Binoviewer eyepiece around 23mm?

[Paz]

I've been thinking about a binoviewer eyepiece set up (with Baader Maxbright 2 binoviewers) and have the following plan...

30mm NLVs

...gap...

17.3mm Delos

12mm Delos

I have the 30mm NLVs and the 17.3mm Delos. If I can't get high enough powers with Barlow configurations then 12mm Delos would be the next step at the short end of the spectrum.

I have a gap to cover for an eyepiece around 23mm, the limiting factors being 1.25" only, genuine eye relief of 20mm, as wide an afov as possible but with a field stop limit of 26mm, and of all the potential abberations I struggle with field curvature the most so want to avoid that as far as possible.

I would mostly be observing with a 102mm f7 refractor, but sometimes a 203mm f10 SCT, and sometimes a 14" f4.6 newtonian.

I thought 22mm LVWs would be the closest fit but they are not available any more.

Would anyone have any tips or pointers for ideas to consider.

If the gap is filled with eyepieces with a similar tfov to the NLVs then I know it is possible that the NLVs might be made redundant but that would be ok if it happened. However the 30mms are likely to remain useful to minimise the magnification for white light solar where I have to use a lot of barlowing to reach focus so I would guess they would stay.

[Saganite]

Hi Paz,

My choice would be 24mm Panoptics. I have used a pair for binoviewing for several years and I would never part with them. They have eye relief of 15mm and 68 AFOV and  are a perfect size to fit a bino.  They also fit the sequence of 1.4x steps from 17.3mm and you could then dispense with the 30mm NLV's if you wished. Field stop is 27mm.

 

Edited January 24, 2021 by Saganite

[Louis D]

I really like my 23mm Vite 62 Aspherics in my binoviewers.  Once you pull off the eyecups, you've got nearly 20mm of usable eye relief.  They're not perfect at f/6, but they're really good at f/12 and above with barlows or slow scopes.  They're super light, small, and comfortable.  There's nothing premium in this size and weight range aside from some Zeiss aspheric surgical microscope eyepieces.

At about £10 apiece on ebay, they're certainly worth a try.

Here's comparison images at f/6 of some of my roughly 24mm eyepieces:

[Space Hopper]

The 24 Panoptics rule.

They are super eyepieces.

[Louis D]

1 hour ago, Space Hopper said:

The 24 Panoptics rule.

They are super eyepieces.

Not if you have to wear eyeglasses at that exit pupil as I do.  Without eyeglasses, they look totally aberrated to me.

The 24mm APM UFFs are too big for me to fit my nose between them, or else I'd probably recommend them to eyeglass wearers.

Remember, the OP specifically said:

5 hours ago, Paz said:

genuine eye relief of 20mm

 

[Space Hopper]

Ok, option b is the ES 24mm / 68º  Possibly they will give you that extra important 4mm.

Or maybe look out for a pair of Vixen LVW 22mm.

But its becoming pretty rare to find a used one. You don't see them crop in the used sections very often.

Edited January 25, 2021 by Space Hopper

[Space Hopper]

12 minutes ago, Space Hopper said:

Ok, option b is the ES 24mm / 68º  Possibly they will give you that extra important 4mm.

Or maybe look out for a pair of Vixen LVW 22mm.

But its becoming pretty rare to find a used one. You don't see them crop in the used sections very often.

Edit: i just noticed you mentioned them and counted them out on grounds of availability.

 

[Paz]

I have been around the houses considering Panoptics due to the excellent write ups but the eye relief is an issue. I know from experience a good 20mm (meaning a real 18mm-19mm at the very least from where your glasses rest on the rubber above the eyepiece glass) is necessary for me.

[jetstream]

I use a pair of 25mm TV plossl's which give stunning performance in my binoviewers. In mono one of these is a preferred eyepiece for viewing the Horse Head.

[Louis D]

2 hours ago, jetstream said:

I use a pair of 25mm TV plossl's which give stunning performance in my binoviewers. In mono one of these is a preferred eyepiece for viewing the Horse Head.

Do they have 20mm of usable eye relief as needed by the OP?  The TV specs page show them to have 17mm of design eye relief, and the eye lens appears to be recessed a bit, so I would expect no more than 12mm of usable eye relief.

I know I can't easily see the entire field of my 26mm Sirius Plossls while wearing eyeglasses.  I've measured mine to have 11mm of usable eye relief.  I do have a pair of them for binoviewer usage, but rarely use them because they're so darned uncomfortable with eyeglasses.  I much prefer the 23mm Aspherics with the eyecups removed.

[jetstream]

49 minutes ago, Louis D said:

Do they have 20mm of usable eye relief as needed by the OP? 

Not exactly sure about the eye relief, maybe it is 1/8" or so short of the mark. My Binotron powerswitch pushes the eyerelief around and I like the 25mm TVs better than the 18mm Tak orthos because of it. I really like the 32mm TV plossls but they absolutely need the eyeguard extenders IMHO.

I have tried heavy eyepieces and also shortish fl eyepieces but the 4 mentioned EPs are the mainstays. I can merge down to 9mm fl or so but don't like it.