Hello and thanks to all who can help with this. I'm using a Meade 16" lightbridge and I took my 8mm Ethos out the other night full of excitement, all ready to look at Saturn, only to find out the travel on the focuser was not long enough to get the eyepiece into focus. With the focuser all the way out the eyepiece was still showing a little doughnut, perhaps another turn and we'd have been good, but alas! Any suggestions on how to fix this situation? BTW I was using the eyepiece as a 2", not with the 1.25" coupler. Any and all help would be very much appreciated! Thanks so much to all!
NEED HELP WITH MY 8MM ETHOS!
Started by aphexeffect, 03/07/2010 11:53PM
Posted 03/07/2010 11:53PM
Opening Post
Posted 03/08/2010 12:28AM
#2
Bruce,
You may try a few different things, depending on how close to focus it is coming.
1) Lower your mirror in your mirror cell by turning the collimation screws all the way out. This may give you a few millimeters depending on the position of the screws. Be sure to re-align your primary after taking care to not turn the screws in a ton.
2) Instead of seating your eyepiece completely down in the focuser, tighten the eyepiece into the focus tube with it "out" just a bit. Again, you may be able to gain a few mm of travel that way. I know Televue uses that undercut groove on their eyepieces to help prevent them from falling out, so I'm not sure how well that would work.
If you could do both, you could gain quite a bit of back focus and possibly make it workable.
If all else fails, send it to me and I'll see if it works in my scope!
Anthony
You may try a few different things, depending on how close to focus it is coming.
1) Lower your mirror in your mirror cell by turning the collimation screws all the way out. This may give you a few millimeters depending on the position of the screws. Be sure to re-align your primary after taking care to not turn the screws in a ton.
2) Instead of seating your eyepiece completely down in the focuser, tighten the eyepiece into the focus tube with it "out" just a bit. Again, you may be able to gain a few mm of travel that way. I know Televue uses that undercut groove on their eyepieces to help prevent them from falling out, so I'm not sure how well that would work.
If you could do both, you could gain quite a bit of back focus and possibly make it workable.
If all else fails, send it to me and I'll see if it works in my scope!
Anthony
Posted 03/08/2010 01:13AM
#3
The quick fix is to use it with a 1.25" adapter, that will allow it to focus. The better solution is to get a baader 28mm finetuning ring and a 2" parfocal ring. That way the eyepiece will fit securely in the focuser and the parfocal ring can be set so the focus point is close to your other eyepices. I had a 16" Lightbridge and 8mm ethos and that was the best solution I found. You can get both parts from Agena Astro products for under $25 including shipping. Better than buying the overpriced televue barrel extension (which should come with the eyepiece considering the price!)
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