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Funny fitting fiddly filter


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Just repeating my question in Deep Sky observations - I have a UHC filter that doesn't quite fit the filter threads in an ep. It has female and male threads on opposite sides, and will jam in an ep, but you can't screw another filter into it, it's a bit too small. Does anyone have a guess as to what this is threaded for?

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I'm sure years ago there was a problem like this with celestron filters only fitting celestron eyepieces, the thread was a slightly different pitch or something. I know at that time my brother had some celestron filters that just wouldnt fit any other eyepieces.

These days I would have thought it should fit, unless its a 2" filter as then you might find its SCT thread on one side ( female) and T thread on the other (male).

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Yeah, I'm not sure who I could sell it to. The fellow who gave it to me is an American astronomer friend I've met at star parties, and online. He had received the filter along with some other kit, and had never screwed it into an ep. He had held it up in front of an ep to compare with his Lumicon Deep Sky filter, and considered them equivalent. He sent it to me on the understanding that I will bring a bottle of Grant's to this year's star party, again. He didn't want the bottle, just a drink or two. He's a very nice guy, as you can see.

I may just pop the glass out of my blue filter and jam the UHC filter into it. I hardly use the blue filter, and if I ever really need one, I can pick one up for less that $20. A UHC filter costs at least $100.

When I used the UHC filter on M41, it made a considerable difference to the darkness of the sky behind the nebula. I would like to try it on other targets now.

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Yeah, I'm not sure who I could sell it to. The fellow who gave it to me is an American astronomer friend I've met at star parties, and online. He had received the filter along with some other kit, and had never screwed it into an ep. He had held it up in front of an ep to compare with his Lumicon Deep Sky filter, and considered them equivalent. He sent it to me on the understanding that I will bring a bottle of Grant's to this year's star party, again. He didn't want the bottle, just a drink or two. He's a very nice guy, as you can see.

I may just pop the glass out of my blue filter and jam the UHC filter into it. I hardly use the blue filter, and if I ever really need one, I can pick one up for less that $20. A UHC filter costs at least $100.

When I used the UHC filter on M41, it made a considerable difference to the darkness of the sky behind the nebula. I would like to try it on other targets now.

Hope Grant doesn't mind!

Hopefully the filter will fit in a normal sized filter holder, that should sort it out.

Captain Chaos

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on the understanding that I will bring a bottle of Grant's to this year's star party, again. He didn't want the bottle, just a drink or two. He's a very nice guy, as you can see.

Hope Grant doesn't mind!

Hopefully the filter will fit in a normal sized filter holder, that should sort it out.

Captain Chaos

No, Grant's a very nice guy, too.

Sorry, don't quite understand "normal sized filter holder." The problem is that it doesn't, or am I just being dense again? :insects1:

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Well, the filters that I have are made with a male thread on the EP fitting end and a female thread at the other end of the same size. The glass bit fits inside the threaded hole and stops where the bore gets smaller. To hold the glass in there is a tiny ring with a male thread on it that screws in on top of the glass. If you can take a filter that you rarely use and unscrew the ring (hold the glass bit between thumb and forefinger and turn the holder) you could perhaps swap two glass bits so that your nice new UHT is in the holder that fits stuff, and the one you don't like is in the holder that doesn't fit anything. I would caution against getting the tiny rings muddled as that could mess you up again.

Captain Chaos

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No need to get greasy fingers all over the glass - if you have iso/prop you can de-grease your fingers first.

Great suggestion of swapping glass holders CC :thumbright: as long as the glass fits eh?

I'll leave the optics cleaning Q to someone else. There's another post from a couple of weeks back covering optics cleaning that I keep meaning to read - must find it.

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These filters look as though they'd go in a dishwasher. Anybody tried that?

I think a lot of dish washer soaps (powder/tabs etc) are caustic so better be careful. I cleaned my orange filter with mild warm soapy water and rinsed with tap water and then distilled water - came up a treat.

And I think filters benefit more from individual attention. A dishwasher would probably just throw it about, and it might get scratched. I often use normal washing up liquid and fingers on my glasses - crystal clear results! Tissues leave bits... (couldn't find the nerdy specs smilie. I'll leave that to the smilie whizkid, Steve!)

Andrew

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These filters look as though they'd go in a dishwasher. Anybody tried that?

I think a lot of dish washer soaps (powder/tabs etc) are caustic so better be careful. I cleaned my orange filter with mild warm soapy water and rinsed with tap water and then distilled water - came up a treat.

And I think filters benefit more from individual attention. A dishwasher would probably just throw it about, and it might get scratched. I often use normal washing up liquid and fingers on my glasses - crystal clear results! Tissues leave bits... (couldn't find the nerdy specs smilie. I'll leave that to the smilie whizkid, Steve!)

Andrew

I don't think CC was being serious. I swear that the detergent in my dishwasher dulls my knives. I prefer to wash them by hand, but Mrs. W keeps putting them in the dishwasher, and I keep running them over the steel again and again. Maybe I'll try it with the blue filter before I take the glass out.

Managed to get a greasy fingermark on the filter while trying to get it out of the ep. (I tried to protect it with a tissue...) My lens pen will take care of that very nicely. A few of my coloured filters had acquired various marks, including the orange filter that I dropped on wet grass, stood on, and picked up between my fingers. I cleaned it and a couple others with the lens pen. It's fine now.

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Got a lens pen cheap off fleabay the other day - my 17mmPL cleaned up nice. I haven't got round to the filters yet but I'm glad I'm not the only one who managed to drop a filter. My NG filter got a quick rinse after the incident - will inspect later (lens pen in hand).

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Baader filters have "ultra hard and durable ion-beam hardened coatings, may be cleaned anytime without fear".

Should be cleanable then, though maybe not in a dishwasher as the stuff in the "soap" contains chemicals that remove a layer off your stainless steel cutlery to make it shiny again. What WH said is true, it does blunt sharp knives.

Gordon, if she gets full of IPA she'll have her pocket money reduced accordingly.

Captain Chaos

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