The Great 40mm Plossl Blagging

[Mak the Night]

For various reasons, including extreme OCD, beans, insatiable curiosity, and possible insanity I’ve decided to have a 40mm Plossl shootout. I find 40mm Plossls extremely useful in Maksutov scopes for gaining decent sized exit pupils. I can also get a four arc degree field of view in an ST80 for a binocular-like 10x magnification. 40m Plossls all have certain things in common; predominantly ridiculously long eye relief and a limited field of view. Many people hate them, but I find that they have their place and can be extremely useful. The Plossls are: a TeleVue (with eyeguard extender), a Vixen NPL, a Revelation Astro (GSO), a Celestron (Barsta) and an SvBony.

All of these perform well in a 102mm Maksutov, and give very similar images, so most of it boils down to overall ergonomics in use for me. I think the coatings on the TeleVue are noticeable, but they don’t detract from the view for me. At 187g the TeleVue is the heaviest of them. It has a 43° AFOV, 27mm field stop and an eye relief of 28mm. Eye positioning isn’t too difficult when used with the eyeguard extender. I’ve owned this EP for over three years and its large eye lens and general build quality make it a joy to use. The chromed brass drawtube has an undercut with a flared lower lip. This makes it no problem to extract from any adapter with a compression ring in my experience.

The Vixen weighs in at 119g, and this is noticeable compared to the TeleVue, with an ST80 mounted on a Sky-Watcher AZ5. The field of view is slightly smaller than the TeleVue at exactly 40°, and according to the Vixen site it has a 36mm eye relief. The plastic twist-up eyeguards always seem a bit rickety at first but I’ve owned NPL’s for several years and they’re hardier than they first appear. As always with NPL’s the image is sharp, bright, well contrasted and easily the equal to the TeleVue. The NPL also has a large eye lens and when the eyeguard is twisted up to its maximum is incredibly comfortable to observe with. In fact, it’s the most pleasant 40mm Plossl I’ve used to date, and eye placement feels very natural, especially with my cheek just touching the top of the eyeguard. Its drawtube has a wide shallow undercut which causes no problems for me.

According to GSO the ‘Revelation Astro’ has a 45° AFOV and it does seem larger than the Vixen, although I’m not sure it’s a whole 5° more, and appears virtually identical to the Celestron Plossl. The field stop width looks very much like the TeleVue to me and I suspect they’re all around the same size. However, the focal points of the Revelation and the Celestron are different and I think the Revelation has a very slight performance edge in my ST80. I can’t really tell any difference between the two in slower scopes. The Celestron came included with my SCT. It now sports a (cannibalised) GSO smooth aluminium drawtube and a GSO rubber eyeguard. The Revelation and Celestron both have a purported 31mm eye relief although Celestron only claim a 43° AFOV. The coating looks ‘greener’ on the Revelation when the EP is held up to a light source and viewed obliquely, although most GSO coatings look the same to me. They both seem an identical weight, GSO claim 156g on their site. 

The SvBony is a bit of an oddball. It’s the least expensive of them all and physically smaller. The lens coating seems basic but the overall build quality is relatively decent. Like the Celestron it seems to perform better in slow scopes. Mine has been customised slightly with a new eyeguard and a smooth chromed brass drawtube. 

Unusually; it can be unthreaded mid-housing allowing greater access to the field lens. Eye placement can be a little awkward at times, as with the Revelation and the Celestron though.

I find that these petite, lightweight ‘SvBony’ (I have no idea who the OEM is) eyepieces are good when utilised either as a bino pair on larger Maksutov scopes or singly in my 90mm Orion StarMax mounted on a tabletop Dobsonian. 

 

 

And the winner is ...

Well, to be honest, there’s nothing intrinsically bad about any of these eyepieces and they all have their respective merits. Of course, the TeleVue is the best in terms of build quality and is my second favourite 40mm Plossl of all time.

I’m going with the Vixen NPL though. Mainly because it has a big eye lens and is just so comfortable to use.

 

Let the trolling commence ...

[Stu]

Nicely written, and interesting report Mak.

Interesting that they are all so close at the end, ergonomics aside, which is great news for people buying on a budget.

I have used a 40mm TV before, plus Celestron Omnis. The eyeguard for the TV works well, even if it is eye watering you expensive for a piece of metal!

The Omnis worked well with Binoviewers but I found I had to make foam eyeguard extenders for them to cut down on glare and help eye positioning. That was with a barlow though so the eye relief was extended further than normal.

Nice review, thanks for posting it.

[chiltonstar]

Very interesting! I use a 40mm Omni as my normal, starting EP with my 180 Mak. Despite the obvious limitations, it works well for me and is good for showing things to youngsters and clearly gives a better exit pupil than shorter fl EPs.  Clearly not everyone's cup of tea though, for example the f4 newt brigade......

Chris

[Mak the Night]

5 minutes ago, chiltonstar said:

Very interesting! I use a 40mm Omni as my normal, starting EP with my 180 Mak. Despite the obvious limitations, it works well for me and is good for showing things to youngsters and clearly gives a better exit pupil than shorter fl EPs.  Clearly not everyone's cup of tea though, for example the f4 newt brigade......

Chris

Thanks, as far as I can tell the 40mm Omni is also made by Barsta. I've owned a few Omni EP's. I've directly compared an Omni 40mm with my 'Celestron' 40mm and they seem identical apart from housing colour. I'm pretty certain Orion Sirius Plossls are also Barsta now. Usually distributors recommend the 30 or 32mm over the 40mm versions for visual observing as they have greater FOV. Although I can get fifteen more arc minutes on an ST80 for only about a 3x loss of magnification. 

These Orion Highlite Plossls (above) came out nearly twenty years ago I believe. Apparently they were incredibly good for the money Orion were asking for them. I've never owned one but I've been told about them. They didn't stay long on the market from what I can gather. 

[JeremyS]

I had the Vixen NPL 40 for a while, but found it a bother to use in my 60mm Mak. The eye relief was so long, it was difficult to keep my eye correctly positioned even with the eye guard in its highest position. I found a 30mm eyepiece more comfortable

[nightfisher]

I have a 40mm Antares plossl that i bought to use in my 127 Mak, but not had the chance to try it yet, the plan was if i like it to sell my 32mm plossl

[Mak the Night]

10 minutes ago, nightfisher said:

I have a 40mm Antares plossl that i bought to use in my 127 Mak, but not had the chance to try it yet, the plan was if i like it to sell my 32mm plossl

I'm not sure who manufacture the Antares Plossls, they look like Barsta. It should be good in a 127mm Mak. A 40mm Plossl gives me a decent 3.3mm exit pupil on my 127mm Mak. 

[Mak the Night]

17 minutes ago, JeremyS said:

I had the Vixen NPL 40 for a while, but found it a bother to use in my 60mm Mak. The eye relief was so long, it was difficult to keep my eye correctly positioned even with the eye guard in its highest position. I found a 30mm eyepiece more comfortable

I have the 25mm & 30mm NPL's. The 30mm spent so long in the diagonal of my ST80 that the 40mm was a no brainer. The 40mm NPL does have a long eye relief, but I found it the most comfortable 40mm I've used so far when the eyeguard is twisted right up. As always YMMV lol.

[Stu]

3 minutes ago, Mak the Night said:

I'm not sure who manufacture the Antares Plossls, they look like Barsta. It should be good in a 127mm Mak. A 40mm Plossl gives me a decent 3.3mm exit pupil on my 127mm Mak. 

So do you prefer the 40 to a 32mm in your Mak? I guess it helps for filtered Nebula views?

[Chris]

Nice report! I enjoy my 40mm Omni Plossl  

[Ricochet]

Where do you get the replacement smooth eyepiece barrels from? Are they all taken from other eyepieces or is there someone selling them separately? 

[Mak the Night]

2 hours ago, Lockie said:

Nice report! I enjoy my 40mm Omni Plossl  

Thanks, 40mm Plossls can be a tad demanding at times, but I find they can be immensely useful.

[Mr Spock]

I have the old black and orange Celestron 40mm Plössl. Despite it's excellent image quality I find it too claustrophobic. A 32mm is much more pleasant to use and gives the same fov.

[Mak the Night]

54 minutes ago, Mr Spock said:

I have the old black and orange Celestron 40mm Plössl. Despite it's excellent image quality I find it too claustrophobic. A 32mm is much more pleasant to use and gives the same fov.

I was hoping I got one of those with my Evolution, but I just got the bog standard Celestron. Although they may be the same thing. If my maths is right my 30mm NPL gives me 3 arc degrees, 45 minutes, 32 seconds of true field of view for 13.3x with my ST80. But the 40mm NPL gives 4 arc degrees for 10x. I'll have to spend more time with the 40mm to see if that extra 15 minutes is worth it.

[Stu]

3 hours ago, Stu said:

So do you prefer the 40 to a 32mm in your Mak? I guess it helps for filtered Nebula views?

@Mak the Night

[Stu]

On 10/03/2018 at 15:05, Stu said:

So do you prefer the 40 to a 32mm in your Mak? I guess it helps for filtered Nebula views?

@Mak the Night I'm sure you just missed my question accidentally. Interested to know your views.

[LukeSkywatcher]

On 3/10/2018 at 17:28, Mr Spock said:

I have the old black and orange Celestron 40mm Plössl. Despite it's excellent image quality I find it too claustrophobic. A 32mm is much more pleasant to use and gives the same fov.

Wow............I had one of the black and orange 40mm Celestron plossl and hated it. Claustrophobic is a very good word for it.

[F15Rules]

On 10/03/2018 at 15:05, Mak the Night said:

The 30mm spent so long in the diagonal of my ST80 that the 40mm was a no brainer.

I've owned the 30mm NPL (and the 20mm) and thought it was a cracking eyepiece, very comfortable to use too. In fact I struggled to seen any difference in that and LV/NLV variants costing much more.

In the 40mm PL class I've used Celestron and Sky watchers and best of all, a Tal 40mm which was so sharp I cut myself on it!.

I recently moved to a 40mm 2" TS Paracor (TMB/SW Aero) 69 degree for low power cruising, but I have to say that one of the sharpest views of M42 I had through my FS128 was with a lowly SW Plossl 40mm..It looked just like a black and white photograph.

I sold that ep recently for £18. Amazing views for not much cash!?

Dave

[Mak the Night]

29 minutes ago, F15Rules said:

I've owned the 30mm NPL (and the 20mm) and thought it was a cracking eyepiece, very comfortable to use too. In fact I struggled to seen any difference in that and LVW/NLV variants costing much more.

In the 40mm PL class I've used Celestron and Sky watchers and best of all, a Tal 40mm which was so sharp I cut myself on it!.

I recently moved to a 40mm 2" TS Paracor (TMB/SW Aero) 69 degree for low power cruising, but I have to say that one of the sharpest views of M42 I had through my FS128 was with a lowly SW Plossl 40mm..It looked just like a black and white photograph.

I sold that ep recently for £18. Amazing views for not much cash!?

Dave

That's interesting about the Tal. 

http://www.talteleoptics.com/eyepieces.html

They look suspiciously like Barsta Plossls to me, and the range has identical focal lengths. 

A lot of people claim their Celestron, Sky-Watcher & Orion Plossls (Barsta) get a bit 'flock of seagulls' (astigmatism) in fast scopes. 

 

[F15Rules]

I agree, the Tal 40 I had did look very like the Skywatcher one, it did feel a bit heavier as I recall but I didn't weigh it so I can't be sure.

The Tal Generation II 25mm was a different kettle of fish though. A huge eyelens and just superb performance. Made a special binoviewing pair.

I always assumed it was Russian built..

Dave

 

[Mak the Night]

14 minutes ago, F15Rules said:

I agree, the Tal 40 I had did look very like the Skywatcher one, it did feel a bit heavier as I recall but I didn't weigh it so I can't be sure.

The Tal Generation II 25mm was a different kettle of fish though. A huge eyelens and just superb performance. Made a special binoviewing pair.

I always assumed it was Russian built..

Dave

 

There's a good chance they were Russian. 

http://www.npzoptics.com/

The 40mm could have been Russian as well. If it was BST/Barsta it may have had a chrome/brass drawtube and so was a bit heavier than the aluminium drawtubes. 

[Stu]

3 minutes ago, Mak the Night said:

There's a good chance they were Russian. 

http://www.npzoptics.com/

The 40mm could have been Russian as well. If it was BST/Barsta it may have had a chrome/brass drawtube and so was a bit heavier than the aluminium drawtubes. 

Seems like Barsta make quite a few of these differently branded eyepieces. Where do you get you info from about them?

[25585]

I have two TV 40s, and they will go into a twin ST80 binocular I am rigging up. Love the eye relief. Wearing glasses I have the whole FOV with eye cup extended. So 10x80 bins with Japanese eye pieces and semi-apo filters ? Are the TV Plossls not symmetricals similar to Clave' ?

Tempting to try a Vixen NPL 40.

(Vixen LVWs give 65 deg AFOV, incl the 42mm. The N/LV range are 50 deg, except the 30mm which is 60 deg)

 

[Mak the Night]

32 minutes ago, 25585 said:

I have two TV 40s, and they will go into a twin ST80 binocular I am rigging up. Love the eye relief. Wearing glasses I have the whole FOV with eye cup extended. So 10x80 bins with Japanese eye pieces and semi-apo filters ? Are the TV Plossls not symmetricals similar to Clave' ?

Tempting to try a Vixen NPL 40.

(Vixen LVWs give 65 deg AFOV, incl the 42mm. The N/LV range are 50 deg, except the 30mm which is 60 deg)

 

I like the 40mm TV, although the eyeguard extender helps. It is a beautifully made eyepiece.

I'm not sure about the TV internal organs, you'll probably have to ask Al Nagler. The 40mm Plossl came out in 1981.

http://www.televue.com/engine/TV3b_page.asp?id=13&Tab=_chron

You might find this interesting: http://www.brayebrookobservatory.org/BrayObsWebSite/HOMEPAGE/PageMill_Resources/Comparison test of TVPlossl vs Brandon.pdf