Long Perng and Guan Sheng Eyepieces

[Globular3 (Jeff)]

Hi All,

I've been looking for a good quality 1.25" high power eyepiece for my 80mm f/5 iOptron Refractor to use for planetary and double star resolving.

The choice so far is a 6mm eyepiece (good eye relief and sharpness) and a 2.5x ED barlow. This will give 167x (2-2.4x dia of lens in mm) which is around the practical maximum. I have a 3x barlow that I got with the scope and could get 200x if seeing permitted, but this is not essential.

I was looking at Guan Sheng for the 2.5x barlow and Long Perng for the 6mm Planetary eyepiece. I also thought I'd get a Guan Sheng or Long Perng erecting 90° diagonal.

Does anyone have any views on these products? (I've heard that Long Perng manufacture for Williams Optics)


Thanks,

Glob.

[dannat (Daniel)]

i heard somewhere the long perng ep's are the same as william optics spl's, of which i have the 6mm, very nice ep at a pretty low price, its no nagler but i really like the ER and less fov doesn't worry me, it is sharp almost right to the edge

[toyos]

I have a couple of WO's wide-angle ep's which I don't use anymore. The images start to blur halfway from the centre, and near the edge the images look worse than any ep's I've ever come across.

[Prickly]

The pick of the guan sheng barlows is the 2 inch 2x barlow.
I find that is quite a good barlow.

I would easily choose this above the guan sheng apo barlows (by a significant margin). Having said that Ive not tried the 2.5x barlow only the 5x.

Cheers
David

[Chippy (Nick)]

The Long Perng eyepieces are similar to the WO SPLs (and may come from the same factory) but they are definitely not "the same". I've had a look at both. They are similar design and size but the WO are lighter and look like they have a superior finish IMO. I haven't looked through either eyepiece though!

I am also interested to hear from someone who has looked through the Long Perng version (or even better - compared with the WO version).

[Globular3 (Jeff)]

Originally Posted by dannat

i heard somewhere the long perng ep's are the same as william optics spl's, of which i have the 6mm, very nice ep at a pretty low price, its no nagler but i really like the ER and less fov doesn't worry me, it is sharp almost right to the edge

Thanks Dannat,

I'll consider the 6mm WO eyepiece.

By the way, is that a plossl you've got?

Regards,

Glob.

[Globular3 (Jeff)]

Originally Posted by toyos

I have a couple of WO's wide-angle ep's which I don't use anymore. The images start to blur halfway from the centre, and near the edge the images look worse than any ep's I've ever come across.

Thanks toyos,

I'll know not to go for the low power eyepieces.

Regards,

Glob.

[Globular3 (Jeff)]

Originally Posted by Prickly

The pick of the guan sheng barlows is the 2 inch 2x barlow.
I find that is quite a good barlow.

I would easily choose this above the guan sheng apo barlows (by a significant margin). Having said that Ive not tried the 2.5x barlow only the 5x.

Cheers
David

Hello Prickly,

Thanks for the advice. I can only use the 1.25" OD eyepieces.

Over the last few days, I've reassessed my needs and a 5x barlow may be better regards the power that I need for the moon and planets.

What didn't you like about The Guan Sheng 5x barlow?

Regards,

Glob.

[Chippy (Nick)]

Not necessarily low power. I believe it is some of the SWANs (Super Wide) that have a bad rap. The UWANs (Ultra Wide) are generally well received, as are the SPLs and others. Toyos may be able to confirm the exact EPs he had issues with?

[Globular3 (Jeff)]

Originally Posted by Chippy

The Long Perng eyepieces are similar to the WO SPLs (and may come from the same factory) but they are definitely not "the same". I've had a look at both. They are similar design and size but the WO are lighter and look like they have a superior finish IMO. I haven't looked through either eyepiece though!

I am also interested to hear from someone who has looked through the Long Perng version (or even better - compared with the WO version).

Hi Chippy,

Thanks for this info.

It's not so easy to decide on these eyepieces.

I do like the Skywatcher brand eyepieces, so maybe I'll stick with the cheaper one's.

Anyhow, I'll think it over some more.

Regards,

Glob.

[VK2KR]

Hi Glob

I have been using the WO 6mm eyepiece with my iOptron and the GSO diagonal. The GSO diag is far better than the one that was supplied with the scope. The ep is brilliant for this scope, good eye relief and contrast.
It is about at the limit for this scope ie 6mm with 2x barlow as anything more
is just fuzzy. I was hoping to pick up a 3mm LP ep due to the cheaper cost compared to the WO version for comparison and complete my ep travel set for this scope.

The apparent field is less than other eyepieces, but for planetary work of no consequence.

The 6mm ep is great for lunar observations, and I have the 12mm WO for better contrast on nebula.

You will not go wrong trying these on your scope as they are much better for planetary viewing than the generic plossels.

regards

Alex

[dannat (Daniel)]

Glob, i think WO spl are a plossl type design, the swan ep's which i have the 9mm are not as good as the spl's . THe 20mm is ok but the 9mm ER is a bit tight and the view suffers near the edge of the field.

[Globular3 (Jeff)]

Originally Posted by VK2KR

Hi Glob

I have been using the WO 6mm eyepiece with my iOptron and the GSO diagonal. The GSO diag is far better than the one that was supplied with the scope. The ep is brilliant for this scope, good eye relief and contrast.
It is about at the limit for this scope ie 6mm with 2x barlow as anything more
is just fuzzy. I was hoping to pick up a 3mm LP ep due to the cheaper cost compared to the WO version for comparison and complete my ep travel set for this scope.

The apparent field is less than other eyepieces, but for planetary work of no consequence.

The 6mm ep is great for lunar observations, and I have the 12mm WO for better contrast on nebula.

You will not go wrong trying these on your scope as they are much better for planetary viewing than the generic plossels.

regards

Alex

Hi VK2KR,

Thanks for the comments on the higher price eyepieces. I guess I needed reassurance that the extra money is going to make a difference. By the way, is your iOptron scope the refractor, mak or newt.? Also, is the GSO diagonal a prism or mirror type and is it normal star or correct image?

Regards,

Glob.

[Globular3 (Jeff)]

Originally Posted by dannat

Glob, i think WO spl are a plossl type design, the swan ep's which i have the 9mm are not as good as the spl's . THe 20mm is ok but the 9mm ER is a bit tight and the view suffers near the edge of the field.

Hi dannat,

Thanks for this advice. I'm interested in the lower focal lengths, so I don't think these problems with the 9 & 20 mm ep's will affect me. It's good to know though as others will possibly read this forum at some time. The lower field of view in some 6 mm ep's shouldn't be a problem either as I intend it for high detail work such as splitting double stars, planetary detail and the moon.

Regards,

Glob.

[pneuman (Leigh)]

Originally Posted by Globular3

Over the last few days, I've reassessed my needs and a 5x barlow may be better regards the power that I need for the moon and planets.

I'd probably steer clear of the GSO 5X -- I've heard from a couple of sources (online and offline) that it's not brilliant, with internal reflection that makes it essentially unusable for observing the Moon in particular. Here's one review that compares the 2.5X and 5X (it doesn't label them as GSO Barlows, but they definitely look like the GSO models from the photos):

http://www.astromart.com/articles/ar...article_id=600

I also have the 2" 2X ED GSO Barlow and I'm quite happy with that, though I guess that doesn't help you much if you can only use 1.25" models.

[jjjnettie (Jeanette)]

The 3x barlow that comes with the Ioptron scope is next to useless.
I use a GSO 2x barlow, while not of the highest quality, it does the job well enough.
I also suggest changing your finderscope. I've put a 9x50 right angle finder on mine little 80mm refractor and it makes the scope a joy to use now.
The diagonal isn't much chop either, if you can spare the cash, buy a mirror diagonal. You can get all of the above quite cheaply from www.andrewscom.com.au.

[Globular3 (Jeff)]

I'd probably steer clear of the GSO 5X -- I've heard from a couple of sources (online and offline) that it's not brilliant, with internal reflection that makes it essentially unusable for observing the Moon in particular. Here's one review that compares the 2.5X and 5X (it doesn't label them as GSO Barlows, but they definitely look like the GSO models from the photos):

http://www.astromart.com/articles/ar...article_id=600

Hello pneuman,

Thanks so much for the article from astromart.com. (Link above in quote)

I agree with you, they do look like the GSO barlow lenses (also, they're made in Taiwan too!)

It has given me loads of help in the decision about the barlow (I'd buy the 2.5x now) as well as answering some questions. I'll summarise this below to help future readers.

1. The 5x barlow is no good for the moon otherwise, both barlows are good.

2. Barlow lenses work well within the low to mid eye relief range. They both increase the eye relief of the eyepiece used however, long eye relief eyepieces may be rendered unusable.

3. TELEVIEW POWERMATES are NOT barlow lenses even though they increase the magnification the same way as a barlow. THEY'RE DIFFERENT in that a POWERMATE WON'T CHANGE THE EYEPIECE EYE RELIEF. This is why POWERMATES CAN BE USED WITH LONG EYE RELIEF EYEPIECES.

4. Parfocal barlow means, focus the eyepiece WITHOUT the barlow. Remove the eyepiece, PUT IN THE BARLOW AND SAME EYEPIECE AS BEFORE, NO NEED TO RE-FOCUS.


All the best from,

Glob.

[Globular3 (Jeff)]

Originally Posted by jjjnettie

The 3x barlow that comes with the Ioptron scope is next to useless.
I use a GSO 2x barlow, while not of the highest quality, it does the job well enough.
I also suggest changing your finderscope. I've put a 9x50 right angle finder on mine little 80mm refractor and it makes the scope a joy to use now.
The diagonal isn't much chop either, if you can spare the cash, buy a mirror diagonal. You can get all of the above quite cheaply from www.andrewscom.com.au.

Hello jjjnettie,

Thanks for endorsement of the GSO barlow. I really feel that it is the right choice now.

Thanks for the advice about andrewscom.com.au. I can underline your point about them being cheaper to buy from as I've already purchased there a couple of times.

By the way, do you like the mirror diagonal more than the prism type? I thought the prism may be better due to 100% reflection and no need to realuminize. What do you think??


Cheers,

Glob.

[Prickly]

Hi Glob3,

What dont I like about the guan sheng 5x apo barlow. Hmmm- well I was being very polite about it.

I use it for accurate 3 star alignment. Nuff said.

There is only one solution as far as Im concerned for a 5x barlow. Thats televue powermate.

Cheers
David

[Globular3 (Jeff)]

Hi Prickly,

Thanks for the advice. I'll get the 2.5x barlow.

Regards,

Glob.