Polar Alignment with DSLR

[RayD]

2 minutes ago, cadams said:

I'll probably have more questions about other aspects (image processing for example) as time goes on.

No probably about it, you definitely will, and believe me they will never stop.

Have fun and let us know how you get on 

[iapa]

Assumption: You are not using an OTA and are not tethering the camera or mount to a PC.

The intention with this tome is to provide some ideas for some one who is doing this for the first time.

In the morning, get up, have a shower, a good breakfast and sit down with a cup of tea until sun rise. Watch a couple of videos on youtube around setting up mounts. You camera & lens is the OTA so the principles of polar aligning a mount are the same.

Have another cup of tea while the outside temperature comes to above 0C.

And ... we go outside.

• Find north, using your compass, smart phone or a paper map - remember you are looking for TRUE North NOT magnetic North
• Draw a 6' long line on the ground (in chalk) running east-west. You can use that in the future for setting up again. A length of twine between a couple if nails in th eground. SAFETY Warning - this is a trip hazard.
• Place the two rear legs on that line, with your weight bar facing north. put a marker at the north leg as well - you now can put the mount in the same place everyone
• level the mount
• Fit camera to dovetail to mount
• release clutches and looking down the dovetail find something on the horizon, a tree, bush, power pylon, then lock the clutches. There is usually a pair of screws, one at each end of the dovetail - sight along those. If there isn't there may be the holes anyway, drop a screw into each so the head sticks up a bit.
• Adjust the ball and socket so the the camera is centered on the same target. This is going to be good enough - your alignments steps later will ensure the mount "knows" where the camera is looking.
• loosen the clutches and return the mount to the two index marks.
• Have a coffee - you will be feeling a little chill
• Using your latitude bolts, adjust the mount to match your current attitude. A spirit level/clinometer app on your phone is good here.
• Have another coffee - with a chocolate biscuit.
• Power on the mount, check date/time are correct, check location is correct. Double check these.
• Check that the index marks are lined up. Now is a good time to set the home position via the hand controller.
• Wait until Polaris, Cappella and Vega are visible ( i am assuming you have North views)
• Double check date/time and location.
• Check the you can see Polaris in the camera live view. Take a picture, 10s may need to be lower if stars trailing, highest ISO setting (you are not worried bout noise here you just want stars) and plate solve - upload it to astrometry.net, this will confirm whether you have Polaris in view. You can use altitude and azimuth adjustments to being it in if it's more then 25% off centre of the camera view.
• Follow the steps on the hand controller to do a two star alignment,
• add two calibration stars, as a minimum
• follow the steps to do All Star Polar Alignment.
• Return the mount to the home position (index marks) and power it off.
• Power mount on, do the 3star alignment followed by ASAP again.
• Check by slewing to a star you can see with the naked eye, take picture and plate solve as above for a final check

You are possibly looking at an hour to do all of this first time round. Remember, though, that at this time of year you can have 6 -7 hours of dark to take images (the other night I had from 7pm through to 6am next day, a once in a decade opportunity I expect) so, one hour isn't much in the grand scheme of things.

If you only remove the camera from the mount you need not repeat the ASPA steps as the mount is not moving.

If you take the mount indoors, set it all back up to the lines on the ground, Polar Alignment will be a bit quicker as you will be close second time around.

You are ready to go - I've managed 15s (may have been able to go higher bit didn't push it) unguided for targets around 30 deg above horizon, using Canon 700D, 50mm f1.8, on the AVX mount.

 

[StevieDvd]

If you buy a polarscope then you are limited to views where polaris is visible.

You could buy a cheap ST80 scope and use that for polar alignment using the mounts polar alignment routines by pointing the mount roughly North and following the ASPA instructions.

Secondly, you could also mount the DSLR on the scope and centre the target in the now aligned scope view and adjust the DSLR so it has the same centred object.

Just a thought as this gives you a scope you can use for more than just alignment.

 

[iapa]

1 minute ago, StevieDvd said:

If you buy a polarscope then you are limited to views where polaris is visible.

You could buy a cheap ST80 scope and use that for polar alignment using the mounts polar alignment routines by pointing the mount roughly North and following the ASPA instructions.

Secondly, you could also mount the DSLR on the scope and centre the target in the now aligned scope view and adjust the DSLR so it has the same centred object.

Just a thought as this gives you a scope you can use for more than just alignment.

 

@cadams will still have his original issue of aligning the DSLR with the direction the mount is facing.

[StevieDvd]

5 minutes ago, iapa said:

@cadams will still have his original issue of aligning the DSLR with the direction the mount is facing.

Not if the DSLR was mounted on the scope though.

[RayD]

Just now, StevieDvd said:

Not if the DSLR was mounted on the scope though.

iapa's bullet list is actually really good for a DSLR mounted directly on the AVX, including the biscuit breaks, so it a very good starting point, and certainly much better than how the OP is currently trying to align.

 

[Marci]

Lose the ball mount. Buy a short dovetail and bolt. Attach camera directly to dovetail. Attach to mount as tho it were a scope.

Polar align the mount with DARV. GoTo align thru the camera.

 

[iapa]

15 minutes ago, StevieDvd said:

Not if the DSLR was mounted on the scope though.

I am missing this then?

The SLR is currently mounted using a ball socket mount to a dovetail. So, requires alignment in two axis (up/down & left/right) to be pointing in the same direction as the mount.

If the DSLR was to be mounted to the ring on the ST80 using the bolt/locking wheel it still needs to be aligned to the view point of the ST80.

Left/right is OK, the locking nut can help there, but there is no control over the up/down now  

I had a degree or so difference between the two image centres so I had to resort to small slivers of 1mm plastic in both the rings around the ST80 - one in the bottom half of the rear ring, two in the top half of the clamp at the front - which helped a bit.

Id stick with the ball/socket mount direct to dover tail.

 

[iapa]

10 minutes ago, Marci said:

Lose the ball mount. Buy a short dovetail and bolt. Attach camera directly to dovetail. Attach to mount as tho it were a scope.

Polar align the mount with DARV. GoTo align thru the camera.

 

Down side of DARV or other adrift alignment processes - in my case certainly - is lack of view of the sky from ESE to SW.

Equally, I suppose, other Polar Alignment options require visibility of Polaris or other northerly views.

Ho hum - now, we could all have our mounts on a hill above all the houses with 360deg views ......

[Marci]

However, for the OP, where his problem with multiple alignment issues is directly as a result of over complicating by using a ball joint unnecessarily... valid.

[RayD]

30 minutes ago, iapa said:

Equally, I suppose, other Polar Alignment options require visibility of Polaris or other northerly views.

I don't believe the AVX built in ASPA does, which is one of the big benefits of it.

[iapa]

11 minutes ago, RayD said:

I don't believe the AVX built in ASPA does, which is one of the big benefits of it.

I was more generally bemoaning that you need to see the sky to polar align

 

[Davey-T]

2 minutes ago, iapa said:

I was more generally bemoaning that you need to see the sky to polar align

 

?

Dave

[RayD]

1 minute ago, iapa said:

I was more generally bemoaning that you need to see the sky to polar align

 

Chance would be a fine thing!!

I actually use the Polemaster myself and have adaptors for each mount so swap it between them, and the camera is double sensitive, so you can start aligning way before it's fully dark. 

[RayD]

2 minutes ago, Davey-T said:

?

Dave

iapa is in Scotland Dave, the land of seemingly eternal cloud.  Unlike us down here in the relatively tropical South (I wished) 

[iapa]

3 hours ago, RayD said:

I actually use the Polemaster myself and have adaptors for each mount so swap it between them, and the camera is double sensitive, so you can start aligning way before it's fully dark. 

Likewise - swear by it. Seriously tempted to get another one. Same for the starsense, they just save so much time.

Sometime swear at it - due user error naturally. If the clouds thin, it will pick up Polaris and couple of the other guides just after 4pm

Oh look it's that time already.

Ah - cloud 

LOL

[RayD]

Just now, iapa said:

Likewise - swear by it. Seriously tempted to get another one. Same for the starsense, they just save so much time.

Sometime swear at it - due user error naturally. If the clouds thin, it will pick up Polaris and couple of the other guides just after 4pm

Oh look it's that time already.

Ah - cloud 

LOL

Yes I also have starsense that I obviously only use with the AVX, but switch the Polemaster between mounts and only then had to buy an additional adaptor.

[iapa]

 

4 minutes ago, RayD said:

Yes I also have starsense that I obviously only use with the AVX, but switch the Polemaster between mounts and only then had to buy an additional adaptor.

I should qualify my statement - I used to have the star sense and loved it. It was handy that it came with two adapted, one fitted my SCT and the smaller bracket fitted the finders hope shoe on my now defunct reflector.

There is a variant for the star watcher mounts as well now. Seems to be the same camera unit with port splitter (which may have additional electronics in it). Shame that that accessory isn't available separately.

[RayD]

Just now, iapa said:

 

I should qualify my statement - I used to have the star sense and loved it. It was handy that it came with two adapted, one fitted my SCT and the smaller bracket fitted the finders hope shoe on my now defunct reflector.

There is a variant for the star watcher mounts as well now. Seems to be the same camera unit with port splitter (which may have additional electronics in it). Shame that that accessory isn't available separately.

Yes agreed.  It's too much for me to justify buying a whole new one for the SW mount, so maybe one day they will just supply the hub bit.