Al's Collimation Aid (for imaging)

[sheeny]

Allan Gould sent me a PM the other day asking if I could come up with a collimation aid for imagers, and this is what I've come up with.:)

Al's Collimation Aid is a resizable transparent window with:


a small cross hair at the centre of the window
3 adjustable concentric circles
variable opacity of the circles and cross hairs

The concept is the "centre" circle can be adjusted to circle the centre spot of the Airy disc when it is visible, the "inner" circle is adjusted to match the inside diameter of the Airy disc, and the "outer" circle is adjusted to the diameter of the outside of the Airy disc. As the circles are concentric, any collimation error should be readily apparent.

The "centre" circle and cross hairs can also be used to centre on the star while in focus and then the inner and outer circles used to estimate the amount of mirror flop or misalignment of the focuser as the focus is adjusted.

If there's too many circles on the screen for you, just adjust them to zero radius;).

As its cloudy here I can't exactly test it myself for real, but feel free to try it out and give me feedback:thumbsup:.

Thanks for the idea, Al!:thumbsup:

Al.

[h0ughy]

can you do A few images to show?

[sheeny]

Love to, Dave, but its cloudy here and I don't have any images of Airy discs...

Hopefully someone will post an example if they get to try it before me.:D

Al.

[sheeny]

Here ya go, Dave.

This Airy Disc image was stolen from the web to illustrate how Al's Collimation Aid works. Unfortunately, the collimation is pretty good (perhaps a tiny bit of astigmatism:shrug:)... a poorly collimated Airy disc would probably illustrate it better.

Perhaps just to explain...

Lets say we aligned the inner circle with the inside of the Airy disc... if the scope is out of collimation the centre dot will be offset and not in the centre of the centre circle or cross hairs, and the outer edge of the Airy disc will be offset the other way relative to the outer circle when its adjusted to the right size. Clear as mud? :P

Al.

[multiweb]

Ha! You're a champion! Very cool. :thumbsup:

[mldee]

Thanks Al, just what I (and no doubt many others) was looking for. Really do appreciate your efforts!

Cheers,

[DavidU]

Noice one Al, I will have a play with it.

[JD2439975]

Very interesting Al, definitely be giving this a go.

Thank you for your efforts. :thumbsup:

[[1ponders]]

:clap: :clap: :clap:

Thanks Al. Just what i need. Another another computer process to do before i start capturing images. :lol: :poke:

But I'll definitely be using it :D

[sheeny]

:lol:

Yeah... but it's wafer thin...!;)

Al.

[Omaroo]

That's brilliantly simple lateral thinking there Al & Al. It's this sort of idea that I admire the most. Well done, and I'm not sure why no-one has come up with it before... invention, necessity, mothers.. all that. :thumbsup:

[allan gould]

This is an example of an SCT and miscollimation. Its particularly good with an SCT as the central x-hairs that Al has put there enable you to place that on the small white central dot you get with these scopes and then place the circles on the image from your camera and it shows you where the eccentricity lies.
One nice little improvement for the dyslexic among us would be to place three numbers (moveable on the circumferance of the outer circle) so that you could rotate this to line up with your Bob's knobs or the collimation screws so that you knew which one to turn to bring the airy disk back to centre. Just a thought, Al.
But as it is at the moment its a ripper.
Allan

[Omaroo]

I'll certainly be using it to properly collimate my Mewlon. It'll be a real boon as once I have it tracking, I can fiddle with the Bobs Knobs at the front while staring at the monitor without having to wizz back around to the EP all the time. It can be done in real time, which is an absolute bonus.

Al, if I may, could I suggest that it may be useful if you put another set of static crosshairs inside a scalable box like the circles (optional, and maybe selectable via an on/off button) right in the middle of the screen. This could indicate that that we're looking at the airy disc on-axis? This would help with Dall Kirkhams such as the Mewlon as even slightly off axis the collimation is pointless. We could position the entire window centrally and resize the box to gauge whether we were sitting on centre within the sensor display area. Idea?

[sheeny]

:confused2:

I'm not entirely sure I follow the need for another set of cross hairs Chris.

You want the Airy disc on axis, so presumably the centre of the CCD is on the axis. The existing cross hairs are positioned on the centre of the window (same point the circles are concentric with), so wouldn't you just need to size the window so it fits and lines up with the capture image? Then move the Airy disc to the cross hairs???

Am I missing something???:shrug:

Al.

[Omaroo]

Hi Al

I stand completely corrected. :thumbsup: I didn't realise that your applet window was completely scalable, and that the crosshair dynamically centred itself depending on the size of the window. Very clever :thumbsup:

Don't mind me....

[irwjager]

That's a brilliant little tool! Very simple, yet very clever! :thumbsup:

[sheeny]

Mother of all evil? Mothers... Oh!... MOTHERS! Yeah, that's us! :D ...wait a minute... you mean mother of invention don't you...:P

Let me think about that one a bit, Al. I've used the e.graphics draw commands to do the circles and cross hairs, so I'm not sure how to do the movable text in any sensible way yet... but I'll work on it:D.

And thanks for the out of collimation example image!:thumbsup:

That's OK, Chris. I don't mind at all... I say and do dumb things increasingly more frequently these days...:P:)

Al.

[h0ughy]

better get a bucket Paul - Light bucket:rofl:

took me a while but after readiong a bit more i understand now Al:thumbsup:

[troypiggo]

Brilliantly simple. Thanks to all concerned!

[sheeny]

OK, here's v1.1 as requested:

It now has the numbers 1,2 and 3 able to be displayed around the outside of the outer circle as per Allan's example in post 12 to represent the screw positions. There is a checkbox to turn the numbers on or off, and a numerical updown control to change the orientation of the numbers through +/- 120° in 5° increments.

For those who might be interested, I've included a PDF of the code. VB.NET programming is so easy (compared to where it was heading when windows first started - that stopped me programming!:eyepop::lol:) the biggest problem is just finding the commands you need among all those available. Fortunately, the web and other resources are excellent help.:thumbsup:

Al.

[Omaroo]

Thanks for the vote of confidence Al. ;)

[allan gould]

Al
That is astoundingly brilliant. Just what Ive needed to have a go with (the numbers). Its numbering and rotationablity will make working with bobs knobs childsplay.
Many, many thanks.
I had a very quick play with the first edition of your software and I think it showed a very, very slight miscollimation of my sct that led to slightly egg shaped stars in one corner. I think you program has fixed it but I need to take some shots to prove it. Thanks for such a great program. I admire your abilities.
Al

[allan gould]

Al
Used the second version. Just easy to use now and numbering the knobs helps determine which one to tweak. Just brilliant.

[sheeny]

Cool!:thumbsup:

Thanks Al.

Al.

[kookoo_gr]

i downloaded your software and run the setup.exe from the ziped file, the program run succesfully but when i tried to run the software again (setup.exe and the other two executables) it shows mr the message "You cannot start application AlsCollimationAid from this location because it is already installed from a different location." any ideas?

[naskies]

Brilliant! As a huge fan of Bahtinov Grabber, I've been looking for something like this for a while. Thanks! :thumbsup:

[DJT]

Hi Al

brilliant..got to this via a request for guidance on a different thread. Will be using this next clear night.

Thanks

[sheeny]

It should appear in your start up menu under "All Programs".

Different versions of windows install to different directories, so without knowing what you have, if you can't find it in the Start Up Menu, search each hard drive you have (starting with C: drive;)) for the program name "AlsCollimationAid" or part thereof. Once you find it, use explorer to go there and make a shortcut, and move it to the desktop.

Thanks David and Dave!

Al.

[Grimmeister]

Gents,

Simply brilliant, I too have purchased an RC8 scope and have struggled with collimation and I am certain this will assist greatly. :D

Perhaps this can be pinned in the software section for easy access in the future for people.

I can't thank you enough. Cheers and may you be blessed with clear skies :thumbsup:

Anthony

[sheeny]

Thanks Anthony. You may find its already in the Resources section in the files library;).

Al.

[Geoff45]

Just stumbled on this thread. The app looks really good and easy to use.
Thanks Al
Geoff

[ribuck]

Hi All,

Not wanting to look stupid, but i'm going to anyway. When using this tool with a defocused star on a RC scope, should i be adjusting the the primary or the secondary for the final collimation tweaks or should i be doing both ?

Rich.

[astronobob]

This is awesome Al, legendary work, !!

[sheeny]

Thanks Bob.

[ribuck]

Hi all,

I have an RC8, and not clear what i should be adjusting. should i be adjusting just the primary or the secondary or both ?

Rich.

[sheeny]

Secondary for sure. I've had a couple of schmidt-cassegrains and the primary is not adjustable on them, but I'm not familiar with an RC.

Play with the secondary to start with, and see if you can get good collimation.

Al.

[glend]

Rich, RC collimation is tricky, and there is a well thought through process of steps and some tools are required. For the RC08, it is also essential to have the GSO Collimation Ring, this is the one you need:

http://www.bintel.com.au/Accessories/Collimation/Bintel-GSO-RC-Focuser-Collimation-Ring--RC8-/1771/productview.aspx

There are several very good threads here on IIS on how to collimate RC08s, I suggest you read through them it will save you alot of frustration and you will get a good idea of what has to be done and in what order. Suffice to say it is more complicated than collimating a newt.

You can start by watching this series of three excellent utube videos on collimating the RC08:

https://www.youtube.com/watch?v=2EC5N5bfB9A

[ribuck]

Hi Glen,

I have spent a small fortune buying all the tools, i.e. a Howie glatter plus circular pattern attachment, i also bought a Tak collimating scope. i've also read all the posts and watched all the youtube video's.

But i've found that, all these tools will get you very close but not perfect, hence wanting to use Al's tool as a final star test.

So all i want to know know is that when i'm doing the star test with Al's tool, as i adjusting the primary, the secondary or both.

Just want to understand the process, before i attempt using it.

Cheers,
Rich.

[ribuck]

Hi Al,

Many thanks sir, i appreciate your help.

Rich.

[glend]

If you've got to the star test point then adjust only the secondary, the rest should be fine if you've been through all the bench alignment, provded your camera sensor tilt is not a problem.

[barx1963]

I know this is an old thread, but I have just used this little tool last night to star collimate my 8" Edge. I had read about this when Al came out with it but at the time it was no use to me with the gear I had. After recent attempts to optimise my collimation I finally remembered it and last night gave it a run and made the process so easy. Thanks Al for a simple idea well executed.

Malcolm