ED80 & GSO SV 42mm EP

[yagon]

I've got a problem with my Saxon ED80 and my GSO superview 42mm eyepiece.

To get the EP into focus, I position the focuser at the shortest possible setting. It feels like the focuser needs to go another 1 or 2 mm shorter still.

Has anyone else expereinced this problem? Is there a solution?

[janoskiss]

This is normal I think. Same thing with my 30mm SV. But the short barrel versions of the Superviews should reach focus.

[[1ponders]]

Try pulling the eyepiece out of the diagonaly a 5 mm or so and see if that makes any difference.

[janoskiss]

Paul, there is not enough in-travel, so pulling the EP out will just make it worse.

Yagon, I just checked my 30mm. Here's a solution to your problem: Unscrew the chrome barrel and the plastic spacer in from the bottom of the eyepiece. Remove plastic spacer and screw the chrome barrel back on the eyepiece. (You might have scew it on upside down to get the threads to mesh.) Now you have an extra inch or so in travel and the EP should reach focus in the ED80.

[[1ponders]]

:doh: :P I knew that. I was just checking that you did Stever :lol:

[acropolite]

I am curious to know how that EP performs inthe ED..??

[ving]

ditto... i know how to deal with not enuff outward, but inward? let us know how you go :)

[yagon]

Strange things are happening.

After getting the feedback from the forum yesterday, I tried the 42mm EP during the daytime. During the day, it came to focus with 1 or 2mm to spare on the focuser. I felt a bit sheepish about posting this thread.

Last night the clouds cleared briefly and I had about an hour of observing. But the 42mm wouldn't focus: again, I needed a 1 or 2 mm shorter tube.

I'm baffled. Nothing in my setup changed from day to night.

Can anyone offer suggestions re the cause of this?

[acropolite]

Focus on terrestrial is probably going to be a little short of infinity, which is where your focus in the night sky will be.

[yagon]

:doh:

of course - a dumb question



I'll try the above and let you know how it goes

[yagon]

OK - I've tryed to fix the EP by removing the plastic spacer, but the threads between the metal tube and the plastic spacer are different - it won't work that way.

I'll get rid of the EP and try to find a suitable replacement.

[janoskiss]

Yagon, screw the chrome barrel back on upside down, i.e., use the filter threads on the end of the barrel.

[yagon]

i tryed this - but the threads don't match - both threads are on the inside of the barrel

[janoskiss]

Maybe you are not using the right threads on the EP body, or the 42mm is different from the 30mm. I'll post some pics of my EP tonight.

[janoskiss]

Sorry I forgot to take the pics! :doh: I'll do them tomorrow.

[janoskiss]

See piccies on ED80-fying my Superview. And a correction to my earlier post: the spacer is blackened metal not plastic. Note the barrel flip in the pics.

[yagon]

It looks like the EPs are a different design - the 42mm doesn't have the same external thread on the upper piece.

I'll try to upload a photo so you can look at it.

[yagon]

photo is attached

[janoskiss]

Bummer! Maybe the middle bit unscrews into two separate pieces...:confuse2:

[yagon]

only if i use a hacksaw...

[yagon]

I've just realised that a possible explanation my inability to focus the 42mm EP is that I am slightly shortsighted in my observing eye. :rolleyes:

Could this explain my problem?

[astrojase]

yagon - are you using a diagonal or putting the ep directly into the drawtube? I have a 120x600mm refractor and use the 42mm ep (awesome FOV!!!) - it will only come to a focus if used in conjunction with a diagonal - it wont focus if placed directly into the drawtube (circumlocutory? - lol) OR, if the drawtude wont go far enough in, remove the diagonal...

[yagon]

I'm using a 2" mirror diagonal, which would lengthen the distance from the objective to the EP.

[janoskiss]

I'm short sighted too, and had the same problem with SV 30mm and ED80. (I only worked out that I could shorten the barrel of the SV 30mm after I sold the ED80. :doh: )

But you have to have a 2" diagonal to use a 2" EP. And when I was buying my 2" diagonal from AOE, they assured me it was worth getting a 2" even if it was only for my SV 30mm. They do sell the SV 30mm, the ED80 and everything else. So I think the eyesight theory has merit. But any well-thought-out design should have tolerance to accommodate some of the most common flaws in human physiology.

[astrojase]

So you can shorten the distance by removing the diagonal and putting the ep directly into the drawtube...should achieve focus then.

[ving]

interesting jase.... hope that works :)

[yagon]

i'll give it a try, but i might have to lie on my back to oberserve anything near the zenith!

[astrojase]

lol yagon - that is one drawback! you can either, a) extend the length of your tripod legs to compensate or b) get plenty of neck-rubs from the loved one...

l