On the Level or not!

[adamsp123]

Recently I was chatting to a friend about spirit levels, a sad topic of conversation I know, and he pointed out a way to check to see if a level was accurate.

Well I had never thought of it but you simply place the level down on something near to horizontal, check where the bubble is sitting, rotate level 180 degrees and do the same, the bubble should "read" the same, ie if bubble aligned to left mark then rotating the level the bubble should still be aligned to left mark.

Well I checked my levels I use to set up my mount and all were rubbish, I checked a whole load of small metal cased ones in my local hardware shop all six were out some very badly!

My mate gave me an old plastic model he had but was spot on.

So the moral of the story is if you use a level to set up your mount it could be out of true, and will muck up the accuracy of any goto function on mounts be it electronic or manual.

Pizza Pete

[Doc]

Interesting Pete off to check mine...

I agree though a very sad topic to talk about

[Psychobilly]

Lets feed the obsession...

Spirit level - Wikipedia, the free encyclopedia

Spirit Level Sensitivity Explained - Accuracy of a Spirit Level

What you want is one of the levels they use to setup a championship snooker table....

[Macavity]

Interesting stuff. I must admit I was using an old bubble one as the "standard" for my "Wixey" - Then resetting on a known star azimuth. IIRC, digital angle gauges are capacitive in nature - I have a bigger one as well! I guess you could use the Ancient Egyptian method: Flood everything with water and use small strategic stone blocks...

[brianb]

So the moral of the story is if you use a level to set up your mount it could be out of true, and will muck up the accuracy of any goto function on mounts be it electronic or manual.

Not necessarily - having the tripod top accurately level helps when drift aligning an equatorial head, but it's actually quite unimportant when using a computerized mount if you do a two or three star alignment as the star alignment process compensates for any inaccuracy in the levelling (and north orientation of an altaz mount). If the tripod base isn't level then the mount's "guess" as to where the alignment stars should be will be inaccurate, but so long as the error is insufficient to get them (or you) confused with other alignmet objects, the accuracy of tracking or the operation of the goto function will be unaffected.

[Rusty Strings]

That explains why my shelves are never level, seriously though, I trust the amount of error here is small and won't affect observing and planetary imaging?

John

[adamsp123]

That explains why my shelves are never level, seriously though, I trust the amount of error here is small and won't affect observing and planetary imaging?

John

Some of the levels were way out a few degrees I would guess.

I am starting imaging, as yet unguided, and having the setup as near right as possible must help.

I don't believe that the goto software can completely fix all the errors in alignment, I have seen myself in using more than one in practice, particually when doing AP over longish periods of time.

Anyway the blasted things should be correct as even an error one degree out over a long run is quite a measurable distance and in astronomy thats 2 full moons out.

[tinvek]

as a matter of interest has anyone tried the spirit level aps for the iphone? and if so how accurate is it?

[dph1nm]

An equatorial mount does not really need to be level - just polar aligned. You could stick the tripod on a hillside if you wanted (although balance might be an issue!).

The alt-az gotos do seem to rely on being level, although I imagine you could write software to track no matter what angle you were at.

I am also rather amused by the idea that leveling a tripod to a fraction of a degree says anything about the orientation of the axes of the mount on top of it! Obviously some people have a lot of faith in manufacturers ...

NigelM

[brianb]

An equatorial mount does not really need to be level - just polar aligned. You could stick the tripod on a hillside if you wanted

Yes, but having the tripod levelled helps when drift aligning because you want to be able to make adjustments in azimuth without affecting altitude & vice versa, if the mount base isn't level then you won't be able to do this & the process will take much longer.

[Catanonia]

Just pop to B&Q and get a new pack of 5 bubbles and replace when needed.

[Mak One]

I’ve recently established that the cat’s eye bubble level on my CG5-GT mount is “out”, so I'm now using a short torpedo level across the tripod head. With or without the bubble, levelling requires lots of tripod leg length adjustments. Relatively quick, but a pain having to scrabble around near the ground then back again to examine the bubble etc, especially if you have back problems – nothing like a tweaked back to ruin an observing session.

Taking on board the points in the posts above, I can see that an accurately levelled tripod is a good idea. Now, surveying instruments (levels and theodolites) come with a triangular base plate with a cat’s eye bubble built in, and a threaded foot screw at each base corner to adjust the level. This has several advantages:

1. VERY fast and convenient levelling (5 secs max) whilst stood at the instrument, rather than up and down trying to make fine adjustments to the leg lengths.

2. It allows the tripod to be planted firmly into the ground to ensure stability before the tripod is levelled. Trying to level it with the legs usually means at least one is inadvertently pulled from the ground, meaning the whole process has to start again. Tripod stability is often questioned on here, so anything that helps this has to be a good thing?

So why don’t astro mounts come with a similar levelling base? Is it cost?, accuracy?, a lack of established need?

[Mr Spock]

You can get obsessed with aligning everything to the n'th degree. I dump my EQ6 outside, align with the pole, two star alignment, and away it goes...

[Peter Drew]

Buy an adjustable level!, they do exist..