Cleaning the Primary on a Z10

[helicon]

Well, after four years I finally did it. I dropped the mirror cell out of the bottom of my Z10 and confronted a dusty mirror. Even though I cover both ends of the OTA I found the amount of dust frightening, plus noticed that there were about 5 pine needles around the base of the cell (from the Monterey pine near to my observing deck)!

Nevertheless, the procedure was very straightforward and could be followed by anyone with a Z8 to a Z12.

1) First, take some blue painters tape and mark a spot on the OTA where you will be removing the first screw holding the cell.

2) Mark the cell with the blue painters tape at the corresponding spot.

3) Gently remove the 6 Phillips head screws which hold the cell in the OTA.

4) Make sure before you remove the screws that the OTA is lying on a table or other flat surface.

5) Slide the cell out of the OTA - should come out very easily.

6) Clean the edges of the cell (below the mirror) with some Q-tips or a soft camel hair brush to remove any lodged dust or debris.

7) Place the cell in the sink and flood the surface of the mirror with distilled water.

8) Drop a tiny amount of dishwashing liquid onto the mirror, flood with a little bit more of the water so the suds spread out.

9) Using soft tissue such as kleenex gently rub the mirror in one direction in horizontal lines.

10) After this the mirror should be clean. Check and make sure any tough to remove deposits such as tree sap are gone, if not gently remove.

11) Flood the mirror once again with distilled water to remove any remaining soap.

12) Let dry, when dry, gently brush with a camel hair brush to remove any remaining dust.

13) Let the cell sit out to dry.

14) When fully dried out, carefully remount the cell into the bottom of the OTA, lining up the screw holes. If you used the tape, this is very easy.

15) Carefully re-insert the Phillips head screws and screw them in one by one with a screwdriver

16) Enjoy what it is like to have a new mirror once again!

So that's it - helicon's method of cleaning a Zhumell mirror to a brilliant and pristine state!

And the result?

[UlteriorModem]

Good job, yea it's not all that hard when you get right down to it. Hardest part is the re-collimation that follows.

But.... Pine needles! My Arch nemesis! Wait till one falls into the objective of a refractor!

[helicon]

Yeah I was shocked to see pine needles in there - fell in on a breezy evening I presume while I was out under the stars.

[kt4hx]

You never know what might find its way in there! My process varies just slightly from yours Michael. I flood my mirror under the faucet with a steady stream for about a minute to dislodge any dust and particles. Then I reduce the flow of water to a steady trickle and add my plain Dawn (blue). I then swirl my finger tips over the surface with only the lightest of touches. Using your fingers as long as you don't press and as along as water/detergent is present does not damage. Personally I prefer the tactile feel of my finger tips over cotton or other materials as I can detect a stubborn particle easier. Once I have done this for a little bit, then I increase the flow of tap water to flood off any remaining detergent. Then turn the tap water off and flood the surface with a gallon of distilled water. I then lean the mirror up at a steep angle on the counter to allow drops to run off. Any remaining ones I will use the corner of a paper towel to pull up, but not rub the towel over the surface.

There are variations to the process which can all work well. The key here is to not be afraid of cleaning a mirror. As long as one approaches the task prepared and know their steps, it can be done with no fear. Coatings are tougher than most people realize, but of course you don't want to overdo it!

I basically follow the procedure used in this video from Optic Wave Labs. I have done this with all my mirrors, 10, 12 and 17.5 inch.

[bladekeeper]

Nice going, Michael!

Man, I've got to do my AD12 again. It has been a few years since I've cleaned it. On Sunday when I set up for the SN viewing, I did a no-no and shined my headlamp down in there. Holy cow!

I need to do the secondary as well. It has never been cleaned and it looks like somebody sneezed on it.

Likely this weekend...

[prowler75]

Nice job, Michael.
It is about time for me to do a cleaning on the Z12 too. I noticed the other week that the shower cap I keep over the primary end has a couple of holes in it so time to replace that as well.
I use a similar technique, but like Alan I prefer to use my fingers (after thoroughly washing my hand of course).
Tom’s right, the biggest pain is re-collimating everything!

[kt4hx]

Nice job, Michael.
It is about time for me to do a cleaning on the Z12 too. I noticed the other week that the shower cap I keep over the primary end has a couple of holes in it so time to replace that as well.
I use a similar technique, but like Alan I prefer to use my fingers (after thoroughly washing my hand of course).
Tom’s right, the biggest pain is re-collimating everything!

Thanks for reminding me Craig - yes washing the hands thoroughly before. Don't be picking your nose or eating fried chicken (especially after picking your nose) then go straight to the mirror cleaning!

I find that the shower caps on both ends of mine over time develop holes and that the elastic finally gives up the ghost as well. So they are replaced after a a period of time.

Actually I find doing the secondary more of a PITA than the primary, since Bryan mentioned that.

[UlteriorModem]

I did a no-no and shined my headlamp down in there. Holy cow!

Tsk Tsk… you of all people!

[Richard]

So did it improve the scope, I did the same with my 8 inch but did not notice any improvement

[helicon]

Last night was cloudy so no "first light" with the freshly cleaned mirror. It was really dusty, as well. So I'm pretty sure there will be a 20-30% difference in light transmission. I was going to try for a few objects such as NGC 3077, the galaxy located close to M81.

[kt4hx]

Last night was cloudy so no "first light" with the freshly cleaned mirror. It was really dusty, as well. So I'm pretty sure there will be a 20-30% difference in light transmission. I was going to try for a few objects such as NGC 3077, the galaxy located close to M81.

That is the thing, the true results depend on the condition of the mirror before cleaning. As optics slowly become degraded due to accumulation of dust and other particulates, we adjust to it and may not truly perceive the degradation as such. While the results may often be subtle, the subtleties can frequently make or break an observation if going after threshold objects.

Good luck with NGC 3077 et al Michael. It is a nice galaxy forming a pretty triangular grouping with M81/82.

[helicon]

I can usually see NGC 3077 as a puff of light. However, over the past few sessions in UM dating back about a year and a half or so it has been invisible. Hoping that it will be visible again.

[UlteriorModem]

Last night was cloudy so no "first light" with the freshly cleaned mirror.

Of course what did you expect!

I cleaned the glass on my camera and the forecast went from clear Friday and Saturday to mostly cloudy... just like that!