March 2003 - Utah-Astronomy - mailman.xmission.com

Re: [Utah-astronomy] SCT or Newtonian?
by UTAHDEB＠aol.com 24 Mar '03

24 Mar '03

Brent, What brand of doublet refractors do you prefer? I hear the Takahashi doublets are not as well corrected as the Astro-Physics refractors. Correct me if I am wrong. I'd like to get my hands on one the AP 130mm f/8.35 refractors doublet or triplet. I wish they would start making them again. Deb

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RE: [Utah-astronomy] SCT or Newtonian?
by David Dunn 24 Mar '03

24 Mar '03

Even a mirror that has been to Monte Cristo and Antelope Island many times a year doesn't need to be cleaned very often. I clean mine every two years or so. I might clean them after one year if they were real dirty. To clean my mirrors, I take the mirror still mounted in it's cell out in the back yard. I run a large quantity of water over it. If there are any spots that need soap I use a little Joy detergent in a lot of water. I use a cotton ball to wipe, no pressure, in one direction only. I then rinse the mirror with a lot of tap water again until the soap is all gone. They I rinse with distilled water. Then I rinse with Everclear. Everclear doesn't seem to leave a film and gets the water off immediately. This process allows you to leave the mirror silconed into the mirror cell so you can just put the cell back in the scope and start observing again. I have also heard of people using compressed air to blow the dust off of the mirror. I haven't seen any damage to the mirrors that I have seen where this process was used. -----Original Message----- From: Chuck Hards [mailto:chuckhards@yahoo.com] Sent: Monday, March 24, 2003 10:22 AM To: Astronomy in Utah Subject: RE: [Utah-astronomy] SCT or Newtonian? Words in caps are for emphasis, I'm not shouting. This subject is too lengthy for me to go into detail right now (at work, as usual) but the secret is PATIENCE and NOT wiping right away. Let the mirror soak in warm water for a few hours. This will loosen most of the dirt and it can be rinsed off using only the pressure from the tap. Wiping is best done judiciously, after a soak, and using only the best grade of cotton, only one wipe per cotton wad, one direction only, rotating as you wipe. All rinsing should be done with distilled water, then drip-and-air dry. If you need to use soap, you waited too long to clean, but let the mirror soak in SOAPY water if it's really filthy. This is just a quick description, many nuances remain undescribed. Cleaning requirements are a good reason to avoid mounting mirrors with silicone glue. You won't be observing the same night that you cleaned the optics if you use silicone. Of course, it goes without saying that you need to keep the mirrors COVERED when not in-use. My 6" f/8 is now 4 years old, and the mirror has hardly any dust on it. C. --- Joe Bauman <bau(a)desnews.com> wrote: > How 'bout a scouring pad? Just kidding, but I think > I may have damaged > either my corrector plate or the mirror by cleaning > with usual photo lens > cleaner material, although I was extremely careful. > But I think there's > really something wrong with my optics now. Thanks, > Joe > > >The next obvious question to me is, what it the > right (careful) way to > >clean a newtonian mirror? > > > >I have read somewhere that using a mild dish soap > like Dawn is prefered. > >Any wiping or rubbing will grind dirt into the > mirror. So how do you get > >the dirt off? How about using an old shaving brush > (probably couldn't find > >one these days) or a photo air brush? > > > >Jim Gibson __________________________________________________ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy

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Re: [Utah-astronomy] SCT or Newtonian?
by UTAHDEB＠aol.com 24 Mar '03

24 Mar '03

Joe, It is true you have to be careful around dusty areas with a Newtonian reflecter. If you ever go to Texas Star Party, be prepared to clean your optics. Even though I kept the dust cover on when not observing, my mirror became dirty and my scope needed cleaning. I am allergic to dust so I try to avoid it so I don't get an asthma attack. I try to wash my mirror every other year or when the mirror needs it. My light shroud is always on when I observe so I think that protects the mirror as well. I drape towels over my scope when I store it in the house. A Crown Royal bag protects my secondary mirror. I gave the contents to a friend. I don't think you made a mistake buying a SCT. My first scope was a SCT and I regard it as a learning experience. I bought a truss tube dob for my second scope so my SCT has seen little use in the past 5 1/2 years because of the aperature gain. Best Wishes, Debbie

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RE: [Utah-astronomy] SCT or Newtonian?
by Kim Hyatt 24 Mar '03

24 Mar '03

The compactness does relate to greater stability, all other things being equal. However, I believe Chuck is right - German equatorial mounts are preferred over fork mounts for astrophotography. Can anyone tell me fork mounts versus German equatorial mounts makes any difference to piggyback photography? -----Original Message----- From: Joe Bauman [mailto:bau@desnews.com] Sent: Monday, March 24, 2003 12:42 PM To: Astronomy in Utah Subject: Re: [Utah-astronomy] SCT or Newtonian? A related question, is an SC's performance T superior in any way other than compactness? That is, does it track better for long exposures? Or was it a mistake for me to buy one when I could have purchased a Newtonian for far less? Thanks, Joe Joe Bauman science & military reporter Deseret News bau(a)desnews.com (801) 237-2169 _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy

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Re: [Utah-astronomy] SCT or Newtonian?
by UTAHDEB＠aol.com 24 Mar '03

24 Mar '03

Brent, I was hoping that would be your answer. The central obstruction is also less right? The central obstruction is 33% on a SCT which is why people say they are soft on planets. I would think a well collimated newtonian reflecter would outperform a SCT on planets. Debbie

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[Utah-astronomy] Fwd: Astrophotography Submissions to Meade Instruments
by Richard Tenney 24 Mar '03

24 Mar '03

If the shoe fits... Note: forwarded message attached. __________________________________________________ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com

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RE: [Utah-astronomy] SCT or Newtonian?
by Kim Hyatt 24 Mar '03

24 Mar '03

Rich - you're giving away your drinking preferences. Everclear is an alcoholic beverage, if you can call pure alcohol a beverage... -----Original Message----- From: Richard Tenney [mailto:retenney@yahoo.com] Sent: Monday, March 24, 2003 11:26 AM To: Astronomy in Utah Subject: RE: [Utah-astronomy] SCT or Newtonian? David, What is Everclear, and where can you purchase it? I've never heard of it. --- David Dunn <david.dunn(a)albertsons.com> wrote: > Even a mirror that has been to Monte Cristo and > Antelope Island many times a > year doesn't need to be cleaned very often. I clean > mine every two years or > so. I might clean them after one year if they were > real dirty. To clean my > mirrors, I take the mirror still mounted in it's > cell out in the back yard. > I run a large quantity of water over it. If there > are any spots that need > soap I use a little Joy detergent in a lot of water. > I use a cotton ball to > wipe, no pressure, in one direction only. I then > rinse the mirror with a lot > of tap water again until the soap is all gone. They > I rinse with distilled > water. Then I rinse with Everclear. Everclear > doesn't seem to leave a film > and gets the water off immediately. This process > allows you to leave the > mirror silconed into the mirror cell so you can just > put the cell back in > the scope and start observing again. > > I have also heard of people using compressed air to > blow the dust off of the > mirror. I haven't seen any damage to the mirrors > that I have seen where this > process was used. > > > > > -----Original Message----- > From: Chuck Hards [mailto:chuckhards@yahoo.com] > Sent: Monday, March 24, 2003 10:22 AM > To: Astronomy in Utah > Subject: RE: [Utah-astronomy] SCT or Newtonian? > > > Words in caps are for emphasis, I'm not shouting. > > This subject is too lengthy for me to go into detail > right now (at work, as usual) but the secret is > PATIENCE and NOT wiping right away. Let the mirror > soak in warm water for a few hours. This will > loosen > most of the dirt and it can be rinsed off using only > the pressure from the tap. Wiping is best done > judiciously, after a soak, and using only the best > grade of cotton, only one wipe per cotton wad, one > direction only, rotating as you wipe. All rinsing > should be done with distilled water, then > drip-and-air > dry. If you need to use soap, you waited too long > to > clean, but let the mirror soak in SOAPY water if > it's > really filthy. > > This is just a quick description, many nuances > remain > undescribed. > > Cleaning requirements are a good reason to avoid > mounting mirrors with silicone glue. You won't be > observing the same night that you cleaned the optics > if you use silicone. > > Of course, it goes without saying that you need to > keep the mirrors COVERED when not in-use. My 6" f/8 > is now 4 years old, and the mirror has hardly any > dust > on it. > > C. > > --- Joe Bauman <bau(a)desnews.com> wrote: > > How 'bout a scouring pad? Just kidding, but I > think > > I may have damaged > > either my corrector plate or the mirror by > cleaning > > with usual photo lens > > cleaner material, although I was extremely > careful. > > But I think there's > > really something wrong with my optics now. Thanks, > > Joe > > > > >The next obvious question to me is, what it the > > right (careful) way to > > >clean a newtonian mirror? > > > > > >I have read somewhere that using a mild dish soap > > like Dawn is prefered. > > >Any wiping or rubbing will grind dirt into the > > mirror. So how do you get > > >the dirt off? How about using an old shaving > brush > > (probably couldn't find > > >one these days) or a photo air brush? > > > > > >Jim Gibson > > > __________________________________________________ > Do you Yahoo!? > Yahoo! Platinum - Watch CBS' NCAA March Madness, > live on your desktop! > http://platinum.yahoo.com > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy __________________________________________________ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy

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RE: [Utah-astronomy] SCT or Newtonian?
by Kim Hyatt 24 Mar '03

24 Mar '03

I only clean my Newtonian optics about once per season. One reason is that scrupulously clean optics are not necessary for most observations. (In fact, it's my understanding that optics are cleaned infrequently at professional observatories, also.) You are correct that cleaning is "dangerous," and that's another reason not to clean too often. I believe that the optical coatings on a SCT corrector are as soft if not softer than the aluminum coating on any mirror. I've owned Newtonians for most of my astronomy life and just haven't found it to be all that much of a hassle to clean the optics. -----Original Message----- From: Joe Bauman [mailto:bau@desnews.com] Sent: Monday, March 24, 2003 7:22 AM To: Astronomy in Utah Subject: Re: [Utah-astronomy] SCT or Newtonian? I'd like to chime in with a question that has always puzzled me. A know some prefer SCTs because they are more compact, but I am wondering about another feature: the fact that the mirrors of Newtonians are open to the air. Doesn't this allow a lot of grit and dust to cover them, for example while observing from the Wedge? And isn't it more dangerous for the optics to clean the mirror than the covering lens of an SCT? Thanks, Joe Joe Bauman science & military reporter Deseret News bau(a)desnews.com (801) 237-2169 _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy

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RE: [Utah-astronomy] SCT or Newtonian?
by Kim Hyatt 24 Mar '03

24 Mar '03

I recall that S&T has from time to time given directions for cleaning. Others have their own preferences but I think the best direction is to not use any kind of rubbing action - ever. Blow off loose dirt (do not brush - a brush will also grind surface particles into the mirror and scratch) and wash off any stubborn particles. It's the washing process and products (distilled water, alcohol, detergent, etc.) that so many people dispute. I know how I would do it but I'd like to hear from others. Maybe it's time for a "Spring Cleaning" lesson at the April SLAS meeting. -----Original Message----- From: Jim Gibson [mailto:xajax99@yahoo.com] Sent: Monday, March 24, 2003 9:33 AM To: Astronomy in Utah Subject: RE: [Utah-astronomy] SCT or Newtonian? The next obvious question to me is, what it the right (careful) way to clean a newtonian mirror? I have read somewhere that using a mild dish soap like Dawn is prefered. Any wiping or rubbing will grind dirt into the mirror. So how do you get the dirt off? How about using an old shaving brush (probably couldn't find one these days) or a photo air brush? Jim Gibson Chuck Hards <chuckhards(a)yahoo.com> wrote: I would agree for the most part with Kim, except that a proper cleaning job really isn't "dangerous" if you are very careful. Aluminum is a soft metal, and coatings are very thin, but mirrors can be cleaned without damage. It's only intimidating the first time. I only clean mine every other year, unless absolutely needed. An improperly cleaned SCT corrector or refractor objective will take damage also, it's just not as visible at a casual glance as a reflective surface. Remember, too, that SCT's do not have sealed interiors, sooner or later they will require cleaning interior surfaces also. C. --- Kim Hyatt wrote: > I only clean my Newtonian optics about once per > season. One reason is that > scrupulously clean optics are not necessary for most > observations. (In fact, > it's my understanding that optics are cleaned > infrequently at professional > observatories, also.) You are correct that cleaning > is "dangerous," and > that's another reason not to clean too often. I > believe that the optical > coatings on a SCT corrector are as soft if not > softer than the aluminum > coating on any mirror. I've owned Newtonians for > most of my astronomy life > and just haven't found it to be all that much of a > hassle to clean the > optics. > > -----Original Message----- > From: Joe Bauman [mailto:bau@desnews.com] > Sent: Monday, March 24, 2003 7:22 AM > To: Astronomy in Utah > Subject: Re: [Utah-astronomy] SCT or Newtonian? > > > I'd like to chime in with a question that has always > puzzled me. A know > some prefer SCTs because they are more compact, but > I am wondering about > another feature: the fact that the mirrors of > Newtonians are open to the > air. Doesn't this allow a lot of grit and dust to > cover them, for example > while observing from the Wedge? And isn't it more > dangerous for the optics > to clean the mirror than the covering lens of an > SCT? Thanks, Joe > > Joe Bauman > science & military reporter > Deseret News > bau(a)desnews.com > (801) 237-2169 > > > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy __________________________________________________ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy _____ Do you Yahoo!? Yahoo! <http://rd.yahoo.com/platinum/evt=8162/*http://platinum.yahoo.com/splash.htm l> Platinum - Watch CBS' NCAA March Madness, live <http://rd.yahoo.com/platinum/evt=8162/*http://platinum.yahoo.com/splash.htm l> on your desktop!

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SCT or Newtonian?
by UTAHDEB＠aol.com 24 Mar '03

24 Mar '03

Will a SCT or Newtonian give better views of the planets or deep sky objects? I want to get some opinions on this before I sell my 8" SCT. Debbie

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