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  1. #1
    Itsthechaz!'s Avatar
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    Exclamation Need help in regards to guide scope as beginner main scope - astrophotography



    Hello everyone, I need some advice from the veterans.

    I own a cheap gallileo reflector that is incapable of astrophotography and i feel its time to purchase a better telescope.

    I've looked into reflector vs refractor and i've decided for refractors for my first.

    Im currently in a position though to obtain a AstroPhysics 80/900mm achromatic refractor Telescope, but i've noticed via google searching that it really is just a guide scope. (seriously is it just me, cause even on their website i cant find anything about it!)

    My questions are:

    1) Would this be a good scope to use as a telescope (even though it be a guide scope)
    2) Can i use this for astrophotography (i have a cannon t3i dslr)
    3) Does anyone have any experience using this scope, and could thusly assist me in their experiential/personal advice?

    Thank you much in advance community!

  2. #2
    jerryTheC's Avatar
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    An 80/900mm scope gives you a focal ratio a bit over f11, which is a bit on the slow side for photography compared to short tube 80mm scopes (my vixen A80SS is a 400mm focal length f5, and would give similar (but smaller scale) images in less than a quarter of the time), but the slower f ratio means you should have less chromatic aberration.

    While it won't be quite as nice as an APO, it should be quite usable within the limitations of an 80mm aperture - the focal length makes it a little nicer for planetary use, compared to short tube 80mm scopes, which are a little nicer for wide field use, but will usually have more CA.

    For imaging, you probably want a 2" focusser for DSLR use - although the longer focal length compared to short tube 80mms means you'll have to track more accurately ( because the larger image scale also magnifies guiding errors) and for longer ( due to the slower f ratio) when doing long exposures.

    For short exposure photos like the moon, the slower f-ratio shouldn't make a major difference.

    I've used both achromatic and apochromatic refractors (as well as reflectors and SCTs), and while the Apos are nicer, a good achromatic scope can get very close a lot of the time - the false colour usually shows up on bright objects and at high magnifications.
    <i><span style="font-family: Times New Roman"><font size="2"><b>SCT:</b> N11GPS <b>Refractors:</b> FS-60C/CSV, ZD-66, A80SS, FSQ106ED <b>Binoculars:</b> 8x42, 15x70<br /><b>Eyepieces:</b> 40mm Meade SWA, 28mm UWAN, 17mmT4, 12mmT4, 2.5mmT6 Nagler, 17mm, 8mm, 5mm LVW, HI-LE2.8<br /> <a href="
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  3. #3
    star2root's Avatar
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    I think I saw that AstroPhysics 80 on ebay for $127, still bidding...
    This might work a lot better...

    Orion StarBlast 4.5 Imaging Reflector Telescope Optical Tube
    $149
    StarBlast 4.5 Imaging Telescope Optical Tube | Orion Telescopes

    Best for viewing Brighter deep sky
    Best for imaging Deep sky
    User level Intermediate
    Optical design Reflector
    Optical diameter 114mm
    Focal length 450mm
    Focal ratio f/4.0
    Optics type Parabolic
    Glass material Soda-lime plate
    Eyepieces None
    Resolving power 1.02arc*sec
    Lowest useful magnification 16x
    Highest useful magnification 228x
    Highest theoretical magnification 228x
    Limiting stellar magnitude 12.9
    Optical quality Diffraction limited
    Finder scope None
    Focuser 1.25" Rack-and-pinion
    Secondary mirror obstruction 47mm
    Secondary mirror obstruction by diameter 41%
    Secondary mirror obstruction by area 17%
    Mirror coatings/over-coatings Aluminum & Silicon Dioxide
    Mount type Optical Tube without Mount
    Astro-imaging capability Lunar, planetary & long exposure
    Tube material Steel
    Length of optical tube 18.0 in.
    Weight, optical tube 3.7 lbs.
    Other features Secondary mirror w/47mm minor axis
    Warranty One year

  4. #4
    star2root's Avatar
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    PS: I'm not a veteran by any means, but I thought that might be helpful.

  5. #5
    Itsthechaz!'s Avatar
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    Thanks a lot guys for the advice, actually star that one on ebay is the one I'm looking at!

    I'm undecided as to what to do really, but i guess i should wait and save up to get a nicer one i suppose.

    I was also looking at another refractor, the orion ED80 f/7.5 do you think this one would be better?

  6. #6
    jerryTheC's Avatar
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    The star blast sounds interesting, but the 1.25" focuser might be limiting for DSLR use - unless it has some sort of t thread direct connection as well.

    On the other hand, I used to have one of the Orion ED80s, and they're very nice scopes for the price point - good for visual and AP, and a handy size for piggybacking on or using alongside a bigger scope if you go that way later - you can guide through one scope and image through the other
    <i><span style="font-family: Times New Roman"><font size="2"><b>SCT:</b> N11GPS <b>Refractors:</b> FS-60C/CSV, ZD-66, A80SS, FSQ106ED <b>Binoculars:</b> 8x42, 15x70<br /><b>Eyepieces:</b> 40mm Meade SWA, 28mm UWAN, 17mmT4, 12mmT4, 2.5mmT6 Nagler, 17mm, 8mm, 5mm LVW, HI-LE2.8<br /> <a href="
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  7. #7
    star2root's Avatar
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    My thoughts were that the Starblast is designed for imaging use, it has a wider aperture thus gathers more light, it has a lower f ratio so should be able to do wide field shots with a lower exposure time, it is a reflector, so it will have no chromatic aberration, and it's not too expensive.

    For a 2 inch focuser, I found this at $300
    Orion 203mm f/4.9 Reflector Tube with Crayford-Style Focuser
    203mm f/4.9 Reflector Tube - Crayford-Style Focuser | Orion Telescopes

    Best for viewing Brighter deep sky
    Best for imaging Deep sky
    User level Intermediate
    Optical design Reflector
    Optical diameter 203mm
    Focal length 1000mm
    Focal ratio f/4.9
    Optics type Parabolic
    Glass material Soda-lime plate
    Eyepieces None
    Resolving power 0.57arc*sec
    Lowest useful magnification 29x
    Highest useful magnification 300x
    Highest theoretical magnification 406x
    Limiting stellar magnitude 14.2
    Optical quality Diffraction limited
    Focuser 2" Crayford
    Secondary mirror obstruction 58mm
    Secondary mirror obstruction by diameter 29%
    Secondary mirror obstruction by area 8%
    Mirror coatings/over-coatings Aluminum & Silicon Dioxide
    Mount type Optical Tube without Mount
    Astro-imaging capability Lunar, planetary & long exposure
    Tube material Steel
    Length of optical tube 38.0 in.
    Weight, optical tube 16.5 lbs.
    Additional included accessories Collimation cap
    Other features 2" focuser with 1 1/4" adapter
    Warranty One year

  8. #8
    jerryTheC's Avatar
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    all good points for imaging though, the f-ratio is more important than the aperture - a lot of great work gets done with refractors around 80-106mm.

    The other thing to watch out for is the weight - for AP the usual recommendation is to try and keep the weight to around 50% or less of the rated maximum load. Bigger scopes get heavier, and need bigger, more expensive mounts...

    Also, fast reflectors often suffer from coma, so you may need to factor in a coma corrector... But you can do good work with most scope types, if you have enough back focus for the bits you want.

    For a pure AP scope, I'd incline towards a fast refractor - for one for visual use as well, the bigger aperture of a reflector has obvious attractions - but for a long exposure AP setup, the essential thing is a good mount, and keeping the weight and size down means you don't have to get a bigger, more expensive mount.

    So maybe the best thing to do is look at the mounts first, and let that set the limit for what sort of scope to put on it
    <i><span style="font-family: Times New Roman"><font size="2"><b>SCT:</b> N11GPS <b>Refractors:</b> FS-60C/CSV, ZD-66, A80SS, FSQ106ED <b>Binoculars:</b> 8x42, 15x70<br /><b>Eyepieces:</b> 40mm Meade SWA, 28mm UWAN, 17mmT4, 12mmT4, 2.5mmT6 Nagler, 17mm, 8mm, 5mm LVW, HI-LE2.8<br /> <a href="
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  9. #9
    Itsthechaz!'s Avatar
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    Default

    sounds good thanks again everyone!

    Ill keep everyone updated as to what i do!

 

 

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