I spent some time collimating my scope last night after which I took a few test shots of M-1 which just happened to be transiting. Knowing there are some folks here on the list getting into astroimaging I made images for a "kit" that could help folks get a feel for what's involved in making color images. The kit contains: 1-Raw exposure with clear filter 1-Raw exposure with green filter 1-Raw exposure with blue filter 1-Raw exposure with red filter 1-Master dark to be used to reduce all of the raw images 1-Master clear flat for reducing the raw clear 1-Master green flat for reducing the raw green 1-Master blue flat for reducing the raw blue 1-Master red flat for reducing the raw red The master dark was made by shooting and median combining 15 darks. The master flats were made by shooting and median combining 15 each flats shot through the clear, green, blue and red filters. I should note that using the kit will not get you "Tyler like" images. Though the final image should look pretty good the main purpose of the kit is to show folks what's involved in making "real" color images (I say "real" as opposed to the one-shot cameras which, like color film, sometimes produce questionable colors). Let me know if you'd like a kit and I'll email it out. Clear skies! patrick
Patrick, Looks like fun. I am looking forward to giving it a shot at processng your kit. jg Patrick wrote:
Let me know if you'd like a kit and I'll email it out.
Clear skies!
?patrick _______________________________________________ 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
Hi Patrick, Thanks for doing this. I'd like a kit. I have shot darks at the time of the exposure, sometimes one per exposure, sometimes one per set of three or four exposures, but I've never combined darks. Also I have yet to shoot a flat, though I know I need to do that. The problem with flats, as far as I am concerned, is that you have to use the same angle, focus, etc., as with the images you're correcting. But in the field it's not possible to shoot a bunch of pics of one target, shoot flats, then go to another target -- at least, that's my understanding. I think I need to shoot flats in the morning, using the latest target, but not a setting for an earlier target. Is that right? Thanks, Joe --- On Thu, 1/8/09, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: [Utah-astronomy] Tri-color samples To: "utah astronomy listserve utah astronomy" <utah-astronomy@mailman.xmission.com> Date: Thursday, January 8, 2009, 6:29 PM I spent some time collimating my scope last night after which I took a few test shots of M-1 which just happened to be transiting. Knowing there are some folks here on the list getting into astroimaging I made images for a "kit" that could help folks get a feel for what's involved in making color images. The kit contains: 1-Raw exposure with clear filter 1-Raw exposure with green filter 1-Raw exposure with blue filter 1-Raw exposure with red filter 1-Master dark to be used to reduce all of the raw images 1-Master clear flat for reducing the raw clear 1-Master green flat for reducing the raw green 1-Master blue flat for reducing the raw blue 1-Master red flat for reducing the raw red The master dark was made by shooting and median combining 15 darks. The master flats were made by shooting and median combining 15 each flats shot through the clear, green, blue and red filters. I should note that using the kit will not get you "Tyler like" images. Though the final image should look pretty good the main purpose of the kit is to show folks what's involved in making "real" color images (I say "real" as opposed to the one-shot cameras which, like color film, sometimes produce questionable colors). Let me know if you'd like a kit and I'll email it out. Clear skies! patrick _______________________________________________ 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
Hi Joe, On 08 Jan 2009, at 22:39, Joe Bauman wrote:
Hi Patrick, Thanks for doing this. I'd like a kit.
Ok, I'll get one out to you with a followup email.
I have shot darks at the time of the exposure, sometimes one per exposure, sometimes one per set of three or four exposures, but I've never combined darks.
A single dark may contain imperfections (like random noise and cosmic ray hits) that are then transferred to the light image. Shooting several (Jerry recommends at least 15 and I know of others that shoot many more) and then median combining (as opposed to adding or averaging) into a master dark keeps the good parts of the darks but tends to remove the bad. Happily it's very easy to make darks. The camera does not even need to be attached to the telescope (although as I'll cover in a minute, it's a good idea keep the camera attached to the scope). Just put the camera in a dark room, chill the chip to the temperature you shoot light images at (I use -10 year round as I can get that low even on warm summer nights) and have the software shoot 15 (or more) darks with the same exposure lengths as the lights you have taken or plan on taking. Darks can be archived. I typically use mine for a month or so and make new ones on nights when it's cloudy (though some insist on new darks every night).
Also I have yet to shoot a flat, though I know I need to do that. The problem with flats, as far as I am concerned, is that you have to use the same angle, focus, etc., as with the images you're correcting.
Yes. While flats typically take much less time to make they are more difficult and can not be reused if anything in the optical train is moved (which is why I leave the camera bolted securely to the telescope).
But in the field it's not possible to shoot a bunch of pics of one target, shoot flats, then go to another target -- at least, that's my understanding.
It is possible. But I can see where it's a pain. I've seen posts from folks on the Software Bisque lists that do it all the time. But it's far easier to do in a fixed observatory.
I think I need to shoot flats in the morning, using the latest target, but not a setting for an earlier target. Is that right?
Waiting until dawn and shooting the dawn sky is one way to do it. Cindy and Jerry do it by covering the front of the scope with cloth diaper material (really!) and shooting through that. I do it by pointing the scope at a blank sheet of white cardboard and then reflecting light off of another piece of white cardboard which then reflects off the first. Like the darks, I shoot the flats at the same temperature as the light images. You also need to shoot them through the same filter as is used for the light image (hence for color shots that means a separate flat for the clear light image and for each of the 3 filtered light images). The big difference from darks for flats is the exposure time. For darks the exposure is the same as for the light image. But for flats you only expose long enough to get about half way to saturating the chip. The purpose of the flat, BTW, is to image the out-of-focus various dust bunnies that exist in virtually every optical train (on the corrector, mirrors, filter, CCD chip window, CCD chip). When applied to the light image the flat removes the shadows caused by the bunnies. And as with darks, you'll shoot at least 15 flats to be made into each of the 4 master flats. So, how many total? 15 darks for one master dark. 15 flats for the clear master flat. 15 flats for the green master flat. 15 flats for the blue master flat. 15 flats for the read master flat. -- 75 Total I should add that some people also make master darks for each of their flats and since the exposures for each color flat is different, that adds another grundle darks. And of course, none of this has anything to do with the light images. Looking through Sky & Telescope it's easy to find images where the photographer spent many hours over many nights shooting each of the clear, green, blue and red images which were combined to make the finished product. This may look pretty complicated. Well, yes, in the beginning it is. But as with most things complicated it's really quite straight forward once you've done it a few times and even easier still when you let the software do most of the work. But it's still very involved and, as I've said many times, no matter how hard you work at getting the perfect image, it seems the next issue of Sky & Telescope always has a better one. :) So maybe the above illustrates why virtually all of my images are black and white data images... patrick
Thanks, Patrick, This is a really valuable lesson. -- Best wishes, Joe --- On Thu, 1/8/09, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] Tri-color samples To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Thursday, January 8, 2009, 11:44 PM Hi Joe, On 08 Jan 2009, at 22:39, Joe Bauman wrote:
Hi Patrick, Thanks for doing this. I'd like a kit.
Ok, I'll get one out to you with a followup email.
I have shot darks at the time of the exposure, sometimes one per exposure, sometimes one per set of three or four exposures, but I've never combined darks.
A single dark may contain imperfections (like random noise and cosmic ray hits) that are then transferred to the light image. Shooting several (Jerry recommends at least 15 and I know of others that shoot many more) and then median combining (as opposed to adding or averaging) into a master dark keeps the good parts of the darks but tends to remove the bad. Happily it's very easy to make darks. The camera does not even need to be attached to the telescope (although as I'll cover in a minute, it's a good idea keep the camera attached to the scope). Just put the camera in a dark room, chill the chip to the temperature you shoot light images at (I use -10 year round as I can get that low even on warm summer nights) and have the software shoot 15 (or more) darks with the same exposure lengths as the lights you have taken or plan on taking. Darks can be archived. I typically use mine for a month or so and make new ones on nights when it's cloudy (though some insist on new darks every night).
Also I have yet to shoot a flat, though I know I need to do that. The problem with flats, as far as I am concerned, is that you have to use the same angle, focus, etc., as with the images you're correcting.
Yes. While flats typically take much less time to make they are more difficult and can not be reused if anything in the optical train is moved (which is why I leave the camera bolted securely to the telescope).
But in the field it's not possible to shoot a bunch of pics of one target, shoot flats, then go to another target -- at least, that's my understanding.
It is possible. But I can see where it's a pain. I've seen posts from folks on the Software Bisque lists that do it all the time. But it's far easier to do in a fixed observatory.
I think I need to shoot flats in the morning, using the latest target, but not a setting for an earlier target. Is that right?
Waiting until dawn and shooting the dawn sky is one way to do it. Cindy and Jerry do it by covering the front of the scope with cloth diaper material (really!) and shooting through that. I do it by pointing the scope at a blank sheet of white cardboard and then reflecting light off of another piece of white cardboard which then reflects off the first. Like the darks, I shoot the flats at the same temperature as the light images. You also need to shoot them through the same filter as is used for the light image (hence for color shots that means a separate flat for the clear light image and for each of the 3 filtered light images). The big difference from darks for flats is the exposure time. For darks the exposure is the same as for the light image. But for flats you only expose long enough to get about half way to saturating the chip. The purpose of the flat, BTW, is to image the out-of-focus various dust bunnies that exist in virtually every optical train (on the corrector, mirrors, filter, CCD chip window, CCD chip). When applied to the light image the flat removes the shadows caused by the bunnies. And as with darks, you'll shoot at least 15 flats to be made into each of the 4 master flats. So, how many total? 15 darks for one master dark. 15 flats for the clear master flat. 15 flats for the green master flat. 15 flats for the blue master flat. 15 flats for the read master flat. -- 75 Total I should add that some people also make master darks for each of their flats and since the exposures for each color flat is different, that adds another grundle darks. And of course, none of this has anything to do with the light images. Looking through Sky & Telescope it's easy to find images where the photographer spent many hours over many nights shooting each of the clear, green, blue and red images which were combined to make the finished product. This may look pretty complicated. Well, yes, in the beginning it is. But as with most things complicated it's really quite straight forward once you've done it a few times and even easier still when you let the software do most of the work. But it's still very involved and, as I've said many times, no matter how hard you work at getting the perfect image, it seems the next issue of Sky & Telescope always has a better one. :) So maybe the above illustrates why virtually all of my images are black and white data images... patrick _______________________________________________ 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, Can you send me sample kit. I would like to play with it too. Thanks, Tyler Allred
Patrick, You give me way too much credit. I thought it might be useful for people to see how different the results can be with a variety of processing techniques, even when using the same data. I will try to get the most out of this data set and may post a few different versions... if I can find the time. I am hoping to process my own data tomorrow. I am headed out to set up for imaging right now!! Clear skies... WAHOOOOOOOOO! Cheers, Tyler _____________________________________________ -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Friday, January 09, 2009 4:37 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Tri-color samples Kind of like sending a "How to Fly" book to Chuck Yeager, but, ok, I'll get a kit off to you when I get home. :) Cheers, patrick On 09 Jan 2009, at 16:18 , Tyler Allred wrote:
Patrick, Can you send me sample kit. I would like to play with it too. Thanks,
Tyler Allred
_______________________________________________ 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
Joe, Yeah I find Flats a problem. When I am shooting and it is 20 degrees outside, to just take off my t-shirt and hold it in front of the camera lens to get off a flat, well I skip that part. ;-). jg
Jim, that was my laugh for the morning. Thanks!! :o) On Fri, Jan 9, 2009 at 7:29 AM, Jim Gibson <jimgibson00@yahoo.com> wrote:
Joe, Yeah I find Flats a problem. When I am shooting and it is 20 degrees outside, to just take off my t-shirt and hold it in front of the camera lens to get off a flat, well I skip that part. ;-).
For anyone who wanted to look at Patrick Wiggins’ kit FITS files in Adobe PhotoShop, can go to a NASA site for the Hubble Space Telescope and get the FITS Liberator: http://www.spacetelescope.org/projects/fits_liberator/download_v22.html a PhotoShop plug-in to read the FITS file format. If you look at the menu on the left you can also download the user’s manual. Jim Gibson
Here's what I got when I combined the images after applying the dark and flats and fixing the two bad columns (grrrr), removing the hot pixels, removing the cold pixels and aligning all four images: http://users.wirelessbeehive.com/~paw/temp/MI_2008_JAN_08.01.JPG Like I said, not Tyler like. 3,900 mm is too long a focal length for needle-sharp stars and 5 minutes is too little exposure to get a lot of color and get rid of the mottled appearance. Remember that the 4 originals were all 1 minute exposures. As I'm pretty sure Tyler will confirm in the real world (not this lab exercise) the amount of exposure for each of the clear, green, blue and red light images varies depending on the object being imaged (I'm not sure but I don't think that can not be done with the 1 shot cameras). Several folks have asked for my kit. I look forward to seeing how their results look. Maybe next clear night I may shoot several one minute exposures of each color and make them available. That way folks can use the same flats and dark and vary the exposure of each color (depending on how many of each color they choose to use). Carpe Noctem! patrick On 08 Jan 2009, at 18:29, Patrick Wiggins wrote:
I spent some time collimating my scope last night after which I took a few test shots of M-1 which just happened to be transiting.
Knowing there are some folks here on the list getting into astroimaging I made images for a "kit" that could help folks get a feel for what's involved in making color images.
The kit contains:
1-Raw exposure with clear filter 1-Raw exposure with green filter 1-Raw exposure with blue filter 1-Raw exposure with red filter 1-Master dark to be used to reduce all of the raw images 1-Master clear flat for reducing the raw clear 1-Master green flat for reducing the raw green 1-Master blue flat for reducing the raw blue 1-Master red flat for reducing the raw red
The master dark was made by shooting and median combining 15 darks.
The master flats were made by shooting and median combining 15 each flats shot through the clear, green, blue and red filters.
I should note that using the kit will not get you "Tyler like" images. Though the final image should look pretty good the main purpose of the kit is to show folks what's involved in making "real" color images (I say "real" as opposed to the one-shot cameras which, like color film, sometimes produce questionable colors).
Let me know if you'd like a kit and I'll email it out.
Clear skies!
patrick
I love it. The central pulsar is clearly visible. Well-done, optimized or not. On Fri, Jan 9, 2009 at 1:19 AM, Patrick Wiggins <paw@wirelessbeehive.com>wrote:
Here's what I got when I combined the images after applying the dark and flats and fixing the two bad columns (grrrr), removing the hot pixels, removing the cold pixels and aligning all four images:
http://users.wirelessbeehive.com/~paw/temp/MI_2008_JAN_08.01.JPG
Hi all, Coming up next month we should get a look at comet C/2007 N3 (Lulin) peaking at 4th mag on 24 Feb. See: http://cometography.com/lcomets/2007n3.html for details and history. jg
If we could see, Venus and Uranus are about 1 degree 13m apart.
participants (5)
-
Chuck Hards -
Jim Gibson -
Joe Bauman -
Patrick Wiggins -
Tyler Allred