Binoviewer eyepiece options 12-15mm range

[chrispj]

After successful first use of my new binoviewer last night in the F10 refractor I'm weighing up options for additional eyepieces.

 

I used a pair of Astro Essential 20mm plossl last night (essentially bought as a proof of concept), which worked well but obviously aren't the sharpest. I had the sad disappointment that the Starguiders don't work for my deep set eyes/long nose and I need to stick with types offering the full 20mm eye relief. I expect when they are back in stock I'll double up with a match for my existing single 18.2mm Delite.  However I then have a big gap down to my next 10mm eyepiece. So I'm pondering either the 12 or 15mm Vixen SLV or the 13mm Hyperion. Concerns being the 15mm might not be a big enough jump in magnification from the Delite to notice a meaningful change, the exit pupil on the 12mm might be small for comfort (given the 2x Barlow in the binoviewer reduces it to a 6mm equivalent or 0.6mm EP - I struggle with my existing 6mm eyepiece sometimes), and there seems to be very few enthusiastic user reviews out there for the Hyperion.

 

Any thoughts or other suggestions gratefully received. I can only really justify buying one additional pair unless the right SLVs start popping up secondhand...

[Louis D]

I can't get my fairly narrow nose bridge between a pair of eyepieces in the Hyperion width class, so double check your width tolerance.

I'm surprised the Plossls aren't sharp at f/10.  Most Plossls are pretty decent at f/6 and really good by f/12.  Perhaps it's the level of polish on them that makes the difference in your case.

I would probably start with a pair of longer eye relief 22mm to 26mm Plossls or similar and put a 1.6x to 2x Barlow nosepiece or similar OCA/OCS/GPC on the front of the binoviewer to get to higher powers.

[chrispj]

It's probably wrong to say the Plossls aren't sharp, I'm stuffed with cold and not good with finding the right words today. More that being £25 Plossls the assumption would be the view can be improved (isn't that why we buy £200+ eyepieces!).

 

I also have no idea on the width TBH - the Delite looks and feels like there should be no problem to use as a pair and from what I remember of the SLV (I had a 9mm before) that should be ok, OTOH my XW would almost certainly not work from the look of it! I haven't seen a Hyperion IRL, only photos.

 

What would a Barlow be likely to do to the focus, I don't have much in-focus left to adjust so if it will be par focal or need out focus that would work.

 

interesting ideas anyway, more to think about... Thanks!

[doublevodka]

2 hours ago, chrispj said:

After successful first use of my new binoviewer last night in the F10 refractor I'm weighing up options for additional eyepieces.

 

I used a pair of Astro Essential 20mm plossl last night (essentially bought as a proof of concept), which worked well but obviously aren't the sharpest. I had the sad disappointment that the Starguiders don't work for my deep set eyes/long nose and I need to stick with types offering the full 20mm eye relief. I expect when they are back in stock I'll double up with a match for my existing single 18.2mm Delite.  However I then have a big gap down to my next 10mm eyepiece. So I'm pondering either the 12 or 15mm Vixen SLV or the 13mm Hyperion. Concerns being the 15mm might not be a big enough jump in magnification from the Delite to notice a meaningful change, the exit pupil on the 12mm might be small for comfort (given the 2x Barlow in the binoviewer reduces it to a 6mm equivalent or 0.6mm EP - I struggle with my existing 6mm eyepiece sometimes), and there seems to be very few enthusiastic user reviews out there for the Hyperion.

 

Any thoughts or other suggestions gratefully received. I can only really justify buying one additional pair unless the right SLVs start popping up secondhand...

It is possible to "decloak" the BST eyepieces, which may enable you to use them, just a thought?

Thread from here showing it on different eyepieces to give you an idea 

 

 

Only info I can find directly about the process on BSTs is on another forum which I'm not sure is allowed, but I'm sure you could google it if needs be

[chrispj]

The 2 new ones have been returned, the 2 second hand have passed on to a new owner so the short-lived BST chapter is over for me. But thanks for the suggestion!

[Louis D]

2 hours ago, doublevodka said:

Only info I can find directly about the process on BSTs is on another forum which I'm not sure is allowed, but I'm sure you could google it if needs be

I can't get the BST Starguider/AT Paradigm eyepieces to decloak.  The eyecup just pulls right off, and the lower ring and color ring unscrew easily enough, but the big metal band that twists the eyecup support up and down seems stuck in place.  If you come across detailed instructions, I'd appreciate it.

2 hours ago, chrispj said:

the Delite looks and feels like there should be no problem to use as a pair

There's a thread on CN about decloaking them for binoviewer usage.  IIRC, It's fairly straightforward to unscrew the lower ring of the adjustable eyecup, and then just lift off the rest.  It helps those with deep set eyes and tall nose bridges like myself.

15x long eye relief microscope eyepieces are about 17mm while 20x ones would be about 12.5mm.  They're designed for binoviewer usage and very slow f-ratios (f/18, IIRC).  Some Leica and Zeiss eyepieces have excellent polish and correction.  You would just need to adapt them to a 1.25" barrel.  I have been using a pair of vintage Bausch & Lomb 15x WF eyepieces in my binoviewer to good effect for years.  I had a machinist make 23mm to 1.25" adapters for me.  3D printing would also work well for this purpose.

A pair of zooms would be another option.  Eye relief might be a little tight, but you can easily change magnification to match seeing conditions.

[Paz]

I use SLVs in binoviewers and they are great, sharp views, and they are light. I currently have 20mm and 10mm pairs.

I also have pairs of 40mm and 30mm NPLs and they are also fine.

Then I have 2 pairs of plain plossls at 15mm and 12.5mm and to be fair they are both fine also. I prefer the SLVs as I like the eye relief and I am used to them but there's nothing wrong with the plossls.

[mikeDnight]

Personally I'd stay with Orthoscopic's or Plossl's in the 35mm to 18mm range. If you're using a barlow you'll have all the power you'll need for viewing the Moon and planets. If you need extreme high power you're better off using something like a Tak TOE or Vixen HR in mono form. Cheap Kson orthoscopic's in your binoviewer will outperform even top end eyepieces such as the superlative TMB Super Monocentric's in mono form. If you place a wanted ad for old 5 element Ultima's, Ultrascopic's, Park's Gold super plossl's, you'll have superb BV eyepieces that will be hard to beat in the 35mm to 18mm focal lengths. After 14 years using a BV I've seen nothing to beat them, but i rarely use shorter focal lengths as the barlow on the BV nose amplify's ~4X, so no need for short fl's.

[chrispj]

Adding to this, this morning I tried an old TeleVue 2.5x Barlow I just picked up,  without the 2x Barlow that came with the binoviewer.  This freed up around 2cm of in focus, but appears to magnify to perhaps 4x given approx only half the FOV I could see with the 2x Barlow was visible. Intriguing,  I might try a similar long 2x Barlow and see what result that gives (I presume somewhere between the 2) since its easier to swap out the Barlow than 2 eyepieces...

 

[Louis D]

Look for a used Meade 140 2x Barlow.  The nosepiece unscrews from the tube and can be screwed onto the nosepiece of the BV for right at 3x.  They have super sharp, 3 element Japanese made optics.

[Don Pensack]

3 hours ago, chrispj said:

Adding to this, this morning I tried an old TeleVue 2.5x Barlow I just picked up,  without the 2x Barlow that came with the binoviewer.  This freed up around 2cm of in focus, but appears to magnify to perhaps 4x given approx only half the FOV I could see with the 2x Barlow was visible. Intriguing,  I might try a similar long 2x Barlow and see what result that gives (I presume somewhere between the 2) since its easier to swap out the Barlow than 2 eyepieces...

 

A Barlow's magnification increases with distance from the eyepiece, so all 2x Barlows will yield high powers that far from the eyepieces.

To move the focal plane back and keep magnification lower, try a telecentric Barlow like the TeleVue PowerMates or Explore Scientific Focal Extenders or Harry Siebert Optics telecentric Barlows.

Edited April 12, 2022 by Don Pensack

[Stu]

On 08/04/2022 at 14:45, doublevodka said:

It is possible to "decloak" the BST eyepieces, which may enable you to use them, just a thought?

Thread from here showing it on different eyepieces to give you an idea 

 

 

Only info I can find directly about the process on BSTs is on another forum which I'm not sure is allowed, but I'm sure you could google it if needs be

No issues posting a link to information on another forum, please go ahead.

[chrispj]

2 hours ago, Louis D said:

Look for a used Meade 140 2x Barlow.  The nosepiece unscrews from the tube and can be screwed onto the nosepiece of the BV for right at 3x. 

I did wonder about trying this, but there is a thread mismatch between the Televue Barlow lens cell and the BV nosepiece. Interesting to try different things and see how they work anyway...

[chrispj]

3 hours ago, Don Pensack said:

To move the focal plane back and keep magnification lower, try a telecentric Barlow like the TeleVue PowerMates or Explore Scientific Focal Extenders or Harry Siebert Optics telecentric Barlows.

Ah, didn't realise the ES focal extenders worked similarly to the Powermates, that's good to know!

[Louis D]

2 hours ago, chrispj said:

I did wonder about trying this, but there is a thread mismatch between the Televue Barlow lens cell and the BV nosepiece. Interesting to try different things and see how they work anyway...

Yep, I have the TV 2x Barlow as well, and its nosepiece threads are smaller than 1.25" filter threads, so it's a no-go to use it as an OCS/OCA/GPC.

Edited April 12, 2022 by Louis D

[doublevodka]

15 hours ago, Stu said:

No issues posting a link to information on another forum, please go ahead.

Thanks for confirming @Stu

@chrispj Link here, post number 10 has the instructions https://www.cloudynights.com/topic/709608-can-you-guess/

 

Edited April 13, 2022 by doublevodka
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