Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Is this super cheap EP worth it?

  • Please log in to reply
19 replies to this topic

#1 Raph-in-the-sky

Raph-in-the-sky

    Lift Off

  • -----
  • topic starter
  • Posts: 4
  • Joined: 15 Jul 2019

Posted 19 July 2019 - 05:00 AM

Hey All,

 

As stated in the title, I found this super cheap plossl, made in China, advertised as fully multi-coated.

 

https://www.befr.eba...RwAAOSw5cZb~51W

 

Has anyone used it? Do you think it's worth it?

 

Clear skies,

 

Raph


  • HellsKitchen likes this

#2 HellsKitchen

HellsKitchen

    Surveyor 1

  • -----
  • Posts: 1921
  • Joined: 05 Sep 2008
  • Loc: Renmark, Australia

Posted 19 July 2019 - 05:08 AM

Been wondering the same thing. My gut feeling says "bugger off", but would like to hear from those more in the know. 



#3 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 19 July 2019 - 05:55 AM

Difficult to say without using it, but many of these budget 'Plossls' probably originate from the same factories. I was using a 20 quid Astro Essentials 17mm Plossl last night to observe the Moon, Jupiter and Saturn with a 72mm Evostar. 

 

gallery_249298_10131_18185.jpg

 

Admittedly it was plugged into a 5x GSO Barlow making the f/5.8 ED72 f/29, but the £20 Chinese Plossl held its own against an 18mm Astro Hutech orthoscopic and a 15mm Vixen NPL.


  • Orion68 likes this

#4 db2005

db2005

    Viking 1

  • *****
  • Posts: 933
  • Joined: 23 Dec 2017
  • Loc: Living in Denmark, under Bortle 5 skies.

Posted 19 July 2019 - 07:19 AM

Plössl eyepieces are usually considered the "best buys" for beginners, offering a very good balance between cost and performance, especially in scopes slower than around ~f/7... their performance isn't great in much faster scopes.

 

One problem is that "Plössl" is (almost) a generic term for any symmetrical 4-element eyepiece with around ~50-52 degrees field of view. Except for buying branded items, there's no easy way to know whether it can be expected to have been made to a high optical standard. That said, most Plössls on the current market today (including the branded versions) are remarkably close in optical performance, so unless you get a "lemon", performance is likely to be very good for the price. When you factor in taxes, the EP you mention is not even remarkably cheap... for instance, check out this Skywatcher-branded version in comparison, which includes German sales tax and is only a little bit more expensive:

 

https://www.teleskop...-4-element.html

 

I briefly owned (bundled with a telescope) a 20 mm Silver top Plössl which was very similar to this one, and I recall I was impressed with its performance, especially considering its cost.


  • Orion68 and NeroStar like this

#5 NeroStar

NeroStar

    Explorer 1

  • -----
  • Posts: 54
  • Joined: 05 Jul 2019
  • Loc: Ashburn, Virginia

Posted 19 July 2019 - 08:13 AM

I have had great experiences with most of the 'cheap' Chinese-made eyepieces, barlows and diagonals that I've purchased on ebay, Amazon and Ali over the years.  In fact, I remember comparing a no-name Chinese 15mm plossl to a 15mm TV that I owned a few years ago and thinking that I couldn't really discern a difference in their optical performance.  That may have been because the scope I was using didn't favor the TV's characteristics.  I think the quality of many no-names has really come up over the years. However, you've got a bit more of a quality 'guarantee' with high-end optics and coatings, but if you're paying 1/3 or 1/10 the prices and getting great performance, you're probably still coming out ahead in value per dollar.

 

As someone else alluded to, I don't doubt that many of these no-names are made in the same factories and to the same standards as many well-known eyepiece brands.  


  • bmurphy495 and Orion68 like this

#6 Raph-in-the-sky

Raph-in-the-sky

    Lift Off

  • -----
  • topic starter
  • Posts: 4
  • Joined: 15 Jul 2019

Posted 19 July 2019 - 08:57 AM

Difficult to say without using it, but many of these budget 'Plossls' probably originate from the same factories. I was using a 20 quid Astro Essentials 17mm Plossl last night to observe the Moon, Jupiter and Saturn with a 72mm Evostar. 

 

gallery_249298_10131_18185.jpg

 

Admittedly it was plugged into a 5x GSO Barlow making the f/5.8 ED72 f/29, but the £20 Chinese Plossl held its own against an 18mm Astro Hutech orthoscopic and a 15mm Vixen NPL.

That's also a model I considered althought it's significantly more expensive (I ll admit it's still very cheap) The 32mm is 29 GBP + 3 GBP postage compared to 13EUR.

 

I suppose the astro essentials are aluminium, glass and fully multi-coated?... I suspect the super cheap EP to be at least part plastic (body and lense)

 

Raph



#7 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 19 July 2019 - 11:23 AM

That's also a model I considered althought it's significantly more expensive (I ll admit it's still very cheap) The 32mm is 29 GBP + 3 GBP postage compared to 13EUR.

 

I suppose the astro essentials are aluminium, glass and fully multi-coated?... I suspect the super cheap EP to be at least part plastic (body and lense)

 

Raph

The Astro Essentials EP I have has a chromed-brass drawtube barrel, so feels quite substantial. Its build quality is as well made as any Barsta, Solomark or GSO 'Plossl' I have.

 

In slow scopes it is as good as anything IMO, showing no discernible colour aberrations and has a sharp field stop. The matte blacking and baffling inside the drawtube barrel seems good quality and there was no visible debris in the FOV. The symmetrical groups appear good quality for the price and the coatings look like the standard multi coatings on GSO or Barsta Plossls.

 

The reason these are 20 quid and not 75 quid like the Japanese orthoscopics is predominantly because they are made in China. If they were made outside of China they'd probably be nearer £40 or more I'd guess.

 

Last night, in a 5x Barlow, I couldn't really tell any difference between the 17mm Astro Essentials 'Super Plossl' and my 18mm Astro Hutech Japanese orthoscopic. The ortho' possibly had a tad more contrast, but ortho's are renown for that. The best image I had of Jupiter last night was with the 20 quid Astro Essentials EP and a #11 Wratten (yellow-green) filter. This was around 15 mins after transit at 123.5x.

 

https://www.cloudyni...ntials-plossls/

 

I don't know who make these, but they're as good as any Plossls made by Barsta (Celestron, Sky-Watcher, Orion).

 

gallery_249298_5348_153079.jpg

 

Not everything plastic is terrible. These SvBony aspherics are actually quite good.


  • Francopoli, Orion68, ww321q and 1 other like this

#8 ww321q

ww321q

    Ranger 4

  • -----
  • Posts: 360
  • Joined: 13 Feb 2019
  • Loc: Winton Ca.

Posted 21 July 2019 - 09:12 AM

The Astro Essentials EP I have has a chromed-brass drawtube barrel, so feels quite substantial. Its build quality is as well made as any Barsta, Solomark or GSO 'Plossl' I have.

 

In slow scopes it is as good as anything IMO, showing no discernible colour aberrations and has a sharp field stop. The matte blacking and baffling inside the drawtube barrel seems good quality and there was no visible debris in the FOV. The symmetrical groups appear good quality for the price and the coatings look like the standard multi coatings on GSO or Barsta Plossls.

 

The reason these are 20 quid and not 75 quid like the Japanese orthoscopics is predominantly because they are made in China. If they were made outside of China they'd probably be nearer £40 or more I'd guess.

 

Last night, in a 5x Barlow, I couldn't really tell any difference between the 17mm Astro Essentials 'Super Plossl' and my 18mm Astro Hutech Japanese orthoscopic. The ortho' possibly had a tad more contrast, but ortho's are renown for that. The best image I had of Jupiter last night was with the 20 quid Astro Essentials EP and a #11 Wratten (yellow-green) filter. This was around 15 mins after transit at 123.5x.

 

https://www.cloudyni...ntials-plossls/

 

I don't know who make these, but they're as good as any Plossls made by Barsta (Celestron, Sky-Watcher, Orion).

 

gallery_249298_5348_153079.jpg

 

Not everything plastic is terrible. These SvBony aspherics are actually quite good.

Do you get a wider true fov with the focal reducer on that 23mm eyepiece? 



#9 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 21 July 2019 - 09:56 AM

Do you get a wider true fov with the focal reducer on that 23mm eyepiece? 

It makes the 23mm a 46mm eyepiece, so I should imagine it doubles it. 



#10 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 30481
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 21 July 2019 - 11:58 AM

Hard not to be worth 13.20 Eur ($14.83).   I can't buy a pizza for $14.83.  Yeah, it's probably worth it.  shrug.gif

 

Mike


Edited by Sarkikos, 21 July 2019 - 12:00 PM.

  • eros312, happylimpet and Orion68 like this

#11 CeleNoptic

CeleNoptic

    Apollo

  • *****
  • Posts: 1212
  • Joined: 20 Dec 2007
  • Loc: Cloudy East Coast

Posted 21 July 2019 - 02:27 PM

I have bad luck with No-name Chinese plossls from eBay I've described earlier somewhere in this forum. Coatings may strip off very easy. Just wasting money. Don't recommend. thumbsdown3.gif . You'd better stick with known brands, IMO.


Edited by CeleNoptic, 21 July 2019 - 02:29 PM.

  • Sarkikos and nicoledoula like this

#12 Raph-in-the-sky

Raph-in-the-sky

    Lift Off

  • -----
  • topic starter
  • Posts: 4
  • Joined: 15 Jul 2019

Posted 22 July 2019 - 02:48 AM

Finally I found a second hand GSO Plossl for 20 GBP ... a tad more expensive but a very safe bet from what I read 


  • Sarkikos, CeleNoptic and nicoledoula like this

#13 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 22 July 2019 - 06:50 AM

Finally I found a second hand GSO Plossl for 20 GBP ... a tad more expensive but a very safe bet from what I read 

Yeah, you can't really go wrong with GSO Plossls. Their drawtube barrel undercuts (if they have them) have tapered lower lips and so rarely cause extraction problems. The field stop edges are a bit soft on some of the range, although that's not really a problem, and they can be used in fast scopes without much edge astigmatism.

 

It's worth pointing out that GSO eyepieces are often sold under other names such as Revelation, TS Optics, Altair and others. The prices can vary considerably. 

 

gallery_249298_10131_23280.jpg

 

All of the GSO Barlows are pretty good. The two inch 2x version is very good for what it costs.


  • nicoledoula and Raph-in-the-sky like this

#14 Raph-in-the-sky

Raph-in-the-sky

    Lift Off

  • -----
  • topic starter
  • Posts: 4
  • Joined: 15 Jul 2019

Posted 22 July 2019 - 09:33 AM

Yeah, you can't really go wrong with GSO Plossls. Their drawtube barrel undercuts (if they have them) have tapered lower lips and so rarely cause extraction problems. The field stop edges are a bit soft on some of the range, although that's not really a problem, and they can be used in fast scopes without much edge astigmatism.

 

It's worth pointing out that GSO eyepieces are often sold under other names such as Revelation, TS Optics, Altair and others. The prices can vary considerably. 

 

gallery_249298_10131_23280.jpg

 

All of the GSO Barlows are pretty good. The two inch 2x version is very good for what it costs.

For the barlow, I just got a Celestron Ultima x2 (japan), which I hear is very good. Some even said that it was the best barlow they ever used!


  • CeleNoptic likes this

#15 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 22 July 2019 - 12:06 PM

For the barlow, I just got a Celestron Ultima x2 (japan), which I hear is very good. Some even said that it was the best barlow they ever used!

The Ultima were nice Barlows. 


  • Raph-in-the-sky likes this

#16 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42430
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 23 July 2019 - 03:29 PM

It makes the 23mm a 46mm eyepiece, so I should imagine it doubles it. 

No, the true field of the eyepiece is just a hair smaller than the limit for a 1.25" eyepiece.

Adding the focal reducer definitely increases the focal length, but only adds, maybe, 10% to the true field width.

You can't squeeze blood out of a turnip.

The maximum FOV for a 1.25" eyepiece of this type is a field stop of about 27.0-27.2mm.


  • Shorty Barlow likes this

#17 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 24 July 2019 - 06:47 AM

No, the true field of the eyepiece is just a hair smaller than the limit for a 1.25" eyepiece.

Adding the focal reducer definitely increases the focal length, but only adds, maybe, 10% to the true field width.

You can't squeeze blood out of a turnip.

The maximum FOV for a 1.25" eyepiece of this type is a field stop of about 27.0-27.2mm.

OK thanks Don. I was calculating the TFOV for a 23mm, 60° EP by dividing its AFOV by the magnification in a particular telescope.

 

So 1500mm (scope focal length) / 23mm = 65.2x.

 

60° (eyepiece AFOV) / 65.2 = 0.902 (54 arc minutes, 7 seconds).

 

I just assumed the reducer turned them into 46mm focal length eyepieces. Maths isn't my subject lol.



#18 Francopoli

Francopoli

    Mariner 2

  • -----
  • Posts: 202
  • Joined: 25 Jun 2013
  • Loc: Ohio Valley, USA

Posted 24 July 2019 - 06:55 AM

Looks like the inexpensive 32mm I bought for outreach.  May be the same glass.  It is not going to win any awards, but then again if it gets scratched or dropped and destroyed at an outreach event, I'm out $20 and not hundreds.  Fine for beginners, fine for most "starter" scopes and works fine in my Nexstar telescopes.

 

https://www.amazon.c...gateway&sr=8-12


  • Raph-in-the-sky likes this

#19 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42430
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 24 July 2019 - 11:06 AM

OK thanks Don. I was calculating the TFOV for a 23mm, 60° EP by dividing its AFOV by the magnification in a particular telescope.

 

So 1500mm (scope focal length) / 23mm = 65.2x.

 

60° (eyepiece AFOV) / 65.2 = 0.902 (54 arc minutes, 7 seconds).

 

I just assumed the reducer turned them into 46mm focal length eyepieces. Maths isn't my subject lol.

Well, the focal reducer doubles the true field of the eyepiece in theory, but the true field seen is a function of the field stop in the eyepiece.

Let's say the field stop is 24mm on the eyepiece and you add a 0.5 focal reducer.  In theory, the new field stop is 48mm.

The problem is the inside diameter of the barrel cannot illuminate a field larger than maybe 27mm or so.

So, though the eyepiece functions in magnification as if it doubled in focal length to 46mm, it becomes a 46mm eyepiece with a 27mm field stop.

Hence, there would be horrible vignetting of the edge of the field.  

 

Our eyes are insensitive to vignetting but only to a point, which is why I said you might see a little larger true field with the focal reducer.

But the light will quickly drop to zero and so the expansion of true field would be small.

 

If the same focal reducer were used on an eyepiece with a 5mm field stop, I would fully expect a doubling of the true field width along with the doubling of the focal length of the eyepiece.


  • Shorty Barlow and Raph-in-the-sky like this

#20 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 25 July 2019 - 07:15 AM

Well, the focal reducer doubles the true field of the eyepiece in theory, but the true field seen is a function of the field stop in the eyepiece.

Let's say the field stop is 24mm on the eyepiece and you add a 0.5 focal reducer.  In theory, the new field stop is 48mm.

The problem is the inside diameter of the barrel cannot illuminate a field larger than maybe 27mm or so.

So, though the eyepiece functions in magnification as if it doubled in focal length to 46mm, it becomes a 46mm eyepiece with a 27mm field stop.

Hence, there would be horrible vignetting of the edge of the field.  

 

Our eyes are insensitive to vignetting but only to a point, which is why I said you might see a little larger true field with the focal reducer.

But the light will quickly drop to zero and so the expansion of true field would be small.

 

If the same focal reducer were used on an eyepiece with a 5mm field stop, I would fully expect a doubling of the true field width along with the doubling of the focal length of the eyepiece.

Thanks Don, that makes a lot of sense. I originally experimented with reducers on eyepieces for my Mak's to get a wider exit pupil. Some EP's vignetted worse than others. I was surprised that my 19mm TV Panoptic didn't seem to vignette badly. Although eventually I came to the conclusion that it was probably easier to use a faster scope than try to squeeze blood out of a turnip lol. 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics