6 mm eyepieces, very few options

[Voxish]

Question for the forum.

Why are there so few 6 mm eyepieces options? 
 

Edited December 20, 2023 by Voxish

[John]

I can think of quite a few. The Vixen SLV 6mm is excellent for example, if that is the sort of spec that you are interested in.

 

[Voxish]

 Yeah I know there are some, but most sets seem to be more 5 - 7 - 11 etc, not so many 6 - 8 - 12

[reezeh]

I was thinking that they come in 2 inch, 1 1/4 inch and 0.965 inch...

Putting humour aside, 6mm is getting to the high power end and as already mentioned the SLV 6mm is a great eyepiece.

So my guess is this:

Most designs at that focal length tend to have uncomfortably short eye relief and a 12.5mm with a 2x barlow is often seen as a better option.

A plössl for instance would need your eye wearing the thing almost as tight as a contact lens.

Most eyepieces with such short focal lengths with good eye relief could be quite pricey, so I guess that manufacturers just don't fancy making them fearing market saturation.

 

[Mr Spock]

SLV 6mm, Delos 6mm - Morpheus is close at 6.5mm.

There are others too. I have a 6mm Circle T ortho and a 6mm TMB Planetary II.

[vlaiv]

When it says 6mm on the eyepiece - it might not be exactly 6mm

When it says something like 52 degrees AFOV - you can be sure it's almost certainly not exactly 52 degrees.

Even x2 barlow won't be exactly x2 and will change its magnification between eyepieces.

All of these should be considered "class" rather than exact number.

5.5mm, 6mm, 6.5 and even 6.7mm are all in the same "class", and there are quite a few offerings in that range.

[John]

I have been using the 6mm spot on the Svbony 3-8mm zoom a lot recently, especially when observing Jupiter. It works very nicely. The AFoV is 56 degrees and the eye relief 10mm (a bit less actually useable). Not great for glasses wearers but quite comfy for others.

[Voxish]

3 minutes ago, John said:

I have been using the 6mm spot on the Svbony 3-8mm zoom a lot recently, especially when observing Jupiter. It works very nicely. The AFoV is 56 degrees and the eye relief 10mm (a bit less actually useable). Not great for glasses wearers but quite comfy for others.

With your Vixen? 

[Voxish]

My apologies, I mean your lovely Vixen! 

[John]

7 minutes ago, Voxish said:

With your Vixen? 

Mostly with my Tak FC100 or Skywatcher ED120. Both 900mm focal length so 6mm gives a very useful 150x.

The Vixen is due a run out soon though 🙂

[Voxish]

I have been looking for a 6 mm Radian for 2 years, rare things these days it seems. ABS used to be a wash with them, not anymore.
 

Mr Asperger here needs all his gear to match sadly, my own self imposed hell. 

[Zermelo]

18 minutes ago, John said:

I have been using the 6mm spot on the Svbony 3-8mm zoom a lot recently, especially when observing Jupiter. It works very nicely. The AFoV is 56 degrees and the eye relief 10mm (a bit less actually useable). Not great for glasses wearers but quite comfy for others.

... and more comfortable than the BCO 6mm, another option at the same focal length.

[cajen2]

The Morpheus 6.5mm is a superb EP (and the 4.5 is too!).

[JTEC]

+1 for the Morpheus. There are the Tak orthos, of course, though no longer available new - I have a pair for binoviewing and they are very good.  The Tak ‘Starbase’ series, available from FLO, also includes a reportedly good value 6mm.  Not tried it though.

 

 

https://www.darkskiesmatter.org.uk/

[globular]

ES 92/12 + 2x Powermate 

[michael.h.f.wilkinson]

I love my 6 mm Delos. Only used in really good seeing in the C8, but very useful in the 80mm F/6

[RT65CB-SWL]

I have a few 6mm e/p’s. The list is shown below:

• unknown 0.965” Ortho... (used with a 1.25” adapter).
• Circle-T Ortho.
• Revelation Astro Plossl.
• TeleVue Radian.
• Svbony ‘goldline’... (used with a Lunt Herschel/solar wedge).
• Svbony ‘redline’.

 

...and the zoom e/p’s:

• TeleVue Nagler 3-6mm ‘planetaty’ zoom.
• Svbony SV215 3-8mm ‘planetaty’ zoom.

Edited December 21, 2023 by RT65CB-SWL

[vlaiv]

There is this eyepiece planner website (still in beta?).

Don't know who built it, but it lists 30ish eyepieces that have exactly 6mm FL - as advertised. Granted, some of them are clones, but I also think that not every eyepiece out there is on the list as well.

Below screen shot is just a segment of the list.

Website is accessible here:

https://eyepieceplanner.com/#/

Just sort by eyepiece focal length and you will find all 6mm eyepieces grouped.

[Zermelo]

And this, as a spreadsheet:

https://www.cloudynights.com/topic/862337-2023-eyepiece-buyers-guide/

[bosun21]

Baader Morpheus 6.5mm is one of the sharpest in the set. Fantastic eyepiece with tons of eye relief and also very comfortable.

[John]

When I had a set of TV plossls (well, all but the 55mm 2 inch one) I added a Nagler 6mm - 3mm zoom to them to get a wider range of higher powers. I figured that the AFoV would match, the zoom is par-focal with the plossls, the additional eye relief would be welcome at higher powers and the optical performance would be very similar. That set did quite well for me for a while.

I've only owned the 3mm and 4mm Radians and found them pretty good. 

I only have two 6mm eyepieces now - the aforementioned Svbony zoom and the Ethos 6mm which is superb but also eye wateringly expensive these days, which is I don't usually recommend it. 

With my scopes, currently and looking back over the years, falling mostly into the focal length range from 650mm to 1200mm, a 6mm eyepiece is a very valuable tool. I have tended to think of it as the first step into the high magnification zone. Of course, if SCT's and mak-cassegrains had dominated my scope choices then 6mm might have been the last step in that zone and only used under particularly favourable conditions.

 

 

[Voxish]

29 minutes ago, vlaiv said:

There is this eyepiece planner website (still in beta?).

Don't know who built it, but it lists 30ish eyepieces that have exactly 6mm FL - as advertised. Granted, some of them are clones, but I also think that not every eyepiece out there is on the list as well.

Below screen shot is just a segment of the list.

Website is accessible here:

https://eyepieceplanner.com/#/

Just sort by eyepiece focal length and you will find all 6mm eyepieces grouped.

I stand very much corrected 

[Naughty Neal]

Xcel -lx 7mm / 16mm eye relief though Ernest reports is as being 6.5mm as the glass is the same as the HD60 /6.5mm.

He recommends the Xcel -lx and they are sub £90  UK supplied ,  about £55 - £60 used or also via AliExp for similar prices  as used.

 

Edited December 20, 2023 by Naughty Neal

[Don Pensack]

See: https://www.cloudynights.com/topic/862337-2023-eyepiece-buyers-guide/?p=12473522

Here is what is available in 6mm (you can scroll the list): [It is plenty of choices!]

Edited December 20, 2023 by Don Pensack

[Voxish]

I must research before I post, I must research before I post, I must research before I post, I must research before I post…..