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Diagonal dropped on main mirror - ouch!
You are unlikely to notice any image degradation. Paint them black.
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#2
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Diagonal dropped on main mirror - ouch!
C.W. Thomas wrote:
My boys accidentally knocked over my 12.5 inch F7 newtonian. In picking it up, the Diagonal fell and struck the face of the main mirror (pyrex) leaving a couple of small "craters" about 0.2" and 0.1" in length. Unfortunately, not in the center of the mirror... Can I paint over these/ black them out with something without there being major ramifications to the mirrors quality? Yes. I am concerned about weather this has caused stress areas surrounding the pits that are signifigantly larger than the pits themselves. Does anybody know anything about pyrex and stresses induced by impacts with diagonals? You don't want to get water or methanol in the fresh crack. Small molecules can encourage stress corrosion cracking. Beyond that something along the lines of epoxy or DPX ought to seal a small defect and then spot it with matt black. It will only be a tiny fraction of the area of the mirror that is lost. Regards, Martin Brown |
#3
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Diagonal dropped on main mirror - ouch!
I would take it outside tonight and test it's viewing on mars or something
else. I would think that small a nick on that big a mirror would amount to next to nothing. -- The Lone Sidewalk Astronomer of Rosamond Telescope Buyers FAQ http://home.inreach.com/starlord Astronomy Net Online Gift Shop http://www.cafepress.com/astronomy_net In Garden Online Gift Shop http://www.cafepress.com/ingarden Blast Off Online Gift Shop http://www.cafepress.com/starlords "C.W. Thomas" wrote in message ... My boys accidentally knocked over my 12.5 inch F7 newtonian. In picking it up, the Diagonal fell and struck the face of the main mirror (pyrex) leaving a couple of small "craters" about 0.2" and 0.1" in length. Unfortunately, not in the center of the mirror... Can I paint over these/ black them out with something without there being major ramifications to the mirrors quality? I am concerned about weather this has caused stress areas surrounding the pits that are signifigantly larger than the pits themselves. Does anybody know anything about pyrex and stresses induced by impacts with diagonals? Thanks in advance; C.W. Thomas |
#4
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Diagonal dropped on main mirror - ouch!
My boys accidentally knocked over my 12.5 inch F7 newtonian. In picking it
up, the Diagonal fell and struck the face of the main mirror (pyrex) leaving a couple of small "craters" about 0.2" and 0.1" in length. Unfortunately, not in the center of the mirror... Can I paint over these/ black them out with something without there being major ramifications to the mirrors quality? I am concerned about weather this has caused stress areas surrounding the pits that are signifigantly larger than the pits themselves. Does anybody know anything about pyrex and stresses induced by impacts with diagonals? Thanks in advance; C.W. Thomas |
#5
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Diagonal dropped on main mirror - ouch!
C.W. Thomas wrote:
My boys accidentally knocked over my 12.5 inch F7 newtonian. In picking it up, the Diagonal fell and struck the face of the main mirror (pyrex) leaving a couple of small "craters" about 0.2" and 0.1" in length. Unfortunately, not in the center of the mirror... Can I paint over these/ black them out with something without there being major ramifications to the mirrors quality? I am concerned about weather this has caused stress areas surrounding the pits that are signifigantly larger than the pits themselves. Does anybody know anything about pyrex and stresses induced by impacts with diagonals? Thanks in advance; C.W. Thomas Ouch is right. However all is not lost. As another poster stated you should seal the chips and place a spot of black paint on the seal. As to interfering with observation, some time ago mention was made of a major instrument that has bullet holes in the main mirror that was still in operation. My only concern would be for any scratches on the silvering material or its protective covering. This might be a problem at sometime in the future but not now. Dave N |
#6
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Diagonal dropped on main mirror - ouch!
C.W. Thomas wrote:
My boys accidentally knocked over my 12.5 inch F7 newtonian. In picking it up, the Diagonal fell and struck the face of the main mirror (pyrex) leaving a couple of small "craters" about 0.2" and 0.1" in length. Unfortunately, not in the center of the mirror... Can I paint over these/ black them out with something without there being major ramifications to the mirrors quality? I am concerned about weather this has caused stress areas surrounding the pits that are signifigantly larger than the pits themselves. Does anybody know anything about pyrex and stresses induced by impacts with diagonals? Worse things have happened; you should be alright... "one February night in 1970 a McDonald Observatory employee [...] suffered a breakdown and carried a pistol to the observing floor of the 107-inch telescope. He fired a shot at his supervisor, and then unloaded the rest of the clip into the primary mirror. Happily, fused silica is more resilent than ordinary glass, and the big mirror did not break. The craters have been bored out and painted black to reduce any light-scattering effect, and the end result is simply a slight reduction in the efficiency of the telescope. It is now the equivalent of a 106-inch telescope." photos and commentry at http://www.astr.ua.edu/keel/telescopes/mcdonald.html |
#7
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Diagonal dropped on main mirror - ouch!
Can I paint over these/ black them out with something without there being
major ramifications to the mirrors quality? Yes. It will be like a very small obstruction. You won't see much change if any. I am concerned about weather this has caused stress areas surrounding the pits that are signifigantly larger than the pits themselves. I wouldn't worry about it. If it gives you peace of mind, you might take it to the folks that repair windshield chips, but I wouldn't worry about it. Clear Skies Chuck Taylor Do you observe the moon? If so, try http://groups.yahoo.com/group/lunar-observing/ If you enjoy optics, try http://groups.yahoo.com/group/ATM_Optics_Software/ ********************************************* |
#8
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Diagonal dropped on main mirror - ouch!
"C.W. Thomas" wrote in message ...
My boys accidentally knocked over my 12.5 inch F7 newtonian. In picking it up, the Diagonal fell and struck the face of the main mirror (pyrex) leaving a couple of small "craters" about 0.2" and 0.1" in length. Have them grind you a new mirror -- Hilton Evans --------------------------------------------------------------- Lon -71° 04' 35.3" Lat +42° 11' 06.7" --------------------------------------------------------------- Webcam Astroimaging http://home.earthlink.net/~hiltoneva...troimaging.htm --------------------------------------------------------------- ChemPen Chemical Structure Software http://www.chempensoftware.com |
#9
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Diagonal dropped on main mirror - ouch!
them who?
Hilton Evans wrote: "C.W. Thomas" wrote in message ... My boys accidentally knocked over my 12.5 inch F7 newtonian. In picking it up, the Diagonal fell and struck the face of the main mirror (pyrex) leaving a couple of small "craters" about 0.2" and 0.1" in length. Have them grind you a new mirror -- Hilton Evans --------------------------------------------------------------- Lon -71° 04' 35.3" Lat +42° 11' 06.7" --------------------------------------------------------------- Webcam Astroimaging http://home.earthlink.net/~hiltoneva...troimaging.htm --------------------------------------------------------------- ChemPen Chemical Structure Software http://www.chempensoftware.com |
#10
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Diagonal dropped on main mirror - ouch!
The perps.
Hint: read the first two words in the C.W. Thomas' first sentence. -- Hilton Evans --------------------------------------------------------------- Lon -71° 04' 35.3" Lat +42° 11' 06.7" --------------------------------------------------------------- Webcam Astroimaging http://home.earthlink.net/~hiltoneva...troimaging.htm --------------------------------------------------------------- ChemPen Chemical Structure Software http://www.chempensoftware.com "Mild One" wrote in message ... them who? Hilton Evans wrote: "C.W. Thomas" wrote in message ... My boys accidentally knocked over my 12.5 inch F7 newtonian. In picking it up, the Diagonal fell and struck the face of the main mirror (pyrex) leaving a couple of small "craters" about 0.2" and 0.1" in length. Have them grind you a new mirror -- Hilton Evans --------------------------------------------------------------- Lon -71° 04' 35.3" Lat +42° 11' 06.7" --------------------------------------------------------------- Webcam Astroimaging http://home.earthlink.net/~hiltoneva...troimaging.htm --------------------------------------------------------------- ChemPen Chemical Structure Software http://www.chempensoftware.com |
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