Cleaning Meade 5000 SWA 24mm
Posted 20 January 2013 - 10:37 PM
Posted 21 January 2013 - 11:22 AM
Posted 21 January 2013 - 11:58 AM
Posted 21 January 2013 - 08:52 PM
I wonder that myself. Perhaps some temperature extremes resulted (from first owner) in some internal fogging and leftover residue after drying out?
Regardless, I dove into it tonight. I'll have to say I have a new respect for lens makers after this. I didn't think I would be able to get it back together after taking it apart. I thought, "what in the world have I done." I had a sinking feeling that I had ruined my eyepiece. I took a deep breath and told myself I could do it. I had put all the lenses in the order exactly in the same orientation that I took them out, and had them on a microfiber towel (including all the spacers). One lens at a time I took them to the sink and cleaned them with a tiny drop of dawn in distilled water, cotton swabs (several), and a final rinse with only distilled water. One at a time I carefully put them back down that seemingly long eyepiece housing. I literally had to drop the first one in. The way I handled that is by placing a thin lens towel (microfiber) in the bottom to cushion the blow so to speak. The two widest lenses I had to just place evenly over the barrel and drop evenly and carefully, and hope for the best. I took my time and it worked out ok. I believe the trapped air offers some measure of cushion as the lens drops and air is forced out (as long as it is dropped evenly). Lastly, the final two elements from what I can tell actually touch each other. One is convex, and the other concave. This is one of the areas I was seeing a tiny bit of residue. In fact, there appears to be slight wear in this area that looks like a very thin ring approximately 1/4 inch in diameter. This is MUCH less noticeable now after cleaning. The way I handled this one was to blow of the lens towel and lay a corner of it across the concave (bottom lens). I carefully placed the final lens (convex side) and carefully slid out the lens towel.
Overall, now that it is over I am very glad I did it. Strictly speaking from an appearance standpoint the optics look much much better. Basically new except for that very thin ring I spoke of, which now you really really have to look closely to see. Even then it is barely noticeable.
HOWEVER, I do not recommend anyone try this unless you really know what you are doing, and unless you really really really need to. Point blank, I was lucky. Lucky I didn't scratch one of the lenses "dropping" them in the barrel. Lucky I didn't scratch one of the lenses using the lens towel as a slider. Lucky I didn't drop one of the lenses in the sink. I'm telling you, I was just plain lucky. Take extreme care if you try this. I don't know that I will ever do it again.
If I had it to do over, I might have tried to put the entire assembly together, standing up on a lens towel, then place the housing over the entire assembly, and carefully lift from the bottom with the towel to position eye lens. Thinking back, that might have been the best way to do it but that would be very tricky as well.
Posted 22 January 2013 - 11:45 AM