Want feedback on my Orion Nebula picture flaws
It's cloudy tonight, so I guess I'll send an email instead of looking at the stars. The Salt Lake southern skies cleared a little last night, so I took my friend's Celestron C8+ (8" CST with a motor drive - the one I'm dusting for him) and my Nikon D80 with a prime focus adapter out to my front porch and took some shots of the Orion Nebula. After about a 100 shots, I'm getting closer to a clear picture, but the problems are getting harder to figure out.. My Orion Nebula emphasizing the fuzzy stars: http://glogan.smugmug.com/gallery/6872266_UTskH/1/#440661533_PeEFc-A-LB The above link is a crop that shows fuzzy stars in the pictures. That was a 30sec. exposure at iso640. The stars definitely have movement, which I'm guessing is my poor polar alignment. My porch faces South and I can't see the North star from it, so I kept moving the tripod until the star trails got short (at the time I thought they went away). I am also wondering how long of an exposure I should expect to be able to get as far as accurate tracking using this Celestron C8+? But the stars should be smaller also, more pin-pointish. I can't seem to be certain of my focus through my camera viewfinder, as the stars are too dim. Are there techniques or equipment that others use to help focus when mounting a camera? Also, (whine) the Celestron seems to have a pretty coarse focus knob, even with the regular eyepieces. My best Orion: http://glogan.smugmug.com/gallery/6872266_UTskH/1/#440655195_68tXH-A-LB Regards Gary Logan _____
Gary, those are terrific for beginner work. The first shot shows a focus problem, possible tracking error, but obvious shift of the focal plane during the exposure. The second shot is better, but still displays the same traits. Let's take these one at a time. Focus problem: Try focusing on a first-magnitude star, Venus, or a mountain-top tower light at least 20 miles away. You also need to know that Schmidt-Cassegrain telescopes have an inherent design flaw in that they focus by moving the primary mirror back-and-forth. Because the primary mirror isn't held firmly in place, it can and does shift when the telescope is moved from one part of the sky to another. Many people using these telescopes for astro-imaging lock-down the primary mirror and focus using an aftermarket focuser attached between the camera and telescope. There are also specialized tools that can help you achieve a precise focus such as a knife-edge focuser matched to your camera. You can also bracket the focus of your shots if in doubt- digital imaging means never running out of film! Tracking error: You do need to be polar-aligned, and not being able to see the NCP complicates the task. But there is a way to achieve a more precise alignment using the "star-drift" method. It does take time, though, and can be confusing for a beginner the first few times, unless someone walks you through it. Focal plane shift: This can be related to the "mirror flop", or shift, mentioned above, but it can also be due to the ground the telescope is set up on. Vibration can be transmitted through the ground and up the tripod, ruining an exposure. Even a concrete pad or porch transmits vibration. A wooden porch would be even worse. Wind can jiggle the telescope, or even movement by the operator. These are just some general areas to look into and there may be others. I'm not right now in a position to direct you to Web resources or books discussing them in detail, but I'm sure some of the active astro-imagers on the list can help you in a more specific manner. Kurt has been doing a lot of work on precisely polar-aligning a portable mount, and Patrick is a treasure-trove of practical imaging advice. Joe has been doing a lot of imaging since retirement, as well, and Tyler sets a high benchmark for everyone who is into imaging. Lots of people who can offer you specific advice on this list. Again, very good work, don't give up. Persistence is key to success! On Sun, Dec 21, 2008 at 8:29 PM, Gary Bulk <garybulk@the-logans.net> wrote:
It's cloudy tonight, so I guess I'll send an email instead of looking at the stars.
The Salt Lake southern skies cleared a little last night, so I took my friend's Celestron C8+ (8" CST with a motor drive - the one I'm dusting for him) and my Nikon D80 with a prime focus adapter out to my front porch and took some shots of the Orion Nebula. After about a 100 shots, I'm getting closer to a clear picture, but the problems are getting harder to figure out..
My Orion Nebula emphasizing the fuzzy stars: http://glogan.smugmug.com/gallery/6872266_UTskH/1/#440661533_PeEFc-A-LB
The above link is a crop that shows fuzzy stars in the pictures. That was a 30sec. exposure at iso640. The stars definitely have movement, which I'm guessing is my poor polar alignment. My porch faces South and I can't see the North star from it, so I kept moving the tripod until the star trails got short (at the time I thought they went away). I am also wondering how long of an exposure I should expect to be able to get as far as accurate tracking using this Celestron C8+?
But the stars should be smaller also, more pin-pointish. I can't seem to be certain of my focus through my camera viewfinder, as the stars are too dim. Are there techniques or equipment that others use to help focus when mounting a camera? Also, (whine) the Celestron seems to have a pretty coarse focus knob, even with the regular eyepieces.
My best Orion: http://glogan.smugmug.com/gallery/6872266_UTskH/1/#440655195_68tXH-A-LB
Gary, Nice work on the photos. Chuck's advice was excellent and I agree with everything he said. I thought I would mention another possible culprit for the jittery stars... shutter vibration! I have taken many images through my scopes with my digital SLR bodies, and I nearly always have problems with vibration unless I use a mirror lockup function. Many cameras have a way to flip up the mirror prior to taking the exposure. That procedure prevents the "snap" that can cause the whole assembly to shake. Take a look at the camera manual to see if your camera offers this function. Happy shooting! Tyler www.allred-astro.com _____________________________________________ -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Gary Bulk Sent: Sunday, December 21, 2008 8:29 PM To: utah-astronomy@mailman.xmission.com Subject: [Utah-astronomy] Want feedback on my Orion Nebula picture flaws It's cloudy tonight, so I guess I'll send an email instead of looking at the stars. The Salt Lake southern skies cleared a little last night, so I took my friend's Celestron C8+ (8" CST with a motor drive - the one I'm dusting for him) and my Nikon D80 with a prime focus adapter out to my front porch and took some shots of the Orion Nebula. After about a 100 shots, I'm getting closer to a clear picture, but the problems are getting harder to figure out.. My Orion Nebula emphasizing the fuzzy stars: http://glogan.smugmug.com/gallery/6872266_UTskH/1/#440661533_PeEFc-A-LB The above link is a crop that shows fuzzy stars in the pictures. That was a 30sec. exposure at iso640. The stars definitely have movement, which I'm guessing is my poor polar alignment. My porch faces South and I can't see the North star from it, so I kept moving the tripod until the star trails got short (at the time I thought they went away). I am also wondering how long of an exposure I should expect to be able to get as far as accurate tracking using this Celestron C8+? But the stars should be smaller also, more pin-pointish. I can't seem to be certain of my focus through my camera viewfinder, as the stars are too dim. Are there techniques or equipment that others use to help focus when mounting a camera? Also, (whine) the Celestron seems to have a pretty coarse focus knob, even with the regular eyepieces. My best Orion: http://glogan.smugmug.com/gallery/6872266_UTskH/1/#440655195_68tXH-A-LB Regards Gary Logan _____ _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
Good call Tyler. I forgot about the vibration the camera can cause. As long as your still awake, care to provide an update on your ASA? I'm still green with envy after seeing your M31 shot (http://71.18.228.62/images/M31_Allred_Astro.jpg ) and can only imagine what images you take with the ASA will look like. patrick :) On 21 Dec 2008, at 23:26, Tyler Allred wrote:
Gary, Nice work on the photos. Chuck's advice was excellent and I agree with everything he said. I thought I would mention another possible culprit for the jittery stars... shutter vibration! I have taken many images through my scopes with my digital SLR bodies, and I nearly always have problems with vibration unless I use a mirror lockup function. Many cameras have a way to flip up the mirror prior to taking the exposure. That procedure prevents the "snap" that can cause the whole assembly to shake. Take a look at the camera manual to see if your camera offers this function. Happy shooting! Tyler
www.allred-astro.com
Here is a basic FAQ I found, for beginning astro-imagers, with some links to more advanced material: http://www.szykman.com/Astro/AstroDigiCamFAQ.html
Just great, Tyler, just great. Here comes a bully ready to rip our galaxy to pieces, and you give it a beautiful portrait! Have you no galactic loyalty??? (Wonderful view, actually!) -- Joe --- On Sun, 12/21/08, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] Want feedback on my Orion Nebula picture flaws To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, December 21, 2008, 11:51 PM Good call Tyler. I forgot about the vibration the camera can cause. As long as your still awake, care to provide an update on your ASA? I'm still green with envy after seeing your M31 shot (http://71.18.228.62/images/M31_Allred_Astro.jpg ) and can only imagine what images you take with the ASA will look like. patrick :) On 21 Dec 2008, at 23:26, Tyler Allred wrote:
Gary, Nice work on the photos. Chuck's advice was excellent and I agree with everything he said. I thought I would mention another possible culprit for the jittery stars... shutter vibration! I have taken many images through my scopes with my digital SLR bodies, and I nearly always have problems with vibration unless I use a mirror lockup function. Many cameras have a way to flip up the mirror prior to taking the exposure. That procedure prevents the "snap" that can cause the whole assembly to shake. Take a look at the camera manual to see if your camera offers this function. Happy shooting! Tyler
www.allred-astro.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
Patrick wrote < As long as you are still awake, care to provide an update on your ASA> Sorry it took me a few days to get back to you on this one. I have had a rough time getting the ASA up and working. There was a problem with the secondary mirror that was causing astigmatism. It took me a while to troubleshoot it because I never suspected the secondary. Steve Dodds helped me out by testing the mirrors. I replaced the secondary with a 1/30th wave Antares that is really top notch... way better than the original secondary mirrors used by ASA. Since getting everything fixed up I have had only one night of shooting between the clouds, but the results were promising. I took a few frames of M109 with the KAF3200XME Finger Lakes camera and you can see at least a dozen other galaxies in the image. I had some guiding issues with the frames however (new guider), so it is a little hard to tell much about the system. I will say that it was nice to finally see focused round stars through the scope. I can't imagine why the secondary was bad. I think everything must now be ready for use because the weather has turned on me completely. :( Tyler _____________________________________________
Hi Tyler, I hope you can get some kind of rebate because of the bum secondary. Meanwhile, all of us would like to see your latest photos! Happy new years, Joe --- On Mon, 12/29/08, Tyler Allred <tylerallred@earthlink.net> wrote: From: Tyler Allred <tylerallred@earthlink.net> Subject: Re: [Utah-astronomy] FORMERLY - Want feedback on my Orion Nebula picture flaws To: "'Utah Astronomy'" <utah-astronomy@mailman.xmission.com> Date: Monday, December 29, 2008, 2:18 PM Patrick wrote < As long as you are still awake, care to provide an update on your ASA> Sorry it took me a few days to get back to you on this one. I have had a rough time getting the ASA up and working. There was a problem with the secondary mirror that was causing astigmatism. It took me a while to troubleshoot it because I never suspected the secondary. Steve Dodds helped me out by testing the mirrors. I replaced the secondary with a 1/30th wave Antares that is really top notch... way better than the original secondary mirrors used by ASA. Since getting everything fixed up I have had only one night of shooting between the clouds, but the results were promising. I took a few frames of M109 with the KAF3200XME Finger Lakes camera and you can see at least a dozen other galaxies in the image. I had some guiding issues with the frames however (new guider), so it is a little hard to tell much about the system. I will say that it was nice to finally see focused round stars through the scope. I can't imagine why the secondary was bad. I think everything must now be ready for use because the weather has turned on me completely. :( Tyler _____________________________________________ _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
Thanks for the update Tyler. Like Joe (and I'm sure many others here) I'm looking forward to you next batch of images. And perhaps Tyler's message can also serve to show those just getting started in astroimaging that having nice equipment and lots of experience still doesn't tame all the gremlins in the system. It's a never ending learning curve. But the rewards can be very satisfying. And speaking of "those just getting started" I see SLASer Dale Wilson has just joined us here. If memory serves that means we've got at least 3 here (Mike, Joe and Gary) just getting started up the curve. Are there any more? Clear skies! (please...) patrick On 29 Dec 2008, at 14:51, Joe Bauman wrote:
Hi Tyler, I hope you can get some kind of rebate because of the bum secondary. Meanwhile, all of us would like to see your latest photos! Happy new years, Joe
--- On Mon, 12/29/08, Tyler Allred <tylerallred@earthlink.net> wrote: From: Tyler Allred <tylerallred@earthlink.net> Subject: Re: [Utah-astronomy] FORMERLY - Want feedback on my Orion Nebula picture flaws To: "'Utah Astronomy'" <utah-astronomy@mailman.xmission.com> Date: Monday, December 29, 2008, 2:18 PM
Patrick wrote < As long as you are still awake, care to provide an update on your ASA>
Sorry it took me a few days to get back to you on this one.
I have had a rough time getting the ASA up and working. There was a problem with the secondary mirror that was causing astigmatism. It took me a while to troubleshoot it because I never suspected the secondary. Steve Dodds helped me out by testing the mirrors. I replaced the secondary with a 1/30th wave Antares that is really top notch... way better than the original secondary mirrors used by ASA. Since getting everything fixed up I have had only one night of shooting between the clouds, but the results were promising. I took a few frames of M109 with the KAF3200XME Finger Lakes camera and you can see at least a dozen other galaxies in the image. I had some guiding issues with the frames however (new guider), so it is a little hard to tell much about the system. I will say that it was nice to finally see focused round stars through the scope. I can't imagine why the secondary was bad.
I think everything must now be ready for use because the weather has turned on me completely. :(
Tyler
Gary, I used to shoot astrophotos with a single-lens reflex camera. I made a flap of cardboard that could be taped to the top of the telescope and flipped down over the front or back up out of the way. A way to address camera vibration when using an SLR is to first, lock the camera's mirror; second, flip the cardboard down over the corrector plate, while the cardboard stays taped to the telescope; third, set off a "bulb" exposure with a camera cable (an exposure that won't end until you tell it to); fourth, wait a few seconds until the camera stops bouncing; fifth, flip the cardboard out of the way; sixth, count however many seconds or minutes you want the exposure to be; seventh, replace the cardboard; finally, end the exposure. This is called the old hat trick. -- Joe --- On Sun, 12/21/08, Tyler Allred <tylerallred@earthlink.net> wrote: From: Tyler Allred <tylerallred@earthlink.net> Subject: Re: [Utah-astronomy] Want feedback on my Orion Nebula picture flaws To: "'Utah Astronomy'" <utah-astronomy@mailman.xmission.com> Date: Sunday, December 21, 2008, 11:26 PM Gary, Nice work on the photos. Chuck's advice was excellent and I agree with everything he said. I thought I would mention another possible culprit for the jittery stars... shutter vibration! I have taken many images through my scopes with my digital SLR bodies, and I nearly always have problems with vibration unless I use a mirror lockup function. Many cameras have a way to flip up the mirror prior to taking the exposure. That procedure prevents the "snap" that can cause the whole assembly to shake. Take a look at the camera manual to see if your camera offers this function. Happy shooting! Tyler www.allred-astro.com _____________________________________________ -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Gary Bulk Sent: Sunday, December 21, 2008 8:29 PM To: utah-astronomy@mailman.xmission.com Subject: [Utah-astronomy] Want feedback on my Orion Nebula picture flaws It's cloudy tonight, so I guess I'll send an email instead of looking at the stars. The Salt Lake southern skies cleared a little last night, so I took my friend's Celestron C8+ (8" CST with a motor drive - the one I'm dusting for him) and my Nikon D80 with a prime focus adapter out to my front porch and took some shots of the Orion Nebula. After about a 100 shots, I'm getting closer to a clear picture, but the problems are getting harder to figure out.. My Orion Nebula emphasizing the fuzzy stars: http://glogan.smugmug.com/gallery/6872266_UTskH/1/#440661533_PeEFc-A-LB The above link is a crop that shows fuzzy stars in the pictures. That was a 30sec. exposure at iso640. The stars definitely have movement, which I'm guessing is my poor polar alignment. My porch faces South and I can't see the North star from it, so I kept moving the tripod until the star trails got short (at the time I thought they went away). I am also wondering how long of an exposure I should expect to be able to get as far as accurate tracking using this Celestron C8+? But the stars should be smaller also, more pin-pointish. I can't seem to be certain of my focus through my camera viewfinder, as the stars are too dim. Are there techniques or equipment that others use to help focus when mounting a camera? Also, (whine) the Celestron seems to have a pretty coarse focus knob, even with the regular eyepieces. My best Orion: http://glogan.smugmug.com/gallery/6872266_UTskH/1/#440655195_68tXH-A-LB Regards Gary Logan _____ _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
A good way to start astro-imaging is to to "piggyback" photography. Instead of shooting through the telescope at long focal lengths, you use the camera with a telephoto lens, attached to the main telescope. You guide using the main scope, with a cross-hair eyepiece (or an autoguider if the mount will accomodate one). Many objects are large enough that a telephoto lens will capture it perfectly. M31 and M33, for instance, subtend an angle greater than the full moon. And there are many star clouds and extended nebula that are excellent subjects for a telephoto- not to mention the occassional comet. Skills honed in this way are easily transferred to imaging with longer focal lengths once the basics are mastered.
Hi Utah Astronomers, This is Sheena over at The Trib. I'm writing you to let you know that I've just gotten permission to start an astronomy blog on The Trib's Web site. I'm super excited about it because now I should be able to get more astronomy news out to our readers. Apparently, after the story I wrote about a big full moon hit No. 1 on our Web site, one of the top editors here made the comment "astronomy sells." So, I'm capitalizing on that while fulfilling my desire to write more about astronomy. The best thing is, the news doesn't have to be super local or huge in scope. I'm planning to kick off the blog when I write about the Quarantids meteor shower coming up on Jan. 4. And yes, blog readers absolutely can make comments on each and every blog post, something I highly encourage! I am also looking for name ideas for the blog, and any ideas about where I can cull information about astronomical happenings. Obviously, this is a great forum, and I've signed up for NASA's mailings, but any other suggestions would be great. I plan to blog as regularly as possible, meaning whenever a cool star/ planet alignment, meteor shower, star party, etc. is happening, I want to know. And if you guys run across cool articles in other publications, let me know, and I can link to it and guide our readers there. Of course, I'll still pitch bigger stories for the paper, so the blog won't steal the thunder from The Trib's astronomy coverage. Anyway, I can't wait to get this going, and I want to thank you in advance for your help (and readership!!) Sheena McFarland State Government Reporter (and resident astro girl) The Salt Lake Tribune 90 S. 400 West, Suite 700 Salt Lake City, UT 84101 Office: (801) 257-8619 Cell: (801) 510-5567 Fax: (801) 257-8525 smcfarland@sltrib.com
Sheena, Way to go! We will help show your editor that not only does Astronomy sell, It inspires! This is Good News Rodger Fry ----- Original Message ----- From: "Sheena McFarland" <smcfarland@sltrib.com> To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Sent: Tuesday, December 23, 2008 10:10 AM Subject: [Utah-astronomy] Astronomy blog at www.sltrib.com coming soon
Hi Utah Astronomers,
This is Sheena over at The Trib. I'm writing you to let you know that I've just gotten permission to start an astronomy blog on The Trib's Web site. I'm super excited about it because now I should be able to get more astronomy news out to our readers.
Apparently, after the story I wrote about a big full moon hit No. 1 on our Web site, one of the top editors here made the comment "astronomy sells." So, I'm capitalizing on that while fulfilling my desire to write more about astronomy.
The best thing is, the news doesn't have to be super local or huge in scope. I'm planning to kick off the blog when I write about the Quarantids meteor shower coming up on Jan. 4. And yes, blog readers absolutely can make comments on each and every blog post, something I highly encourage!
I am also looking for name ideas for the blog, and any ideas about where I can cull information about astronomical happenings. Obviously, this is a great forum, and I've signed up for NASA's mailings, but any other suggestions would be great.
I plan to blog as regularly as possible, meaning whenever a cool star/ planet alignment, meteor shower, star party, etc. is happening, I want to know. And if you guys run across cool articles in other publications, let me know, and I can link to it and guide our readers there. Of course, I'll still pitch bigger stories for the paper, so the blog won't steal the thunder from The Trib's astronomy coverage.
Anyway, I can't wait to get this going, and I want to thank you in advance for your help (and readership!!)
Sheena McFarland State Government Reporter (and resident astro girl) The Salt Lake Tribune 90 S. 400 West, Suite 700 Salt Lake City, UT 84101 Office: (801) 257-8619 Cell: (801) 510-5567 Fax: (801) 257-8525 smcfarland@sltrib.com
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Great idea Sheena, just one caveat with astronomy going public- Most of the time, astronomical events are either total duds, or visible only to a very specific geographical location on earth. Utah and the Intermountain west especially, seem to get far less than our fair share of the "biggies", when you take cloud-cover into account. As amateur astronomers, we get excited over a few meteors per hour, for example, but to the general public, it's a non-event. An unusually huge full moon is one thing, Venus & Jupiter low in the western sky at sunset is another. A club member with a telescope at a star party to take someone by the hand and give a personalized, guided tour is often needed for many of these admittedly esoteric "events". It will put a huge burden on you as writer and astronomy popularizer to not "cry wolf" too often. That said, I wish you good luck; I'm sure all of us will help feed you leads when we can. On Tue, Dec 23, 2008 at 10:10 AM, Sheena McFarland <smcfarland@sltrib.com>wrote:
Hi Utah Astronomers,
This is Sheena over at The Trib. I'm writing you to let you know that I've just gotten permission to start an astronomy blog on The Trib's Web site. I'm super excited about it because now I should be able to get more astronomy news out to our readers.
Apparently, after the story I wrote about a big full moon hit No. 1 on our Web site, one of the top editors here made the comment "astronomy sells." So, I'm capitalizing on that while fulfilling my desire to write more about astronomy.
The best thing is, the news doesn't have to be super local or huge in scope. I'm planning to kick off the blog when I write about the Quarantids meteor shower coming up on Jan. 4. And yes, blog readers absolutely can make comments on each and every blog post, something I highly encourage!
I am also looking for name ideas for the blog, and any ideas about where I can cull information about astronomical happenings. Obviously, this is a great forum, and I've signed up for NASA's mailings, but any other suggestions would be great.
I plan to blog as regularly as possible, meaning whenever a cool star/ planet alignment, meteor shower, star party, etc. is happening, I want to know. And if you guys run across cool articles in other publications, let me know, and I can link to it and guide our readers there. Of course, I'll still pitch bigger stories for the paper, so the blog won't steal the thunder from The Trib's astronomy coverage.
Anyway, I can't wait to get this going, and I want to thank you in advance for your help (and readership!!)
On Tue, Dec 23, 2008 at 10:10 AM, Sheena McFarland <smcfarland@sltrib.com> wrote:
I am also looking for name ideas for the blog, and any ideas about where I can cull information about astronomical happenings. Obviously, this is a great forum, and I've signed up for NASA's mailings, but any other suggestions would be great.
As a source of information I'd recommend http://www.spaceweather.com. I've been alerted to a lot of current astro-happenings from them. -- Kiva.org - Loans That Change Lives
You do realize that, as a journalist writing about astronomy in Utah, you are bound by the Unwritten Law that Patrick must be quoted at least quarterly. *NASA knows where you live. ;o) *
On Tue, Dec 23, 2008 at 10:10 AM, Sheena McFarland <smcfarland@sltrib.com> wrote:
I am also looking for name ideas for the blog, and any ideas about where I can cull information about astronomical happenings. Obviously, this is a great forum, and I've signed up for NASA's mailings, but any other suggestions would be great.
Is that the rule?? Darn, when I was the science guy at the DesNews, I thought it was at least weekly! Now you tell me! Actually, Patrick is the best source for astro info I know, with great answers to any question. -- Joe --- On Tue, 12/23/08, Chuck Hards <chuck.hards@gmail.com> wrote: From: Chuck Hards <chuck.hards@gmail.com> Subject: Re: [Utah-astronomy] Astronomy blog at www.sltrib.com coming soon To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Tuesday, December 23, 2008, 1:35 PM You do realize that, as a journalist writing about astronomy in Utah, you are bound by the Unwritten Law that Patrick must be quoted at least quarterly. *NASA knows where you live. ;o) *
On Tue, Dec 23, 2008 at 10:10 AM, Sheena McFarland <smcfarland@sltrib.com> wrote:
I am also looking for name ideas for the blog, and any ideas about where I can cull information about astronomical happenings. Obviously, this is a great forum, and I've signed up for NASA's mailings, but any other suggestions would be great.
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A few suggestions on achiving focus while in prime focus mode I found at: http://www.covingtoninnovations.com/dslr/EOS300Dastro.html Try adding diffraction by putting a piece of window screen in front of the lens. It will produce bright spikes on all the stars, and you can focus the stars so that the spikes are brightest. Try a Hartmann mask (a lenscap with two big holes in it) in front of the lens while focusing. It will make out-of-focus stars appear double. The holes need to be big to admit enough light. You may be able to get some help from focus confirmation if you are using a Canon lens that is f/6 or faster. This is a way of getting the autofocus mechanism of the camera to tell you whether it thinks the picture is in focus. To try it, bring a bright star into the very center of the frame (the autofocus box). Hold the shutter button halfway down and adjust the focus. There will be a red blink, just like the autofocus signal, when the focus is correct. Hope this helps. Jim
Hi Gary, Welcome to the wonderfully frustrating world, of astroimaging. Chuck put it best when he said "Persistence is key to success!". Focus: Chuck's suggestion of focusing (using the SLR's view screen) on a bright star is a good one. I've also been known to use the edge of the Moon. That will certainly get you close. But as you noted, what you see on the view screen isn't always what you actually get. So for better focus try shooting a 3 or 4 second exposure of a bright star and immediately display it on a computer monitor and then continue to do that over and over whilst making tiny adjustments between exposures. Coarse focus is a problem that can be addressed by removing the existing knob and replacing it with a much bigger knob. On my scope I replaced the knob with an old gear that's about 100mm across. Plus you'll want to try to make all of your focus knob adjustments CCW as that pushes the primary mirror away from the camera and against gravity which makes for more accurate adjustments. You could also invest in an external focuser. With one of those installed you do the coarse focus with the focus knob moving the primary mirror but then use the external focuser for critical focus. Alas, they are not cheap. You can also try shooting with a focal reducer. As it is you are trying to shoot with the C-8's full 2 meter focal length and that is a BIG challenge. Depending on the focal reducer, you can get that down to 1 meter or less and the shorter the focal length the brighter, crisper and more forgiving of error the system will be. Also, have you checked the scope's collimation? If the mirrors are not aligned the stars will always be out of round and brighter on one side of each star image than on the other. I think I see evidence of that in your images. Star trails: As for star trails, that can be caused by poor polar alignment but it can also be caused by the drive. Considering the age of the scope you are using I'm guessing at least part of the problem is the drive. My first "real" scope was an orange tube C-8 and the drive was great for visual use but lacking for imaging. There are devices called drive correctors with which you can correct errors in real time but that also means buying a device you insert in the optical train that allows you to monitor the drive's performance. But now we're talking pretty serious money. I'm pretty sure SLAS has those devices which (if you are a member of SLAS) you might be able to borrow. However, another way around tracking errors is to just shoot a whole slew of short exposures and then use software to align and stack them. This is common practice with SLRs since most are not designed for long exposures anyway (more than a few seconds and you start getting a bunch of "noise" in the image). I use CCDSoft and TheSky, both available from Software Bisque for my image processing. Practice: Like Chuck said, you'll need to be persistent. And, unless you're willing to be as dedicated to the project as people like Tyler are, you pretty much have to resign yourself to the fact that no matter how well you do, the next issue of Sky & Telescope is going to have pictures that are better. :) So how do you get the practice? I'm a strong proponent of the idea that the easier it is to do something (like practicing) to more you will do it. So start off by putting in a backyard pier (basically a piece of pipe stuck in the ground with the telescope's wedge semipermanently attached and polar aligned. That way when the weather's clear you just carry the scope out and plop it on the wedge and you're all aligned and ready to go. This works even in a light polluted city as all you're trying to do is develop your technique and you don't care if the images are fogged by light. Once you've got technique down you can head for dark skies. BTW, I understand Tyler has agreed to talk at an upcoming SLAS meeting about his imaging technique and show some of his pictures. I highly recommend you or anyone else interested in astroimaging attend his talk. Clear skies (please!), patrick
participants (9)
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Chuck Hards -
Dan Hanks -
Gary Bulk -
Jim Gibson -
Joe Bauman -
Patrick Wiggins -
Rodger C. Fry -
Sheena McFarland -
Tyler Allred