I have purchased a secondhand SW ED80, i am having issues, i dont think its focusing issues, although it does look like it, i fear a collimation issue but hoping for something less serious.
I took it out for a test the other night and pointed at ETA Carina Nebula and again tonight to confirm that it wasnt dew the first time. I posted the issue on another page to which people replied its dew, it is 100% not dew.
It only seems to occur on the brighter stars, as you can see in the pics below.
I have also taken a shot of Sirius for comparison.
Image details:
ETA Carina single shots x 2, 25 sec, ISO 1600.
Sirius Single shots x 3, 1 sec, ISO 400
Gear:
Skywatcher Pro Series ED80 (Gold)
Canon 60D (Not-Modified)
Skywatcher EQ5 Pro Mount
Pic 1: ETA Carina 2 nights ago (Focused)
Pic 2: ETA Carina tonight (Focused)
Pic 3: Sirius (Focused)
Pic 4: Sirius (Unfocused)
Pic 5: ETA Carina (Same focus as pic 4)
Pic 6: Sirius (Out of focus the other way)
Pic 7: Acrux double star to show its in focus
I have and use three different ED80 scopes.
What I see looks like pinched optics ( the notches visible at the edges)
I fixed one (an older York ED80) which had similar, by easing the collimation screws...but the SW 80 - I honestly don't know - I've never had to adjust the collimation.
May be some other user can comment.
I have and use three different ED80 scopes.
What I see looks like pinched optics ( the notches visible at the edges)
I fixed one (an older York ED80) which had similar, by easing the collimation screws...but the SW 80 - I honestly don't know - I've never had to adjust the collimation.
May be some other user can comment.
Thanks for the reply Merlin,
I cleaned the lens today and noticed that there are finger prints inside on the outer edges of the glass, so someone has had it open i guess.
Does the (Pinched optics) cause that halo around the stars though?
This infers the front cell is just screwed onto the tube with no other adjustment.
I just unscrewed the cell from my ED80 and I can't see any collimating screws within the cell.
The spacers - do they intrude much into the lens???
No, collimation would not cause those halos. Did you have any optical elements - filters etc in the optical train when you imaged?
If not, then to me it feels like the objective is not assembled correctly....
This infers the front cell is just screwed onto the tube with no other adjustment.
I just unscrewed the cell from my ED80 and I can't see any collimating screws within the cell.
The spacers - do they intrude much into the lens???
No, collimation would not cause those halos. Did you have any optical elements - filters etc in the optical train when you imaged?
If not, then to me it feels like the objective is not assembled correctly....
Hi Merlin,
Have spoken to the previous owner and its possible the objectives weren't assembled correctly after cleaning.
So, perhaps the front objective is in back to front.
A bit apprehensive about opening it up, i cant find anything online to direct me.
Yes, If that was not between the 2 lens's then try it between the lens's ?
Here a pic of how the lens configuration is when in scope -
Light enters from the left , so its important the outside lens surface is ConVex as in the pic
Yes, Nik, The Double Convex objective was in back-to-front. I assume the convex's are of a different curve radius ?
There is still a slight fogging issue, tho seems like either very high humidity in Melb recently & currently I see its still averaging 90%; 'Or' maybe a slight possibility of a very thin smear/film left from cleaning ?
