x Powermate is a bit more powerful than the 2x Barlow. 
 

Anyone have any idea what’s going on? The 1.85x is going in the trash for sure. It’s horrible. 


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#138 Joe1950

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Posted 08 February 2020 - 09:24 PM

Adding an external Barlow to a binoviewer will alter the power, but usually upward, since there is more distance between the Barlow lens and the eyepiece. So a 2x Barlow becomes 3x, 3.5x or more.

 

I don’t understand why the Power-mate is less. But it’s good the images are good. 

 

If if you want to replace the 1.8x nosepiece you might consider this one.  It works as well as any I’ve used and you can’t beat the price. It will screw into the straight-through nosepiece.

 

Also, on some Barlows you can unscrew the lens from the housing and screw it onto the straight-through nose piece. You’ll get an amplification closer to the Barlow’s original power.  But not all will unscrew and match the straight-through nosepiece.

 

Added:  Just for the heck of it, you might also take the faulty 1.8x lens out of the housing and reverse it. It wouldn’t be the first time lenses have made the trip across the pond and were installed backwards... talking refractor objectives also!

 

With most Barlows, the more curved side faces the eyepiece. Usually.


Edited by Joe1950, 08 February 2020 - 09:33 PM.

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#139 johnpeter2

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Posted 08 February 2020 - 09:40 PM

StarAlert:  I'm late to this discussion, but if I hadn't been, I would've asked you if you were using the 1.85X nosepiece, because I have gotten similar results with it.  For example, it really gave me a smeared image of part of the Moon.  Yeech!  I also have several pairs of Meade plossls, and they do great as long as I don't use that nosepiece.  The 3X nosepiece seems to work OK, but I think my TV barlow and ES focal extender give a sharper image.

 

As for your question about the powermate, Eddgie provided some info in this thread about the powermate as oca (esp. post #3):

 

https://www.cloudyni...ca#entry9599435

 

John


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#140 StarAlert

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Posted 08 February 2020 - 09:43 PM

I just went to the Televue website to see what the difference is between a power-mate and a Barlow. A Barlow shifts the exit pupil of the EP out. A power-mate does not. Maybe that has something to do with the power-mate performing much closer to the 1.8 than the 2x Barlow. 
 

I like your idea... I love to take things apart. Didn’t realize these nose pieces came apart. 


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#141 Joe1950

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Posted 08 February 2020 - 09:46 PM

One more trick.

 

Get a yardstick and place it outside in your yard about 50 to 75 ft. From your scope. Put the 20mm (eyepiece only)  in your scope and focus on the yardstick. See how much of the stick, in inches, you see, across the field, edge to edge. Call that measurement ‘A.’

 

Then, put the binoviewer with a given Barlow in the scope and use the same 20mm eyepiece(s). See how much of the stick you can read across the field, edge to edge. Call that measurement ‘B.’

 

The power of the Barlow in that configuration with the binoviewer is:

 

P = A/B 

 

Pretty close. 

 

Ex. If in condition A you read from 0” to 30”, and in condition B you read from 0” to 9”, the magnification power of the Barlow in that set-up is  30/9, or  3.3x.


Edited by Joe1950, 08 February 2020 - 09:50 PM.

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#142 Joe1950

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Posted 08 February 2020 - 09:49 PM

With me it was the opposite.  The 1.8x worked great, but the 3x was bad. I didn’t try to reverse it, but the manufacturer, in my case Astromania (same binoviewer and kit) sent a replacement that was good. 



#143 johnpeter2

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Posted 08 February 2020 - 09:54 PM

Zwick:  The difference in achieving focus is likely to be the eyepieces provided with your Astromania binoviewer, if they're the same eyepieces as with the Arcturus.  They're designed to give you maximum outward focus with a binoviewer.  Try your binoviewer with another pair of eyepieces and see how much the focus changes.

 

John 


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#144 StarAlert

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Posted 08 February 2020 - 10:23 PM

StarAlert:  I'm late to this discussion, but if I hadn't been, I would've asked you if you were using the 1.85X nosepiece, because I have gotten similar results with it.  For example, it really gave me a smeared image of part of the Moon.  Yeech!  I also have several pairs of Meade plossls, and they do great as long as I don't use that nosepiece.  The 3X nosepiece seems to work OK, but I think my TV barlow and ES focal extender give a sharper image.

 

As for your question about the powermate, Eddgie provided some info in this thread about the powermate as oca (esp. post #3):

 

https://www.cloudyni...ca#entry9599435

 

John

That helps a lot. Explains exactly what I saw. 



#145 StarAlert

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Posted 08 February 2020 - 11:46 PM

 

 

If if you want to replace the 1.8x nosepiece you might consider this one.  It works as well as any I’ve used and you can’t beat the price. It will screw into the straight-through nosepiece.

Joe,

Can the Burgess OCA be screwed directly into the BVer housing or can it only be screwed into the straight-through nosepiece. 



#146 StarAlert

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Posted 09 February 2020 - 12:04 AM

Joe,

Can the Burgess OCA be screwed directly into the BVer housing or can it only be screwed into the straight-through nosepiece. 

Disregard, it can only go into the nosepiece. 


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#147 StarAlert

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Posted 09 February 2020 - 05:10 PM

Finished up with running a few experiments in the backyard with the Arcturus BV and a couple different OCAs. 
 

First, using the 20mm Meade 4000 EPs with the 2.5x Powermate yields 2.1x. The 2x Barlow yields 3.6x. The 3x nosepiece that came with the BVer is spot on, yielding 3x by my measurements. 

Second, I have an Orion 2x shorty Barlow that I screwed directly into the straight through nosepiece. Much lower profile and results in slightly lower power (3.3x) than the 2x TV Barlow which I’m unable to attach directly to the nosepiece. 

 

Finally, if you’re using the 30mm EPs that come with the BVer, it might be helpful to know that those EPs, by my measurements, have a field stop of 28mm (about 54*). However the BVer only has a clear aperture of 22mm. So the AFOV one gets when using them in the BV at native power is actually reduced to about 39*. 


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#148 Joe1950

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Posted 09 February 2020 - 05:35 PM

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#149 StarAlert

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Posted 10 February 2020 - 09:12 AM

Does anyone know what kind of threads the Arcturus uses for its nosepiece? It’s not the same as a 1.25” filter thread. Why wouldn’t they have made it the same? 



#150 Zwick

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Posted 10 February 2020 - 03:04 PM

The nosepieces on my Astromania binos accept standard 1.25" filters (1.125" x 42TPI). The threads on the end that attaches to the BVs measure 28TPI (to the best of my ability to read my old thread gauge with my old eyes). The diameter is slightly smaller on the BV as well. I have no idea on the why question.

 

Edited to correct typo:1.25" rather than 1.25'


Edited by Zwick, 10 February 2020 - 05:16 PM.

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