33 replies to this topic

[Jeff B]

If you are willing to do some sleuthing for used Denk components, you can have a wonderfully flexible bino-viewer set up.  

 

A little known secret, one I mentioned to Ed, was to thread the OCS element directly into the 2" nosepiece of the PowerSwitch.  See the picture.

 

This reduces the power switch magnification levels to about 1.15X, 1.7X and 2.5X (depending on the OCS) and less out travel is needed to reach focus for refractors and Cass's.  Give it a try.   You should be able to reach focus in the mid and high power modes, but, with some refractors, you may not have enough in travel to reach focus in the low power mode.  But you might, so, again, give it a try.

 

The other secret is more historical.   There are actually two versions of the "Multi-Purpose" OCS.  One was/is called the low power OCS (1.3X) and the other the high power OCS (1.4X).  They carry the same labeling on the side of the OCS, and look basically identical, except that the OCS element retaining ring for the "high power" unit is almost flush with the top of the cell.  The retaining ring for the "low power" unit is recessed about 1/8" from the cell's top.  I have both and I have a lot of flexibility in customizing my power switch configurations to specific scopes and uses.   Highly recommended.

 

Jeff

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[Jeff B]

And yes, you can easily adapt your viewers that have the Baader Quick Change dovetail feature to your Denk power switch with an adapter.

 

Precise Parts offers them but they are a little pricey.  But they work very well.

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[Lookitup]

His review was more ads rather than real recommendation.

 

Another question: I have only experienced Denk B27 Binoviewer and another Chinese cheap one.

Is B27 considered as a good one?  Is it necessary for me to get a Baader Binoviewer? Maxbright2 or even MKV?

Bought the Binotron 27 with OCS and power-switch when Russ released them and used two of them ever since. 

Besides having excellent views they can be quite easily collimated as Ed mentions. This was crucial to me since I have issues merging from X15 on. 

Russ also sells a matching diagonal with direct connection and a power-switch diagonal. I never used the 3D eyepieces only the D14's which match the Binotron perfectly.

  

Here's a pic with DM diagonal. Highly recommended 

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[Chen Sir]

I have owned the Binotron and Denk II and both are excellent. Each has some things I don't like, but that is true with most things. As far as performance, they are both excellent. 

Hi Eddgie,

 

Ask a question. Do I need the OCS A45 if I use the B27 with SCT?

 

Someone once told me that the mirror of the SCT will be pushed forward to focus the binoviewer without an A45, resulting the effective aperture decreasing.

 

Is it correct?

[photoracer18]

I was one of Russ's beta testers in the early days when I worked at Hands On Optics. I was also the one who caused them to redesign the Star Sweeper wide field adapter because the original would not reach focus in a C9.25 due to the different optical formula. So they made a special C9.25 version which they gave me and I still have even though I no longer own a C9.25. I have never bothered yet to upgrade my original BV Deep Space model because I don't do as much astronomy as I did in my younger days. I did acquire a Power Switch diagonal a couple of years ago about the time I switched from Plossls to WO SWAN eyepieces. Also have a pair of LOMO zooms for them but seldom use them. As for the 21 3D eyepieces I have always liked the effects and can make them work pretty much at will because I have the ability to focus my eyes independently from the distance of whatever I am looking at. Made it easy to also  look at those 3D image pairs they had in S&T and bring out the 3D effect at will. I find every few people can do that. I acquired the BV I was testing because they worked so much better than the few I had tried before. I also in general only use them in BV ready Stellarvue refractors with the removeable focuser extension, in this case my first run SVX127D but have used them in SCTs from time to time.

[noisejammer]

Not precisely, you can get magnification lots of different ways unrelated to the eyepiece used, like scope focal length, barlows in front of binoviewers, etc. For example one might not be able to merge 5mm eyepieces at 300x, but could merge 15mm eyepieces with a 3x effective Barlow in front of binoviewers giving 300x. The merging difficulty doesn’t care what magnification you’re at, it just cares about the focal length of eyepiece's in the binoviewer.

I disagree completely with this statement. I have tested eyepieces from 5-35 mm in my Mk V’s and merging is never an issue.
The crucial point is that the eyepieces must be accurately algned. This requires that the binoviewer components are truly square and that, that the eyepiece are correctly assembled and their mounting mechanism holds them perpendicular to the optical axes.

My primary reason for inserting a Barcon or extender into the light path is that I can then achieve useful magnification with a ZAO II.

I happily use a NT6, 5XW, 6 Delos or 7T6. When I’m not ogling planets

[betacygni]

I disagree completely with this statement. I have tested eyepieces from 5-35 mm in my Mk V’s and merging is never an issue.
The crucial point is that the eyepieces must be accurately algned. This requires that the binoviewer components are truly square and that, that the eyepiece are correctly assembled and their mounting mechanism holds them perpendicular to the optical axes.

My primary reason for inserting a Barcon or extender into the light path is that I can then achieve useful magnification with a ZAO II.

I happily use a NT6, 5XW, 6 Delos or 7T6. When I’m not ogling planets

People’s ability to merge is not universal, some people are more tolerant to misalignment than others. Even in a very well aligned system I struggle sub 10mm. I need to look up the exact post, but I believe it was TOMDEY that posted the math behind why shorter focal length eyepieces are harder to merge. This doesn’t mean some people can’t do it, but people like Ed who apparently struggle, or those without perfectly aligned binoviewers, amplification ahead of the binoviewer is the best option.

Even for those can still merge there are other good reasons to amplify ahead. Roland makes the recommendation to stay above 12mm for other reasons here, see the lower section of his post: https://ap-ug.groups...0,2,0,102208781

Edited by betacygni, 15 March 2024 - 12:34 PM.

[Sarkikos]

As long as eyepieces can be seated squarely in the eyepiece holders of the binoviewer, I have no problem merging the image with shorter focal length eyepieces.  I sometimes used 6mm focal length eyepieces in my Burgess binoviewer for viewing bright planets.  Some of my favorite pairs, though, were the 8mm and 12mm Paradigms.  This was in my 10" f/4.8 Dob.  A Barlow or Barlow equivalent lens assembly was needed to come to focus.  

 

The problem is to seat the eyepieces squarely.  After that, why should merging be a problem?  

 

Mike

Edited by Sarkikos, 19 March 2024 - 08:27 PM.

[betacygni]

As long as eyepieces can be seated squarely in the eyepiece holders of the binoviewer, I have no problem merging the image with shorter focal length eyepieces. I sometimes used 6mm focal length eyepieces in my Burgess binoviewer for viewing bright planets. Some of my favorite pairs, though, were the 8mm and 12mm Paradigms. This was in my 10" f/4.8 Dob. A Barlow or Barlow equivalent lens assembly was needed to come to focus.

The problem is to seat the eyepieces squarely. After that, why should merging be a problem?

Mike

No guarantees the prism are square to the eyepiece holders. In a complex system like binoviewers i suspect there are a lot of places alignment can be a little off.