star trailing: used EQ5 with GotoStar

[silv]

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.)

[silv]

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.

[silv]

The good parts:
the 900 Amp jumpstarter battery had no problem and still appears half full.
The Hotteeze (http://www.iceinspace.com.au/forum/www.hotteeze.co.nz) , 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.

[brian nordstrom]

:) 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.

[silv]

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!

[silv]

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.

[naskies]

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 (http://www.iceinspace.com.au/forum/showthread.php?t=91077) I've found that it helps a LOT.



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.

[jenchris]

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.

[naskies]

Hi Jennifer! Was that the trip when we met? I'm sorry to hear about all the dramas you had!

Dave

[widow18]

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

[silv]

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. :prey:
star trailing was not improved, though.

[silv]

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. :rolleyes:
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.

[silv]

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 :D
- 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! :rolleyes:)
- 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.

[adman]

Hi silv,

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

Adam

[silv]

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?

[silv]

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!

[silv]

Jennifer, so getting frustrated with a wedge is worse than getting frustrated with an EQ? My heart goes out for you ;)

Found this 10-liner drift alignment how-to. doesn't sound too involved. maybe we can both benefit from it?
http://www.stephenmacmillan.com/astro/tipsandtricks.html

[MrB]

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.


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.

[silv]

"Yes, 54 from level. 36 from zenith."
..
"In this photo, ... 0 on the level, and the arrow pointing around 37deg."
uhm..

what?
so, in my picture, you can see 36 degrees measured from level.
It should measure 37 and then I'm (almost) good?

what does this mean, MrB? : "Yes, 54 from level. 36 from zenith."
That's the opposite, isn't it?

[MrB]

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."


Yes

[silv]

:rofl:
again, my brain sees an 8, not a circle.

in my picture, we see 36 degrees from level.
you say: "54 degrees from level."
but then, you also concur that 37 from level will be correct.

uhm.

:D what am I missing?

[MrB]

I'm not sure why it is so difficult to understand my replies?
My first reply ("54 degrees from level") is in reply to your question "assuming it was a scale that had 0 at the zenith and 90 at level"

My second reply was to the photo you posted.

I'm not sure how I can make this any clearer :shrug:

[silv]

yup, me neither. maybe, someone else can shed some light :)

when 90 degrees is at level (and 0 is at the zenith as assumed) and I adjust the mount 54 degrees from level as suggested by you - it would sit at 54 degrees from level - or 36 degrees from zenith.

that makes it the opposite to what we see in my picture where it sits at 36 degrees from level.

which is exactly my question:
from where should I measure 36 degrees? from zenith or from level?

[jenchris]

Brain Freeze..............:S
At 90 South (ie at the south pole, you'd have to be level @ 90 from Zenith) each degree north would mean you have to depress your OTA a degree to stay looking at the pole so at 37 south you would have to depress your OTA 90-37=53 degrees from Zenith or raise it 37 degrees from horizontal

[MrB]

I'm not sure why you asked the question about the scale being 0 at zenith and 90 at level, as it is clearly not the case in your photo, so forget the 54deg thing.

Go with the 37deg with the scale set as per your photo.

[adman]

Hi Silv,

if Aucklands latitude is 36.85 degrees south then you will need to set the altitude to 36.85 degrees from level. (The SCP will be 36.85 degrees above the horizon and you need the RA axis to be pointing at it.)

Similar to the bubble level, I would not trust the latitude scale on the mount. If you have one - use an electronic inclinometer, or even a protractor to get it somewhere close. Then when you drift align you can refine it from there. I spent days trying to drift align my EQ5 before I realised that the altitude scale could slide around.....it was out by nearly 10 degrees.

Adam

[silv]

oh, thank you for clearing that up for me, adam!

drift aligning sounds like fun ;) next week will have many cloudless nights and I can practice a lot. yay!

and now off to Placemaker for a proper bubble scale and to the pharmacy for a pirate outfit.
ah, hang on, first, I'll wait for that sun noon thing at 12.22pm, of course.

ah, I feel very confident that I will tame my dragon soon.
big thanks to all of you!

[silv]

wow!

aligning - using the solar noon method (http://www.builditsolar.com/SiteSurvey/FindingSouth.htm) :thumbsup:
(2 bamboo sticks used. gives me a nice long line on the concrete to visually align the scope's body in park position)

- my new mantra: levelling, levelling, levelling, oooommmm :prey:
don't trust the bubble in the mount.

- latitude setting via trial and error. (scope aims too high during initial star alignment? then back to park position and turn off controller. then down with the angle. star align again: now it's too low? scope into park, controller off, up the angle.)

after "all" this 3 star alignment was (almost solely) a matter of how fast the scope slews.

almost solely: I left myself a bit of fine tuning. because it felt like I had lost something when everything fell into place, all of a sudden....

128 seconds wide field overhead : no trailing on the camera display.
(on the 32" in full resolution: yeah, a bit. .. thank god. ;) )

the moon was glaring. the clouds rolled in. the feeling of loss subsided and celebration mood kicked in.

yay!

:jump: :cheers: :thanks:

[silv]

2 new things, though :o

that the stars now show a pink cone to their right can't be helped, right?
the cone being more prominent on the image edges than on the centre. it's to do with the lens and I can't tweak that with existing gear, right?

fine focussing with the controller showed a new "feature" tonight.
whereas before, pushing the left-right-up-down buttons almost immediately reacted and moved the scope into that direction,
tonight, the scope first performed a tiny backwards circle before it then "found" the direction it should move to.
I wonder whether that is not only an annoying feature but could also be a sign for correct tracking being jeopardized.
it only happened today.
I had not taken off the mount head during levelling.
all I did was fine tuning the latitude setting while the mount was fully loaded ... :o

[NCC-2893]

Hi Silv, I feel your pain. This whole scp thing drives me nuts. Just wondering, have you thought of relaying your driveway?:lol:

[silv]

I appealed to the landlord about it.
His reply: it's either fixing the power issue in the house or re-paving the drive way. your choice.
:lol:

hope you were able to get your head around perfect SCP, by now?
(solar noon method is really handy.
and then of course the trial and error method.)

did you try drift aligning? I didn't have a chance, yet, but will give that a go next.

[2stroke]

Trying out http://www.alignmaster.de/ here on our next clear sky will post back how it goes, you should be able to use this with your syncscan hand unit and update cable setting it into PC Direct mode ( or get a eqdirect cable for best result). Will post back results anyhow. What we have done is used some spray paint on each good drift alignment and sprayed around the tripod legs, so next time its a simple matter of placing the mount in the unpainted areas :) This is provide its a level surface.

Give this a shot http://www.cementaustralia.com.au/wps/wcm/connect/website/packaged-products/home/our-products/just-add-water/self-levelling-cement.html i wouldn't use it for a driveway but maybe a section in your backyard.

[silv]

Thank you 2stroke! Please do post back your results and the obstacles!
That would be really helpful for all noobs, including me.
Maybe in a separate thread?

My system is called GotoStar, not Synscan. But I'm sure alignmaster.de would work by using Ascom and a generic system like LX200 or something.

Manual drift aligning it is for me in the next step.
following the famous yet simple Octane 15 (http://www.iceinspace.com.au/forum/showthread.php?t=73263) rule :D
also mentioned with hands-on experience in this thread (http://www.iceinspace.com.au/forum/showthread.php?t=72389).

Doing it manually will give me so much more insight into all aspects.
Adding another few devices/cabling and software into the equation makes trouble shooting more complex. And for me as a beginner in all this I'd like to keep the probable mistakes to a minimum of devices involved. I learn more this way. And can apply that knowledge to an extended computerized environment, later on.

On the side: I'm also reluctant taking my macbook out into the dewy field on a regular basis. I think I'd buy a cheapish notebook when I come to the bridge of using Alignmaster and Phd.

How will you protect your laptop against moisture?
Foremost, once you depend on it and want to go to a dark site?

[2stroke]

Yer its probably best to grab a cheap notebook for the job no doubt, nothing would be worse then stepping on a macbook pro. As for moisture you won't have a problem due to the heat the notebook puts off, it keeps dew in check most of the time. You can get protective sleeve's but we have never used them, it just hasn't being an issue. As for power we use a 1900 amp jumpstart so its no real issue with a 12volt notebook psu, how else would we guide with PHD lol. Will be putting this whole new rig into testing soon and prey it holds up :) You can also get extended 9-12 cell notebook batteries for most notebooks with rear mount batteries, 2 of them is a whole night nearly :)

[silv]

yeah, the power issue... another thought to keep in mind. (and a reason not to use the macbook because that battery is a joke... no sign of the advertised 8 hour battery life)
re the dew: I read somewhere a simple card board box covering the setup would do, too.

amazing... how much gear I will have to carry at some stage... :D
the card board box would come in handy, then.

all these beautiful sky-scape images people are taking from remote sites... can you imagine their luggage?
and I bet they need to walk quite a while sometimes to get a nice tree or something into the foreground of their wide field shots.
uuuhahhhhhh!
and of course, they are taking also prime focal photos of the horse head nebula or something at the same time. with alignmaster, phd, multiple cameras, power, multiple scopes .... :lol:

I will find myself doing that - maybe in 5 years from now or later or earlier. anyway. I will be one of those people... :lol: can't imagine that now, really.

[2stroke]

Got about 20 secs without trail tonight using alignmaster on one align, problem was i had to rotate the tripod which meant it was no longer level :( hence 20secs max with a f9 ed100. Next time it will be level and i think its should be pretty much perfect, using a guide cam so i can guide out a bit anyhow. I will say the program prefect, quick and simple to use, will worth $20 :) It does a very nice job and the only downfall is if you have to rotate your mount due running out of az adjustment leaving the mount non leveled then you can't get a perfect result. This is to be expect, so use a level surface :) It took no more then 5mins to polar align and 5mins for a 3 point + nearest in eqmod, giving a perfect platform for goto and tracking :) Ill never Drift Align again apart from if its for a perm obs :)

[silv]

how boring is that??? only 5 minutes for aligning??? phhhh! :rofl:

20 seconds at prime focal?
this is really good result! congrats! :thumbsup:

Thanks for posting your experience.
I will definitely include that at a later stage, too.