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Modification that makes my Binoviewer easy to use

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#1 vpraghavan

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Posted 31 July 2019 - 11:44 AM

The Binoviewer is a fantastic addition to astronomy as long as it is tuned correctly. Most observers have no problem getting the main focus correct when mono viewing. However with a BV, you also have to get the IPD (Inter Pupillary Distance) correct. Very few people know their IPD which compounds the issue further.

My goal is to be able to change between observers while giving each the full benefit of Binoviewing. To achieve this, I focused on IPD settings – getting the correct IPD for each individual and then changing the Binoviewer to this setting in a fast, precise and repeatable way (without interaction from the observer).

This is a photo of my modified Zeiss Binoviewer with two Hyperion Mark IV Zooms (8 – 24mm).

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#2 vpraghavan

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Posted 31 July 2019 - 11:47 AM

Listed below is the process and modification I use with this Zeiss BV.

Step 1 – Measure IPD.

I use a cheap measurement scheme which is a combination of an Internet purchase and a slider made from old cutup credit cards (shown in this photo). Using it, I would first measure the individual’s IPD. This value would then be dialed into the modified Zeiss BV by me – see step 2.

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#3 vpraghavan

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Posted 31 July 2019 - 11:51 AM

Step 2 – Dialing in IPD on the BV.

This Zeiss BV is a unit where the IPD is adjusted by ‘pulling out’ or ‘pushing in’ the eyepieces. It has an IPD indicator dial (built in) which I found difficult to use. Further, the pulling/pushing action is also not very precise and difficult to accomplish while mounted on the scope. The modification I made to the unit (shown in this photo), converts the push/pull action into one of rotation using the black knobs on either side. I also fixed a linear measurement scale to the top which is use to read the IPD while making the rotational adjustment. As can be seen from this photo, it is much easier to use the linear (white and blue) scale mounted on top rather than the built in (black and white) rotational scale located between the eps. Photo shows 70mm IPD on the linear scale.

Once the IPD measurement from step 1 is dialed into the BV, all that the observer has to do is adjust the main focuser while looking into the BV using both eyes. I find little need for individual ep focusing (diopter adjustment - in most cases). This seems to be the fastest & most reliable way to get to the …….. Wows (especially with high mag and a very steady mount).

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#4 vpraghavan

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Posted 31 July 2019 - 11:57 AM

A few other things I do to get the most out of my BV:

1) I purchased this Zeiss Binoviewer with clicklocks from Dennis. I wanted the clicklocks for better grip. Eyepiece used are two Hyperion Mark IV zooms (8 – 24mm). In addition to the zoom, I chose these as they don’t have the ‘undercut’ and are held firmly by the clicklocks without any slop. The ‘on the fly zoom’ is important in getting to maximum usable magnification for the night. As stated previously by another observe, I can use a higher magnification with the Binoviewer as opposed to what can be achieved with mono viewing (using Ethos eyepieces). The scintillation is still there with the BV but all details are very visible at the higher mag. The ‘shimmer’ seems to overcome seeing faster with mono viewing which then forces a lower magnification.

2) I use an equatorial tracking mount. This means that horizontal level adjustments of the BV are needed every so often. I mounted a bubble level on the BV that makes this easy (seen in the above photo). An Altaz mount would be more desirable as this eliminates the need for this adjustment. Also, an adjustable observing chair is important with bino viewing. Seat height adjustments provides for long periods of stable viewing keeping both eyeballs along the centerline of the parallel optical paths.

3) The Hyperion Mark IV zooms have their eye coverings removed. This takes up less space and gives you the ability to get to tighter IPDs. As purchased, these units had bulky covering around the eye section which can be removed by unscrewing. Otherwise, these units are not very suitable for BV use – cannot get the eyeballs close to the lens. This can be seen in this photo.

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#5 John Miele

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Posted 31 July 2019 - 11:57 AM

Very clever!



#6 vpraghavan

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Posted 31 July 2019 - 12:01 PM

The modifications were designed by me and made in a machine shop I use. The ability to change zoom in multiple steps (8, 12, 16, 20, 24) is really very helpful. I do remove the BV from the scope while ‘GoTo’ slewing to a substantially different part of the sky. Small slews are not a problem.

I did test the IPD range after the modification was made. For my eye, a change of about +/- 1mm from the best IPD was making observation a little less desirable (skewing the centerline of the optical path). As long as I stayed within this 2mm range, eye stress was tolerable. All details were still in focus. However, using the exact IPD provides the best viewing – sharpest details with the least eye stress. With the rotation adjuster, I am able to get 0.2mm (or better) resolution on IPD which is more than adequate. With the mounted linear scale, the IPD positioning is also very repeatable. This enables fast switching between observers - going back and forth (wife and self for example).

Overall, this Zeiss BV unit with two Hyperion Mark IV zooms is on the heavy side. It is also not a cheap solution. However, the view with this BV mounted on a TEC140 ……. is unmatched, which makes it all worthwhile.

Prior to the modification, an observer would at times indicate that Mono viewing was better than Bino viewing. This was a clear sign that the IPD had not been set correctly on the BV (by the observer). It is what prompted me to think about a repeatable solution that was under my control. All that the observer has to do now, is adjust the main focuser while looking into the BV with both eyes - a far less problematic adjustment.

Hope some of this information will help maximize your BV’s potential. Also, hope others would add their modifications and procedures that they find helpful when using Binoviewers.

V.P
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#7 denis0007dl

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Posted 31 July 2019 - 02:59 PM

Gteat job!!!
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#8 Eddgie

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Posted 31 July 2019 - 03:48 PM

Very nice!

 

Now I usually don't let other people use BVs when I invite them to the scope simply because it is a lot of effort to get them to the point where I am sure that it is working well for them (and you never really know for sure) but if you were changing back and forth with an observing buddy that was a BV user, I could see this being useful.

 

I love to see creative things. 


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#9 vpraghavan

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Posted 31 July 2019 - 05:12 PM

I was in the same camp – not letting others use the BV (prior to modification). This scheme is now working with about 5 to 8 people (folks known to you). I just make sure I write down each person’s IPD so I can dial it back in for the next round.

When a line forms, I would not do it …. primarily because people don’t seem to want to get up from the observing chair. They simply get glued to the BV.

To answer another comment, I do consider the IPD a critical element. Focusing part is easy, especially if you have an electronic/manual focuser with digital readouts. Another number to write down if they are using eyeglasses.
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#10 Saturnalia

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Posted 09 August 2019 - 05:04 PM

This is a great insight into custom binoviewer work and very helpful.

 

Full marks.


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#11 Kenoguy09

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Posted 31 October 2019 - 03:49 AM

Great article VP, thanks for all your advise and it was a pleasure meeting you at the star party last Saturday. 

Bill Johnson


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#12 De Lorme

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Posted 31 October 2019 - 08:49 PM

What a great idea!

 

Clear Skies,

 

De Lorme


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