Hi guys a friend of mine bought one of these 2 inch 26mm GSO eyepiece last week and lent it to me today to try it out. I tried it out on the moon since it's pretty fogy out here at the moment. Not being a very experienced observer I found it to be quite good on my 10 inch F7.3 newtonian. I compared it to some 1.25 inch plossls that I have 25mm 30mm and 40mm and a 20mm 68 fov. the 20mm is a good lens sharp right to the edge made in japan but I can't remember the name. I haven't tried the 2 inch on star clusters yet but I was wandering if anybody has had any experiences with these eyepieces. For $39 they are pretty cheap. Here is a picture of it compared to a 25mm 1.25inch plossl
I used to own the same 26mm eyepiece. They are a modified Kelner design and although sharp and with good transmission, I found the seaguls intolerable at f5. In fact its the worst eyepiece I have seen in this regard.
Yeah, a push in my F6, too. (Seagulls refers to the distorted shape of stars in the periphery of the field, prinicipally due to coma and most noticable in "fast" newtonians. Might be all right in you F7.3. How tall is that thing? And where did you get it?) Still, nice big eye lens, which makes it easy for newbies on open nights.
areas where the light disappears in a seagull or figure 8 shape, you cant see a thing. I would say that these are ok on f10 or longer scopes, I had one and it was ok on the meade SC 12"
Thanks guys I'll keep an eye on the seagulls once the sky clears. I made the telescope myself ground the mirror etc. It's 1.8m tall. There are pictures of it here somewhere in the DIY section.
Yeah, a push in my F6, too. (Seagulls refers to the distorted shape of stars in the periphery of the field, prinicipally due to coma and most noticable in "fast" newtonians.
Hi,
With these cheap Chinese eyepieces, like the 26mm GSO Kellner we are talking about here, the predominant aberration is off axis astigmatism, not Coma. I have used this eyepiece myself in an F5 scope and it is terrible.
FWIW, Coma is an aberration eminating from the fast mirror itself not the eyepiece. The astigmatism you are seeing in this eyepiece is caused by the eyepieces own inability to handle the steep light cone (fast scope) away from its central axis.
The 2" 32mm version was supplied with our 12" f5 Dob and it is my 'start the session'/finder EP, I have to say that I have not noticed sufficient aberration to call this ocular "Terrible". In fact it renders reasonably pleasant views of clusters, nebulae etc. For the money, ($NZ90.00), not a bad bit of glass even in a fast scope. I can't see how the 26mm could be significantly worse so I might just buy one and check it out. Johnno hit the nail on the head, if you have nothing better to compare it to its the best you have, be happy and enjoy the view. Sometimes its easy to get overwhelmed by the technical stuff and forget that amateur astronomy is FUN!!! whatever the glass.
I regularly view beside a mate who has a big/fast dob, home built from the ground up, mirrors, sink drain focuser and all.
He has a range of home built ep's made with binocular lenses etc, to my eyes some of his eps have more seagulls than the local rubbish dump but he can see/describe detail that I can't get anywhere near with my storebought kit.
Telescope views are, like beauty, very much in the eye of the beholder.
