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Thread: Beginner needs help...

  1. #1
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    Beginner needs help...

    Im a photographer for years, and im new to astrophotography.

    I have Canon 40D. I plan to buy Celestron Omni 102 Refracter, is it good for astrophotography? (as for beginner)

    What do i need to connect them together?
    I read some post, i seem to need a T-ring and a T adapter. I wonder what model is it? can anyone provide link or photos about them?

    If i want to shoot the Nebula, what telescope should i use?

    And for the Celestron Omni 102, does anyone have any idea where i can buy it in Canada? Or any recommended store in Toronto?

    Thank You SO MUCH!!!
    Last edited by rocco2005; 2008-Jun-06 at 12:26 AM.

  2. #2
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    If it is the model I am thinking of, it should have threads to accept a T-Ring already built in to the focuser.

    Here is an example, although I do not know if it looks exactly like this:

    http://www.escience.ca/telescopes/RE...051/10377.html

    This threads onto the telescope, and then attaches bayonet style to the camera. When that is done the telescope is now your lens.

    Efston is Canadian and should carry the telescope you are looking for.
    This should be adequate for most deep sky objects, as long as you have a stable tracking mount on which to put your telescope & camera assembly. Deep sky objects usually need longer exposure times

    Note that aiming must be done with the eyepiece in place, focusing is tricky, and you will either have to use a guidescope or hope you can keep things aimed properly with the finderscope.

  3. #3
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    Great Thanks!!!!

    One more thing i would like to ask.
    In order to shoot a Nebula, is it necessary to use a nebula filter?
    is 102mm enough for shooting deep sky such as nebula?

    Thank You

  4. #4
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    I believe that scope comes on only a CG-4 mount. With the added drive it would be very marginal in my opinion for deep sky work. That scope is about f/10 so a very long tube with lots of leverage. Even a slight touch of the tube by a light wind would create problems.

    For a beginner I'd recommend a faster scope such as one of the many ED 80 short tube refractors out there. They can do an excellent job with nebula and are far easier to mount. A CG-4 might be sufficient. Still you'd be pressing things.

    For nebula the mount is FAR more important than the scope. There is no such thing as too good of a mount when it comes to deep sky work. Even a rather poor scope can do great work on a good mount but no scope can do anything on a rather poor mount. For an example of what an ED80 type refractor can do see:
    http://www.bautforum.com/astrophotog...8-h-alpha.html
    This is a recently posted shot of a very faint nebula, far fainter than any you are likely thinking of imaging. Note though he's using a CG-5 mount, one big step up to carry the much shorter tube scope.

    As to nebula filters they will alter the color balance of things. Emission nebula though should come through fairly well. Still, unless you are in a very light polluted sky I find it better to use far more sub frames than a nebula filter. For most skies they aren't needed. I have a friend who images from "downtown" Berlin and he gave up with nebula filters finding 45 5 minute exposures or more a far better solution. I've never used them but I don't live under such skies.

    Note that unless you replace the IR filter it will block most of the hydrogen alpha light from nebula but will pass Hydrogen Beta and OIII thus greatly increasing exposure time and turning many emmision nebula very blue green compared to the normal pink seen in photographs. This though is close to the eye's color vision so in that sense more "real". The eye is very insensitive to Halpha light. Nebula filters usually try to isolate the Hbeta and OIII lines as well. Some pass Halpha well too some don't. But with Halpha mostly blocked by either type of filter (or both) exposure time is greatly increased since the majority of the light of most emission nebula (not planetaries however) is H-alpha light. Planetary, reflection and SNR nebula wouldn't be hurt much however by the standard IR blocking filter nor are star clusters or just Milky Way starfield shots.

    Rick

  5. #5
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    Quote Originally Posted by RickJ View Post
    I believe that scope comes on only a CG-4 mount. With the added drive it would be very marginal in my opinion for deep sky work. That scope is about f/10 so a very long tube with lots of leverage. Even a slight touch of the tube by a light wind would create problems.

    For a beginner I'd recommend a faster scope such as one of the many ED 80 short tube refractors out there. They can do an excellent job with nebula and are far easier to mount. A CG-4 might be sufficient. Still you'd be pressing things.

    For nebula the mount is FAR more important than the scope. There is no such thing as too good of a mount when it comes to deep sky work. Even a rather poor scope can do great work on a good mount but no scope can do anything on a rather poor mount. For an example of what an ED80 type refractor can do see:
    http://www.bautforum.com/astrophotog...8-h-alpha.html
    This is a recently posted shot of a very faint nebula, far fainter than any you are likely thinking of imaging. Note though he's using a CG-5 mount, one big step up to carry the much shorter tube scope.

    As to nebula filters they will alter the color balance of things. Emission nebula though should come through fairly well. Still, unless you are in a very light polluted sky I find it better to use far more sub frames than a nebula filter. For most skies they aren't needed. I have a friend who images from "downtown" Berlin and he gave up with nebula filters finding 45 5 minute exposures or more a far better solution. I've never used them but I don't live under such skies.

    Note that unless you replace the IR filter it will block most of the hydrogen alpha light from nebula but will pass Hydrogen Beta and OIII thus greatly increasing exposure time and turning many emmision nebula very blue green compared to the normal pink seen in photographs. This though is close to the eye's color vision so in that sense more "real". The eye is very insensitive to Halpha light. Nebula filters usually try to isolate the Hbeta and OIII lines as well. Some pass Halpha well too some don't. But with Halpha mostly blocked by either type of filter (or both) exposure time is greatly increased since the majority of the light of most emission nebula (not planetaries however) is H-alpha light. Planetary, reflection and SNR nebula wouldn't be hurt much however by the standard IR blocking filter nor are star clusters or just Milky Way starfield shots.

    Rick
    Thank you SO MCUH for your information!!
    Looks like im one step closer to it.
    ED80 means Orion ED80?
    Seriously, CG-5 is so expensive....is there anything u would recommend between CG-4 and CG-5? or with other brands? like...EQ2?
    My budget is around 600 in total, what kind of combination can i get?

    Thank You

  6. #6
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    There are many 80 mm refractors using an ED type objective. Orion's is one of them. While at f/10 you can get fair color correction with only crown and flint glass as in the scope you mentioned, deep sky work demands better color correction which is impossible at short focal ratios without using ED type glass for one element of a two element objective. Nearly all makers of refractors have one in their line. Check postings on this and other forums for lots of images taken with various ones. Most are rather similar optically. You need a top focuser for astrophotography as the in focus image is only a few thousandths of an inch thick so you have to hit it very precisely. I'd look at those with 2 stage focusers.

    As to mounts I'm not all that familiar with low end mounts. $600 for mount and scope is cutting things awfully thin however, most would say too thin. Prices have come down with all the Chinese products out there but I'd look to spending more new. Check places like AstroMart for good used gear that might hit that price if you are patient.

    Deep sky work demands very high precision. Far higher than most beginners realize. It doesn't come cheap. I fought mounts for many years and while you might get the CG-4 to work with a short tube scope (maybe someone with more experience with the mount will weigh in here) it wouldn't carry anything larger and is thus pretty much a dead end for future expansion.

    The EQ2 is more a mount for a camera with up to about a 200mm lens than a full scope in my opinion. I know some who have taken great widefield shots with it using DSLR's and medium focal length camera lenses.

    Also remember that for good deep sky work you'll need a guider of some sort. Even mounts costing far beyond your stated budget can't track a short tube scope more than a couple minutes before tracking errors become objectionable. Stacking many short exposures can be done but in my opinion a poor substitute for longer, guided exposures.

    Rick

  7. #7
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    Quote Originally Posted by RickJ View Post
    There are many 80 mm refractors using an ED type objective. Orion's is one of them. While at f/10 you can get fair color correction with only crown and flint glass as in the scope you mentioned, deep sky work demands better color correction which is impossible at short focal ratios without using ED type glass for one element of a two element objective. Nearly all makers of refractors have one in their line. Check postings on this and other forums for lots of images taken with various ones. Most are rather similar optically. You need a top focuser for astrophotography as the in focus image is only a few thousandths of an inch thick so you have to hit it very precisely. I'd look at those with 2 stage focusers.

    As to mounts I'm not all that familiar with low end mounts. $600 for mount and scope is cutting things awfully thin however, most would say too thin. Prices have come down with all the Chinese products out there but I'd look to spending more new. Check places like AstroMart for good used gear that might hit that price if you are patient.

    Deep sky work demands very high precision. Far higher than most beginners realize. It doesn't come cheap. I fought mounts for many years and while you might get the CG-4 to work with a short tube scope (maybe someone with more experience with the mount will weigh in here) it wouldn't carry anything larger and is thus pretty much a dead end for future expansion.

    The EQ2 is more a mount for a camera with up to about a 200mm lens than a full scope in my opinion. I know some who have taken great widefield shots with it using DSLR's and medium focal length camera lenses.

    Also remember that for good deep sky work you'll need a guider of some sort. Even mounts costing far beyond your stated budget can't track a short tube scope more than a couple minutes before tracking errors become objectionable. Stacking many short exposures can be done but in my opinion a poor substitute for longer, guided exposures.

    Rick
    So...i need a 80mm ED glass telescope, CG-5 mount.
    lol...i have a higher budget now, my dad is supporting me =)
    the Orion ED 80 is discontinued.....
    I read some post from other forum; i need a f/5.5-f/10 focul ratio telescope
    that means....Meade Series 5000 80mm ED APO Refractor Telescope is a good choice?
    if so, can a Meade Series 5000 mount onto the Celestron CG-5?
    What do you mean by Top focuser? like a focuser at ~$100-$200?
    even if i have taken care of all equipment, i still need a guider, ha
    i better learn a bit more astronomy by myself.

  8. #8
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    rocco2005,

    Others have hinted at it, but nobody has come right out and said it.

    Going from photographer is not a big step. It is two steps, a big one and a giant one! Both with minimum entrance prices and steep learning curves!
    1) Photography to astronomy. Mostly new vocabulary, but also new things you need to know and new ways of doing things.
    2) Astronomy to astrophotography. Some, but not all of your photographic knowledge will be of help here, but probably not as much as you might think. As has been said, the mount is everything! There is a reason why serious astrophotographers are willing to pay thousands of dollars just for a mount.

    Theres no reason to start at, or even near the top, but there is every reason not to start at the bottom. Starting too low just leads to frustration and that leads to giving up on what can be a very rewarding (if somewhat expensive) lifetime hobby.

  9. #9
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    Quote Originally Posted by Kaptain K View Post
    rocco2005,

    Others have hinted at it, but nobody has come right out and said it.

    Going from photographer is not a big step. It is two steps, a big one and a giant one! Both with minimum entrance prices and steep learning curves!
    1) Photography to astronomy. Mostly new vocabulary, but also new things you need to know and new ways of doing things.
    2) Astronomy to astrophotography. Some, but not all of your photographic knowledge will be of help here, but probably not as much as you might think. As has been said, the mount is everything! There is a reason why serious astrophotographers are willing to pay thousands of dollars just for a mount.

    Theres no reason to start at, or even near the top, but there is every reason not to start at the bottom. Starting too low just leads to frustration and that leads to giving up on what can be a very rewarding (if somewhat expensive) lifetime hobby.
    Expensive is expected.
    Im a Geographer with remote sensing guy, and i have touch base on astronomy already. I know it is a big plus a giant step up, therefore i need to gather as much information as i can before i really go to buy a telescope.
    I can learn astronomy by myself, but equipment knowledge is based on user reviews and current astrophotographer's experience.
    so.....i post my questions here =)

  10. #10
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    You have the right attitude. I just wanted to make sure that you knew the pitfalls and possibly hidden downsides to the jump you are about make. Good luck!

  11. #11
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    A simple scope on a simple mount works for planetary photography though there aperture is a big help (far more than deep sky) so I'd want a 6" scope or larger though a good 5" mak works fairly well. Since exposure time with a web cam is short, 30th of a second or so, the mount isn't much of an issue. Software pulls out the good frames from the rest for processing. A web cam makes it easy and fast to take 1000 or more out of which a few dozen yeild great results.

    This is something you can do within your budget.

    Another possibility is to start like I did with starfield shots with a camera and lens. For this you can build a barn door drive. I built a two hinge (sometimes called two arm) version and powered it with a 1930's alarm clock spring and gears. It took a lot of tinkering but gave good results for 10 minutes unguided and even worked for 30 minute when guided with a spotting scope.

    Deep sky work with a scope proved far more difficult. Keep in mind that for deep sky imaging you need to track a star with accuracy that is the same as tracking a moving target a mile away and never deviating by more than a fraction of an inch during the hour or two of the exposure. This requires great precision aided by some guiding system that is very accurate with little backlash. Precision like this doesn't come cheap. For years I used mounts in the $2000 range and cussed constantly. I finally splurged and got a good mount, many times that cost. My bank account cusses but I don't. Best investment I've ever made.

    Covington's book Astrophotography for the Amateur is a must for any beginner. Then since you are looking at DSLR get his DSLR book. It assumes you've already read the first one so you can't just get the "Digital SLR Astrophotography" one. The former is a must, the latter a helpful addition.

    Rick

  12. #12
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    Yeah, there's a reason why Software Bisque wants $12,500 for the Paramount and why they sell every one the can make!

  13. #13
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    Ok....im looking at SkyWatcher EQ5 + SKyWatcher ED 80
    is this combination good for so far everything? like...planet, nebula?

  14. #14
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    That would be a reasonable beginner package for deep sky if you're up to using a solder iron to add the needed guiding port. Planetary imaging takes aperture to get the needed resolution. A 6" f/6 scope would be a bit shaky on that mount but should suffice for planetary work. It is sort of a clone of the Vixon GP. For deep sky work you'll need the dual axis motors and for guiding you'll need to look up some articles on the net on how to add a ST-4 type guiding input which it doesn't have. The EQ5SynScan already has the port but you pay a big price for it. There's no PEC which limits unguided exposure time. No mount in this price range has it however and reports I've seen indicate the periodic error is easily controlled by a guider though you need the modification for that. This is what I meant by fighting inexpensive mounts.

    Beginning deep sky and planetary photography take very different scopes for good results with both. You want a short focal length wide field scope for starters for deep sky to keep mount requirements within budget but need longer focal length with higher resolution (aperture) for good planetary work. There mount quality isn't nearly as important as it is for deep sky work. There is no one scope that can do both well. You can get some planetary results with a fast 80mm scope but the lack of light and resolution will limit you. I always used different scope for these two very different purposes. Again, get that Covington book. It explains all this very well. Only then will you really be able to determine what's best for you and what you want out of the set-up versus what you can afford.

    Rick

  15. #15
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    Quote Originally Posted by Kaptain K View Post
    Yeah, there's a reason why Software Bisque wants $12,500 for the Paramount and why they sell every one the can make!
    Same for the somewhat less expensive AP1200 mount. It only took 40 years of saving to get it and Softgware Bisque didn't even exist when I started saving for a top mount. And then it was "only" 10 grand when I finally wrote the check. but it is overkill for a ED80 type scope.
    Rick

  16. #16
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    Quote Originally Posted by RickJ View Post
    Same for the somewhat less expensive AP1200 mount. It only took 40 years of saving to get it and Softgware Bisque didn't even exist when I started saving for a top mount. And then it was "only" 10 grand when I finally wrote the check. but it is overkill for a ED80 type scope.
    Rick
    I wasn't suggesting it was the right mount for Rocco. Just pointing out that there's a reason that top of the line equipment costs top of the line bucks. I'll drop out now. He's in capable hands!

  17. #17
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    Quote Originally Posted by Kaptain K View Post
    I wasn't suggesting it was the right mount for Rocco. Just pointing out that there's a reason that top of the line equipment costs top of the line bucks.
    I realized that. Sorry if it sounded otherwise. I was just saying that for new comers who might get the wrong idea.

    Rick

  18. #18
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    Quote Originally Posted by RickJ View Post
    I realized that. Sorry if it sounded otherwise. I was just saying that for new comers who might get the wrong idea.

    Rick
    ha...ya, software are crazily expensive
    btw
    I wanna buy SkyWatcher ED 80
    is that a good telescope?
    i think i will do sky watching right now, moving on to Astrophotography once i get the mount, SkyWatcher EQ5, back in my Country(cheaper)
    Thank You So Much for your help!!!

  19. #19
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    rocco2005 goto the (rasc) site and look around you can get some solutions from them

  20. #20
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    Quote Originally Posted by rocco2005 View Post
    ha...ya, software are crazily expensive
    btw
    I wanna buy SkyWatcher ED 80
    is that a good telescope?
    i think i will do sky watching right now, moving on to Astrophotography once i get the mount, SkyWatcher EQ5, back in my Country(cheaper)
    Thank You So Much for your help!!!
    For general viewing a 6 or 8 inch Dob gives you by far the best bang for the buck.

    Scopes are designed for various purposes, there is no such thing as a do everything well scope. Maybe that's why I own 8 of them. The 80 ED type refractor is great for entry in deep sky photography, a good grab and go scope but for general viewing. But its resolution needed for planetary viewing is limited by the aperture as is deep sky work. The Dob design gives you a super solid and smooth mount for visual work with the light and resolution needed for thousands of objects and does so at very low cost. It isn't equatorially mounted so unsuited for photography as is. But it can be put on a more solid mount like the EQ-6, Atlas or equivalent at a later time and turned into a photo scope capable of deep sky work. Focal length is a bit long for a beginner being the main problem.

    Best advice I can give here is to attend a few star parties thrown by your local astronomy club. There you can try out many different scope designs and sizes to see which one best fits what you want out of a scope. All scopes are a compromise. Buying without understanding the compromises of each scope is an all too common problem. Many buy a scope then attend their first star party. The scope they bought is usually wrong for them compared to some they see at the star party yet they are now committed to a scope not so well suited to their wants and budget. We tend to call this realization the "V8 moment". It is all too common. While the dob is a good general viewing scope for many it isn't everyone's idea of such a scope.

    Just remember to also budget for a pair of 10x50 binoculars, a good star atlas, and a red LED light (variable intensity) to read it. Some like computer star atlases rather than paper. I find they hurt my night vision more so won't use them. An eye patch can be a useful as well. Wear it over your non dominant eye when at the scope and over your dominant eye when using the light to read charts, find eyepieces etc. That way the dominant eye stays dark adapted and you don't have problems keeping one eye closed when at the eyepiece, a common beginner problem as the night wears on. Also you will want a couple more eyepieces and or a barlow to better fill in the power range the scope is capable of. That runs from about 3.5 to 50 power per inch of aperture. Always start with low power and work up. Rarely will you find powers of more than 30x per inch or 300x (whichever is lower) to be useful unless you have unusually good seeing.

    Rick

  21. #21
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    Quote Originally Posted by RickJ View Post
    For general viewing a 6 or 8 inch Dob gives you by far the best bang for the buck.

    Scopes are designed for various purposes, there is no such thing as a do everything well scope. Maybe that's why I own 8 of them. The 80 ED type refractor is great for entry in deep sky photography, a good grab and go scope but for general viewing. But its resolution needed for planetary viewing is limited by the aperture as is deep sky work. The Dob design gives you a super solid and smooth mount for visual work with the light and resolution needed for thousands of objects and does so at very low cost. It isn't equatorially mounted so unsuited for photography as is. But it can be put on a more solid mount like the EQ-6, Atlas or equivalent at a later time and turned into a photo scope capable of deep sky work. Focal length is a bit long for a beginner being the main problem.

    Best advice I can give here is to attend a few star parties thrown by your local astronomy club. There you can try out many different scope designs and sizes to see which one best fits what you want out of a scope. All scopes are a compromise. Buying without understanding the compromises of each scope is an all too common problem. Many buy a scope then attend their first star party. The scope they bought is usually wrong for them compared to some they see at the star party yet they are now committed to a scope not so well suited to their wants and budget. We tend to call this realization the "V8 moment". It is all too common. While the dob is a good general viewing scope for many it isn't everyone's idea of such a scope.

    Just remember to also budget for a pair of 10x50 binoculars, a good star atlas, and a red LED light (variable intensity) to read it. Some like computer star atlases rather than paper. I find they hurt my night vision more so won't use them. An eye patch can be a useful as well. Wear it over your non dominant eye when at the scope and over your dominant eye when using the light to read charts, find eyepieces etc. That way the dominant eye stays dark adapted and you don't have problems keeping one eye closed when at the eyepiece, a common beginner problem as the night wears on. Also you will want a couple more eyepieces and or a barlow to better fill in the power range the scope is capable of. That runs from about 3.5 to 50 power per inch of aperture. Always start with low power and work up. Rarely will you find powers of more than 30x per inch or 300x (whichever is lower) to be useful unless you have unusually good seeing.

    Rick
    After talking to someone who is a teacher of astronomy in the sch, i know a lot more than before.
    Im getting Celestron C8 for planetary first, slowly get into deep sky stuff.
    may be a good Japanese mount or a chinese made first.
    But the problem is....the chinese mount is not accurate at all
    i wonder if they have polarize error correction in it...
    And i will get a 8x50 binoculars for now.
    And i got a thick, complete, colored book about Universe
    I should be fine with everything, Thank You so much for pumping in so much information into my head, ha

  22. #22
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    I think you meant Periodic Error Correction.

  23. #23
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    A 8" SCT is a good choice and with a compressor to bring it down to f/6.3 usable for deep sky as well. For planetary work use a web cam. Mount accuracy is immaterial here due to the short exposure time.

    The CG-5 is a pretty light weight mount but would work for planetary work and general viewing. I'd think the Orion Atlas EQ-G about the minimum for serious deep sky work though if you have it well sheltered you can likely make the CG-5 work for starters. The pair cost about 1500 plus shipping new. This is well beyond your first budget figure so I didn't consider this route but it is a common one.

    Check used markets such as AstroMart and Cloudy Nights for good buys on used gear from those moving up.

    Check with your local astronomy club. They can be a great source of both information and used gear.

    Rick

  24. #24
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    Quote Originally Posted by Kaptain K View Post
    I think you meant Periodic Error Correction.
    Oh, Yes.
    My mistake

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    No problem. There is a steep learning curve on acronyms as well!

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