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Celestron Binoviewers seeing Double

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#1 Nessark

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Posted 20 June 2020 - 07:12 PM

So I purchased myself some Celestron brand Binoviewers from Amazon and they arrived yesterday.  I used them last night and I was seeing double of what was there.  I used them on my 12" Dobsonian Telescope.  To reach focus I used a two-inch 2x Barlow.  For eyepieces I used two 9.7mm Meade eyepieces.  So the actual magnification was about 5mm im guessing. Also both the eyepieces were not 100% the same, im guessing one was of older design and was with yellow writing and the other was written with white, also one was heavier than the other so im guessing one is cheaper than the other.  But they are both Meade DS 4000 Series 9.7mm eyepieces.

 

Why was I seeing double through the binoviewer?  I tried focusing and doing what I could but I could not get the images to merge.

 

Could it be because the eyepieces were not 100% exactly the same?

 

Is it because I used too high magnification?

 

Could my binoviewers be terrible quality?

 

 



#2 eyespy

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Posted 20 June 2020 - 07:57 PM

Hi Nessark,

 

I have the same 9.7mm Meade eyepieces and use a Celestron binoviewer.  Have you tried rotating the two eyepieces relatively to each other.  Even eyepieces from the same batch can have slightly different optical and physical 'centres' and which usually corrects by rotating one or both eyepieces.

 

It sounds like you have two different versions of the 9.7mm Meade eyepiece and as they even weigh differently, I would suggest that the 'yellow' one is probably from Japan or Taiwan and the 'white' one is from China.

 

When I was putting together my bino eyepiece pairs, I deliberately ordered the pairs together to ensure they were from close or similar batches.  I still need to sometimes slightly rotate one of the 6.4mm eyepieces in order to merge both images.

 

Doug..... 


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#3 Eddgie

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Posted 20 June 2020 - 08:28 PM

Doug has given you a very good answer,  These inexpensive binoviewers are quite excellent performers, but they lack a feature of more expensive binoculars called a self centering diopters.  Self centering diopters do as the name suggests, which is to center each eyepiece over the center of the optical axis. 

 

IF your Celestron has three screws to hold each eyepiece, it might require that you try centering the the eyepieces by using different depths on the different screws.

 

If it has the single brass compression ring, as Doug suggests, you would want to make sure the eyepieces are fully inserted and then try rotating them.

 

Last, if either of your eyepieces have undercuts, these can be very difficult to get to sit straight if there is a compression band.  Smooth sided barrels work best in BVs without self centering diopters.  See if you can find a pair of inexpensive smoot sides.


Edited by Eddgie, 20 June 2020 - 08:30 PM.

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#4 eyespy

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Posted 20 June 2020 - 11:43 PM

Hi Eddgie,

 

Fortunately those Meade 4000 Plossls have smooth barrels and just need a possible slight rotation in the bino to check the optical centering particularly for the shorter focal length ones.

 

Doug.....


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#5 charlesgeiger

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Posted 21 June 2020 - 02:08 AM

Some things to ponder:

Make sure your interpupillary distance is correct.  These binoviewers accommodate approximately 55 mm to 75 mm.  But I hear some binoviewers are not marked accurately for this measurement.  You can consult your eye doctor or measure yourself the distance from center to center of each eye.  If your binoviewers are not set correctly, you will have trouble merging.

The two eyepieces should be a matched set and you probably want to start with 20 mm to 25 mm eyepieces first.  Higher powered eyepieces such as in your range of 9.7 mm are harder to merge.

As stated above, your Celestrons probably have the single set screw witch can tweak the individual eyepieces from side to side when locking them in place.  You may try rotating one eyepiece at a time to see if you can get image to merge.  If you still do not have luck then it might be time to see if your Celestrons are collimated properly.  Eddgie and others can help you discern that.

Good luck and let us know how it turns out.


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#6 Nessark

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Posted 24 June 2020 - 09:24 AM

Hello all, thank you for the info and advice. I think the issue is the fact that I am not using two eyepieces that are 100% the same. They are both Meade and same mm but the build must be different since they weigh different and are marked with different colors. I ordered an SVBony eyepiece 23mm because I have onejust like it from a few years back. Waiting on it to arrive and will test out the binoviewers again, maybe will have better luck next time. I tried using the same 9.7mm eyepieces last night again and for some reason when I point the telescope directly above the view thru the binoviewers is fine but when I try to see Polaris which is closer down to the horizon I see it doubled. And when I rotate the eyepieces it doesn't change anything but only when I point/move the eyepieces to point closer together does the image merge into one.

#7 Nessark

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Posted 24 June 2020 - 09:25 AM

My binoviewers are the type that just have one screw that tightens a compression ring inside and doesn't allow for custom setting of the eyepiece seating.

#8 eyespy

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Posted 24 June 2020 - 12:10 PM

Hi Nessark,

 

My vintage Celestron binos only had one thumb screw each side and no compression rings.  I don't actually use the thumb screws and have removed them.  Only my 6.4mm eyepieces occasionally need rotating to merge and then usually only one is needed to be rotated maybe an 1/8 to a 1/4 of a turn.  I think in your case, if the pupil distancing setting is correct and that if rotating one or both eyepieces does no correct the merging issue, then your binos might be out of collimation.  As your merging seems to be affected by the position of your scope, maybe one of the prisms is loose.  Does your bino rattle at all if gently shaken ?

 

Doug.....


Edited by eyespy, 24 June 2020 - 12:13 PM.

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#9 Nessark

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Posted 25 June 2020 - 07:43 AM

When people say rotating, what does that mean exactly? Spinning the eyepiece in the holder? I did that and it absolutely makes no difference to what is seen in the binoviewers.

#10 Nessark

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Posted 25 June 2020 - 07:45 AM

Also what is pupil distancing setting?

#11 skywolf856

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Posted 25 June 2020 - 06:28 PM

The pupil distance setting is the adjustment to widen or shorten the center to center distance between the eyepieces and your eyes.


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#12 eyespy

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Posted 25 June 2020 - 07:28 PM

Hi Nessark,

 

As Skywolf said above its the setting of the distance between the eyepieces to match your own eye separation. The binoviewer can be adjusted via its center hinge the same as a pair of binoculars.

 

We don't mean to 'spin' the eyepieces.  Just rotate either one of them maybe a quarter of a turn and see if the focused star image moves relative to the other eyepiece image.  Sometimes the physical lens train in one eyepiece might not be exactly in line optically with the other eyepiece.  By slightly rotating one eyepiece relatively to the other, we are going through a process of elimination to determine what could be causing the double image.  Once you get above about 10 mm and longer in focal length I have not seen the requirement to rotate an eyepiece to optical center them.  It's just not usually a problem as it usually only applies to short focal length eyepieces when it does occur.  The fact that your two eyepieces are from a different production and possible optical differences could be your issue.

 

Doug....


Edited by eyespy, 25 June 2020 - 07:38 PM.

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#13 Eddgie

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Posted 25 June 2020 - 08:35 PM

To set your IPD, use a medium focal lenght eyepiece pair.  

 

While looking through the eyepiece, close one eye and the position your open eye over the eyepiece and get it as centered as possible so that you can easily see the field stop all the way around.

 

Now, keeping your head as still as possible, wink that eye closed, then open the other eye.  If when your other eye opens, if you cannot see the entire field stop of the other eyepiece, your IPD is not set correctly or the BV is rotated (if it is cut off on the top or bottom, that is rotated, if it is cut off on the left or right, that is IPD.

 

Rotate or open/close the spread of the binoviewer until you get the adjustment set so that blinking back and forth, the field of each eyepiece is directly centered in the field of view of each eye.


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#14 Nessark

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Posted 25 June 2020 - 10:22 PM

Okay i think i figured it out.  I found out how to merge the images.  I was suppose contract the binoviewer to get the eyepieces closer (not exactly sure how you say it).  But i got the images to merge and i noticed the 3D effect.  BUT i have another problem now...  after viewing like this for 10 minutes, i am getting a headache right in my forehead and slight nausea feeling?  Is this normal, am i going to get used to this soon?  feels much worse than looking with one eye.  any ideas on why this is happening? 



#15 eyespy

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Posted 26 June 2020 - 02:32 PM

Hi Nessark,

 

Should not be getting headaches after only ten minutes so I think that you might have a collimation issue that your eyes and brain are trying to compensate for.

 

Doug.....


Edited by eyespy, 26 June 2020 - 02:33 PM.


#16 Nessark

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Posted 28 June 2020 - 10:27 AM

Hi Nessark,

 

Should not be getting headaches after only ten minutes so I think that you might have a collimation issue that your eyes and brain are trying to compensate for.

 

Doug.....

Thank you for the advice Doug.

 

Now can someone guide me step by step on how to check the collimation of my Celetron Binoviewers?



#17 Eddgie

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Posted 28 June 2020 - 10:59 AM

https://www.cloudyni...er-collimation/



#18 Nessark

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Posted 28 June 2020 - 08:56 PM

Okay guys I did Test#2 and these are the numbers:. Pointed my binoviewers at my kitchen cabinets 38'10.5" (thirty eight feet and ten and a half inches) away. Then upon switching the collimation laser with each eyepiece socket I saw there was a half inch of space separating the markings. Are my binoviewers with terrible collimation?

#19 Nessark

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Posted 28 June 2020 - 09:05 PM

I made 2 pencil dot markings on my cabinets.  They are diagonally spaced.  Is this normal for binoviewers?

 

https://i.imgur.com/24MZO0T.jpg




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