astrophotography

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spike77

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i have a cpc 1100 and im in astrophotography i do not have a wedge for it so i have found out that i cant burn for over a minute and a half before i start to get star trails hyper star says that with there unit i would not have to polar align or use a auto guider to do long exposer do u no anything about this
 
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Fallingstar1971

Guest
"i have a cpc 1100"
(Im guessing a telescope with camera rig. Which model in particular?)

"i do not have a wedge for it"
(not sure here)

"so i have found out that i cant burn for over a minute and a half before i start to get star trails "
(This is because the Earth is turning, which is why you need motorized tracking. Im guessing "burn"="exposure time")

"hyper star says that with there unit i would not have to polar align or use a auto guider to do long exposer"
(No idea who they are, but polar alignment is required for tracking. Some models use "guidestars" like the goto scopes)

"do u no anything about this"

Im thinking at some hop along the bunny trail either the question to your vendor was misunderstood, or the answer that was provided. You can not stop the rotation of the Earth, which means that if you want to avoid star trails you will have to compensate for it. This is done with tracking, but the tracking will not function properly if the mount isnt properly aligned.

There is no short cut for this that I know of. Either track or your limited to one or two second exposures low magnification shots.

There is an astrophotography thread where maybe you can find some more help as well.

Good luck, post what you learn. Im learning as I go as well.

Star
 
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MeteorWayne

Guest
As suggested by the title of this topic, this also belongs in the Astrophotography forum, so will be moved there tomorrow.
 
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Fallingstar1971

Guest
On second thought, thats almost a three thousand dollar telescope.

You dropped 3 grand on something you do not know how to use? Or a hobby you do not understand?

Wow, you should of went with a cheaper rig to learn. This way if you loose interest you wont be out all that cash.

On the upside, it is a very nice scope. When you tire of it, shoot me a PM and some photos of the scope itself. If I have the funds Ill buy it. For now Ill stick with the afocal method, next year Ill try out direct focus, and the following year Ill buy a scope similar to yours.

Patience, and one step at a time.

Star

PS this scope uses "Sky Align" According to telescopes.com. Your manual should describe the procedure.
 
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Mee_n_Mac

Guest
Fallingstar1971":39i0ipj9 said:
"i have a cpc 1100"
(Im guessing a telescope with camera rig. Which model in particular?)

"i do not have a wedge for it"
(not sure here)

"so i have found out that i cant burn for over a minute and a half before i start to get star trails "
(This is because the Earth is turning, which is why you need motorized tracking. Im guessing "burn"="exposure time")

"hyper star says that with there unit i would not have to polar align or use a auto guider to do long exposer"
(No idea who they are, but polar alignment is required for tracking. Some models use "guidestars" like the goto scopes)

"do u no anything about this"

Im thinking at some hop along the bunny trail either the question to your vendor was misunderstood, or the answer that was provided. You can not stop the rotation of the Earth, which means that if you want to avoid star trails you will have to compensate for it. This is done with tracking, but the tracking will not function properly if the mount isnt properly aligned.

There is no short cut for this that I know of. Either track or your limited to one or two second exposures low magnification shots.

There is an astrophotography thread where maybe you can find some more help as well.

Good luck, post what you learn. Im learning as I go as well.

Star
The wedge is a equitorial wedge mount. It allows the rotation to happen in one axis (vs 2 for an Alt-Az mount). In turn (pun intended) this means the view does not rotate in the eyepiece as the telescope tracks (which is what happens with an Alt-Az). You need to align the scopes rotational axis with that of the Earth of course, hence the polar alignment. The only reference I could find to "HyperStars" was an lens/imager system that replaced the secondary mirror in a reflector thereby increasing it's sensitivity but this wouldn't help for true long duration imaging, you'd still need to do a polar alignment and track to prevent trails or a rotating FOV. You just don't need to be as accurate (in alignment) or rely on an auto-guider. Now perhaps you could do a series of short duration exposures (see below) but that still doesn't get you the same exposure as a true single long duration exposure. Then again perhaps his viewing doesn't need a true long duration exposure.

Alternately you could rotate the imager in the focusser but at this point wouldn't it be simpler, better, cheaper to get the proper mount ?


From the website ...

http://starizona.com/acb/hyperstar/whatis.aspx

Aside from the obvious savings in time and effort, short exposure times have a secondary advantage: capturing images is much easier. With typical exposure times of 20-60 seconds, HyperStar imaging allows unguided imaging. Long exposures require a telescope to be guided due to inherent tracking errors in the drive. This requires a second CCD camera or self-guiding CCD and often other hardware such as a guidescope. HyperStar images can be shot unguided thanks to the extremely short exposure.

An additional benefit of short exposures is that it is often possible to image with a telescope in alt-azimuth mode. This means it is possible to capture deep-sky images with a fork-mounted SCT without needing an equatorial wedge. This saves the trouble of mounting the scope on a wedge plus having to polar align the telescope. CCD imaging simply doesn't get any easier than that!
 
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Fallingstar1971

Guest
Mee_n_Mac":39cix9v7 said:
Fallingstar1971":39cix9v7 said:
"i have a cpc 1100"
(Im guessing a telescope with camera rig. Which model in particular?)

"i do not have a wedge for it"
(not sure here)

"so i have found out that i cant burn for over a minute and a half before i start to get star trails "
(This is because the Earth is turning, which is why you need motorized tracking. Im guessing "burn"="exposure time")

"hyper star says that with there unit i would not have to polar align or use a auto guider to do long exposer"
(No idea who they are, but polar alignment is required for tracking. Some models use "guidestars" like the goto scopes)

"do u no anything about this"

Im thinking at some hop along the bunny trail either the question to your vendor was misunderstood, or the answer that was provided. You can not stop the rotation of the Earth, which means that if you want to avoid star trails you will have to compensate for it. This is done with tracking, but the tracking will not function properly if the mount isnt properly aligned.

There is no short cut for this that I know of. Either track or your limited to one or two second exposures low magnification shots.

There is an astrophotography thread where maybe you can find some more help as well.

Good luck, post what you learn. Im learning as I go as well.

Star
The wedge is a equitorial wedge mount. It allows the rotation to happen in one axis (vs 2 for an Alt-Az mount). In turn (pun intended) this means the view does not rotate in the eyepiece as the telescope tracks (which is what happens with an Alt-Az). You need to align the scopes rotational axis with that of the Earth of course, hence the polar alignment. The only reference I could find to "HyperStars" was an lens/imager system that replaced the secondary mirror in a reflector thereby increasing it's sensitivity but this wouldn't help for true long duration imaging, you'd still need to do a polar alignment and track to prevent trails or a rotating FOV. You just don't need to be as accurate (in alignment) or rely on an auto-guider. Now perhaps you could do a series of short duration exposures (see below) but that still doesn't get you the same exposure as a true single long duration exposure. Then again perhaps his viewing doesn't need a true long duration exposure.

Alternately you could rotate the imager in the focusser but at this point wouldn't it be simpler, better, cheaper to get the proper mount ?


From the website ...

http://starizona.com/acb/hyperstar/whatis.aspx

Aside from the obvious savings in time and effort, short exposure times have a secondary advantage: capturing images is much easier. With typical exposure times of 20-60 seconds, HyperStar imaging allows unguided imaging. Long exposures require a telescope to be guided due to inherent tracking errors in the drive. This requires a second CCD camera or self-guiding CCD and often other hardware such as a guidescope. HyperStar images can be shot unguided thanks to the extremely short exposure.

An additional benefit of short exposures is that it is often possible to image with a telescope in alt-azimuth mode. This means it is possible to capture deep-sky images with a fork-mounted SCT without needing an equatorial wedge. This saves the trouble of mounting the scope on a wedge plus having to polar align the telescope. CCD imaging simply doesn't get any easier than that!
This rig is not designed for long exposures or "burns". Sorry Charlie

Star
 
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spike77

Guest
thanks everyone for ur coments i no how to work skyalign and all that i was tring to get away from the wedge a auto guider but i guess not
 
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Mee_n_Mac

Guest
spike77":x2sjn2e8 said:
thanks everyone for ur coments i no how to work skyalign and all that i was tring to get away from the wedge a auto guider but i guess not
It all depends on how faint the objects you're trying to capture are. I'm surprised that in only 90 seconds you're getting enough residual rotation to create star trails. I've not done the calculations to be sure but it sounds more like your scope isn't aligned quite right. Lastly don't discount doing a series of "short" duration exposures and stacking them.
 
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spike77

Guest
Mee_n_Mac":37oshs8h said:
spike77":37oshs8h said:
thanks everyone for ur coments i no how to work skyalign and all that i was tring to get away from the wedge a auto guider but i guess not
It all depends on how faint the objects you're trying to capture are. I'm surprised that in only 90 seconds you're getting enough residual rotation to create star trails. I've not done the calculations to be sure but it sounds more like your scope isn't aligned quite right. Lastly don't discount doing a series of "short" duration exposures and stacking them.
yeah i think ur right i need to check out the backlash and c if that helps but i am geting into some stuff where i will need a wedge and auto guider is on its way i got the orion 80mm short tube and the star shoot ccd now i just need the wedge this hobby sure does cost a lot but i almost there
 
S

spike77

Guest
well
Fallingstar1971":2adee2rr said:
On second thought, thats almost a three thousand dollar telescope.

You dropped 3 grand on something you do not know how to use? Or a hobby you do not understand?

Wow, you should of went with a cheaper rig to learn. This way if you loose interest you wont be out all that cash.

On the upside, it is a very nice scope. When you tire of it, shoot me a PM and some photos of the scope itself. If I have the funds Ill buy it. For now Ill stick with the afocal method, next year Ill try out direct focus, and the following year Ill buy a scope similar to yours.

Patience, and one step at a time.

Star

PS this scope uses "Sky Align" According to telescopes.com. Your manual should describe the procedure.
well u no i had to test everybody out on this web site and i also have a nexstar 4 se that i have dun a lot of imaging with guess im looking for isite on the hyperstar compared to wedge and guide scope
 
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gscs0001

Guest
spike77 said:
thanks everyone for ur coments i no how to work skyalign and all that i was tring to get away from the wedge a auto guider but i guess not[/Sky Align usually involves manual alignment of say 1 , 2 or 3bright wide spread objects :p andstorint them in the system memory. the scope will then require your local coordinates eastings & Northings and local time to allow he computerised Goto to work out exactly where it is in the sky.I use a CeleStron Next Star 4" & 8 "the 8" also has a wedge as an additionl option which fits underth alt-az drive you need to set up our local angle with the pole starmine is around 52 degrees
 
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