Orientation of camera

[beamer3.6m]

I control my scope from 30 feet away so running to the camera and then back to laptop is a pain.

For ease what is the best orientation for a DSLR on a newtonian scope to reduce the need to twist it...

... I expect you will say depends on the object but thought I would ask.

[ronin]

If you look at the assorted images of things I don't think it matters. I have seen M42 at almost every rotational angle possible.

It will be more important that the camers is set to be the least hazard to the mount when imaging.

I suppose the words get the images, create the stacked final and rotate it last are a bit simplistic. Just do not alter the position when getting the exposures.

[Bizibilder]

I don't think it matters much unless you plan imaging over several nights.  I now always align my camera "square" to the scope when in the home position - I have an aluminium plate on top of the tube rings with the guidescope mounted on it - so I align to that.  It means that I am usually within plus or minus a degree or so (of rotation) when it comes to stacking images from different nights.

I really must design a device so I can replace the camera precisely every time!

[Dave_D]

i made a paper scale that fits exactly round my t-ring

I don't think it matters much unless you plan imaging over several nights.  I now always align my camera "square" to the scope when in the home position - I have an aluminium plate on top of the tube rings with the guidescope mounted on it - so I align to that.  It means that I am usually within plus or minus a degree or so (of rotation) when it comes to stacking images from different nights.

I really must design a device so I can replace the camera precisely every time!

i made a paper scale that fits round my t-ring

[RikM]

I try to have mine aligned with DEC on the vertical and RA on the horizontal. At the moment it is a couple of degrees off because I didn't check it before starting on my last target. That paper scale looks just the business for getting a good consistent orientation if you need to rotate it for correct framing.

[steppenwolf]

A two part answer (part one isn't quite what you asked but I hope the info is useful nonetheless)

1. Arrange for your focuser to be set so that it points towards the mount. This places the centre of gravity of the camera/telescope closest to the mount thus reducing the counterbalance required and giving a 'known orientation' point to start from for part 2.

2. The image below shows the orientation degrees for a DSLR camera on a Newtonian reflector with the focuser positioned as 1 above. By referencing the 'best fit' orientation of the camera to suit the object that you wish to image using planetarium software like Cartes du Ciel, you can be sure of the best framing. For many purposes, it is surprising just how many objects only require either 0 or 90 degrees of camera rotation!!

However, remember, in space there is no up or down so the final choice is purely down to you ......

[Bizibilder]

The paper scale looks like a good, simple idea!

[ollypenrice]

Because I return to images over the years adding data, etc, I like easy repeatability so I align along RA and Dec, either in portrait or landscape depending on the target. To find this orientation I just expose for four or five seconds and slew slowly on one axis during the exposure. This produces star trails which need to be precisely aligned with the chip - or the virtual crosshair in my case. SInce I image with a tandem rig this gives very accurate alignment between instruments as well. I agree that a well made scale would be a good idea though. You can also use a spirit level to set your CW bar horizontal and then set the camera horizontal or vertical with it as well.

And because I'm frightened of Dennis over on PAIG   I also try to present images in 'North is up' orientation. Sometimes I feel an image demands a different orientation, though.

Oh, making mosaics when not aligned along RA and Dec is also a terrible faff unless you can make Astrotortilla work, which neither I nor any of our guests have ever been able to do!

Olly

[laser_jock99]

I always align the camera parallel with focusing knobs- mainly so I can use my 'flats library' if there are no session specific flats available (i.e. most of the time!).  As 0 degrees in Steve's (Steppenwolf's) graphic but the with focuser knobs at the camera base plate (just to keep the same orientation from session to session AND from scope to scope (a memory thing if you have multiple scopes- so it always the same)).   

Kind of a 'fixed but repeatable' approach that doesn't always help with framing the subject. However with a DSLR sized CCD you should have a bigger FOV to play with anyway.

[Firas]

On 5/12/2014 at 09:07, ollypenrice said:

Because I return to images over the years adding data, etc, I like easy repeatability so I align along RA and Dec, either in portrait or landscape depending on the target. To find this orientation I just expose for four or five seconds and slew slowly on one axis during the exposure. This produces star trails which need to be precisely aligned with the chip - or the virtual crosshair in my case. SInce I image with a tandem rig this gives very accurate alignment between instruments as well. I agree that a well made scale would be a good idea though. You can also use a spirit level to set your CW bar horizontal and then set the camera horizontal or vertical with it as well.

And because I'm frightened of Dennis over on PAIG   I also try to present images in 'North is up' orientation. Sometimes I feel an image demands a different orientation, though.

Oh, making mosaics when not aligned along RA and Dec is also a terrible faff unless you can make Astrotortilla work, which neither I nor any of our guests have ever been able to do!

Olly

Hello Olly, 

Old thread, but I am trying to understand this, as it giving me a headache when trying to polar align using Alignmaster, since Polaris isn't visible from my location. I hope you could explain the following; 

I align the cdd camera either at 0 or 90 degrees to the focuser. But after centring the stars using the virtual hand controller (EQ mod) and the program slews to realign manually, the azimuth and attitude bolts don't move the star perfectly left or right for azimuth or up and down for the latitude. They move rather in sideways, making entering the star on the virtual crosshair impossible. Now I have tested many orientations just a little around 0 or 90 degrees, but the issue was still present. I didn't try your method, using exposure to determine the right orientation yet. But you wrote that the star trail needs to be precisely aligned with the chip, how do you go about it? Would you explain a little more here if you please? Is centring the star necessary? Wouldn't be ok if I just made the star land on the horizontal line using azimuth and on the vertical line using altitude of the crosshair?  

What can be the issue if even this method didn't prove friutfull?  

Thank you in advance, 

Firas 

[ollypenrice]

1 hour ago, Firas said:

Hello Olly, 

Old thread, but I am trying to understand this, as it giving me a headache when trying to polar align using Alignmaster, since Polaris isn't visible from my location. I hope you could explain the following; 

I align the cdd camera either at 0 or 90 degrees to the focuser. But after centring the stars using the virtual hand controller (EQ mod) and the program slews to realign manually, the azimuth and attitude bolts don't move the star perfectly left or right for azimuth or up and down for the latitude. They move rather in sideways, making entering the star on the virtual crosshair impossible. Now I have tested many orientations just a little around 0 or 90 degrees, but the issue was still present. I didn't try your method, using exposure to determine the right orientation yet. But you wrote that the star trail needs to be precisely aligned with the chip, how do you go about it? Would you explain a little more here if you please? Is centring the star necessary? Wouldn't be ok if I just made the star land on the horizontal line using azimuth and on the vertical line using altitude of the crosshair?  

What can be the issue if even this method didn't prove friutfull?  

Thank you in advance, 

Firas 

Hi, no worries about the age of the thread. The physics hasn't changed!

You need to separate polar alignment from camera orientation. They are not connected. I think this might be the source of the confusion.

Camera orientation. The first thing to do is visually get your camera roughly aligned with RA and Dec. This is easliy done on a German equatorial mount simply by setting one side of the camera to be parallel with the counterweight bar. Equally you can try to set it to be aligned parallel with the dovetail bar/saddle plate. It won't be perfect but it will do for now. (Don't align it with the focusser unless the focusser is parallel with the dovetail as well. It might not be, since the entire tube, including focusser, can be rotated in the tube rings - assuming you have these.)

Polar alignment. Once you have done as above, moving the mount's alt-az polar alignment adjusters will not move the star vertically/horizontally unless you are at the north pole or the equator. While one of these locations is even less likely than the other*, let's discount them both! I'm in the mid northern latitudes at 44.19N. You're in Stockholm at around 59 N. For me, moving the alt-az adjusters on the mount will move a star at 44 degrees relative to one side of the chip and at 46 degrees relative to the other. For you, your stars will move at 59 deg relative to one side and 31 deg relative to the other. This is to be expected.

If you are going to drift-polar-align through the camera you now need to perfect your camera orientation. You don't really need to centre a star, you just need to take a (say) 5 second sub while slewing slowly. You'll get star trails. Note their angle. They need to be parallel with the chip. Rotate the camera slightly and repeat until they are parallel with the chip. Now you are ready to drift align using your camera.

Olly

*For most people being at the north pole would be very unlikely but my late and much missed friend Per Frejvall, also from Stockholm, was a north pole veteran.

 

[Firas]

On 10/31/2017 at 21:53, ollypenrice said:

Hi, no worries about the age of the thread. The physics hasn't changed!

You need to separate polar alignment from camera orientation. They are not connected. I think this might be the source of the confusion.

Camera orientation. The first thing to do is visually get your camera roughly aligned with RA and Dec. This is easliy done on a German equatorial mount simply by setting one side of the camera to be parallel with the counterweight bar. Equally you can try to set it to be aligned parallel with the dovetail bar/saddle plate. It won't be perfect but it will do for now. (Don't align it with the focusser unless the focusser is parallel with the dovetail as well. It might not be, since the entire tube, including focusser, can be rotated in the tube rings - assuming you have these.)

Polar alignment. Once you have done as above, moving the mount's alt-az polar alignment adjusters will not move the star vertically/horizontally unless you are at the north pole or the equator. While one of these locations is even less likely than the other*, let's discount them both! I'm in the mid northern latitudes at 44.19N. You're in Stockholm at around 59 N. For me, moving the alt-az adjusters on the mount will move a star at 44 degrees relative to one side of the chip and at 46 degrees relative to the other. For you, your stars will move at 59 deg relative to one side and 31 deg relative to the other. This is to be expected.

If you are going to drift-polar-align through the camera you now need to perfect your camera orientation. You don't really need to centre a star, you just need to take a (say) 5 second sub while slewing slowly. You'll get star trails. Note their angle. They need to be parallel with the chip. Rotate the camera slightly and repeat until they are parallel with the chip. Now you are ready to drift align using your camera.

Olly

*For most people being at the north pole would be very unlikely but my late and much missed friend Per Frejvall, also from Stockholm, was a north pole veteran.

 

Hello again,

well, I thought they were connected because it isn't possible to center the star using the bolts, which confuses me even more when I think of how people uses the bolts to center the star in the crosshairs, with Aligmaster or even manually through the polar scope! I thought if the camera ordination is sorted, I will be able to centre the star. But then again, you write that, that won't be possible unless one is at the north pole or the equator. How people do it? I wonder! 

You mentioned Per Frejvall, that brilliant man. I stumbled upon a video not so long ago where he talks about the 10Micron mount, as he was one of the first owners, I believe. Then I read his posts here and was most fascinated by his knowledge, energy and wit. I thought meeting him would be a great pleasure, only to read that he suddenly passed away. Very unfortunate. I am sorry for your loss Olly.

Here is the video he did with the Astro Imaging Channel, if you haven't seen it; 

  

[ollypenrice]

11 minutes ago, Firas said:

Hello again,

well, I thought they were connected because it isn't possible to center the star using the bolts, which confuses me even more when I think of how people uses the bolts to center the star in the crosshairs, with Aligmaster or even manually through the polar scope! I thought if the camera ordination is sorted, I will be able to centre the star. But then again, you write that, that won't be possible unless one is at the north pole or the equator. How people do it? I wonder! 

You mentioned Per Frejvall, that brilliant man. I stumbled upon a video not so long ago where he talks about the 10Micron mount, as he was one of the first owners, I believe. Then I read his posts here and was most fascinated by his knowledge, energy and wit. I thought meeting him would be a great pleasure, only to read that he suddenly passed away. Very unfortunate. I am sorry for your loss Olly.

Here is the video he did with the Astro Imaging Channel, if you haven't seen it; 

  

Thanks. Yes Per was a remarkable guy.

I'm not saying that you can't centre Polaris using your alt-az alignment bolts (which you need to do), I'm saying only that, away from the poles or the equator, moving one of these axes will not move the star horizontally or vertically but at an angle. This doesn't matter.

Getting the camera orientated so that moving it in RA or Dec moves the stars horizontally or vertically makes drift aligning much easier.

Olly

[Firas]

1 minute ago, ollypenrice said:

Thanks. Yes Per was a remarkable guy.

I'm not saying that you can't centre Polaris using your alt-az alignment bolts (which you need to do), I'm saying only that, away from the poles or the equator, moving one of these axes will not move the star horizontally or vertically but at an angle. This doesn't matter.

Getting the camera orientated so that moving it in RA or Dec moves the stars horizontally or vertically makes drift aligning much easier.

Olly

Alright! I will give that a shot as soon as I get a clear night! 

Thanks for your help. 

Firas