Accurate alignment when i cant see south, or east

[sketchism]

Polar aligning, for me is a pain, i cant see south so i cant use my polar scope, and i cant see east.

Can someone correct me if i'm wrong here, but this is what i have for accurate drift aligning steps in southern hemisphere.

here are my notes, does anyone have any other tips? have i got anything back to front, as i have compiled these notes by reversing other directions etc

1. Level Mount
2. Compass Align mount to S (-11Deg offset for me) and angle to 28.3deg for Latitude

3. Point to star low (20 degrees) on the WEST horizon within 5deg of the celestial equator (slightly north)..
If the star drifts SOUTH my angle is set too low so angle it up (drift NORTH = too high)

4. Point straight up to meridian and C equator (straight up and slightly north)
If star drifts NORTH, axis is too far EAST - so rotate mount further West (clockwise) if drift = SOUTH then EAST(counterclockwise)

5.repeat

i am getting CLOSE, i can do about 30 sec at 400mm, or 1Min at 100mm but i cant quite nail it, and i can't see the SCP to check, i'm wondering if i'm missing a trick, and almost everything i read is relating to Polaris, or using the polar finder etc


http://www.iceinspace.com.au/forum/attachment.php?attachmentid=233700&stc=1&d=1536969799

[Tinderboxsky]

You sound as though you are on the right track. You just need a few tricks to improve the sensitivity of your drift detection.
Are you using an illuminated reticule?
Do you have a barlow to increase your focal length and hence the magnification? This will “magnify” any apparent drift.
Perhaps allow a longer period of drift before making adjustments.

At some stage, though, you will reach a point where your mount will not allow any finer, more accurate adjustments.

[sketchism]

i don't have an illuminated reticle on this mount as its just the camera and optics, but i am using the grid on the camera screen on full zoom mode so i can quite quickly see drift

the single star method would be practical for me, does this sound correct for southern hemisphere? (again this is adapted from the northern hemisphere method so i've had to flip everything

SINGLE STAR METHOD:

ANGLE adjustment
Select a star in the West low on the horizon and in the southern hemisphere of the sky
If the star in the WEST drifts S the elevation is too LOW.
If the star drifts N the elevation is too HIGH

COMPASS adjustment
Select a star on the celestial equator and meridian

If, the star drifts South in the eyepiece then the southern end of the polar axis is pointing East of the SCP.
SO if it drifts south, need to turn mount west(clockwise)

If the star drifts North then the southern end of the polar axis is pointing West of the SCP.
SO it drifts North, need to turn east (CounterClockwise)

[Tinderboxsky]

Looks spot on Matt.
I use the same technique except I have a good eastern horizon and a poor western horizon.

[sketchism]

i thought i was close, but i found this, which i think says the opposite

im all spun around now




"""Adjust the azimuth of the mount
Pick a star on the meridian near the equator. If the star drifts N, turn the mount clockwise as viewed from above. If it drifts S, turn the mount anticlockwise as viewed from above. ""

[Tinderboxsky]

That does not look right Matt. I have attached the summary I use which might be helpful. I cannot remember it’s source unfortunately.
Your original process steps in your early posts are consistent with this summary.

[skysurfer]

When no pole star available I use a 'star-zenith' alignment.
If you have an inclinometer, and setting circles, then it is easily done.

https://www.skysurfer.eu/eqmount.php

I use this for looking up daylight objects, but for night use it is even easier.
Years ago I was in Bali and used this approach for astrophotography as the pole star is only 8 degrees above the South. With success !

[OzEclipse]

Matt,

I agree with Steve, it's not right. My guess is that it is northern hemisphere instructions or instructions incorrectly transposed from north hemisphere instructions for the southern hemisphere that have not had the north hemisphere directions reversed.

The instructions Steve posted are correct.


Joe

[silv]

The photo of your setup looks as if you connected your camera to the finder scope. Is that how you drift align?
And do you then take your photos via finder scope or do you move the camera to the focusser (wobble inevitable)? How trustworthy is your finder scope alignment in regards to the main tube (has to be 100% accurately parallel)?

***
You could maybe save some time of the drift alignment process if you used solar noon method to mark the proper tripod location during daylight.
Then drift align during the night.
And when it's really good - mark the perfect spots for tripod legs.
I always loved drift aligning. I'm probably a masochist.

[sketchism]

Thanks for the feedback and clarification,


in that image i had the cam on the 1--400 G-master lens on the OTA, but i've just picked up a sky guider pro which i have the cam and lens mounted directly on for wide imaging

as soon as i decided to test my new notes out its been cloudy of course haha

today ill hedge my bets and mark solar noon as well as working through everything tonight!

i've attached a quick cheat-sheet based on everything ive found over the last week or so

[doppler]

Hi Matt, you can get these old mounts polar aligned pretty well but I think you will find the accuracy of the drive mechanism the limiting factor as far as astrophotography goes.

I have a cave optical mount of similar design and vintage that I have used for imaging, this has an add on drive corrector to manually slow down or speed up the motor to adjust for the drives inaccuracies.

With careful monitoring I have been able to capture 30sec exposures at 1200mm, good fun with an old scope but a bit of work to get there. Of course back in the days of 35mm film, prime focus imaging was a near impossibility with these scopes, needing hour long subs to capture anything.
Nice to see a classic old scope seeing star light.
Cheers Rick

[The_bluester]

I would do the alignment the other way around, do the drift pointed at the meridian first then low in the west. I do it that way as you can point the scope at the meridian and be basically dead on it, meaning that the azimuth alignment of the mount is the only error that will show up in the drift of the star used, but when doing the altitude by pointing at a star near the horizon you are likely to be pointing 15 degrees or more up from horizontal so any star drift is caused by a mix of any errors in altitude AND azimuth. Basically at the zenith you can isolate the azimuth error and not be trying to adjust out what is actually a result of two different errors, doing the alt alignment you cant isolate to just altitude error.

I would not get too hung up on which way to adjust the mount to correct an error in which direction, basically just work it out for yourself. By that I mean start with a deliberate large error in a known direction and get it straight in your own head which way to move the mount to fix it, "Star moves up, move the mount west" etc.