Up here in Auckland, yesterday evening was clear sky, at last.
5 hours I spent outside with my new used EQ5 mount, GoToStar and camera. unsuccessful. and not because of the moon.
-reasonable south-pole alignment with a compass on my iphone along the concrete slabs seam of the driveway,
-balancing okay,
-the bubble scale almost centered, the controller set up with NO DST, 720 hours ahead of UT, correct time, date and longitude, latitude
- 3 star alignment with Canopus (southwest), Antares (almost overhead) and ... ah, Arcturus (north) -
and then the camera still produces trailing stars.
The 3 stars all required 1 1/2 inch of correcting to the left and a bit down (or up?) to focus them after the mount had slewed to them.
Also, when choosing a star, afterwards, to GoTo slew to, I would always have to correct a fair amount; almost as much as during 3-star-alignment.
Doing several 3-star alignments, I noticed that the controller computes a different offset of error correction each time.
very different, each time.
As in a number difference of 100+ in 2 alignments (whatever they mean, these numbers.)
Before the last alignment, I chose to "reset everything" in the controller.
After which, Canopus no longer appeared in the 3-star alignment list.
Although, Canopus was still clearly visible far above horizon.
Oh, now, that I write this I have an idea ... is it possible that Canopus was added manually to the list of alignment stars and was lost from the list during reset?
The whole list was quite shorter after the reset .. I thought that was only because by then it was much later and all the other stars had disappeared below horizon...
but maybe...
So this is the story. It was the 3rd or 4th night for me and my scope and while I enjoy the process of learning, it does become a bit frustrating.
The good parts:
the 900 Amp jumpstarter battery had no problem and still appears half full.
The Hotteeze , attached to an old sock wrapped around my lens, worked really well and kept the dew at bay.
Will have to use it on the finder scope, too. Good recycling of these odd single socks that keep popping up from a different universe.
Hi Silv, do you realise that magnetic south and polar south are not the same ?
polar south ( the south you need ) is 14 degrees from magnetic ( using a compas ) , I cant remember weather its east or west , but if you google it you will find which way .
Also its great to see you out there giving it a go , its a major learning curve , but stick with it , it does get easier . I know I have been here . .
Hope this helps , if not I am sure someone here will sort you .
Brian.
Oh, I need polar south?!
geez!
From Auckland, the deviation is 19 degrees - that much I already know and my compass app shows that, too, as a number, at least. not as a pointer guide, though. okay: I will google whether it's left or right deviation. cheers!
btw regarding star trailing:
I aim for 3 minutes exposure in wide field and maybe 30secs with 200mm lens. but so far, I have hardly any gain over the simple camera-on-tripod exposures.
-reasonable south-pole alignment with a compass on my iphone along the concrete slabs seam of the driveway,
From my personal experience, this won't give you an accurate polar alignment. This is most likely causing your three-star alignment problems.
The iPhone compass is very susceptible to interference (including the mount itself!), and at best you may end up within a few degrees. Lately, I've found that eyeballing the Southern Cross and Pointers can be more accurate than my iPhone compass for initial alignment. My bulky handheld marine grade GPS, on the other hand, has a much more reliable digital compass.
Note that for imaging, you'll want accurate polar alignment - e.g. using drift alignment, or software such as Align Master. I know that the conventional wisdom says alignment doesn't matter too much for DSLR wide fields, in my experience I've found that it helps a LOT.
Quote:
-the bubble scale almost centered
The bubble level on the EQ5/6 mounts are notoriously poorly aligned straight from the factory... on both EQ6s I've used they weren't even remotely close - after very careful polar alignment, it turns out the centre of the bubbles were actually outside the marked circle.
Oh that polar align is such a pain, isn't it?
I went out to Leyburn a few weeks back and after a couple of hours, it was still not playing - had to give up in the end as my back gave out!
Wedges are even more dicky than an EQ5, so be grateful you aren't trying it with one of those.
I would suggest that you use the hole in the axis of the mount to shine a green laser through - it'll give you a good idea of where you're going wrong.
I reckon the best way to get south is the solar noon method, check it out on the web, all you then need is a string, weight, and accurate timepiece,like an iphone.
Regards
Peter
thanks for all your suggestions!!
I got an analogue compass. that helped - if only to see that the app "Commander compass lite" is not that bad at all.
during 6 hour sessions, my brain added some reason to the equation of the many unknowns.
while 3-star aligning, I noticed that the mount assumed the star always very far to the right of it's actual location.
so I moved the mount to point more east. and yet more east after the next try. ...close enough, now.
once the Crux' pointer stars were far enough away from that other one you use to find SCP, I found the mount being pointed very nicely south.
checking on the 2 compasses: no noticeable difference to what I had used, before. they are just too small tools to be correct enough.
so that was the one problem solved.
star trailing was not improved, though.
the other problem: during alignment, the assumed position was too low and I had to slew quite a bit up before I got the star in focus.
again applying some unusual reasoning:
if the mount assumes stars to be lower than their actual position, the mount must "think" it is closer to the equator.
now, hm, the DEC axis wheel which shows the latitude degrees is missing on this used mount.
So I fetched a geometrical triangle and tried to find the 36th degree on the axis... in the dark.
adjusted it, tested alignment: it aimed a bit better. adjusted it more: another bit better.
left out the triangle during adjustment and just let "the force be with me": a bit better aiming, still.
to my naked eye, the angle now looks like 45 degrees though. that can't be right…….
still - that issue explains for Canopus being off the list for 3-star alignment in the previous session.
NO improvement in the star trailing issue, though.
I will give it one more session to do this:
- find a totally level spot to put the mount on.
the ground is not level and I have to adjust the tripod legs quite a bit to get the little bubble centered.
- adjust the mount so that no more correcting upwards is necessary.
the good thing:
- my body got a good flexibility work out during countless 3 star alignments
- hotteeze on finder scope helped heaps!
- learned to use red dot finder (no red dot, though. got to get new battery.)
- learned new stars to use for alignment
- learned how to align to SCP by trial and error.
- had a glimpse of Saturn.
(an oblong shaped bright star as opposed to his neighbouring star which was a needle pin.
used the 10mm Meade ploessel to see the gorgeous oblong shape. yay! )
- successfully moved the mount during the night ( to a more level spot) and completed the whole set up in the moonlit darkness. good practice, too.
when you are levelling the tripod, take the equatorial head off and put a builders level across the top of the tripod. I usually did this in three directions - pointing the level towards each leg in turn. It takes 2-3 goes on each leg getting closer every time. I wouldn't trust those bubble levels at all.
Aslo, +1 for the solar noon method. Spot on every time, and once you have marked true south out, you don't have to do it again
re the solar noon: dooh! cool! so obvious... thanks!
thanks, adman, will do that once I have found the perfect spot and aligned with that solar-noon rule.
re the latitude and the missing scale on the mount (the little white arrow is there, though):
assuming it was a scale that had 0 at the zenith and 90 at level -
should I aim for 36 degrees measured from the level? or aim for 54 measured degrees from the level?
attached pics of 1. 36 degree angle measurement from the middle of the axis bolt (level);
2. mount
maybe one of you guys can post a pic of their adjusted southern hemisphere mount?
reading around the internet and understanding how important levelling is!!!
if the mount base is not level all my playing around with the latitude is meaningless!
assuming it was a scale that had 0 at the zenith and 90 at level -
should I aim for 36 degrees measured from the level? or aim for 54 measured degrees from the level?
Yes, 54 from level. 36 from zenith.
Auckland's latitiude is 36.85 degrees, so you should probably shoot for 37. You will still need to fine tune that ~0.15 degree out for photography.
Quote:
attached pics of 1. 36 degree angle measurement from the middle of the axis bolt (level)
In this photo, your protractor's outer scale is the one to work from.
0 on the level, and the arrow pointing around 37deg. (or 143 deg on the inner scale.)
Again, you will still need to fine tune this for photography.
Yes, in that case, it is the opposite. Did you not read my quotes of you?
You said:
"assuming it was a scale that had 0 at the zenith and 90 at level - should I aim for 36 degrees measured from the level? or aim for 54 measured degrees from the level?"
To which I answered:
"Yes, 54 from level. 36 from zenith."
Quote:
Originally Posted by silv
so, in my picture, you can see 36 degrees measured from level.
It should measure 37 and then I'm (almost) good?
Hi Silv, do you realise that magnetic south and polar south are not the same ? 
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