Jump to content

sgl_imaging_challenge_2021_annual.thumb.jpg.3fc34f695a81b16210333189a3162ac7.jpg

Making myself an accurate digital level


Recommended Posts

Hi chaps,

Before I set off on another project - I want to check if something exists for this first.

Problem : levelling the tripod. We all know how important it is, but we are expected to do this with great accuracy using a small bubble of air in a plastic blob of water. This seems kinda primitive to me.

The solution: a small oled screen device which can be permanently attached to the tripod (now I grant you we are getting into a turtles all the way down problem here.. what levels the level.. however lets ignore that for now), and shows you visually degrees out, plus dot digital bubble. it can use an extremely accurate accelerometer to do this.

total cost will be about 15 quid - esp32 dev board with battery and oled screen, accelerometer. and some noddy code to show it all graphically in an easy to see at night view.

I've looked around and can't see anything that does this. and trying to use a mobile phone is tricky because no flat surface on most mounts.

Now, of course a simple solution is a 'flat' deck fixed to the mount to put mobile phone on, and just use that.

But where's the fun in that ?

So - before I get hacking - has this been done before ?

  • Like 1
Link to post
Share on other sites
Link to post
Share on other sites

The village carpenter has a little doo-dah called a Digi-Pas, it's a twin axis level with a bluetooth connection and an app so it can be levelled off without actually being able to see the level.  Cost wise it wasn't cheap at about 200€ but at the same time I don't think I'd be able to build something as precise (0.1º) with a similar sort of capability once I've taken the time in to account for less.

Link to post
Share on other sites
2 minutes ago, Dr_Ju_ju said:

Why must the tripod be perfectly level ??  as long as it close, good polar alignment will take care of any 'inaccuracies'...

This ^^^^

Unless you want to do the project just for your own satisfaction (which is a perfectly valid reason, of course), then it is a waste of time. A standard spirit level will get you well within the accuracy needed, actually, so long as your PA is accurate, whether the tripod is level or not is completely irrelevant. All it does is ensure there is no or minimal interaction between the az and alt adjustments for PA.

  • Like 1
Link to post
Share on other sites
7 minutes ago, Dr_Ju_ju said:

Why must the tripod be perfectly level ??  as long as it close, good polar alignment will take care of any 'inaccuracies'...

It is probably not so important for AP but us photographers do want absolute accuracy and having a spirit level at 6 foot is no use to someone 5 foot 6 inches tall...

Alan

Link to post
Share on other sites
42 minutes ago, bottletopburly said:

you know I'm happy to admit when I've missed the obvious - I have never thought of just sticking it on the tray!

Link to post
Share on other sites
19 minutes ago, Stu said:

This ^^^^

Unless you want to do the project just for your own satisfaction (which is a perfectly valid reason, of course), then it is a waste of time. A standard spirit level will get you well within the accuracy needed, actually, so long as your PA is accurate, whether the tripod is level or not is completely irrelevant. All it does is ensure there is no or minimal interaction between the az and alt adjustments for PA.

I have to disagree with you there - as you say yourself in the final sentence. Once it's PAed it is, fair enough - but PAing is hard enough in ASIAIR without me having to worry about ALT offset changing when I change the AZ offset. The closer I can get it before I start, the quicker my PAing will be - especially as my old EQ5 is a bit rough with ALT in the first place. It's a heck of a lot  easier if the two can be corrected independently imho. Standing there for 20+ mins fannying around trying to get it PAed is not my idea of fun. Anything that can make that quicker I'd gladly do.

However, see above - the glaringly obvious sitting the phone on the tray will be my goto next time - embarresssed I never thought og that - I'll been trying to sit in on a square corner of the mount... sheesh.

stu

  • Like 1
Link to post
Share on other sites
7 minutes ago, powerlord said:

I have to disagree with you there - as you say yourself in the final sentence. Once it's PAed it is, fair enough - but PAing is hard enough in ASIAIR without me having to worry about ALT offset changing when I change the AZ offset. The closer I can get it before I start, the quicker my PAing will be - especially as my old EQ5 is a bit rough with ALT in the first place. It's a heck of a lot  easier if the two can be corrected independently imho. Standing there for 20+ mins fannying around trying to get it PAed is not my idea of fun. Anything that can make that quicker I'd gladly do.

However, see above - the glaringly obvious sitting the phone on the tray will be my goto next time - embarresssed I never thought og that - I'll been trying to sit in on a square corner of the mount... sheesh.

stu

What makes you think the tray is anywhere near level  with the tripod/head😋

Alan

Edited by Alien 13
  • Like 1
Link to post
Share on other sites

I suspect that if you're doing AP and the lack of independence between the alt and az axes is any kind of a worry then you're using the wrong polar alignment tool :)   Of course ASIAir may not give you much choice, which would be unfortunate.

I further suspect that the engineering standards used for the manufacture of many Skywatcher mounts in no way guarantee that levelling the tripod will actually mean the alt and az axes are in fact genuinely parallel/perpendicular to the top face of the tripod once the mount is in position.

So it may be that fairly close is the best you can do with any spirit level unless you have access to moderately decent engineering kit.

James

Link to post
Share on other sites

I do find the ASIAIR routine a bit onerous. I'm hoping with a bit of experience to note a correlation between what it's trying to achieve and the liveview in the DSLR - then I can use the liveview (maybe if I check the polaris position first, then note where the clock face is on the screen, etc.. draw it on with a marker..) . The lack of real time feedback is the main issue with ASIAIR imho. You're setting maybe 5 second exposure, then it has to download it over USB2, then another couple of seconds to process the raw and display it. not quite sure if that includes your change or not, so you wait for it to refresh again, then repeat again and again and again. oh you've went by it.. so back we go again... arggggg. synscan was soooo much easier with liveview and 'centre it in the view' buisness. I may end up using syncscan do PA first, then start ASIAIR, but that would be admitting defeat!

stu

 

Link to post
Share on other sites

Could be I'm missing the problem here but...plumbob weight hanging under the mount, fix a circular scale under it somehow. Probably more accurate, cheaper and no batteries required. Feel free to ignore if it's not a practical solution!

  • Like 1
Link to post
Share on other sites
36 minutes ago, wulfrun said:

Could be I'm missing the problem here but...plumbob weight hanging under the mount, fix a circular scale under it somehow. Probably more accurate, cheaper and no batteries required. Feel free to ignore if it's not a practical solution!

And, bonus ! You can do water divining with the plumbbob at the same time ... 🤪

(No,of course I don't think it actually works , see the smiley . )

Link to post
Share on other sites

Even though I see it nearly pointless and overly optimistic at 15 quid (a decent industrial grade 3D accelerometer chip is around $300), I would recommend to ditch your fancy OLED screen idea immediately. Using a fixed on the mount leveling feedback device means you are simply replicating 1:1 the ordinary bubble level's deficiencies (if not adding more of specific ones, e.g. killing EDA). With the ESP32 you can go the proper IoT way instead. The screen must be remote (e.g. on your phone or on your imaging workstation). Ready to integrate with an arbitrary leveling flow, not just with one involving eyeballing it on some "screen". So, I'd just make a box with the battery and put it anywhere on the mount. Then make an app to allow reproducing any mount position on demand (e.g. leveled). And calibrate it with the real life data.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.