TS Planetary HR vs Vixen SLV

[Ags]

Ten years ago when I bought a couple of TS Planetary HRs (6mm and 9mm) the general buzz was they were almost as good as a Radian. I certainly liked mine and the effect they gave of looking into a magic pool of light (caused I think by the smallish FOV, the twist-up eyecup, and comfortable eye relief).

Fast forward to 2020 and the same TS Planetary HRs are now generally considered worse than BSTs... Really?

I am looking at getting a few oculars around the 5mm mark for planetary, lunar and double star viewing - and the two types I have my eye on are the TS Planetary HRs and Vixen SLVs. I know the SLVs would be better on axis than the HRs, but by how much? Certainly for lunar viewing 58 degrees would be better than the 45 degrees of the SLVs (the shorter SLVs only have 45 degree fields, not 50). Also weight is a consideration for me - the HRs will be significantly lighter. 

Can't recall why I sold my HRs... was it because I switched from an F13 to an F5 scope? Is this a factor now I have F6 scopes?

But I see that the styling of the HRs has changed since I bought them. Has quality declined?

Edited June 30, 2020 by Ags

[michael.h.f.wilkinson]

I have Vixen SLVs at 5, 9, and 15 mm focal length, mainly for my travel set-up and for outreach. They are a close match in terms of image quality for my Pentax XWs, and that is saying a lot. They only lack the XW's 70 deg FOV. They are ortho-like in quality, without the need to glue your eye to the lens at short focal lengths. I have looked through some Planetary EPs of different brandings (and the TS seem to be among the best of the lot), and at longer focal ratios they are pretty good, but in faster scopes they don't perform as well. I would certainly prefer an SLV over a TS Planetary.

[michael.h.f.wilkinson]

Where in the Netherlands were you located again? If you are not too far away, you could try out the SLVs

[Ags]

That's a kind offer, but I live in the warm glow of Schiphol! Groningen is practically another country 😀

But you've sold me on the SLVs already.

Edited June 30, 2020 by Ags

[michael.h.f.wilkinson]

8 minutes ago, Ags said:

That's a kind offer, but I live in the warm glow of Schiphol! Groningen is practically another country 😀

But you've sold me on the SLVs already.

Up here in the north we always say the distance from Amsterdam to Groningen seems to be much longer than from Groningen to Amsterdam . Whenever proposing a meeting with colleagues from the west of the country here in Groningen they look at you as if they have to travel to Hammerfest up by the North Cape

It is a bit far to travel up and down for just an evening (only to find clouds have arrived, most likely)

 

[Ags]

I used to live in Lelystad, and travelled up to Sneek and Leeuwaarden a few times, never quite to Groningen. I don't have a car any more or I would be happy to make the trip 😀

[michael.h.f.wilkinson]

There is a good train connection

[Ags]

@michael.h.f.wilkinson I will PM you about EP peregrinations!

Back on the topic of the SLVs, how do you find the 5mm specifically as that is the one I will get first? I am also thinking of getting the 4 and 6 and 9... and maybe the 15... and then the 25 too to have a complete range... This is to complement ES 68 degree EPs (16, 20, 24) for widefield and ES 82 degrees (6.7 and 11) for the midfield.

[michael.h.f.wilkinson]

I really like the lot of them. I did a direct comparison between the SLV 5mm and the mighty Pentax XW5, which is the only pair that matched directly in terms of focal length, and the little SLV 5 held its own in all matters except FOV. It is comfortable, very sharp, very neutral in terms of colour (the old LVs had a slight brown cast, I seem to remember, especially the 7). Yes I prefer the XW, but that is only down to FOV.  In more than one outreach event people were struggling to get good eye position with something like a 10mm Ortho. I lent them my 9mm SLV, and they were immediately impressed, both in terms of comfort and the tack sharp image.   They immediately wanted to know the type, how much they cost, and where to buy one.

[Louis D]

2 hours ago, michael.h.f.wilkinson said:

I really like the lot of them. I did a direct comparison between the SLV 5mm and the mighty Pentax XW5, which is the only pair that matched directly in terms of focal length, and the little SLV 5 held its own in all matters except FOV. It is comfortable, very sharp, very neutral in terms of colour (the old LVs had a slight brown cast, I seem to remember, especially the 7). Yes I prefer the XW, but that is only down to FOV.  In more than one outreach event people were struggling to get good eye position with something like a 10mm Ortho. I lent them my 9mm SLV, and they were immediately impressed, both in terms of comfort and the tack sharp image.   They immediately wanted to know the type, how much they cost, and where to buy one.

I wonder if Vixen discontinued the use of rare earth glass types in the SLV line to keep down expenses.  I know that both the Vixen LVs and TV Radians used rare earth glasses, and both were accused of having slightly dimmer, coffee toned images as a result.

[Ags]

@Louis D Vixen state SLV use lanthanum glass.

https://www.vixenoptics.com/Vixen-SLV-2-5mm-Eyepiece-p/37202.htm

[Ags]

Just to clarify my above statement - Lanthanum is a rare earth element, so to say the eyepiece has a lanthanum element is the same as saying it uses rare earths.

[Louis D]

8 hours ago, Ags said:

Just to clarify my above statement - Lanthanum is a rare earth element, so to say the eyepiece has a lanthanum element is the same as saying it uses rare earths.

Yes, I got that.  Perhaps something else contributed to the coffee tone.

That may be why production was moved to China, to get Lanthanum glass cheaper.  China has pretty much cornered the rare earths market and is reserving them for use "in house" by inflating prices to everyone else.  It's one of the main reasons the Radians were discontinued because new productions runs outside of China had become cost prohibitive.

[Don Pensack]

Lanthanum oxide in glass was a replacement for thorium oxide as knowledge of radiation's effects blossomed after WWII (thorium is radioactive).

The change in refractive index was about the same.  It's well know that it can impart a "warm tone" to the image, but the effect is slight, and certainly not deleterious to views of

Mars, Jupiter, and Saturn, or carbon stars.  It seems to be mostly lunar observers who object.  Many modern eyepieces use lanthanum oxide glass so it's quite common.

To my knowledge, TeleVue doesn't use lanthanum oxide glass in the Ethos, Delos, or Delite eyepieces in order to avoid a hang up in supply if China decides to double the price of lanthanum oxide

or cut off Japan's supply completely, as has happened in the past.

 

[Ags]

On the subject of TS HRs, here's a glowing review from back in the day.

 Do you still have the HRs, @John?

I certainly don't regret my HRs but I did feel the 9mm was a bit behind a Hyperion 17 + fine tuning rings. 

Edited July 1, 2020 by Ags

[John]

12 minutes ago, Ags said:

On the subject of TS HRs, here's a glowing review from back in the day.

 Do you still have the HRs, @John?

I certainly don't regret my HRs but I did feel the 9mm was a bit behind a Hyperion 17 + fine tuning rings. 

No, I didn't keep them for long - I caught the "ultra wide" bug shortly after then

 

[Louis D]

56 minutes ago, Don Pensack said:

To my knowledge, TeleVue doesn't use lanthanum oxide glass in the Ethos, Delos, or Delite eyepieces in order to avoid a hang up in supply if China decides to double the price of lanthanum oxide

or cut off Japan's supply completely, as has happened in the past.

Thanks for confirming that as that was my understanding as well.  It would be interesting for Al or Paul to discuss what changes had to be made to account for the loss of lanthanum glass as a design option.  Have they ever given a talk on the subject to your knowledge?

[michael.h.f.wilkinson]

22 hours ago, Louis D said:

I wonder if Vixen discontinued the use of rare earth glass types in the SLV line to keep down expenses.  I know that both the Vixen LVs and TV Radians used rare earth glasses, and both were accused of having slightly dimmer, coffee toned images as a result.

Colour tone can be corrected by the coatings, of course at the expense of transmission. I really didn't notice any colour tone in either the XWs or the SLVs. I did notice it in the Radian 8 and 10 mm EPs I used to have, but it didn't really bother me

[Louis D]

1 hour ago, michael.h.f.wilkinson said:

Colour tone can be corrected by the coatings, of course at the expense of transmission. I really didn't notice any colour tone in either the XWs or the SLVs. I did notice it in the Radian 8 and 10 mm EPs I used to have, but it didn't really bother me

My Vixen LV 9mm always seemed to view a bit dark, but I never noticed any distinct color tone, although I never specifically went looking for it.  Despite seeming a bit dark, it didn't seem to affect dim stars right at the edge of visibility relative to other eyepieces.

[Don Pensack]

3 hours ago, Louis D said:

Thanks for confirming that as that was my understanding as well.  It would be interesting for Al or Paul to discuss what changes had to be made to account for the loss of lanthanum glass as a design option.  Have they ever given a talk on the subject to your knowledge?

No, not that I know of.  I read someone else speculate it necessitated a larger and heavier eyepiece than if it used lanthanum oxide glass.

But I don't know that to be true.

The Apollo 11 shows the eyepiece needn't be huge in order to have long eye relief or excellent correction without that kind of glass.

It's 85° and 530g (620g with the 2" adapter), versus the 12mm ES 92°, with equally long eye relief, at 1017g

[Louis D]

4 hours ago, Don Pensack said:

The Apollo 11 shows the eyepiece needn't be huge in order to have long eye relief or excellent correction without that kind of glass.

It's 85° and 530g (620g with the 2" adapter), versus the 12mm ES 92°, with equally long eye relief, at 1017g

Too bad it's price makes the Noblex 12.5mm look affordable.

Edited July 2, 2020 by Louis D

[michael.h.f.wilkinson]

11 hours ago, Louis D said:

My Vixen LV 9mm always seemed to view a bit dark, but I never noticed any distinct color tone, although I never specifically went looking for it.  Despite seeming a bit dark, it didn't seem to affect dim stars right at the edge of visibility relative to other eyepieces.

I think the brain interprets a blue or neutral tone as brighter than a slight brownish cast, that would explain your observation. I have seen that effect when designing and setting up stage lighting (as a student). Using using the equivalent of an 80B filter turning the quartz halogen light into daylight, always seemed to make the stage look brighter than if you used salmon or gold filters.

[John]

I've seen measured data on the light transmission of various eyepieces and there is some variation (as you might expect) between the designs which might also contribute to the perception of one being dimmer / darker than another. Of course a dark background sky is desirable but not dimming of the intended targets, especially faint ones !

The range was between 88% and 98% of visible wavelengths.

 

 

[Ags]

Here is a direct and recent shootout between a another TMB Planetary clone and an SLV at F4.9:

Looks like a draw or near draw (considering only on-axis performance) according to the OP and some replies in the thread. Gives me pause for thought.

[John]

I've not used the 4mm SLV.

I did review the 20mm, 12mm and 6mm for the forum a while back and thought them excellent. I compared the 6mm SLV at some length (ie: over several sessions) and found that it matched the Baader Genuine Ortho 6mm in performance and was more comfortable to use. I was rather surprised at this because the Baader GO 6mm is one of the best 6mm eyepieces that I've owned or used but there was no doubt that the 6mm SLV was providing comparable views:

https://stargazerslounge.com/topic/217971-vixen-slv-eyepiece-report-6mm-12mm-and-20mm/