Olly, how do you orientate your images night after night?

[kirkster501]

Olly, you mentioned framing your objects in a certain way by aligning north and south or something like that then letting the star drift to see it's lined up in a certain way - I recall you mentioning something like this???  Can you let me know please how you do this?   This reframing the object after the camera has been moved is a big area of weakness for me and I need to get it sorted pronto.

Edited February 19, 2020 by kirkster501

[vlaiv]

I'm not Olly, but can give it a go

Place bright star in the center of the frame (hopefully center of the frame is aligned with focuser central axis and rotating camera will result in rotation of FOV around this same point).

Using only RA controls - move star off center some distance (more is better - increased accuracy, but make sure it stays in FOV). Do frame and focus subs repeatedly so you can see what is going on.

If star remains on horizontal line that represents X axis of FOV center - you are done, if not, rotate camera until star gets to this horizontal line.

I'll do some diagrams to explain it better

Step 1 - put star in center:

Step 2 - move mount in RA until either of the two happen:

2.a - star is not on X axis:

or 2.b - star is on X axis:

 

If 2.b. happens - star on horizontal line - you are done, RA axis is aligned with X axis of the image.

If 2.a. happens - rotate camera checking star position until it comes to horizontal line like this:

You can always check if your camera is oriented RA/horizontal - by getting bright star in center of the frame and then moving only in RA or DEC direction.

If you move in RA direction - star should stay on horizontal line - move only in X direction. If you move in DEC - star should only move in vertical direction - stay on vertical line - move only in Y direction.

Hope this helps.

 

[ollypenrice]

Hi Steve, for a long time now I've had my cameras set orthogonally with RA and Dec. If the long side of the chip lies along the lines of RA we call it 'landscape' and if the long side aligns with Dec we call it portrait, following the daytime convention.

To get to one of these orientations simply set up a 5 second sub and during the exposure do a slew in either RA or Dec. This will produce long trails. When the trails align with the chip you're orthogonal in one of the two possibilities.

The virtue of this is that it's repeatable. Any time you want to add data your camera will be at the same angle as last time - or 90 degrees out. If it's 90 degrees out you can soon turn it, do the trails test and be ready to add new data.

Finding a random camera angle wastes hours. Also it's far easier for mosaics. I tried to make a mosaic with an angled camera orientation. Once!

Olly

Edited February 19, 2020 by ollypenrice
Typo

[Gina]

I to set my sensor orientation to either landscape or portrait.  I use the screws and connectors on the back of the camera and align them with the mount or at right angles.

[Laurin Dave]

As Olly and Vlaiv have replied..   if you’re using it plate solving will also tell you the camera angle 

[Gina]

Yes, I check with plate solving too.

[ollypenrice]

7 minutes ago, Gina said:

I to set my sensor orientation to either landscape or portrait.  I use the screws and connectors on the back of the camera and align them with the mount or at right angles.

That's my starting point, too, though I do the trails test to tighten it up. I've just been helping to set up a CMOS camera in our robotic shed and the daft designers have given no external clues as to the chip orientation. GRRR. What you can still do, though, is look down the spout (sometimes known as the objective) and see the chip from the front. Put in the lum filter for this task. WOn't work with a shutter though!

For setting up a dual rig I'm even more particular and set up a camera crosshair on the capture program then slew between quick subs on one axis to make sure a central star stays on the line of the crosshair right across the chip.

Plate solving? Hey, we run on steam here.

Olly

Edited February 19, 2020 by ollypenrice

[Adreneline]

14 hours ago, Gina said:

I to set my sensor orientation to either landscape or portrait.  I use the screws and connectors on the back of the camera and align them with the mount or at right angles.

I am interested in how you do this Gina.

I image with an ASI1600 + ZWO-EFW + Samyang 135mm. If I rotate the camera through 90 degrees then the EFW rotates through 90 degrees as well (and of course the lens) and my whole dec balance goes  completely awry - not to mention having to release the EAF belt to allow the lens to rotate.

Do you rebalance your dec axis every time you rotate the camera? It's taken me ages to balance out the offset moment due to the focus motor; I've ended up using small (150g, 100g and 50g) laboratory scale balance weights on the opposite side of the lens mount.

Forgive me if I'm missing something obvious.

Adrian

[Gina]

I don't bother to balance the DEC axis.  The focus motor is a 28BYJ-48 stepper attached by a bracket to the lens and drives a quadrant gear on the focus sleeve.  The whole rig rotates so this means that the focus doesn't change when the camera is rotated.

[kirkster501]

Thankyou guys! 

[david_taurus83]

Platesolving for me gets fairly close. If you use APT you can also create a framing mask. Pick your reference image in APT and you can create a mask in the form of circles around a number of bright stars. Save the mask and when you return another night, centre the image with platesolving again and load the mask. The circles will be where they were the first night. Rotate camera until the stars match the circles.

As also mentioned, platesolving will also tell you the orientation of the frame.

Like Olly and Gina, I also try and image with my camera in either landscape or portrait.

@Adreneline I found one of these handy brackets for my ASI1600. It let's you rotate the camera body independent of the rest of the imaging train. Adds about 6.1mm to your spacing.

https://www.365astronomy.com/TS-T2-Thread-360o-Rotation-Adapter-and-Quick-Changer-Extra-Short-5.5mm.html

[Adreneline]

32 minutes ago, david_taurus83 said:

I found one of these handy brackets for my ASI1600.

Interesting! I could be tempted and I've bookmarked the page - thank you David.

For now I will stick with my fixed 'landscape' orientation. At 135mm most things fit the frame anyway, however, if I get around to imaging again with my trusty old ED80DS one of these might be very handy.

Thanks again.

Adrian

 

[kirkster501]

Yes, familiar that plate solve will get you to so the object in the centre but then getting the camera at the right orientation by eyeballing it is a PITA and I end up that my registered subs have to be cut significantly and I am fed up of this now.  I've never quite worked out this rotation thing in SGP, it never seems to work when I have tried it.

I wish SGP had that frame markers feature too like that APT has.   

[Laurin Dave]

58 minutes ago, kirkster501 said:

Yes, familiar that plate solve will get you to so the object in the centre but then getting the camera at the right orientation by eyeballing it is a PITA and I end up that my registered subs have to be cut significantly and I am fed up of this now.  I've never quite worked out this rotation thing in SGP, it never seems to work when I have tried it.

I wish SGP had that frame markers feature too like that APT has.   

Steve once on the target take a short sub and plate solve it by right clicking.. the result will tell you the camera angle..  rotate and repeat until you have it as you want.   Easy to test indoors If you're not familiar with the feature by opening SGPro loading a sub and plate solving it.

HTH

Dave

[ollypenrice]

1 hour ago, kirkster501 said:

Yes, familiar that plate solve will get you to so the object in the centre but then getting the camera at the right orientation by eyeballing it is a PITA and I end up that my registered subs have to be cut significantly and I am fed up of this now.  I've never quite worked out this rotation thing in SGP, it never seems to work when I have tried it.

I wish SGP had that frame markers feature too like that APT has.   

 

BTW, if you want to take the camera off and replace it quickly, just lock up the mount with the OTA and counterweights horizontal, stick some masking tape on the camera back, hold a spirit level against it and rule a line on the tape. When you replace it you can use this line and the spirit level to find the original orientation. Saves some faffing.

Olly

Edited February 22, 2020 by ollypenrice

[david_taurus83]

58 minutes ago, kirkster501 said:

Yes, familiar that plate solve will get you to so the object in the centre but then getting the camera at the right orientation by eyeballing it is a PITA and I end up that my registered subs have to be cut significantly and I am fed up of this now.  I've never quite worked out this rotation thing in SGP, it never seems to work when I have tried it.

I wish SGP had that frame markers feature too like that APT has.   

Platesolving should tell you the image orientation. You just rotate until you match the original frame.

[harry page]

Hi

when using sgp I do the following

1) Use the mosaic and framimg tool to select a target and field rotation to suit the object and then save this imformation as a target ( you can use a previous image as a referance )

2) when setting up I just do a blind solve to get things going so the scope knows where its looking and the camera rotation

3) make sure the manual rotator is selected

4) right click on the target saved earlier and there will a option to rotate the camera - select this

5) sgp will then work out the differance between your current camera rotation and the targets rotation and tell you how much to rotate the camera by ( inc clockwise or anticlockwise info )

6) do the amount suggested and let sgp tell you again how far you are out

It might take 2 or 3 goes but I can get to less than 1 deg very easily- of course this is all done by plate solving , which you must have set up first

all this can be done while off target , make it easier to make sure you can access camera rotation easily

cheers

Harry