Starguider 30mm Ultra Wide Angle 80 degree 2"

[Raph-in-the-sky]

Hey Guys,

While browsing through some EPs on Ebay, I stumbled upon this EP (https://www.befr.ebay.be/itm/One-High-Quality-2-F30mm-Ultra-Wide-80-Degree-Eyepiece-for-Telescope-Brand-New/143351523207?hash=item21606aa787:g:TDkAAOSwkhJZ5MQu) which is really cheap (only £65). 

Has anybody used it? How do you think it would perform in a F4.7 10'' Dob? 

Obviously I am not expecting Nagler performance but maybe it compares ok to something like a 30mm ES 82°.

Finally I see that there is a 30mm EP and a 20mm/32mm (both focal lenght at once by removing a barlow element). I like the idea of having both 20 and 32mm as it would complete my range quite nicelly but this one seems to be a completely different built. How does this EP compare to the rest?

Cheers,

Raph

 

[Raph-in-the-sky]

Could anybody help?

[Ricochet]

2 hours ago, Raph-in-the-sky said:

Has anybody used it? How do you think it would perform in a F4.7 10'' Dob? 

I've not used it but I would expect it to perform quite badly. Wide angle eyepieces require lots of elements to get good correction at low focal ratios and using 2" glass the cost adds up quickly. You might find that quite a proportion of the field is lost to distortions. 

[Raph-in-the-sky]

20 minutes ago, Ricochet said:

I've not used it but I would expect it to perform quite badly. Wide angle eyepieces require lots of elements to get good correction at low focal ratios and using 2" glass the cost adds up quickly. You might find that quite a proportion of the field is lost to distortions. 

I know this general rule of thumb: Wide field, well-corrected, cheap... choose 2 out of 3 but from what I read this EP punches above its weight. just wanted to hear from some people who have first hand experience.

[CraigT82]

Seems to be the same as these units from Opticstar...

http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Ascension.asp?p=0_10_5_1_1_0

To be honest I'd much rather buy from Opticstar than ebay.

If I was looking for a widefield EP I'd probably give that one a try... might have fuzzy edges in your f/4.7 dob but it's a cheap way to get that 'spacewalk' effect and would make a decent finder EP.  If you plan to acquire a longer F ration scope in the future it might become more useful still.

[Louis D]

It's the same as my Agena 20mm/30mm 80° UWA in the following comparison image.  Notice how much better it is than the MPL (6 element Erfle) and Kasai eyepieces.

It is terrible as a 20mm, so bad I didn't even do a test photo through it.  The barlow element vignettes the field of view and adds distortions.  It really needs a TV PBI type element in between to realign the diverging rays as in a Powermate.  It barlows quite well in such an arrangement, but the barlow element is much further removed yielding a 15mm eyepiece.

It has really comfortable eye relief thanks to that giant eye lens.  There are no blackouts, either.

As a 30mm, it isn't bad in the central 50% at all.  In fact, it's sharper than the 30mm ES-82 there.  The biggest problem with it is extreme field curvature.  I once over corrected the field correction in my AT72ED with my TSFLAT2 just to flatten its field, and it only shows minor astigmatism in the outer field once the field is flattened.  If your eyes are younger and have large amounts of focus accommodation, it is quite usable, at least until you get presbyopia in your mid-40s. 😉

If you can pick one up used or new for around $60 to $70, it's totally usable until you can afford a 30mm APM UFF.

[Raph-in-the-sky]

34 minutes ago, CraigT82 said:

To be honest I'd much rather buy from Opticstar than ebay.

 

Good point. There a bit cheaper and delivery is much faster with Opticstar. If I decide to buy it I 'll go through them.

[johninderby]

Check Opticstar’s eBay shop as they usually have free shipping Wheras you may have to pay £5.00 for shipping if bought from their website.

[John]

I've owned one of those. Great at F/10, rather poor in the outer 50% of the field at F/5. The problem is that controlling aberration over a wide field at F/5 of faster needs careful design, top quality optical glass, accurate figuring and polish and excellent assembly. Thats why the better corrected wide field eyepieces for faster scopes have somewhat higher price tags.

If you could pick one up for, say, £30 or so it would give you a feel for the ultra wide experience I guess but I'd not pay any more for one.

 

 

[Raph-in-the-sky]

9 minutes ago, Louis D said:

It's the same as my Agena 20mm/30mm 80° UWA in the following comparison image.  Notice how much better it is than the MPL (6 element Erfle) and Kasai eyepieces.

It is terrible as a 20mm, so bad I didn't even do a test photo through it.  The barlow element vignettes the field of view and adds distortions.  It really needs a TV PBI type element in between to realign the diverging rays as in a Powermate.  It barlows quite well in such an arrangement, but the barlow element is much further removed yielding a 15mm eyepiece.

It has really comfortable eye relief thanks to that giant eye lens.  There are no blackouts, either.

As a 30mm, it isn't bad in the central 50% at all.  In fact, it's sharper than the 30mm ES-82 there.  The biggest problem with it is extreme field curvature.  I once over corrected the field correction in my AT72ED with my TSFLAT2 just to flatten its field, and it only shows minor astigmatism in the outer field once the field is flattened.  If your eyes are younger and have large amounts of focus accommodation, it is quite usable, at least until you get presbyopia in your mid-40s. 😉

If you can pick one up used or new for around $60 to $70, it's totally usable until you can afford a 30mm APM UFF.

Have you used this EP with only one focal length (the one with only the 30mm printed on the EP, https://www.befr.ebay.be/itm/163778031584?ViewItem=&item=163778031584). Apparently the design is not the same.

Regarding the APM UFF, this is the one with 80° AFOV (https://www.astroshop.eu/eyepieces/apm-2-30mm-80d-uw-eyepiece/p,52793)? Is it that good? Better than an ES 82°? If so I think I could spend 100 Eur on this (or I might wait for a second han to pop up ... I have a GSO 32mm plossl that does the job for the time being)

[Raph-in-the-sky]

49 minutes ago, Louis D said:

If you can pick one up used or new for around $60 to $70, it's totally usable until you can afford a 30mm APM UFF.

 

Just realized you were not talking about the 80° APM... The 70° is 200 EUR while the 80° is only 100 EUR. Have you tried the 80° one?

[John]

13 minutes ago, Raph-in-the-sky said:

Just realized you were not talking about the 80° APM... The 70° is 200 EUR while the 80° is only 100 EUR. Have you tried the 80° one?

The APM 80 degree 30mm is the same as the one you linked to earlier I believe. These are produced under a number of brandings and have been for over a decade now. These are chinese clones of the original Japanese Kokusai Kohki WideScan III 30mm eyepiece which I've also owned. The Japanese version was a little better corrected but still showed large flocks of seagull shaped stars in my F/6.5 102mm Vixen refractor !

 

 

[Raph-in-the-sky]

1 minute ago, John said:

The APM 80 degree 30mm is the same as the one you linked to earlier I believe. These are produced under a number of brandings and have been for over a decade now. These are chinese clones of the original Japanese Kokusai Kohki WideScan III 30mm eyepiece which I've also owned. The Japanese version was a little better corrected but still showed large flocks of seagull shaped stars in my F/6.5 102mm Vixen refractor !

 

So now way around it. I'm gonna have to rob a bank... again

[Louis D]

4 hours ago, Raph-in-the-sky said:

Just realized you were not talking about the 80° APM... The 70° is 200 EUR while the 80° is only 100 EUR. Have you tried the 80° one?

As @John correctly pointed out, the 30mm APM 80° is the same as the 30mm Agena 80° described in my comparison and many others rebrandings.  There have been minor design variations over the years.  The latest versions have fully blackened lens edges and other improvements over the original KK Widescan clone from over a decade ago.  Is it worth $100, no.  But at $50 to $70, it compares very favorably to the various 32mm 70° SWA designs out there in that price range, and you get a few extra degrees of marginally usable field for recentering purposes.  Watch the classifieds for them to come up used.  They have such a bad rep that their resale value is just terrible.  If the 20mm comes up for the same price, all the better because you get a free 2" filter threaded 2x barlow element in the package deal that becomes usable with a 2" filter threaded extension tube.

[joe aguiar]

I would say get s 2 inch ep 30mm in the 50 to 55 degree fov instead of the ultra wide like the one u memtioned. Having a wide fov  eps and a wide field scope together is not needed. 

Joejaguar 

[John]

24 minutes ago, joe aguiar said:

I would say get s 2 inch ep 30mm in the 50 to 55 degree fov instead of the ultra wide like the one u memtioned. Having a wide fov  eps and a wide field scope together is not needed. 

Joejaguar 

You can get a perfectly good 52 degree 32mm focal length eyepiece in the 1.25" fitting which will show the same true field of view. I can't see the point of having a 2 inch barrel on a 30mm focal length eyepiece if the field stop fitted restricts the AFoV to 50 something degrees

Having wide FoV eyepieces in a short focal length scope delivers some wonderful observing opportunities eg: the whole of the Veil nebula in the same field - one of my favourite views in the hobby

 

[joe aguiar]

13 minutes ago, John said:

You can get a perfectly good 52 degree 32mm focal length eyepiece in the 1.25" fitting which will show the same true field of view. I can't see the point of having a 2 inch barrel on a 30mm focal length eyepiece if the field stop fitted restricts the AFoV to 50 something degrees

Having wide FoV eyepieces in a short focal length scope delivers some wonderful observing opportunities eg: the whole of the Veil nebula in the same field - one of my favourite views in the hobby

 

That's kinda what I was getting at he doesnt need a 80 degree fov ep with that scope. A regular plossl would do.altho I figure he could still use a 2 inch ep if he wanted .the 1.25 ep works fine too

Edited October 25, 2019 by joe aguiar

[John]

1 minute ago, joe aguiar said:

That's kinda what I was getting at he doesnt need a 80 degree fov ep with that scope. A regular plossl would do

In his original post Raph was looking at 82 degree eyepieces in the 2 inch fitting and also mentions Naglers and the ES 30mm 82 degree eyepiece so it's reasonable to assume that he is looking for a wider field of view than the 1.25 inch fitting can provide perhaps ?

 

[joe aguiar]

Just now, John said:

In his original post Raph was looking at 82 degree eyepieces in the 2 inch fitting and also mentions Naglers and the ES 30mm 82 degree eyepiece so it's reasonable to assume that he is looking for a wider field of view than the 1.25 inch fitting can provide perhaps ?

 

Yep agree but since his scope is very fast sounds like both us agree that's not necessary. As others said may have lots issues being  corrected in the ep unless it's a very well made ep.

[John]

I think a low power, wide angle eyepiece is a great asset in a fast scope - the challenge is finding one that performs reasonably well without breaking the bank

Going for 70 degrees rather than 80 would help - there are reasonable performers such as the Skywatcher Aero ED 30mm or the Panaview 32mm.  They won't be perfectly corrected at that focal ratio but they will be better than a low cost 80 degree eyepiece I think.

 

[Raph-in-the-sky]

9 hours ago, John said:

I think a low power, wide angle eyepiece is a great asset in a fast scope - the challenge is finding one that performs reasonably well without breaking the bank

Going for 70 degrees rather than 80 would help - there are reasonable performers such as the Skywatcher Aero ED 30mm or the Panaview 32mm.  They won't be perfectly corrected at that focal ratio but they will be better than a low cost 80 degree eyepiece I think.

 

Thanks, I think it would be nice to have a low power wide field EP. I was hoping I could get a decent EP that gives me about 2° TFOV.  The 70° 30mm would give me 1.75° which I suppose is close enough. My idea was that this EP could help locate fainter objects and provide me with good views of extended objects (Veil and orion nebulae come to mind). 

I'll check the ones you mention and see if I can find them second hand... I'm in no rush since I got a nice GSO 32mm plossl from another SGL member.

[John]

I can get 1.6 degrees with my 12 inch dob and the 31mm Nagler eyepiece. This shows the whole of the eastern or western segments of the Veil Nebula but not both in the same field of view. You need something like 3.5 degrees to get that which is where shorter focal length scopes combined with the wide / ultra wide eyepieces come in.