Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

  • Announcements

    sgl_imaging_challenge_banner_nb_dso.jpg.eb6cd158659331fd13e71470af6da381.jpg

Recommended Posts

darren west    27

please forgive me as I'm new at this 

me and my daughter own a 8" skywatcher dobsonian 

i really like the idea if being able to take a few pics with this scope but am i right to assume that because it is just a dobsonian that this would not be possible 

i have a cannon 550d totally standard but the scope came with a sense adapter that fits mo camera perfectly 

also if its possible where do i go to be able to start learning how to take photos 

thanks

 

Share this post


Link to post
Share on other sites
ronin    3,667

It is one of those areas where if you say "No, you cannot get images." then people come along showing an example that was taken with a dobsonian. And generally upset that you have suggested othewise.

Best way to look on it is that they are not the best and it will/can be difficult. So what happens is that you are generally told No, you cannot. Likely depends on the number of attempts and the number of good final results that it takes and you get. With a dobsonian the ratio is likely to be poor. There is a thread somewhere on imaging without an EQ. That should be a start point to ask and get suggestions.

The moon is always an option, but for the moon a DSLR and standard lens will take an image, so attaching a DSLR to a dobsonian is in some ways making it more difficult then you need to.

Planets may be an option, Jupiter and Saturn. You would dset it all to Manual, then take a video, then stack the best 30% or 40% of the images in something like Registax. For DSO's I will suggest it will be simply very difficult. What options there are for DSO imaging I am unsure.

Are you a member of NEAS, there may be imagers there that could offer advice.

Share this post


Link to post
Share on other sites
billyharris72    299

Hi and welcome.  No need to apologise - whole point of this forum is to ask questions and learn.

You are correct that a Dobsonian pretty much rules out most imaging. DSOs are too faint to image without a tracking (preferably equatorial) mount. The Moon and planets ought to be fine though, and are a good place to start.

First task will be to attach the camera to the scope and see if you can reach focus on the Moon. If you can then think of it as a big, manual telephoto lens. You'll need to experiment with exposure times and iso, and focusing is tricky at first, but keep at it and see what comes out.

Best of luck,

Billy.

Share this post


Link to post
Share on other sites
Peter Drew    5,117

Provided you can reach the focus there should be no problem taking photos of the Moon and planets or indeed the Sun with an appropriate full aperture filter. Stars and galaxies will be a compromise due to the lack of a drive and a suitable mounting. Users have had satisfactory results by stacking several short exposures.  :icon_biggrin:

Share this post


Link to post
Share on other sites
billyharris72    299

On another note, if you want to try photographing star fields and DSOs you could use the camera and lenses rather than a scope. Two options here.

For wide field shots you can typically get away with a fixed tripod and an exposure of about 400/ focal length in seconds. With a 50mm, or even better 35mm lens you can grab okay wide shots, enough to show some larger, brighter DSOs. 

Another option if you don't want to buy an equatorial mount would be to build a barn door type mount. That would let you use slightly longer focal lengths and longer exposures to go that bit deeper.

Share this post


Link to post
Share on other sites
Timebandit    979

Hello and welcome to SGL

The Dobson 8" is great for visual and their are plenty of people that do some planetary and lunar photos with a reflector.

But if you are more interested in Astro photography in regards DSO you are probably better off going for something like a Ed 80 refractor on a decent quality eq mount to track.

I hope the above helps☺    

 

Share this post


Link to post
Share on other sites
Floater    2,083
2 hours ago, darren west said:

8" skywatcher ... because it is just a dobsonian ...

Oh, no! We can't have this, Darren! 🙀

With provocation like that the Dob Mob will become enlivened and cause a great consturmation among the members!

You and your daughter are the proud owners of not 'just a dobsonian' but of a good reflecting telescope on a Dobsonian mount. And anyone who says that what you have is not a wonderful telescope is a fool, likely a cad and probably a mountebank, to boot.

p.s. It is generally accepted that Dobsonian-mounted reflectors are not the best if one wishes to practise the Dark Art of AP, but you have a good telescope. Enjoy the views.

🤘

Edited by Floater
  • Like 1

Share this post


Link to post
Share on other sites
Louis D    656
10 hours ago, darren west said:

please forgive me as I'm new at this 

me and my daughter own a 8" skywatcher dobsonian 

i really like the idea if being able to take a few pics with this scope but am i right to assume that because it is just a dobsonian that this would not be possible 

i have a cannon 550d totally standard but the scope came with a sense adapter that fits mo camera perfectly 

also if its possible where do i go to be able to start learning how to take photos 

thanks

 

You're unlikely to come to focus with your DSLR without either a 2" barlow or a coma corrector convertible to astrophotography so it can be pushed far down into the focuser.  Try digiscoping to start with instead.  Start by pointing your telescope at the moon with a mid power eyepiece (14 to 22mm work well for your scope) in the focuser, hold your smartphone camera up to the eyepiece and try snapping a photo.  You may need to move it about and in and out a bit to find the best alignment.  It may not be great at first, but there's zero cost of investment.  Next, try it with a planet like Jupiter or Saturn.  You'll probably have to dial down the exposure because the camera will try to make the black background 18% gray, overexposing the planet.  If you have a solar filter, give photographing sunspots a try as well with this technique.  The trick to getting a decent photo is to place the subject just outside the field of view and photographing it as it drifts across the FOV.  It will be sharpest at the center.

If you have an older digital camera with a lens that has a small front lens element and threads for an adapter tube and an eyepiece with threads around where the eyecup attaches, you can find step-up or step-down rings to attach the two together.  My favorite combination remains my circa-2002 Olympus C-4000 camera and a 22mm Astro-Tech AF70 eyepiece.  The camera's adapter tube has M43 threads that go straight onto the eyepiece once I've unscrewed the eyecup.  I already had everything, so this rig cost me nothing additionally.

You're not going to take photos of DSOs with a dob unless it's on an equatorial platform (preferably dual axis to allow for some amount of guiding) or has goto and you limit your exposure times and derotate and stack in post processing or you get a field derotator to compensate for the field rotation inherent with alt-az mounts.

Share this post


Link to post
Share on other sites
Dave In Vermont    4,477

Hello again, Darren and daughter - it's good to hear from you again in these forums (fora)!

And hey - put your worries of asking us all questions to rest. Billy hit the nail square-on in saying that questions, and their answers, is indeed why we're here. And sooner than you think, you'll be one who starts answering them, too. Really.

Give my best to all & enjoy!

Dave

Edited by Dave In Vermont
syn.
  • Like 1

Share this post


Link to post
Share on other sites
Waldemar    250
19 hours ago, darren west said:

please forgive me as I'm new at this 

me and my daughter own a 8" skywatcher dobsonian 

i really like the idea if being able to take a few pics with this scope but am i right to assume that because it is just a dobsonian that this would not be possible 

i have a cannon 550d totally standard but the scope came with a sense adapter that fits mo camera perfectly 

also if its possible where do i go to be able to start learning how to take photos 

thanks

 

Must read:  https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

This will answer all your question about ap.

Share this post


Link to post
Share on other sites
glowjet    1,178
19 hours ago, Peter Drew said:

Provided you can reach the focus there should be no problem taking photos of the Moon and planets or indeed the Sun with an appropriate full aperture filter. Stars and galaxies will be a compromise due to the lack of a drive and a suitable mounting. Users have had satisfactory results by stacking several short exposures.  :icon_biggrin:

Peter has mentioned the Sun, in objects to photograph, with an appropriate full aperture filter, which can be acquired from Astronomy outlets for this purpose. As you describe yourself and Daughter as being new to the World of observational Astronomy, if you were not aware already, it can`t be stressed strongly enough, that extreme care MUST be taken when dealing with observing or photographing, this particular subject in our solar system. Should you want to go down this route, it would be better to take advise or research the matter before doing so, enjoy the forum and your new scope :)

  • Like 1

Share this post


Link to post
Share on other sites
darren west    27

can i ask what extreme care is needed and why

 

today i purchased a a sun filter sheet a moon filter and 2 new eye pieces 

 

Share this post


Link to post
Share on other sites
Davey-T    8,864
1 minute ago, darren west said:

can i ask what extreme care is needed and why

 

today i purchased a a sun filter sheet a moon filter and 2 new eye pieces 

 

Never look at the Sun with anything that hasn't got a proper safe solar filter.

Dave

  • Like 1

Share this post


Link to post
Share on other sites
Waldemar    250
3 minutes ago, darren west said:

can i ask what extreme care is needed and why

 

today i purchased a a sun filter sheet a moon filter and 2 new eye pieces 

 

NEVER look at the sun without proper filtering. Not even point your scope close to the sun area without filter...You will be blinded within a fraction of a second. The filter should be suited for visual, for two kinds are available: for visual and for photographic use.
Be sure there is not even the smallest hole in the filter foil. If you are going to make your own filter ring for the Baader foil, make sure it fits and cannot fall off. The foil should not be tight but roomy, that will give the best results and prevents tearing.

Do NOT just wrap the foil over your scope and keep it in place with a rubber band or so to have a quick glance...it may be your last one. First make a nice, well fitting holder for it and make absolutely sure that it does not leak sunlight.
I cannot stress this enough, too many people lost their eyesight by not being cautious enough....

It is said that you do not really need a filter for the moon, that maybe true for some stages with a very little lighted part of the moon. As soon as it gets close to a quarter, you should use a filter. The proof is in the pudding: When you turn your eye away from looking at the moon, it will take considerable time before you have normal vision again, and I am not talking about night vision. That means the nerve ends that translate light into understandable signals for your brain are overloaded... overloading is always bad, not just for your back...

 

  • Like 1

Share this post


Link to post
Share on other sites
darren west    27

i have posted up on a new thread about how to make a mount for the filter nd i also purchased a moon filter today 

thanks for the warning , i am trying to do things the right way first time 

thanks

  • Like 2

Share this post


Link to post
Share on other sites
Cosmic Geoff    195

A four inch telescope is probably nearer the optimum size for studying the sun (this is the biggest size recommended for projecting the sun's image, for instance.) An 8" will collect four times more light and heat than a 4" telescope.  An 8" isn't better, just more dangerous.  Unfiltered, this level of concentrated solar heat will rapidly melt plastic, or set fire to things. Please take care. 

Personally, I use a 102mm scope to project the sun for viewing sunspots. Using the 127mm didn't end well when I part melted the plastic in a cheap eyepiece when I took too long to line it up. 

As for moon filters, many people (including myself) don't use them.  But if you think you need one, then you probably do. :icon_biggrin: 

  • Like 1

Share this post


Link to post
Share on other sites
glowjet    1,178
3 hours ago, darren west said:

i have posted up on a new thread about how to make a mount for the filter nd i also purchased a moon filter today 

thanks for the warning , i am trying to do things the right way first time 

thanks

Darren, It is very nice to note that you have made us all aware that you are trying to follow the advise from our seasoned Astronomers, so that you and your Daughter can undertake the correct procedures when it comes to practical observing. One reason why I mentioned observing the Sun, I think by the wealth of advise that followed, you will now be aware that a simple mistake could mean permanent blindness.

To aide in the pleasure of searching the heavens, I am not sure whether the publication "Turn Left at Orion" has been mentioned to you in past threads. Without doubt the most popular work on Astronomical observation that has been written in recent times, serves both those just starting out to the seasoned Astronomer :)

  • Like 1

Share this post


Link to post
Share on other sites
darren west    27

thanks , i purchased the book this week and it was delivered today 

i do understand how important it is to protect eyes , i have done a lot of welding and had arc eye by accident and i was in a lot of pain 

i do not want to have any issues with eye sight 

 

Share this post


Link to post
Share on other sites
alanjgreen    687

Darren,

remember that you must also protect your telescopes finder scope from the sun, if it is one of the monocular style finders.

either leave the caps on and don't use or remove it from the scope is the safest option.

if you want to use it to find the sun, then you also need to use the solar film to make a front cover for the finder.

you can't test for holes in the solar film, by holding it up to a household light bulb to check if any light comes through the film -it should not.

 

you don't want this to happen (or worse), the sun is very powerful and dangerous once you start to focus the light to a single point

Alan

Edited by alanjgreen

Share this post


Link to post
Share on other sites
Louis D    656

It's best to just remove all sighting devices from your telescope when viewing the sun.  It's not particularly hard to aim any telescope at the sun with no sighting aids.  All you have to do is keep moving the OTA until its shadow is minimized on the ground below and behind it.  This also works for the full or near full moon.

I followed Baader's solar film cell construction instructions from the early 2000s when it first came out.  I cut two donut shapes from craft foam board, used double sided tape to secure the film to both pieces, ensuring I did not stretch or otherwise stress the material (waviness is fine).  I then wrapped five or six lengths of 2 to 3 inch wide strips of poster board snugly around the end of the tube taping it tightly with clear packing tape.  I then attached the filter cell to the tube mount with more clear packing tape.  In 16 years or so, neither of the two solar filters I made in this manner has loosened or come apart.

I recommend keeping a piece of rigid cardboard over the front of the solar film while in storage to protect it from scratches or punctures.

The biggest problem with solar viewing in Texas is avoiding getting sweat drips on your eyepieces or telescope.  It gets hot really quickly in the full Texas sun.  A wide brimmed hat helps shade the eyepiece immensely.  It's only mid-February and it hit 86° F with full sun today!

Just be careful and use common sense.  Don't let kids mess around near the scope during solar observation.  They need to treat it with respect.  I showed the 2006 Mercury transit to a group of second and fourth grade girl scouts without incident.

Share this post


Link to post
Share on other sites
Charic    1,942
On 2/17/2017 at 17:03, darren west said:

like the idea if being able to take a few pics with this scope

There are limitations but you can achieve  some  basic results. The first image was from an old HTC Android, the second using a Nikon D5000 DSLR
The problem with the basic 8" Skyliner is its inability to track anything for longer exposures.

The Android was hand held over an eyepiece, the Nikon would have had a 'T' Ring adapter and extension tubes/s.

Moon Up-close.jpg

DSC_0010.JPG

Edited by Charic
  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×