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Dobsonian Astro Photography Beginning

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#26 charotarguy

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Posted 18 September 2019 - 02:48 PM

I would love to get some images like these!

When you say to align the viewfinder very very fine, not sure how to do this. Once the camera is attached with the adapter, their isn't much else i can do to be sure it's aligned any finer.

Apologies, should have said, make sure your view finder is accurately aligned with your scope, at the time I used a widefield eyepiece first to do rough alignment then use a higher magnification eyepiece like 9mm to do an accurate alignment with viewfinder. My viewfinder had crosshairs so thats what I used as a reference while in the eyepiece view made sure it was in the center. You can get an eyepiece with crosshairs which would make it easy to do the alignment. Hope this helps.



#27 Stephen Kennedy

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Posted 18 September 2019 - 03:14 PM

Stephen, when i said are you pausing the video, i mean, do you hit the pause just as the planet goes out of view, then return the planet so it drifts back into view, resuming the video, so that it amounts to 30" total, all in a single video? Their is a progam call PIPP which joins videos together.

The planet does not go out of the FOV.  My German Equatorial Mount (GEM) has a motor that rotates it and where the telescope is pointing at the exact angular speed that the Earth is rotating but in the opposite direction so that a planet at the center of the FOV stays exactly at that point during the entire exposure and there is no need to pause the video and re-position the planet.  Depending on the planet, it will appear to move a very small amount over a couple of hours because my mount only tracks at the sidereal rate and planets have some motion with respect to the much more distant fixed stars.  I believe that some newer mounts can be set at lunar and planetary tracking rates keeping the Moon or planet at the center of the FOV.



#28 patindaytona

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Posted 18 September 2019 - 03:19 PM

The planet does not go out of the FOV.  My German Equatorial Mount (GEM) has a motor that rotates it and where the telescope is pointing at the exact angular speed that the Earth is rotating but in the opposite direction so that a planet at the center of the FOV stays exactly at that point during the entire exposure and there is no need to pause the video and re-position the planet.  Depending on the planet, it will appear to move a very small amount over a couple of hours because my mount only tracks at the sidereal rate and planets have some motion with respect to the much more distant fixed stars.  I believe that some newer mounts can be set at lunar and planetary tracking rates keeping the Moon or planet at the center of the FOV.

I was refering to using the dob without tracking. I got it now though.



#29 Maxtrixbass

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Posted 19 September 2019 - 11:10 AM

I did a little video planet imaging with my Z12 dob. It was a challenge with the small sensor on the ZWOASI120MC. It was tough to find the planet with a 3x barlow at 4500 FL and had no luck with trying to get video before it drifts out. never tried it with a DSLR with a larger sensor. I believe you want your video to be under two minuets or less or the planets rotation will affect the image. I built a EQ platform and was able to get this without pulling my hair out lol.....

 

attachicon.gif Capture sat.PNG

Nice image. I too have the z12 and again, although its possible, couldn't imagine trying to do what you did. Trying to center a 4500mm fl onto a small sensor camera using a manual dob mount is an act of heroism.

 

I guess my point is there are things that are possible and by all means give it a go, but realize its a pretty uphill struggle. I've seen people  get frustrated and walk away thinking they just don't have the "knack" for it when it was a pretty tough tool for the job.

 

I was trying to do deep sky imaging for 2 years with a Starfinder mount, a good mount for visual, but not so well adept at AP. It did teach me some good lessons, but it was simply maddening. If I wasn't so stubborn I would have given up. In time I ended up putting the scope on a Losmandy mount and got a small Apo on a CG4 mount and my thought was "this is SO easy!". I'm big on working with what you have, but AP is a challenging enough even with the right tools..

 

On another note, something to note with regards to making an EQ platform for a large dob is how close you are to the poles.I  thought about it, but my 12" scope would be sitting on a 49 degree platform since I live just south of the Canadian border.. That's not a stable angle. It becomes less "steep" as you move closer to the equator.


Edited by Maxtrixbass, 19 September 2019 - 11:22 AM.


#30 zxx

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Posted 19 September 2019 - 01:37 PM

Nice image. I too have the z12 and again, although its possible, couldn't imagine trying to do what you did. Trying to center a 4500mm fl onto a small sensor camera using a manual dob mount is an act of heroism.

 

I guess my point is there are things that are possible and by all means give it a go, but realize its a pretty uphill struggle. I've seen people  get frustrated and walk away thinking they just don't have the "knack" for it when it was a pretty tough tool for the job.

 

I was trying to do deep sky imaging for 2 years with a Starfinder mount, a good mount for visual, but not so well adept at AP. It did teach me some good lessons, but it was simply maddening. If I wasn't so stubborn I would have given up. In time I ended up putting the scope on a Losmandy mount and got a small Apo on a CG4 mount and my thought was "this is SO easy!". I'm big on working with what you have, but AP is a challenging enough even with the right tools..

 

On another note, something to note with regards to making an EQ platform for a large dob is how close you are to the poles.I  thought about it, but my 12" scope would be sitting on a 49 degree platform since I live just south of the Canadian border.. That's not a stable angle. It becomes less "steep" as you move closer to the equator.

Agree, It was vary tedious to get this image, I had no luck with the drift method at that FL and if I did get 2 or 3 seconds of video it took 10 minutes to find the planet again lol. The EQ platform made it much easier but still tedious. I also have the CG-4 and added a guide port and had good results with it with my ED80. In fact I use the motor drive from the CG-4 with the EQ platform. Having the HC is nice to control the RA speed and the DEC motor was used to focus. After I got the platform PA and the planet focused and on the sensor I could easily track it until it was time to reset the platform.

 

The most difficult part for me was looking through the finder scope with one eye while the other eye was on the PC screen lol

I did come up with a way that made this easy with my guide scope and a old backup cam for a vehicle and a old 12" tv.

After getting the planet on the sensor with Sharpcap on the PC, I then could put a mark on the tv screen where the planet was. After getting this method calibrated I could find the planet vary quickly after resetting the platform.


Edited by zxx, 19 September 2019 - 07:45 PM.


#31 zxx

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Posted 20 September 2019 - 03:59 PM

 

 

On another note, something to note with regards to making an EQ platform for a large dob is how close you are to the poles.I  thought about it, but my 12" scope would be sitting on a 49 degree platform since I live just south of the Canadian border.. That's not a stable angle. It becomes less "steep" as you move closer to the equator.

Not sure I follow you on this, I believe the scope will sit flat on the platform and only tilt 10 degrees at most. They make them for different latitudes. I also believe if you have one built for your latitude it will also work 350 miles south or 350 north of your latitude.

Here is a site you can get one for latitudes between 46 and 56 degrees north http://www.reinervog...lattform_e.html


Edited by zxx, 20 September 2019 - 04:23 PM.


#32 Maxtrixbass

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Posted 22 September 2019 - 12:48 PM

Not sure I follow you on this, I believe the scope will sit flat on the platform and only tilt 10 degrees at most. They make them for different latitudes. I also believe if you have one built for your latitude it will also work 350 miles south or 350 north of your latitude.

Here is a site you can get one for latitudes between 46 and 56 degrees north http://www.reinervog...lattform_e.html

Wow, my concept of what an EQ platform was and how it works was quite wrong. I was thinking it had to elevate the base up to the RA angle which would put the base and  scope at a precarious angle...probably confusing it with a wedge.

 

Thanks for pointing that out. I'll have to do some more research on it since I'm on the fringes of grasping how it works...


Edited by Maxtrixbass, 22 September 2019 - 12:50 PM.


#33 zxx

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Posted 22 September 2019 - 01:41 PM

Wow, my concept of what an EQ platform was and how it works was quite wrong. I was thinking it had to elevate the base up to the RA angle which would put the base and  scope at a precarious angle...probably confusing it with a wedge.

 

Thanks for pointing that out. I'll have to do some more research on it since I'm on the fringes of grasping how it works...

I used this vid to make mine, he explains how it works. Being in construction I had all the tools and materials so all it cost me was a little time.  https://www.youtube....h?v=YM9YCbeeGjI


Edited by zxx, 22 September 2019 - 01:45 PM.

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