RE: [Utah-astronomy] Re: Utah County Harmons
I have a few, maybe 10 pieces left. As Joe mentioned they are $4 and are about 4.5" square. You can call me at work 961-3253 or home 544-7705 if you want some. Dave -----Original Message----- From: Joe Borgione [mailto:jborgion@xmission.com] Sent: Thursday, June 06, 2002 11:36 AM To: utah-astronomy@mailman.xmission.com Subject: RE: [Utah-astronomy] Re: Utah County Harmons I was able to purchase a couple of pieces from Dave Dunn, who also subscribes to this list. He'll probably respond before long, as he responded to my query about it last week or so here; I don't know how much material he has stockpiled, but he was selling a 4.5 inch square for $4.00. As far as I know, the Baader film is top of the line, and preferred by many. I'm not sure what Tuthill sells or how it compares, although, I'll lay odds somebody on this list can fill us in. Knowing Tuthills reputation, his material his excellant as well. Joe Borgione -------------------
Joe, where did you get the Baader film??? Locally? Price? Thank you VERY much. Is this comparable to mylar like Tuthill sells? Jim Stitley
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As a lot of people re-sell mylar, usually without a copy of the manufacturer's safety precautions, I thought it might be good to remind everyone using mylar: ALWAYS check it for pinholes before use. If you spot any, do not use it until you've closed the hole with a small piece of opaque tape, or a drop of lacquer. White-Out works well for this. The tape or lacquer will not harm the image at all. The filter won't have to be replaced until it looks like a polka-dot pattern, in fact. If the hole does not go all the way through the material, but is just a spot where the aluminum has come off the substrate, you can opaque it with a permanent black marker. Usually two or three "touch-ups" are required to get the ink opaque enough. If the sight of the dots offends you, do it on the back side. Chuck __________________________________________________ Do You Yahoo!? Yahoo! - Official partner of 2002 FIFA World Cup http://fifaworldcup.yahoo.com
Great reminder ! --- Chuck Hards <chuckhards@yahoo.com> wrote:
As a lot of people re-sell mylar, usually without a copy of the manufacturer's safety precautions, I thought it might be good to remind everyone using mylar:
ALWAYS check it for pinholes before use. If you spot any, do not use it until you've closed the hole with a small piece of opaque tape, or a drop of lacquer. White-Out works well for this. The tape or lacquer will not harm the image at all. The filter won't have to be replaced until it looks like a polka-dot pattern, in fact.
If the hole does not go all the way through the material, but is just a spot where the aluminum has come off the substrate, you can opaque it with a permanent black marker. Usually two or three "touch-ups" are required to get the ink opaque enough.
If the sight of the dots offends you, do it on the back side.
Chuck
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Chuck, I know this is the standard safety warning, but it has never made any sense to me. If the pinhole is 1/100 inch (.010") in diameter, and it is in a filter that is 70 mm in diameter for a bino, then the pinhole represents only .00015% of the area. This is a miniscule increase in the energy transmitted. If there were 100 pinholes, the area would still be only .015% of the total. I have actually heard some folks say that the pinholes did NOT matter because they were so small. Your opinion? Brent --- Chuck Hards <chuckhards@yahoo.com> wrote:
As a lot of people re-sell mylar, usually without a copy of the manufacturer's safety precautions, I thought it might be good to remind everyone using mylar:
ALWAYS check it for pinholes before use. If you spot any, do not use it until you've closed the hole with a small piece of opaque tape, or a drop of lacquer. White-Out works well for this. The tape or lacquer will not harm the image at all. The filter won't have to be replaced until it looks like a polka-dot pattern, in fact.
If the hole does not go all the way through the material, but is just a spot where the aluminum has come off the substrate, you can opaque it with a permanent black marker. Usually two or three "touch-ups" are required to get the ink opaque enough.
If the sight of the dots offends you, do it on the back side.
Chuck
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Brent: Pinholes do not come in a "standard size"; indeed for the hole size you mention, you are quite correct in that the throughput is miniscule. But if the hole is just a bit larger, say .050" (4x the unfiltered area of a .010" hole), then I think it's time to get concerned, especially when the eye will be at the eyepiece for an extended period. To err on the side of caution, if you don't have a measuring loupe, just opaque them all and don't worry about it. Safety aside, pinholes can have a harmful effect on contrast. Chuck --- Brent Watson <brentjwatson@yahoo.com> wrote:
Chuck,
I know this is the standard safety warning, but it has never made any sense to me. If the pinhole is 1/100 inch (.010") in diameter, and it is in a filter that is 70 mm in diameter for a bino, then the pinhole represents only .00015% of the area. This is a miniscule increase in the energy transmitted. If there were 100 pinholes, the area would still be only .015% of the total.
I have actually heard some folks say that the pinholes did NOT matter because they were so small.
Your opinion?
Brent
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Chuck, I agre - err on the safe side. I just like to dig a bit deeper. Brent --- Chuck Hards <chuckhards@yahoo.com> wrote:
Brent:
Pinholes do not come in a "standard size"; indeed for the hole size you mention, you are quite correct in that the throughput is miniscule.
But if the hole is just a bit larger, say .050" (4x the unfiltered area of a .010" hole), then I think it's time to get concerned, especially when the eye will be at the eyepiece for an extended period.
To err on the side of caution, if you don't have a measuring loupe, just opaque them all and don't worry about it.
Safety aside, pinholes can have a harmful effect on contrast.
Chuck
--- Brent Watson <brentjwatson@yahoo.com> wrote:
Chuck,
I know this is the standard safety warning, but it has never made any sense to me. If the pinhole is 1/100 inch (.010") in diameter, and it is in a filter that is 70 mm in diameter for a bino, then the pinhole represents only .00015% of the area. This is a miniscule increase in the energy transmitted. If there were 100 pinholes, the area would still be only .015% of the total.
I have actually heard some folks say that the pinholes did NOT matter because they were so small.
Your opinion?
Brent
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Hi Brent: Keep on digging, you perform a valuable service. Amateur astronomers display a variety of practices, and we sometimes tend to do things "because it's always been done like that". Always better to know why, than "just because"...sometimes a little investigation can seperate the myths from the facts. You've been doing this longer than I (34 yrs. this yr.) and you still manage to teach me a thing or two once in a while! C. --- Brent Watson <brentjwatson@yahoo.com> wrote:
Chuck,
I agre - err on the safe side. I just like to dig a bit deeper.
Brent
--- Chuck Hards <chuckhards@yahoo.com> wrote:
Brent:
Pinholes do not come in a "standard size"; indeed for the hole size you mention, you are quite correct in that the throughput is miniscule.
But if the hole is just a bit larger, say .050" (4x the unfiltered area of a .010" hole), then I think it's time to get concerned, especially when the eye will be at the eyepiece for an extended period.
To err on the side of caution, if you don't have a measuring loupe, just opaque them all and don't worry about it.
Safety aside, pinholes can have a harmful effect on contrast.
Chuck
--- Brent Watson <brentjwatson@yahoo.com> wrote:
Chuck,
I know this is the standard safety warning, but it has never made any sense to me. If the pinhole is 1/100 inch (.010") in diameter, and it is in a filter that is 70 mm in diameter for a bino, then the pinhole represents only .00015% of the area. This is a miniscule increase in the energy transmitted. If there were 100 pinholes, the area would still be only .015% of the total.
I have actually heard some folks say that the pinholes did NOT matter because they were so small.
Your opinion?
Brent
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This is good advice Chuck. I prefer the Baader film too. Over the last three or four years I have purchased a few sheets of it from Astro-Physics. If people will visit the Astro-physics web site they have some good information and instructions on how to use it. If you have an odd size or irregular shape you can use the poster board method that they describe. It actually works pretty well and with care it can look pretty nice too. The stuff isn't cheap though. I doubt that Dave is making any profit at $4. .sounds like a good deal to me. Larry ----- Original Message ----- From: "Chuck Hards" <chuckhards@yahoo.com> To: <utah-astronomy@mailman.xmission.com> Sent: Thursday, June 06, 2002 4:14 PM Subject: [Utah-astronomy] RE: Mylar solar filter safety reminder
As a lot of people re-sell mylar, usually without a copy of the manufacturer's safety precautions, ...
...
If the sight of the dots offends you, do it on the back side.
Chuck
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I have some of those glass-plated solar filters. Is there a worry about them too? I looked at some under strong light and a couple seemed to have extremely light scratches on the glass, not really scratches, just like marks where they were cleaned. When I looked at the sun with them I saw nothing odd. What's your take on this, Chuck? Best, Joe
Joe, the same safety measures apply to glass filters, where the metal is deposited on glass instead of mylar. If the holes and streaks are extremely small and few in number, there is probably no reason to be concerned. If larger, they should be opaqued. My own Thousand Oaks steel-on-glass filter has those same flaws, and it arrived like that from the factory. Glass solar filters are not made of a dark glass, like a welder's glass; they typically use steel or nickel evaporated onto a clear glass substrate, much like a telescope mirror. Install the filter on your telescope, and aim it at the sun with no eyepiece. If you can't detect any pinpricks when looking through, there's probably nothing to worry about. Chuck --- Joe Bauman <bau@desnews.com> wrote:
I have some of those glass-plated solar filters. Is there a worry about them too? I looked at some under strong light and a couple seemed to have extremely light scratches on the glass, not really scratches, just like marks where they were cleaned. When I looked at the sun with them I saw nothing odd. What's your take on this, Chuck? Best, Joe
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I think the one that covers the telescope is OK, but I have some glass ones like that that you hold up to your eyes. Thanks, Joe
Hi Dave, Was wondering if you received my phone message about being interested in buying 3 of your Baader pieces and maybe getting them saturday morning??? I live in West Jordan. You? My home number is 260-0265. I will be out of my office tomorrow, friday june 7 but you can leave a message on my home phone above. Thank you, Dave Jim Stitley --- David Dunn <david.dunn@albertsons.com> wrote:
I have a few, maybe 10 pieces left. As Joe mentioned they are $4 and are about 4.5" square. You can call me at work 961-3253 or home 544-7705 if you want some.
Dave
-----Original Message----- From: Joe Borgione [mailto:jborgion@xmission.com] Sent: Thursday, June 06, 2002 11:36 AM To: utah-astronomy@mailman.xmission.com Subject: RE: [Utah-astronomy] Re: Utah County Harmons
I was able to purchase a couple of pieces from Dave Dunn, who also subscribes to this list. He'll probably respond before long, as he responded to my query about it last week or so here; I don't know how much material he has stockpiled, but he was selling a 4.5 inch square for $4.00.
As far as I know, the Baader film is top of the line, and preferred by many. I'm not sure what Tuthill sells or how it compares, although, I'll lay odds somebody on this list can fill us in. Knowing Tuthills reputation, his material his excellant as well.
Joe Borgione
-------------------
Joe, where did you get the Baader film??? Locally? Price? Thank you VERY much. Is this comparable to mylar like Tuthill sells? Jim Stitley
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participants (6)
-
Brent Watson -
Chuck Hards -
David Dunn -
Jim Stitley -
Joe Bauman -
Larry Frisk