strange eyepeice for newton

[hes not well again]

I was given an old homemade 8 inch newtonian in need of some tlc. It has a focusing tube which is just a 1.25 inch threaded tube. it is not home made and has an eyepeice that seems to have a 5mm focal length and is of doutbfull utility. Is it still possible to get eyepieces to fit it or will a new focuser be in order?

[Peter Drew]

The focus tube eyepiece fitting sounds like it is of the old 1.25" RAS (Royal Astronomical Society) screw thread which is virtually out of use these days.

[rightguard]

if its a shop brought focusser then all 1.25" ep's should fit

**Edit** - or maybe not...

[nicnac]

try this

First Light Optics - Skywatcher SP Plossl eyepieces

a cheap n cheerful, not fabulous but for £20, its 1.25" and if you get the 10mm, usable

you could change out the focuser but not for 20 quid

these are better for the extra tenner

First Light Optics - Vixen NPL eyepieces

[hes not well again]

Sounds like that may be the one [RAS]. It has a proper cast in saddle mount to screw to the tube but the eyepiece has an alarming amount of play in the thread. curiously this doesnt seem to affect the image when you woggle it.

[nicnac]

image wont be effected by the EP wobble, if it was naff mirrors... oh yes.

you had the tape measure out to check?

[hes not well again]

oh yes, had the tape measure out. actually the image is not bad. the mirror has a few spots and watermarks but seems to work quite well, will be getting it recoated at some point tho. it is handmade and has been recoated only once in 40 years. the image is sharp pretty much to the edge of field but the secondary seems badly sratched. in veiwing bright targets [jupiter] without the filter that i havn't got, two flares of light that is wedge shaped radiating out from image at 180 degrees. this rotates as i turn the eyepiece so i assume that the eyepiece has a problem. out of focus on a star the airy rings are gratifyingly regular and central. it is quite slow[about f7] so quite forgiving in the matter of collimation. the focuser is an old pattern that is obsolete and i only have the one lens so i will have to fork out for a modern one. by the by if anyone is still using that type and can use it and the eyepiece for a project give me a shout. going free

[nicnac]

f7 eh, those EPs i mentioned before should work nice with your telescope if you are on a budget

will you be upgrading your kit at some point or are you happy with what you have?

[hes not well again]

I was thinking about getting some plossells as they do seem good value. Probably the eight inch that I have would be enough to be going on with for now. Seems a good compromise between power and size.

[tom714uk]

I was given an old homemade 8 inch newtonian in need of some tlc. It has a focusing tube which is just a 1.25 inch threaded tube. it is not home made and has an eyepeice that seems to have a 5mm focal length and is of doutbfull utility. Is it still possible to get eyepieces to fit it or will a new focuser be in order?

Just get someone to cut the right thread onto a Delos...