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Post by Deleted on Jan 24, 2014 0:18:55 GMT
Hi all thought this one could do with some suggestions. To me there are three areas,
1. Dust on the ccd.
2. Dust on the glass protecting the CCD
3. Dust on the Filter/lens.
So the questions are, how to know which is the problem and what is the best way to clean them?
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Post by Dragon Man on Jan 24, 2014 11:58:28 GMT
Carl, you can usually tell where the dust is by its focus. Is it a big blurry circle or a sharp black dot? A sharp black dot will tell you the dust particle is on the Sensor (rare because the sensor is usually protected by an optical window but it still happens sometimes). If it is a smallish faint circle with a definite edge it sounds like it is on the Optical window (the glass covering and protecting the sensor). If it is a largish faint blur it is probably on a filter of Focal reducer/Barlow. Dust particles on the Primary lens of a Refractor, the corrector plate of an SCT or a Primary mirror of a reflector don't show up. The 2 methods I use to clean my sensors optical window, filters, and Focal Reducer is either by cotton bud (ear cleaner) and Isopropyl Alcohol, or a Lens Pen. If I know for sure that it is a dust particle on the sensor window, and I can see it, I will very slightly dampen a cotton bud with some Iso Alcohol and gently wipe it off by wiping the cotton bud from one side of the sensor to the other, ONCE. If I need to wipe it twice I use the other end of the cotton bud. Never the same end twice. The first wipe may have picked up some tiny dust particles and by scraping it across the surface again may make those tiny dust particles scratch the surface. That's all I do and it always works. If the sensor has a smear on it I use the cotton bud and Alcohol then a lens Pen. I move the lens pen in a fast circular pattern using light pressure for about 2 seconds, but only after I have removed any possible dust with the cotton bud and alcohol. Otherwise the lens pen with grind any dust particles around and around on the surface. On filters, Focal Reducers, and barlows, I use the Iso Alcohol and cotton bud to remove the dust, then the lens pen after the alcohol has evaporated. I hope that helps
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Post by Dragon Man on Jan 24, 2014 13:15:18 GMT
Thanks Dave.
Another tip for discovering where the dust bunnies are:
Step 1: Point your scope at a moderately dull surface like a distant wall or some light polluted sky.
Step 2: Play with focus, brightness contrast etc until you can easily see the dust bunnies.
Step 3: Notice where the dust bunnies are on your monitor. (mark them with a whiteboard marker if you want to).
Step 4: Remove the camera, and starting at the furthest item from the sensor, usually a filter attached to the end of the Focal Reducer or Barlow, without rotating the camera or any other object attached, rotate the filter about 1/4 of a turn, then put the camera back into the scope at the same orientation it was at before.
Question: Did the dust bunnies move by 1/4 of a turn on your monitor? - If so, that is the surface they are on. - If not, remove that filter, refocus and try the next item, usually the Focal Reducer. Turn it 1/4 of a turn, but keep the camera orientation the same.
Question: Did the dust bunnies move by 1/4 of a turn on your monitor this time? - If so, that is the surface they are on. - If not, remove the focal reducer, refocus and rotate the camera in the focuser by 1/4 turn.
Question: Did the dust bunnies move by 1/4 of a turn on your monitor this time? - If so, the dust is on the optical window or sensor. - If not, you are sunk!
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Post by Deleted on Jan 24, 2014 15:55:05 GMT
Cheers Ken just the right info. When I was last out and turned to the moon there was a nest of bunnies in the top corner. Judging by your examples they are on the glass in front of the sensor.
Thanks again.
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Post by Deleted on Jan 30, 2014 14:23:13 GMT
I know basically everyone says never clean the front lens on your scope... But im pretty sure they weren't talking about a scope as dirty as mine! Have a look. I tested how it looks when cleaned on a wee section. Im pretty sure i need to clean the full thing! Opinions?
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Post by Deleted on Jan 30, 2014 14:42:03 GMT
I know basically everyone says never clean the front lens on your scope... But im pretty sure they weren't talking about a scope as dirty as mine! Have a look. I tested how it looks when cleaned on a wee section. Im pretty sure i need to clean the full thing! Opinions? Gordon Bennett Chris, where do you store it man Okay, I had the same issue recently and despite all the excellent advice not to clean it I did anyway! All I can say is if you want to feel pressure like never before go ahead... Spent hours on mine and had it stripped down completely and the concentration this took was immense. That said, and though I've not had much chance since to test properly I seem to have got away with it. I have checked collimation since and this too looks to be fine so I've not touched it but I really need to get a bit more use first before I'm completely satisfied.
It may be for you though you could get away with just the front of the corrector plate, is this inside okay? Mine had dust and bad watermarks from too much humidity and I just could not resist giving it a go.
So I say, it's doable but not for the faint hearted
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Post by Deleted on Jan 30, 2014 14:52:08 GMT
I use compressed air to blow off the bunnies. For stubborn stuck on dust I use distilled water
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Post by Deleted on Jan 30, 2014 14:55:50 GMT
Haha it stays setup in my livingroom but with all the dew and random rain drops etc (maybe pollen too?) Its gained a layer of stuff that cant be brushed/blown off. The inside if fine from what i can tell... and was not planing on removing the corrector! just clean the front a little. I can imagine how annoying a job it will be...but i think it really needs it! Was planing on just using cotton buds and that mad alcohol stuff. Seems to work fine on my eyepieces and filters etc.
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Post by Deleted on Jan 30, 2014 18:00:55 GMT
Get a camel hair brush or lens pen to lightly remove dust in conjunction to the compressed air.
If it still will not come off, use alcohol dilute it 50/50 with distilled water, dip Kleenex into the alcohol solution a VERY Lightly go over surface followed by compressed air to assist drying and to remove any tissue fibers
And as a last resort
If you have bad streaks an smears and must clean the corrector with liquid. Try the following at your own risk
Warning do not do this on lenses or reducers with multiple cells, you could get water and soap between the cells and never get it out. If there is a chance that the lens is not completely sealed don't do it.
Try a spray bottle with distilled water, then use compressed air to blow off the excess water. If that does not clean it off, make a solution of dish soap and distilled water (only a couple of drops of soap). Spray the soap water solution on the collector very lightly and use a Kleenex (unsented) to lightly clean the surface. Do not apply any pressure, just enough spread the solution around. Then rinse with distilled water and dry it off with compressed air.
Be very careful not to use too much solution or water, it could leak inside the scope. Use very sparingly!
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Post by Dragon Man on Jan 31, 2014 7:04:37 GMT
Good advice Lee. And never ever rub hard when cleaning optics. You will actually rub off the Coatings. I've done it
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Post by Deleted on Jan 31, 2014 10:12:58 GMT
Cheers for the advice I went ahead and cleaned it. Its not 100% perfect but hey it was far from perfect before i started Looks much better now!
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