That 15mm is a superview wide angle not a super plossl. It is actually a sleeper, the best in the superview line, that 30mm being the 2nd best. They are much better in slow scopes, f8 f10 and slower, however, there is a trick. Unthread the black part of your gso barlow with the lenses, onto the 15mm, thus making it about a 10mm , which happens to be sharp to the edge in your f5 dob. I discovered this back in 2006. The 15mm superview is 4 element unlike the rest of the superview line which are 5 element . Compared to other similarly priced 15 and 16mm 65-70 degree eyepieces, the superview has more contrast and better light throughput. Try the thread on barlow trick sometime , it is a much more enjoyable experience than the 9mm plossl that you have. Also a few other notes, the hyperion is a chinese made eyepieces, if they were actually made in germany, they would probably cost as much as that 20mm es100. About the es20, it is actually not that good at the edges. The 14mm was right up there with the 13 ethos, but the 20 falls way short of the 21 ethos. The good news, is the now grossly inflated prices of the ES and the transferable warranty makes the resale value pretty good, you could sell it and get a much better performing 20mm 100deg eyepiece and come out with a nice chunk of change. I am talking about the XWA/HDC line of 100-110 degree eyepiece offered by many brands like lunt, apm, stellarvue, william optics and several others, as low as $300 new, and some closer to $200 now. You won't be dissapointed. You may even have enough left over for the excellent 28mm 82deg uwan/pwa type that goes for $200-329 new depending on which brand and housing style it has. These started as the william.optics UWAN about 20 years ago, and was also the orion megaview and currently is the meade PWA. Stellarvue apm and others sell these for as little as $200 new with the basic flip up rubber eyeguard , I think i saw the 199 price at stellarvue. They come in 4mm 7mm 16mm and 28mm, some brands may fudge a mm on how they want to brand them, but they are all the same. Other than the 26 and 31mm naglers, which these come damn close to, the 28mm is the best of the big boy 82s, better than the 30mm ES82 (which was also the same as the 30mm meade UWA and celestron 31mm axiom LX), and they absolutely destroy the 31mm luminos. The perfect close to max field low power eyepiece for your dob, sharp to the edge. I have an orion megaview version of the 28mm, and the william optics 20mm XWA. I previously had a 31 nagler, among many other nice eyepieces and the 14 and 20mm es100s, before I had my storage broken into and lost everything . I am satisfied with the 28 as a replacement for my 31, though I do wish they made these in more sizes,.maybe squeeze out a 32-34mm, and fill in some of the gaps in the line, but that never happened. And I am way more pleased with my 20xwa than i ever was with my 20es,.but at the time i bought it, I was majnly using it in f10 scts that don't show the edge issues as much, but when I took it to a star party and compared it to the 21 ethos in an f5 dob, I was very dissapointed. I did the same thing in scoopes ranging from f5 down to f4.2 with and without paracorr, and the 20xwa was so close to the $800.ethos, that I was very happy with my $180 used purchase. And now some versions are new for jist a tad more. Hold onto that 15mm superview though. I haven't replaced mine yet, but I have an even cheaper 15mm sleeper celestron plastic body widefield that is only 3 elements as well as svbony 16mm wa65, 16mm uw80, 15mm 2" irpd 80deg, a 17mm vixen LVW, a few 15-17mm japanese plossl/super plossl, and my massive 14mm meade UWA to keep me busy in that focal length range. And the 15mm superview was mainly an outreach eyepiece, which the svbony and the plastic body 3 element wide angle will be almost.as good at. And I used to get employee discount on all opt branded gso accessories back in the day, which makes it hard for me to shell out 3x as much for just an outreach eyepiece I allready have covered by so many others. But I have a special place in my heart and optic nerve for that 15mm superview, which clearly beat my old meade QX 15mn in contrast and light transmission, a much prettier view of the double cluster in my 4"f10 refractor. Edit: oh crap, i forgot I already commented 3yrs ago lol

Twoje rady i wskazówki sa dla początkuących , a także dla weilu zaawansowanych . Dużo wiedzy zdobyłem z Twego kanału mimo , że obserwuję niebo dość długo . Człowiek się uczy całe życie . Dziękuję i pozdrawiam . Poland

@benjaminpoole9383 Hi Benjamin, Thank you for your contribution to amateur astronomy. You did a really good job presenting the materials progressively, methodically, and in a manner clear and easy to understand. Thank you! And I hope you are still active and are able to continue your contributions perhaps via extending the series you have here. Cheers!

What a cool uncle! Wish I were your niece / nephew! What a wonderful gift to give at early age! I have had limited exposure to astronomy, taking my kids to museums of science and local observatories or events here and there. I am now just getting started. I should receive my first 8” dob soon. I still have a pre teen so hoping to expose them a bit more to the experience as well.

Dude, seriously thanks. I don't know what it is about telescope videos, but most of them are waaay too simple or way to complicated. Your the first person ive found who discussed focal length in the eye peices. Good understandable discussion!

You have an excellent ability to communicate concepts clearly! I’m a fan!

Dude - i know this was years ago but you could rock YT if you wanted to. Love your vids .......but also ....take advantage of your GOOD LOOKS!. Get out there and sell what your folks gave you because you are a handsome guy!!!!

Don't you have to tighten the screws? There is a big difference in mine if its not tightened

Thank you for this video!

Max magnification is double the apature

Only just found you but it seems i was too late. Love your enthusiasm and explanations. Youve got the face for this stuff ;) I hope youre still around and happy doing Astronomy

I need help, I did exactly what you said but I'm not able to see anything in the skies. Any reason why?

can you actually see up to magnitude 14 with a 12 inch dob?

astronomy Cbum here

i like this video

I just asked why you don't upload content anymore? Your work is very good, where can we follow you? I hope you resume your channel.

This was a great explained, thanks!

Could a couple of possible advantages of using the Barlow that would duplicate magnification with other individual eyepieces be the use with a wider angle eyepiece, or one with longer eye relief? ....or even the larger orifice of a shorter eyepiece, like the difference between a 20mm Plossl and 10mm. I suppose stacking more glass might have some disadvantages, but ease of use and flexibility with FoV would seem to be worth it. Opinions?

Great explanation, enjoy your vid! Thank you :)

while observing at sea level ... 200 times is max .. dont bother beyond that as it looks crap

Do you have a link for those eyepieces?

Why not just get a zoom eyepiece than having all of those

Dude kind of reminds me of a bigger Apollo from the new Battlestar Galactica.

Thanks for the quick tut. I seriously need to fix my collimation. And I got this weird thing where my Superview 68 degrees eyepiece from GSO when attached to the scope. I can see a circle tiny reflection of me in the middle. I just noticed it and I got no idea wtf is causing it lol.

ترجمة ليش ماكوا

وين الترجمه

Great videos i just got a telescope for my birthday and thank you for making a noob friendly series that is easy to follow! I commend you good sir!

Very good discussion on eyepieces. I learned a lot. Thanks for making the video. I am going to subscribe to your channel. Best to you.

Thanks for the series. Very helpful.

Wonderful

'Strive not be a success, but rather to be of value". Brilliant job, thanks for sharing that knowledge!

Anyone else just watching this because Benjamin is cute? (I know I am)

Quick question 😆 moved onto a reflector 750pds now my eyepiece projection is too heavy so I got a badder click lock eyepiece holder now I have lost inwards focus by 20mm so I bought a Xcel 3 X Barlow use it on T2 adaptor question is its 2 powerful for moon I got 2 x crop on Panasonic Lumix g85 how do I decrease magnication of Barlow

So helpful!

Thanks for the informative video.

hey, i dont have the 3 screws infront of the telescope, oof

Great 👍 job man very nice 👍 ⭐️⭐️⭐️⭐️⭐️

Wow…just wow. Remarkable work. #goals

Great video and very informative. What I was searching for about focal lengths is extensions added to the focuser? I’m a newbie for the most part. Had a small scope as a gift and dove in and bought a Explore Scientific 16 Dobsonian used. Bought some good eyepieces. I found I had a hard time focusing as there were two extensions added to the focuser before the eyepiece. So with that confusion of those, not sure what they are for or when to use them? I’m assuming it has something to do with the math formula of length. ( I do collimate too) I believe I do that right and have a nice collimating laser.

Fantastic job Benjamin........saving people a lot of time with this information.

I just want to correct you on tge part where you said that the eyepiece changes focal length when barlow lens is added. Eyepieces does not change focal length but, instead barlow lenses makes your telescope focal length longer by 2 times

Nice video, why you doesnt uploads more videos?

First check your laser is collimated otherwise you are wasting your time

I've just bought my first telescope and about to have my first lesson in how to use it, but your videos are super interesting and helpful. I can't wait to get started. P.S. Where do you plug your hairdryer?

why is there a cooling fan behind the primary mirror?? what does it do?

Hi, I am amature and just began my adventure with astronomy, got Meade LX90 (SCT). The question is: can I use this laser tool in my telescope or are there some contraindications ?

Thanks for making this video. This was very helpful.

is the black screw collimating screw or tightening screw?

Thank you so much! This was super helpful :)

New sub. Great series! Thanks!