Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Jack16 on January 25, 2011, 08:15:50 PM
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Can someone teach me or know any really good internet tutorials on how to Polar align my telescope and track objects?
I have a Meade LXD 10" Schmidt Newtonian
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If you are using the same mount my LXD55 has then you need to make sure you have your GPS coords set correctly in the autostar and align the mount to polar north not magnetic north.
Then you need to make sure the weight on the telescope mount is balanced.. on mine, a 6" refractor the weight can easily throw the tracking off.
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I don't have GPS, I have Go-To. And during setup there is an option to use polar or magnetic north.
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damn you guys my telescope I had, just had two little dials to move it along its path.....:-(.......it is cool as heck lookin at the moon up close, I tried to look at the andromada galexy, but my scope just wassnt powerfull enough, id like to get a new modern one,one of these days maybe.
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Can someone teach me or know any really good internet tutorials on how to Polar align my telescope and track objects?
I have a Meade LXD 10" Schmidt Newtonian
One of the guys in my club has that scope.
What kind of mount is the scope on, that will help a lot.
This is a link to my club's website, it may have some information on it to help you. http://www.limaastro.org/
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What kind of mount is the scope on, that will help a lot.
LXD75 German Equatorial Mount
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I don't have GPS, I have Go-To. And during setup there is an option to use polar or magnetic north.
GPS coords you can get from the internet. Just type in the city you're in. It doesnt have to be perfectly accurate. Its just so the autostar go-to system knows where on the planet you're in so it can slew correctly :P
If your mount has the magnetic north option then you're set. Just aim the tripod to it with a compass and select that option..the scope system will compensate the difference between magnetic and polar.
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If your mount has the magnetic north option then you're set. Just aim the tripod to it with a compass and select that option..the scope system will compensate the difference between magnetic and polar.
I do that, but when it goes to align, it's always way off
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Probably because you have a German mount and you're in America.... :lol :lol :lol ....sorry I have no idea but thought that was funny...well it was in my head anyway.
you guys have nice scopes though...wish I get one...mine is ok but man those meade's are nice.
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Im not familiar with the 75 mount but my 55 also has a physical dial on the mount body itself that needs to be set to the correct settings.
...and I admit I had this mistake once... make sure the telescope swivel head is actually aligned correctly.. it has two little triangles along the swivel head and they should meet. I once spent an hour wondering why the hell the scope was pointing in completely random directions and it turned out i had the swivel triangles 'backwards'. :bhead
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yes, the triangles do line up.
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I know others have asked, but if you don't mind (and it's not your place of residence or you don't mind the AH BBS general public knowing) what are the GPS coords you are using? Assuming the coords are corect, one of us should be able to quickly figure out what your settings should be and see if those match up to what you're using.
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Hmmm, I don't remember ever having to put coords in. Would I have to do that through the settings menu?
According to this website: http://itouchmap.com/latlong.html my coords are 40.148667,-75.102921
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Yes, in the autostar menu settings it should have a GPS coord input option.
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K thanks. I'll give it a try on a not so cloudy night :P
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I don't have your exact mount but if its anything like mine, not only must you set the Lat, Lon, but make sure your date and time and DST settings are accurate.
And I assume you have to mount mode set to polar not alt-az. Don't laugh, I had that problem once.
I assume you've walked thru the steps in the manual?
Doesn't that mount have a polar alignment scope built into the RA axis?
Another thing I do is after I think I am set, I've have it navigate to a bright star I know and if its slightly off I'll have it adjust with the hand set and then "Sync" on that corrected position. It remembers that correction and applies it to future Go-To's.
However, I've been on a permanent mount for several years so life is easier for me. ;)
Wab
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Any new pics Wab? Love the shots u take sir :aok
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Wab~ thats very cool...I had a 4" once I lived on top of a mountain in NH,man I had crazy clear skys, I want to get a huge one like a 10" mirrior......I want to see andromada for some reason just lookin at anouther galexy shows you how small we are lol. the rings of saturn I could see....well I could see them but it look solid, I truly love checking out the night...you ever see moving stars? I did it was messed up. Lots of times, a small star would move from one to another at a extreme rate of speed,cover an inch or more of sky, in a less then a second.
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Any new pics Wab? Love the shots u take sir :aok
Thanks.
I'm ashamed to say I haven't taken a single picture all last year.
I've had too much crazy watermelon going on in my life lately and besides had some minor damage to the scope drive I need to fix. I've used it visually a couple of times ok, but I need to replace some marred gears before doing an precision work again.
One of my goals for the year is to do some more photography. I might concentrate more on planetary/solar stuff this year instead of deepsky.
:salute,
Wab
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Wab~ thats very cool...I had a 4" once I lived on top of a mountain in NH,man I had crazy clear skys, I want to get a huge one like a 10" mirrior......I want to see andromada for some reason just lookin at anouther galexy shows you how small we are lol.
If you can get out to some dark country skies, on a Moonless night, before the air humidity gets to humid and hazy in the Summer, you can view Andromada quite nicely with a descent 7x50 pair of binocs.
Its a reasonably bright, extended object. It doesn't need much magnification. I can usually pic it up with the naked eye from my site when there is no Moon. Its actually pretty big. If it was bright enough, you'd see it extends, end to end, about twice the width of a full moon from our vantage point. Binocs just help pull in more light and a tad of mag.
you ever see moving stars? I did it was messed up. Lots of times, a small star would move from one to another at a extreme rate of speed,cover an inch or more of sky, in a less then a second.
I've seen satillites and aircraft pass in front of my view at the scope, but not what your describing. Sure it wasn't just the scope vibrating? :noid
Clear Skies,
Wab
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I don't have your exact mount but if its anything like mine, not only must you set the Lat, Lon, but make sure your date and time and DST settings are accurate.
And I assume you have to mount mode set to polar not alt-az. Don't laugh, I had that problem once.
I assume you've walked thru the steps in the manual?
Doesn't that mount have a polar alignment scope built into the RA axis?
Another thing I do is after I think I am set, I've have it navigate to a bright star I know and if its slightly off I'll have it adjust with the hand set and then "Sync" on that corrected position. It remembers that correction and applies it to future Go-To's.
1.)Yes, date and time are asked during setup.
2.)No idea, I guess it is.
3.)Yes, I tried following the manual.
4.)Yes, there is a polar alignment scope in the mount.
5.)I understand if the stars are slightly off, but when I say way off, I mean way off (The star could be on the horizon, but the scope would point upwards. lol)
Any new pics Wab? Love the shots u take sir :aok
Here are a couple of mine:
1.)Bad pic of M42(Orion Nebula)
(http://i180.photobucket.com/albums/x311/archywood/orion-neb1.jpg)
2.)
(http://i180.photobucket.com/albums/x311/archywood/IMG_0213-1.jpg)
3.)A composite of 103 single-frame exposures at 30 seconds each.
(http://i180.photobucket.com/albums/x311/archywood/Startrails2.jpg)
Wab~ thats very cool...I had a 4" once I lived on top of a mountain in NH,man I had crazy clear skys, I want to get a huge one like a 10" mirrior......I want to see andromada for some reason just lookin at anouther galexy shows you how small we are lol. the rings of saturn I could see....well I could see them but it look solid, I truly love checking out the night...you ever see moving stars? I did it was messed up. Lots of times, a small star would move from one to another at a extreme rate of speed,cover an inch or more of sky, in a less then a second.
Wab is right. Andromeda is a reasonably bright object. But were I'm from, I can't see it with the naked eye and it only looks like an extremely faint blob of grey through a really small scope.
As for your moving stars, they are most likely satellites. They look like airplanes, but without the blinking lights. They also vary in magnitude(brightness) as well. Every so often you might come across a "Satellite Flair", which is when a satellite with a dim magnitude crosses the path of the sun at a certain angle and it gradually gets extremely bright, then it dims again.
Here is a pic I took that shows Cassiopeia and Andromeda galaxy(circled in red in second pic) (Sorry, for small pic)
(http://i180.photobucket.com/albums/x311/archywood/58676_1491166411849_1614669996_1175463_5943605_n.jpg)
(http://i180.photobucket.com/albums/x311/archywood/58676_1491166411849_1614669996_1175463_5943605_n2.jpg)
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2.)No idea, I guess it is.
I'm not complete sure which one you are refering to here.
If its wether the AutoStar is set to polar or alt-alz mode, then thats important. If you are using the wrong setup mode it will completely calculate the wrong position for stuff.
Don't ask me how I know this. ;)
Wab
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Those are very nice pics. I especially love the Moon and star trails.
I can't remember. I think I've given you my link before so I'm probably repeating myself.
But just in case you can find some of my photos and setup here:
http://jasonirby.net/Astronomy/ (http://jasonirby.net/Astronomy/)
Clear Skies,
Wab
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I want to see andromada for some reason just lookin at anouther galexy shows you how small we are lol.
Yep, it certainly helps give you a different perspective.
Here is a shot I did of Andromeda a while back:
http://JasonIrby.zenfolio.com/p557407765/e164fb67b (http://JasonIrby.zenfolio.com/p557407765/e164fb67b)
Of course don't expect it to look this way in a telescope. It took a couple of hours exposure to gather enough light to look like this. Expect more of an elongated gray smudge visually.
I might be making myself look stupid, but notice how one half is more redish and one half more blueish?
I believe this is caused by the rotation of the glalaxy.
The one half is rotating towards us, slightly blueshifting the light from those stars.
The other half rotating away from us, slightly redshifting the light from the stars on that half.
Sort of like the doppler effect of a train whistle transitioning from high frequency (blue) to low frequency (red) as it passes by.
Wab
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I'm not complete sure which one you are refering to here.
If its wether the AutoStar is set to polar or alt-alz mode, then thats important. If you are using the wrong setup mode it will completely calculate the wrong position for stuff.
Don't ask me how I know this. ;)
Wab
I beleive it's set to polar.
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I beleive it's set to polar.
The other question I'd have, is it significantly off in both axis, or just the axis that rotates around the pole star?
Wab
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Hmmmm. Haven't thought of that. I'll check it out next time I go out.
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Hmmmm. Haven't thought of that. I'll check it out next time I go out.
Another thing you might want to try is determine if its a mechanical alignment issue or an AutoStar issue.
Get things basically setup. Tripod base leveled. Polar axis scope lined up correctly on Polaris.
Then skip the calibration part. just manually slew over to a bright star and center it in a med mag eyepiece with the tracking motor running. Make sure the star basically stays in the field of view for at least 5-10 minutes just due to the tracking motor.
If that basically works, then I'd say you getting the mechanical axis of your mount properly aligned with the Earth's axis of rotation. If not, work on that first or the Auto star will never work properly.
Once that is proven, if you still have problems we know if must be the Autostar calibration or settings.
Clear Skies,
Wab
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Another thing you might want to try is determine if its a mechanical alignment issue or an AutoStar issue.
Get things basically setup. Tripod base leveled. Polar axis scope lined up correctly on Polaris.
Then skip the calibration part. just manually slew over to a bright star and center it in a med mag eyepiece with the tracking motor running. Make sure the star basically stays in the field of view for at least 5-10 minutes just due to the tracking motor.
If that basically works, then I'd say you getting the mechanical axis of your mount properly aligned with the Earth's axis of rotation. If not, work on that first or the Auto star will never work properly.
Once that is proven, if you still have problems we know if must be the Autostar calibration or settings.
Clear Skies,
Wab
ok I'll try that as well :aok
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I cant see crap with my eyes unless upclose, good thing I do tattoo's :-) others told me its satelites, If they are im shocked at how fast they move.
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I was thinking about getting a telescope myself, what would you guys consider a good buy? I am not looking for anything too fancy, at least to start with, but I do not want some wimpy little scope either.
My purchase range is ~$200, of course anything less is great.
Here is a couple I have seen, but I do not know what to look for exactly:
http://www.opticsplanet.net/barska-675x900mm-starwatcher-reflector-telescope-ae10758.html
http://www.opticsplanet.net/meade-114-eq-a-model-45-f-8-equatorial-telescope-04055.html
http://www.opticsplanet.net/sky-watcher-sw-80ars-mm-telescope.html
I am currently just interested in looking at the planets/moons
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I was thinking about getting a telescope myself, what would you guys consider a good buy? I am not looking for anything too fancy, at least to start with, but I do not want some wimpy little scope either.
My purchase range is ~$200, of course anything less is great.
Here is a couple I have seen, but I do not know what to look for exactly:
http://www.opticsplanet.net/barska-675x900mm-starwatcher-reflector-telescope-ae10758.html
http://www.opticsplanet.net/meade-114-eq-a-model-45-f-8-equatorial-telescope-04055.html
http://www.opticsplanet.net/sky-watcher-sw-80ars-mm-telescope.html
I am currently just interested in looking at the planets/moons
For $200 you can get some pretty decent scopes for novice/beginers.
I'd either go with the Meade or the Barksa. It may just be my opinion, but I'd say the Meade. The Meade scope you have chosen also has a few reviews when the Barska doesn't. Always read some of the reviews before you buy anything.
The specs say the meade is a 4.5 inch. The scope I had before(http://www.opticsplanet.net/meade-ds-2130ats-lnt-goto-autostar-reflector-telescope-20135.html) (It's also on sale now!) the one I do now is just .5 inches larger and has a go-to mount, was perfect for looking at the moon and planets. Though a low powered eyepiece you can easily see the moons of Jupiter and some of the cloud belts. It's also really good at looking at looking at brighter deep sky objects like the Orion Nebula or Andromeda Galaxy. These would do just as well.
Do some more research on these scopes and read the customer reviews. You may find a better one in your price range.
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Nice Pics Jack, thanks for posting. :aok
Ive been looking into getting one myself, I know this is going to sound newbish, but if i get a decent telescope, will i be able to literally see the planet? Not just a bright dot in the sky, but the full planet itself? For example, if i get a decent ( 200 to $400 scope) could i see say.....the rings on Saturn etc?
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Honestly, save a bit and get a schmidt-casselgrein type scope. Its good for everything, very compact (easy to store/move), light and best of all... needs no fieldwork besides wiping the lens (like a refractor).
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Nice Pics Jack, thanks for posting. :aok
Ive been looking into getting one myself, I know this is going to sound newbish, but if i get a decent telescope, will i be able to literally see the planet? Not just a bright dot in the sky, but the full planet itself? For example, if i get a decent ( 200 to $400 scope) could i see say.....the rings on Saturn etc?
Yes. You should be able to see the rings of Saturn with a really small scope and the right eyepiece, but it would be hard to see because of the size and glare. $400 dollar range is good.
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Yes. You should be able to see the rings of Saturn with a really small scope and the right eyepiece, but it would be hard to see because of the size and glare. $400 dollar range is good.
By size and range you mean that Id be able to see the planet, and that the glare of the planet would make the rings hard to see? So seeing say...Jupiter, i might be able to see the storms and such on the surface?
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By size and range you mean that Id be able to see the planet, and that the glare of the planet would make the rings hard to see? So seeing say...Jupiter, i might be able to see the storms and such on the surface?
Yes, you will be able to see it. I mean the size of the planet in a small scope will be small. That plus the glare might make it a little difficult. Larger scopes not only make the view larger, but also it has the ability to gather more light, so you'll be able to see more detail. The bigger the scope, the larger the view/the more detail that is shown.
The scope won't be powerful enough to see the actual storms on Jupiter(Mine isn't even able to see that). The reason is that the sun's glare off it would be to bright, but with the right eyepiece you'd be able to make out the cloud bands. Unless you had a filter which cuts down on light glare. That might bring out some more detail.
When looking though a telescope, you don't see color. For example, if you were to look at the Orion Nebula, which is one of the brightest deep space objects in the night sky, you wouldn't see the colors you do in photographs. Instead, you'd see a greyish blob. The reason for this is because the light from that object takes awhile to actually get to earth and our eyes aren't sensitive enough to pick up the color. The Sun's light takes about 8 minutes to reach earth. If you were to see a star randomly erupt into a supernova while looking up at the sky, that would have taken place maybe thousands of years ago, but the light from that explosion is just reaching earth/our eyes. Most deep space objects aren't really even visible to the naked eye, because their light doesn't reach earth fast enough and our eyes aren't sensitive enough to see them. This is where a camera comes into play. The reason a camera captures what it does is because it's film/ccd chip is more sensitive to the light and is able to gather it together much better than a human eye can.
So, the planets would basically look greyish in color, too, but because they are close enough to earth, you might be able to see some color. If you looked at Mars (would just appear as a red dot in a small scope) then you could see the reddish hue of it, but not a lot of detail because of the glare.
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a good rule is the bigger the mirror the better the scope, I had a 4" mirror I could see saturns rings, but they looked like one solid ring.
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a good rule is the bigger the mirror the better the scope, I had a 4" mirror I could see saturns rings, but they looked like one solid ring.
Yes, because the bigger mirror is able to absorb more of the light, which brings out more detail in the object which you are viewing.
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Don't know what I did, but the I got it to work. The Go-To is still a little off, but tracking is working 100% better!
(http://i180.photobucket.com/albums/x311/archywood/Orion_neb.jpg)
(http://i180.photobucket.com/albums/x311/archywood/Orion.jpg)
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Don't know what I did, but the I got it to work. The Go-To is still a little off, but tracking is working 100% better!
Glad to here you're "on track"!
Nice job on the images. I hope you don't mind, but its a compulsion I have to try and enhance peoples images. Its just how I practice when I don't have images of my own to work on. ;)
This is what I was working toward:
(http://jasonirby.net/Astronomy/Test/orion_neb.png)
It looks to me there might have been lots of good data in there that could be enhanced but the image you posted looks like it was bit-clipped or heavily compressed.
Jpg mangles image data. Its a lossy compression. I always prefer png myself. That wasn't captured in jpg or 8bit was it? If you still had the original 16bit data I'd like to try on that if your interested. What are you imaging with btw?
Any way, keep up the good work. You're shaming me into getting out the cameras again. I think I might fiddle with some solar stuff.
Clear Skies,
Wab
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Look's pretty good.
I'm using a Canon Digital Rebel XSI. The images it gives me are in .jpg format, but I have it set so it gives me both the .jpg format and the original RAW(.CR2) file.
Is there a way to attach a file in a PM?
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Look's pretty good.
I'm using a Canon Digital Rebel XSI. The images it gives me are in .jpg format, but I have it set so it gives me both the .jpg format and the original RAW(.CR2) file.
Is there a way to attach a file in a PM?
You might try putting it up on DRopbox.
http://www.dropbox.com/
Wab
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is able to absorb more of the light,
You mean it " Gathers " light.
One more thing that hasn't been mentioned on this thread:
Light pollution......check your area on a dark sky chart to see if your in a dark area.
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ouf... good luck!
(http://www.lightpollution.it/worldatlas/images/fig2.jpg)
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I'm always intrigued with images of space. When wab takes multiple shots and uses them together to enhace the light from the objects..... it's flat out amazing.
Thanks for posting pics.
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This is what I was working toward:
Whoa. That looks a lot darker on my monitor at work than it did at home. Thats the problem with posting astro photos on the net. Its so sensetive to monitor calibration.
Wab
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ouf... good luck!
(http://www.lightpollution.it/worldatlas/images/fig2.jpg)
Yeah. That’s a sad state of affairs. I’m blessed with some really dark skies still at my observatory site, but that won’t last forever.
Your grandchildren might grow up never having seen the Milkyway. I had a buddy of mine who grew up in the metroplex his whole life and he was looking up saying “Are those clouds coming in?” and I answered “No dude, that’s the Milkyway.” He had never seen it before.
On the bright-side (pardon the pun) if you are in a urban area, you could focus your observing more towards Solar, Lunar, and planetary viewing. That is unaffected by light pollution. If fact, due to the temp inversions that develop over some cities, you can get quite excellent, steady air for high resolution observing. The big factor then is if you are unlucky enough to be in a location that is permanently under the Jet stream. The jet stream will greatly limit planetary viewing.
Clear Skies,
Wab
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I beleive it's set to polar.
It's funny, with the new scopes. Just set it them up, punch in lat/long and dial up what you want to see. If it's in the sky, the scope takes you there. Wiz bang. You don't have to know one single constellation anymore.
I miss the days before the automation, where the reward was just finding the deep sky objects with charts and lots of patience. I did most of the Messier objects in high school, over the course of two years of peering and checking charts on cold, cold nights. Then taking photos with actual.... film... GASP! Hell, my first mount didn't even track.... had to move with fine adjustment constantly.
My old school planetarium still has the bound notes and observations/pictures I did.
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Ok, for my next question. It's about my camera. What's with modifying the camera by taking out the IR Cut Filter? Is this necessary? And what will change about the way my camera works if I decide to take it out?
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Here I twiddled with your raw image. That at least didn't suffer from the compression. There is a bit of noise in the data. I may have streched it a bit far for some tastes. I'll take a bit of noise if I see actual structure there too.
(http://jasonirby.net/astronomy/test/oriontest2.png)
How long an exposure was that?
You did a good job on the focus.
I use a program called "Images Plus" mainly for tweaking my images. If you took several images of that one after another, you can average them with this software and reduced the noise. That allows you to strech the data further without making the noise noticable.
Eventually you might want to experiment with "Darks" and "Flats". These are calibration images you can use to remove various artifacts in your images.
Keep it up!
Clear Skies,
Wab
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Looks great! :aok
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Looks great! :aok
Crap its still hosed! ;)
It looks one way on my home laptop and totally different on my work machine. Maybe I AM outa practice. :lol
To your camera question:
I have a XSi and bought it with its filter pre-removed from a company who's name escapes me now.
I hear a guy that does good work post modifying cameras is Hap Griffin:
http://www.hapg.org/camera%20mods.htm (http://www.hapg.org/camera%20mods.htm)
It does make a fair bit of difference in improving your sensetivity to the red spectrum where a lot of nebula will live. Maybe not so much help on galaxies.
It will throw off your white balance. I only use mine for astro so its not a problem, but might be if you intend dual use. I believe however you can use a custom white balance setting and account for it just fine. That entails taking a photo of a white evenly illuminated surface (posterboard?) in normal day light and through your camera settings telling to use that as white balance photo. Now the camera now what white should look like and will comensate.
Have you tried webcam photography for solar, lunar, planets?
Wab
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UV filters are ideal for daylight outdoor photography, they prevent the camera from absorbing too much of the UV rays that are bouncing around out there from the sun and give you a more balanced photo with less glaring hot spots. Since most shots taken outside durign the day, or inside under daylight conditions, are more plentiful in light than not (including flash photography), having a permanent (or opting not to remove a removable one) UV filter is usualy just fine. This mild filtering though is not ideal for very sensitive camera work though where you're scraping to get as much exposure in your shots to capture every bit of the faintest amount of light, such as night time no-flash heavy-exposure photography including astronomy. With astronomy photography you want to capture as much of the faint light as you can during your long exposures, including UV or anything else.
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I think I'll keep my camera the way it is. If I astrophotography becomes a serious hobby of mine, I might get another camera.
Wab, I did take a few other shots if you want to try to fiddle with and stack them.
How do I work the dark frames? I know I have to put the cover on the scope, but what do I do after that?
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Wab, I did take a few other shots if you want to try to fiddle with and stack them.
Sure, just put them on your dropbox. I'll give it a try.
How do I work the dark frames? I know I have to put the cover on the scope, but what do I do after that?
Darks provide a calibration to account for system artifacts like hot pixels and amp glow. (You camera looks pretty clean but with longer exposures might start showing more. My guess your biggest immediate bang for the buck would be from stacking.)
You don't even to have the camera attached. Ambient temp is important. Put the cap on your camera and take a series of images at the same ISO and duration as you "Light" or image frames are going to be. If you expect a large temp drop during the session I'd take half the darks before and half after you image frames to average out the temp drop. Ambient temp greatly effects the amount of noise in the image.
Just a rough example:
I'm planning to take 20 x 5min exposures of M42 at ISO800.
So before my session I turn on the camera and let it warm up a little then take maybe 5 darks (cap on) at ISO800 at 5min.
I then set up and take 20 x 5min @ ISO800 images of my target (light frames).
When I'm done I take off the camera, put the cap on, and take another 5 x 5min @ ISO800 dark frames.
(For the kind of image I do I usually don't need to mess with flat frames but you might want to get to that someday.)
Later, with software, I stack and average the 10 dark frames toget a master dark frame to use for calibration.
I then align, stack, and average the light frames to get a master light frame.
The software will then subtact the master dark frame from the master light frame to remove systemic noise.
You can find this stuff on the net. However I can recommend "A Guide to Astrophotography with Digital SLR Cameras" by Jerry Lodriguss. Its a great resource to get started with.
The idea behaind stacking the light frames is that the noise is distributed randomly in each frame. The image should be consistent between each frame. So averaging them together tends to reinforce the image and weaken the noise. Noise will decrease to the inverse square Root of the number of frames. stacking 4 images cuts the noise in half compared to a single image.
There is a trade off between taking a long exposure versus a shorter exposure. A long exposure tends have worse tracking errors creep in. Many bad things like a passing plane or bumping the scope might ruin the frame. On some cameras you start to get amp glow. On the other hand a shorter exposure has more noise and might not be long enough to separate data from the background noise. ON the other hand if you are taking 20 5min images and bump the scope you only ruin 1 sub-frame and still have 95 min good data. If you were taking a single 100min exposure, you would be hosed.
However, digital cameras have a magical property. Assuming the exposures are at least be long enough to separate the image data from the systemic and background noise, then their combined exposure time is virtually equal to a single exposure of the total. With my camera and skies, a 5min sub-frame exposure is ideal. So 20 x 5min exposures is virtually equal to a single 100 min exposure without all the other problems. Also, stacking allows you to use a much higher ISO setting that normal because the stack can overcome the increased noise due to the higher ISO settings. Its worth the extra sensetivity. I often use ISO1600 if I'm taking 20 or so sub-frames.
Regards,
Wab
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Wab-damn dood you know your stuff when it comes to camara's.....kudos......
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I often use ISO1600 if I'm taking 20 or so sub-frames.
Wow. Gonna have to try that.
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Wow. Gonna have to try that.
Assuming of course that you are stacking enough sub-frames to increase signal-to-noise ratio sufficiently.
Wab
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It's funny, with the new scopes. Just set it them up, punch in lat/long and dial up what you want to see. If it's in the sky, the scope takes you there. Wiz bang. You don't have to know one single constellation anymore.
I miss the days before the automation, where the reward was just finding the deep sky objects with charts and lots of patience. I did most of the Messier objects in high school, over the course of two years of peering and checking charts on cold, cold nights. Then taking photos with actual.... film... GASP! Hell, my first mount didn't even track.... had to move with fine adjustment constantly.
My old school planetarium still has the bound notes and observations/pictures I did.
At my Astronomy club, to get on the key list(list of people with access to observatory) you have to be able to set up the scope, dial it in, then find a not so easy target and focus it in.
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Yep, I can do 20 frames.
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This is a good discussion of SNR and stacking:
http://www.samirkharusi.net/sub-exposures.html (http://www.samirkharusi.net/sub-exposures.html)
Clear Skies,
Wab
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And if you aren't ready to dish out for ImagesPlus you might try this:
http://deepskystacker.free.fr/english/index.html (http://deepskystacker.free.fr/english/index.html)
Its free. I've never used it myself, but I've heard good things.
Wab
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Thanks Wab.
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I tried stacking the images myself with the Deep Space Stacker program and this is what I came up with.
(http://i180.photobucket.com/albums/x311/archywood/nebtest.jpg)
There is still a lot of noise and it's kinda grainy, too, but loads better than the original!
Wab, I sent you the images still if you would like to try.
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I tried stacking the images myself with the Deep Space Stacker program and this is what I came up with.
Now THATS what I'm talkin about! Tons better! Thats sweet!
I might play with it a little but I doubt I'll improve on that. I might try and see if I can keep the central region from over saturating. You had some excellent detail in there I think got clipped. I also remembered I used to use the other program called "Neat Image" to remove some of the noise. I'll see if it helps at all.
Now, you might have notice that your images had a radial brightening toward the center? I think thats what flats would help you remove. The good news is, if you want to try that later, you can create pretty good ones any time. Take you scope and camera out in the morning or evening. Set it up like you were going to image. Take a white t-shirt or similar and stretch it across the front of the scope and point the scope and a cloudless, evenly illuminated area and take about 10 frames at the same iso and duration as you did your light frames. Stack and use that master flat frame to calibrate your original data and that should give you an even illumination across the frame. Then you are only dealing with the targets data not that intruduced by the optical system.
Great work. Now you just need to start webcaming. ;)
Clear Skies,
Wab
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Here is my try:
(http://jasonirby.net/Astronomy/Test/orionstacked.png)
I only stacked 3 of the 4 images. One looked really smeared. Maybe I should have added it anyway.
Still I think you can see the amazing benefits of stacking. Look at the improvement over the original single image frame. Think if you had a stack of 20! :D
Now you have a whole new avenue to explore. Hope to see some more soon and congrats on the fine image!
Clear Skies,
Wab
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Oh I forgot one last suggestion.
Once you start taking large number of subframes you might want to look into something like:
http://www.google.com/products/catalog?q=canon+timer+remote+controller+tc-80n3&hl=en&prmd=ivns&resnum=1&biw=1579&bih=1027&wrapid=tlif129674988538310&um=1&ie=UTF-8&cid=3412511021821397184&sa=X&ei=VdVKTcCYI8X6lwfLlIkS&ved=0CFgQ8gIwAQ# (http://www.google.com/products/catalog?q=canon+timer+remote+controller+tc-80n3&hl=en&prmd=ivns&resnum=1&biw=1579&bih=1027&wrapid=tlif129674988538310&um=1&ie=UTF-8&cid=3412511021821397184&sa=X&ei=VdVKTcCYI8X6lwfLlIkS&ved=0CFgQ8gIwAQ#)
NOTE: this might not plug into your XTi without an adapter! They may have fixed that or made a new one. You'll have to research.
I originally bought one for my 10D and later when I got my XSi realized the plug was different. There was a guy on the net that sold custom converter plugs and I bought one and it works fine.
It allows you to pre-program the number of frames, the duration of each exposure, and the time delay between frames. Makes life much simpler. I set it up, stick it with velcro the the forks of my mount and start it. I don't have to touch anything again for a couple of hours until its done with the program.
Wab
I also think you can use ImagesPlus to do this. The smarts are in the program and they have instructions on how to make the simple bulb cable.