Jump to content

Hello

gsxrgirl7

By gsxrgirl7
in Welcome

Recommended Posts

gsxrgirl7

gsxrgirl7

Posted
Posted

My name is Julie. I recently inherited an original Odyssey 1 dobsonian, type 1, 13.1 inch mirror, 16 inch tube. I am looking forward to learning as much as I can as it is hard to find things for those if you want to upgrade. And just to learn about new things as well to get into modern things. I look forward to this new adventure.

Sent from my DROIDX using Tapatalk

Link to comment
Share on other sites
  • Replies 37
  • Created
  • Last Reply
gsxrgirl7

gsxrgirl7

Posted
  • Author
Posted

Thanks guys for the welcome! Yes I absolutely love it so far. I now am trying to figure what's the best piece to swap put the original rack and pinion focuser. It has a 1.25 inch focuser now. I would like to put a 2 inch focuser on this beast. As I want to also use it for photography as well. I already have some good eyepieces but want to find a good brand focuser whether still staying with a rack and pinion style or whatever will work best with the weight of camera, etc. But yes nothing beats it!! :)

Sent from my DROIDX using Tapatalk

Link to comment
Share on other sites
JamesM

JamesM

Posted
Posted

HI and welcome to the forum. Dobsonians are fine to image with if your intended targets are the moon and the planets. The general process is to use a webcam to capture several 'frames' of which the best ones are selected and 'stacked' on top of each other to construct a final composite image. There is plenty of free software that is great to use and will help you get results, examples include Registax, Sharpcap, Wx Astrocapture and Craterlet etc. Now imaging deep sky objects (DSO's) like galaxies and nebula will require a different set up, namely one that is mounted on an equatorial type mount not an Alt-Azimuth mount which is the typical way a dobsonian type scope is mounted. DSO'a are faint and far away which will require very accurate tracking as you collect enough 'data' to build a final image. Planets and the moon being nearer and certainly brighter require no tracking at all because the exposure times will be short. To help you understand more fully the fun (or frustration?) of imaging, may I recommend Steve Richards' "Making Every Photon Count" (FLO £19.99) to give you a comprehensive understanding of all that is involved in what can be a very satisfying aspect of astronomy. It is important to have this overview before you start, in order to help you formulate an accurate budget because although a lot of good software is free, for DSO work you will need to factor in the cost of some additional software.

Hope that helps you and hopefully the weather will play along to get you up and running.

Clear skies

James

Link to comment
Share on other sites
haitch

haitch

Posted
Posted
Thanks guys for the welcome! Yes I absolutely love it so far. I now am trying to figure what's the best piece to swap put the original rack and pinion focuser. It has a 1.25 inch focuser now. I would like to put a 2 inch focuser on this beast. As I want to also use it for photography as well. I already have some good eyepieces but want to find a good brand focuser whether still staying with a rack and pinion style or whatever will work best with the weight of camera, etc. But yes nothing beats it!! :)

Sent from my DROIDX using Tapatalk

Before picking a focuser check the height of the focuser with each of your EPs at focus and check the replacement is in the same range.

I ended up moving my mirror up the tube when I swapped the original 1.25" R&P on mine for a 2" Crayford. Someone else I know, having heard of my problems bought a low profile and then ended up adding an extension tube!

Also check the dimensions with this...

Dale Keller's Newt Software page

to make sure you're not messing anything up by causing vignetting

Link to comment
Share on other sites
haitch

haitch

Posted
Posted

PS how are you going to mount it for photography?

Edit: Just read James' reply regarding photographyso you'll know already why this question popped up in my mind if you were thinking of deep sky stuff.

Link to comment
Share on other sites
gsxrgirl7

gsxrgirl7

Posted
  • Author
Posted

Wow! Thanks guys! This gives me some fantastic starting points to get learning and to play around with some software. And I want to do both lunar, planetary, and deep space photography. I can't wait to start looking thru these starting points. Thanks again and I know I will be coming to you guys with more questions as I continue. Regarding the mount, we know someone here in our local area that knows how to build a tracking mount for dobs. He has done it on his and will be sharing the plans with us so we can build one for ours. YAY! His dob will track for up to 50 minutes. So hopefully I can make mine the same!

Sent from my DROIDX using Tapatalk

Link to comment
Share on other sites
JamesM

JamesM

Posted
Posted

The requirements that make good imaging tracking must not be confused with those that are sufficient for observing. Imaging requires very precise tracking both in terms of speed and direction. Motorised Alt-Azimuth mounts that are typical seen supporting Cassegrain type scopes (forked or single arm types) track objects across the sky in a stepped fashion, miniature steps that although unseen to the eye, will most definitely show up in the final image. Now equatorial mounts (or platforms) attempt to cancel out the fact that earth is tilted backwards when it rotates. The idea is to ensure that the mount (platform) is tilted in such a way as to compensate for this tilt in order that the scope can move from left to right (...if we're looking south) in a nice gentle arch that exactly mimics the path of celestial objects as they move across the sky. Remember, it is really us that is moving which gives the appearance that the stars etc are the ones floating around! This adjustment to the mount is known as 'polar alignment' because the easiest way to compensate the earth's tilt through mount, is to ensure that its RA axis (left to right movement) is 'aligned' to polaris. However real life is not that simple, (...is it ever?) because in fact you actually have to offset the mount a little bit to one side of polaris and the degree to which you offset it depends on the date and time that you are performing the alignment. Most people find that they have to use a certain quality of mount to get the precision required because these mounts have built into their RA axis a small alignment scope to help. If a mount doesn't have this then it is a matter of guess work which is good enough for observing but not for imaging.

Now how are you going to adjust your proposed platform to the same accuracy that is sat on the floor? The answer, is with great difficulty especially if this is not going to be a permanent setup. So far I have talked about positioning the mount, but what about the actual tracking itself? Well very accurate motors are required and in fact one of the advantages of the more precise (...read expensive) mounts is that you are able to record and adjust the accuracy of the tracking - what facility will your intended platform have? Having said all the above regarding the need for both accurate polar alignment and tracking motors, what most people quickly discover is that even if you have paid a good price for an accurate mount, that actually its is still not 'consistently' accurate enough and that these mounts are still made to a price - so what's the next stage? Well, the real solution comes in the form of auto guiding. This is when a very small scope is placed alongside the main imaging scope and is trained on a nearby star to the object being imaged. The guide scope, through autoguiding software, is able to adjust the motors of the mount in such a way as to keep the reference star in its cross hairs and so by default, the main scope on the imaged object. Takes a bit of setting up and alignment itself but represents a way of automatically tracking an object without just relying on the original tracking created by polar aligning the mount. This also explains why you find that many imagers on the forum tend to use Skywatcher HEQ5 and NEQ6 mounts in their equipment signatures, because those mounts have a specific 'guide port' that allows you to connect the autoguiding equipment to the motors inside.

Technically, you could track manually by hand but the results would be far too inconsistent and explains why imaging DSO's objects can appear relatively expensive when you realise that need to have the right quality mount that can facilitate the necessary add-ons to obtain good results. Most people will typically have a permanent setup to again help iron out the inconsistencies that can occur when you are regularly setting up and taking down the kit each time you image. It is also why there is quite a big difference in the requirements for imaging the moon and planets when compared with requirements of imaging DSO's as explained in my earlier post. If you want consistent results and you want to be able to collect a lot of data to construct a good final image with structure and detail, an equatorially mounted scope (with auto guiding) is the way to go.

Hope that helps and apologies for the length of reply but it unavoidable when trying to describe something that is a little tricky.

Clear skies

James

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.