Plossls - how relevant are they today?

[Star Struck]

I have just started in astronomy and my 200p dobsonian came with two plossls. I have read on this forum about a wide range of eyepieces and so I was pondering the following questions:

1. How relevant are plossls today given the more exotic eyepieces that are out there.

2. What kind of viewing are they good for?

3. Are they better at high magnification or low magnification?

4. Is it worth buying the higher priced ones?

I would be interested in your opinions.

[Jim Steele]

1. Plossls are still good value in my opinion, but I suppose it depends on the speed of the scope as some distortion at the field stop edges will be present in faster scopes

2. This depends on the scope, I use my 25mm most for seeing clusters and the like and I suppose the most mag I would like to use is 10mm

3. they are good for mid magnification, too high power eye relief becomes a problem and too wide the angle they can see over becomes narrower

4. This is personal choice, I'd say a good mid range plosl is the BST range, televue's at the higher end add some contrast but if it is worth it is a personal choice.

Hope that helps

[ronin]

First I will ask is are you sure the scope came with plossl's?

Simply Skywatcher seem to be reducung the standard of the supplied eyepieces and I would not be overly surprised to find they are Huygens or something else (who's name evades me).

The problem is, as ever, the quality of a plossl. A good plossl is good but they are not necessarily cheap. They suffer from being easy to make and turn out, sort of ideal for a mass produced, low price, low quality eyepiece. And the market is full of these. A good plossl like the TV's will sell for £50 on the used market, you can get 2 new plossl's exlsewhere for the same cost. So you can see that there are a lot of inexpensive ones out there.

Best for low and mid power, the optics of them mean that he eye relief is dependant on the focal length so at high power there is little eye relief. This is a problem. Also they are not parfocal which is somewhat of a nuisence. If you have a Mak or SCT altering focus quick can be troublesome.

Do you mean higher priced plossl's or higher priced eyepieces?

When the price starts to get to the area of the BST's then I suppose you may as well consider the BST's. The BST's are good, have decent eye relief and are parfocal (none of this being optical performance you will notice), they will deliver a good image but not as sharp as a TV plossl.

A TV plossl will deliver a good image, there is just 4 elements so if done right there is as a consequence little to go wrong. All those surfaces on each lens is spherical and that is not the best so in effect every face can contribute a problem the may need to be fixed. Before BST's sort of appeared and TV increased the prices the TV plossl was the recommended upgrade. A lot of this was that it was unheard of (?) to get a bad TV plossl.

One aspect I have noticed is that Meade seem to say "Plossl" on many of their eyepieces, yet many of their plossl's have 5 or even 6 elements, whereas a plossl has just 4 elements.

Ultimately it is that old, old problem - What is your budget?

If 20-40 per eyepiece then Vixen plossl's, or GSO.

If up to £60 per eyepiece then Vixen plossl's and BST's and a few others.

At £64 X-Cels come in.

TV plossls are not a fixed cost so they are sort of £65-80 or something like that.

Strange thought - I wonder if anyone makes a plossl with ED glass and how it performs.

Relevance today, well there are other designs in some ways similar that have a following - Monocentrics and Orthoscopics. A set of Zeiss Orthos has gone on sale at $10,000 (think the set is 4 eyepieces). In some aspects the design is similar as in 4 elements.

[Moonshane]

Personally I prefer simpler designs like plossls and orthos for solar system objects and doubles. I do have Naglers etc but reserve these for faint or large objects. That said plossls and orthos are good for smaller faint stuff too.

My preference is televue and bgo both used

[John]

....Strange thought - I wonder if anyone makes a plossl with ED glass and how it performs.

I believe Tele Vue use high index Lanthanum and Flourite type glass in all their eyepieces.

[alan potts]

How relevent are Plossl eyepieces, very! I am just going to place an order for an 8mm and 11mm to compliment my others. They will be Televue, can't break good habits.

Alan

[nightfisher]

If i were to buy plossl`s again i would get Revelation/GSO, the price difference versus optical quality does not stack up for me, 2 new rev/gso`s for the price of a used TV

I do use a few plossl`s and rather like them, these are the skywatcher silvertop 20 and 25mm, they seem fair quality and very well suited for A-focal work

To answer the question, yes plossl`s are still very relevant and will be for years to come

[Beulah]

What's relevant to me about Plössls that they are affordable. For me, they are absolutely essential, otherwise it would take me an age to save up for anything else.

Generally they are great all across the board; I have owned telescopes from 3" to 16" and Plössls deliver every time.

A great quality Plössl such as ones made by Tele Vue are keepers for life if looked after properly.

[mert]

How relevent are Plossl eyepieces, very! I am just going to place an order for an 8mm and 11mm to compliment my others. They will be Televue, can't break good habits.

Alan

I have an 8mm TV Plossl that's never used, it's too much for my scope Alan

[michael.h.f.wilkinson]

My kids have a 20mm Plossl which is very nice and affordable.

[Dude_with_the_tube]

nothing wrong of having a nice plossl in your armoury.a good quality plossl will give you good views on everything.Original plossls where 4 element,but these days there are plenty of modified multi lens plossls available with up to 6 elements,and yes they are still called plossls as the concept of plossl was kept in lens assembly.

[John]

nothing wrong of having a nice plossl in your armoury.a good quality plossl will give you good views on everything.Original plossls where 4 element,but these days there are plenty of modified multi lens plossls available with up to 6 elements,and yes they are still called plossls as the concept of plossl was kept in lens assembly.

I've used what used to be called "Super Plossls" which had 5 lens elements but I've not come across a 6 element version of the design - could you point me towards one that features this ? - I'd be interested to try one 

[astrofox]

Nothing wrong with plossls.

I have and a set from 40mm down to 9.7mm.  Then  I get eye relief problems so my next step is a 8mm BST. Below that I use BGO's from 7mm to 5mm.

Frederick

[Dude_with_the_tube]

I've used what used to be called "Super Plossls" which had 5 lens elements but I've not come across a 6 element version of the design - could you point me towards one that features this ? - I'd be interested to try one 

Meade HD 60 series are 6 elements and still a plossl.Hope that helps.

[John]

Meade HD 60 series are 6 elements and still a plossl.Hope that helps.

Thanks. If they are classed as plossls then I have used some of those. I believe they are the same optical design as the Celestron X-Cel LX too ?. 

Come to think of it Fullerscopes marketed a Superwide Plossl series years ago that sported 77-84 degree apparent field of view and 7 elements. Sounds like the term "plossl" is very flexible !

[LeeB]

I like plossls, still have 3 in the box, halloweens 7.5, 12.5 and 17,  the 17 is superb, at less than 7.5 the eye relief is tight, but still useable down to a 6mm

[great_bear]

There are some misconceptions above.

For what it's worth (plus some additional clarifications):

• BSTs are not Plossls (and there is no apostrophe in "Plossls" either)
• Celestron X-Cel LX and Meade HD-60s are not Plossls either - Meade just cut-and-pasted, word-for-word, their marketing materials from the S5000 Plossl range (and even those were Erfles anyway)
• "Super Plossls" used to imply a "Modified Plossl" (additional lens between the achromats) but that's no longer the case
• There's no reason at all why a Plossl series can't be parfocal
• To be truly pedantic, one can argue that no-one makes "genuine" Plossls, as all current models (including Tele Vue) are "Symmetricals" these days, but most people are forgiving enough to overlook this.
• There's no evidence that Sky-Watcher are reducing the standard of supplied eyepieces
• The "Super 10" and "Super 25" eyepiece supplied with Sky-Watcher scopes are Kelners not Plossls
• There's not a wide variation in the quality of Plossls in the market. The main ones on sale in the UK: Vixen, Tele Vue, Meade S4000, Sky-Watcher and Revelation (GSO) are pretty much on a par with each other optically for the most part; the Tele Vues having marginally better astigmatism correction, at the expense of some geometric non-linearity - but still not sharp to the edge in fast scopes on bright stars. The main difference is body build quality, with the Vixens feeling the cheapest, although optically still good.
• You don't necessarily need "blackened lens edges" on such simple designs
• Revelation (GSO) Plossls are sold under other brand names such as Celestron and Orion. The 15mm and 6mm models have no defined field stop.
• Too much eye-relief can be a problem at longer focal lengths (25mm+) unless the lenses are recessed into the body. I found the 40mm Tele Vue Plossl unbearable in this regard.
• A good Barlow/Plossl combination can provide excellent results for shorter focal-length applications
• My favourite so far are the older Meade S3000s - although (like Tele Vue) very non-linear

[John]

Good post Jeremy - clears up a lot of things 

My understanding on Tele Vue plossls is that they revised the curvature of some of the lens surfaces slightly to get better astigmatism control. It was enough for Al Nagler to lodge a patent on the revised design.

I liked the old Japanese Meade 3000 plossls too. Great bargains when they turn up on the used market.

I also think the current Vixen NPL's good eyepieces for their cost.

[bingevader]

How relevent are Plossl eyepieces, very! I am just going to place an order for an 8mm and 11mm to compliment my others. They will be Televue, can't break good habits. Alan

I can highly recommend both Alan!  I wondered how I would manage with the ER on the 8mm, but it has not been a problem at all.

Cheers

[alan potts]

I have an 8mm TV Plossl that's never used, it's too much for my scope Alan

With a scope the size of that I am not suprised, the focal length will be in meters I would of thought. I have much the same issue with my LX at 3048mm an 8mm Plossl would be a little over the top but I have used this F/L once in this scope. I would be wanting the 8mm and 11mm for my shorter scopes really though the 11mm could well be used in it.

Ben,

Thanks for that bit of advice, I was wondering about the 8mm though I use a 6mm BGO without too much of a problem.

Alan

[mert]

I'm putting the 8mm Plossl and my TV Nagler 12mm on the classifieds later, I need a change lol

[YKSE]

  I was wondering about the 8mm though I use a 6mm BGO without too much of a problem.

Alan

TV plössl should have better ER by numbers, 6mm vs BGO's 4.9mm, but the recessed and concave eye lens in TV plössl might actually mean shorter availble ER.

[Star Struck]

Thank you all for the thought provoking information.

Looks like I will have to start trawling the websites for some used Tele Vue plossls.

[bingevader]

I'm putting the 8mm Plossl on the classifieds later, I need a change lol

Only 47 posts to go!

Just avoid the spam! 

[mert]

Only 47 posts to go!

Just avoid the spam! 

lol, it's listed, I need a new wardrobe of eyepieces.