I'm very curious

[Cosmic]

Has anyone made or even purchase something along the lines of adaptive optics :D . What kind of price tag would we be looking at I wonder .....but then again I mite be dreaming!!

Cheers,
Dan

[mswhin63]

I intend to make an apodising (apodizing if you live in the US) mask which is supposed to reduce the affects of atmospheric disturbance. I have the gear so I hope to make one for my 12" soon. Actually I am thinking of making it today.

http://www.astronomyhints.com/apodize.html

[multiweb]

Around the $1.5-2K mark. Orion, Starlight Xpress. Otherwise proprietary stuff from SBIG AO7/8. They use a flip mirror though I believe which is way more efficient as it's lighter and 'vibrates'. The conventional glass plate on the other models is approx 10-15mm thick but will give you good results still.



That's a really interesting concept. Will keep watching to see what you come up with on first light. :thumbsup:

[Cosmic]

That's awesome!! so its most definitely within reach for an amateur. Looks like there's a few ways of getting rid of that atmospheric disturbance.

Well that's now my next bit of kit :) time to save.

:thanx: Malcolm & Marc for the info :thumbsup: (http://www.iceinspace.com.au/forum/member.php?u=6949)

[mswhin63]

Hi Daniel and anyone interested,

I have mixed feelings after testing a mask I made. My first test was visual, and as the post describes is a horrible diffraction node coming out from a bright target like Jupiter. I am quite sure that the moon would be terrible.
One thing I noticed was in the centre Jupiter was so clear I could even see the a shadow of Io on Jupiter surface. This I have never seen before.

It took me a while to remember but managed 2 sequences of Jupiter shots. The air conditions where I live are horrid at the best of times so it was a good test, although I would rather a better test run another day as the humidity didn't give me enough time to setup properly.

The first image is the Apodising mask put together but not permanently. It is quite easy to make although cutting circles in fly-wire is difficult. Lots of pin holding it together. Removing the mask left me with a neat aperture reduction screen for some bright planets on good day. My webcam is very sensitive.

The second image was a fast test with the mask, while the third image is without the mask. I am surprised by the results, and still do not want to finalise my results as yet without more testing. It is just my way of testing.

[Cosmic]

This is great work you have done here Malcolm, looks easy enough to do. There is most definitely a difference there that's for sure, a more crisper and clear image is displayed by the looks. Its hard when you see a digital image and try imagine it live.

I'm going to be doing visual and web-cam'n of the night sky when she clears up. So in the mean time I mite just give this a crack and make one myself. All this rain and cloud grrr wish I was back in Perth looks clear over there now.

Anyway looks quite promising by all means :thumbsup: ....better than spending 2 grand if this dose the job instead. What mag did you use out of interest on Jupiter.

[mswhin63]

I don't think it is a good as the camera adaptive optic and really still need more testing. If there is too much exposure the picture is way washed out with strange light reflections. Although it is very cheap and easy to make though.

[michaellxv]

Any further test results from this concept? I would be interested to know if you think it is worth making one.

[Poita]

Very interesting stuff:
http://home.digitalexp.com/~suiterhr/TM/apodize.htm

I'm going to give it a go.

[mswhin63]

I had shoulder surgery earlier this year so the 12" DOB is difficult to handle. I hope to get back to testing this later. Still have it waiting to be used but I think I have the dimension a bit out on my initial design though.

[irwjager]

Pretty cool! Though I think, purely from a technical point of view, this does nothing to 'cancel out' atmospheric turbulence like AO would. However it does reduce the area any atmospheric turbulence can 'smear' photons to a degree (at the expense of total light input - bad for DSOs, not an issue for planetary).

To be honest, in bad seeing, for general use, you would probably get much better mileage from a Deconvolution plug-in, using a Gaussian point spread function to 'de-blur' your stacked image.

However, if you're doing planetary, an apodising mask may be beneficial as you're stacking lots of short exposures (does depend on your stacking algorithm!), not giving the atmosphere enough time to smear out over a larger area (as in a long exposure). In the latter case (again depends on your stacking algorithm) the atmospheric wobble is not random enough but clearly shows a direction/distortion ('the heat haze effect').

The whole point of using a Gaussian point spread function when deconvolving is that, over time (e.g. in a long exposure), the atmosphere's smearing approximates a 'random smear in all directions' distribution (which matches a Gaussian distribution). That's why a Gaussian 'de-blur' works so well in this type of scenario.

Understanding the point spread function (e.g. how a point light is diffracted into these patterns) really helps understanding why images look the way they look and how you can improve them. Once you understand that, you will understand mis-collimation and all sorts of aberrations. Plus, there's all kinds of neat tricks you can do (including deconvolution, apodising masks) and problems you can solve. :P

[Poita]

I'm only interested in this for planetary work, and the minimal cost and fun of discovery make it a worthwhile exercise. I'm digging through the detail on the .pdf files I linked to, to make sure I get it right.

I'll take compare pictures with and without the attachment and see how it fares.

[mswhin63]

My main reason was for planetary work. I found 2 problems, too much aperture and turbulence. Hoping to resolve both at the same time. I did see an improvement in stability on the first try. but saw other issue that were not pleasant. This may have been incorrect placement of the masks.

[Poita]

It looks as if you need to plan the design carefully going on the first document on those links I posted.
I'm using the spreadsheet on the 3rd link to calculate what I need.

If it doesn't work, it was still an interesting experiment and I learned a lot of new things about light.

[mswhin63]

I think the best thing is apart from the frame it is soooo cheap

[michaellxv]

Given the minimal expense I think I will make one up and see what happens.

[alistairsam]

very interesting.
from what i've read, its more effective in scopes with smaller central obstruction, something around 20%.
and the pitch of the mesh needs to be between 1-2mm.
will give it a go.
thanks