Astro Mosaic Tutorials/ How To's

[dugnsuz (Doug)]

Hello all,

Feel like I want to try my hand at mosaics with my 400mm lens, but the few times I've tried (with decent data) have been disasters!
How does one seamlessly merge panels/ match colour balances etc etc!
Driving me mad!
Anyone got links or tips on how to go about starting in the 'wonderful' world of mosaics!?

Cheers
Doug

[koputai (Jason)]

It's easy Doug. If you want to make a 2x2 panel, get rid of the 400mm and get a 200mm!

Cheers,
Jason.

[multiweb (Marc)]

All you need is registar and photoshop. It's pretty straight forward. With a bit of practice you'll stitch panels in no time.

[dugnsuz (Doug)]

Originally Posted by koputai

It's easy Doug. If you want to make a 2x2 panel, get rid of the 400mm and get a 200mm!

Cheers,
Jason.

You bugger!! LOL

[dugnsuz (Doug)]

Originally Posted by multiweb

All you need is registar and photoshop. It's pretty straight forward. With a bit of practice you'll stitch panels in no time.

Jeez - I'm missing summit fun-da-mental I reckon. Stitching panels was a nightmare! Is there an easy way to do it Marc?

Doug

[mithrandir (Andrew)]

Originally Posted by multiweb

All you need is registar and photoshop. It's pretty straight forward. With a bit of practice you'll stitch panels in no time.

Or do like some of us have and throw a couple of hundred euros in the direction of AutoPano. Pro should be enough for most people.

[avandonk]

Your biggest enemies for doing mosaics of wide fields is vignetting and sky gradients.

Very good flat correction is critical. Even then the corners and edges are very difficult to merge seamlessly.

I have gone to extraordinary lengths to limit any stray light with an extended lens hood and front aperture. I use a 82mm Hutech LP filter mounted in front of the lens.

For a two panel mosaic I use Registar to register the two frames. The combination of the two will quickly tell you where there is a colour brightness missmatch at their overlap.

It is important to process both panels the same way.

Trick one.

Use the full frame of both panels to produce a registered version of panel two to the reference panel one.

You can now trim/crop both with photoshop to have a far thinner overlap region where there is minimal vignetting etc. You trim both panels to make the overlap an even width. Since the second panel is already registered no distortion will occur due to a small area of overlap. Make sure there is no black region in the overlap from panel two.

Now run RegiStar again and calibrate the second panel for colour and brightness. Average combine the reference (panel one) with the calibrated panel two.

Inspect for a good match. It should be far better than using the complete panels.

When you have got this correct I will explain how I go about three, four and more panels.

Feel free to ask questions if I am not clear.

Bert

[dugnsuz (Doug)]

Cheers Bert - lots to take in there. Thanks for taking the time to lay it all out - much appreciated. No doubt I will have many more questions, so thanks for the offer of further input.
Doug

[leon]

See Doug now that was easy, wasn't it, I got lost after the first sentence.

Leon

[avandonk]

Originally Posted by dugnsuz

Cheers Bert - lots to take in there. Thanks for taking the time to lay it all out - much appreciated. No doubt I will have many more questions, so thanks for the offer of further input.
Doug

Doug I have tried many methods in my quest for wide field high resolution quality mosaics. It has taken about five years to get to where I am now. I do not claim all knowledge but I am willing to openly share what I have learned by much trial and error and research.

Most of the knowledge I have I gained is from others far smarter and preceding me. If I work out something new it is important to pass it on freely to pay back even a bit for what I gained through the work of others.

I am fortunate as I am retired and can spend a lot of time on what I really want to do. My forty years in working in science really helps as I found out long ago that I know only a tiny amount. It is the open sharing of knowledge with many others that has a cumulative effect far more than the simple sum of the knowledge. It is not about being the best. It is about participation and learning.

Even the longest journey starts with one step.

Bert

[Phil Hart]

it won't always work, but Photoshop CS5 is much better at astro mosaics than previous versions. you can sometimes throw your images at it and get a darn good result straight out of the box.

Bert's advice sounds interesting too.. may have to try that myself some time. Marc and Houghy also have done good work with PixInsight but that's another learning curve..

Phil

[dugnsuz (Doug)]

Originally Posted by philiphart

it won't always work, but Photoshop CS5 is much better at astro mosaics than previous versions. you can sometimes throw your images at it and get a darn good result straight out of the box.

Bert's advice sounds interesting too.. may have to try that myself some time. Marc and Houghy also have done good work with PixInsight but that's another learning curve..

Phil

Thanks Phil - I'll take a look. I tend to do most work in CS4, but CS5 is sitting there right next to it (unused) in my Mac dock!
God bless those P2P devils!!
Doug

[avandonk]

To save repeating it here Doug have a look at this thread.

http://www.iceinspace.com.au/forum/s...ad.php?t=75344

Bert

[dugnsuz (Doug)]

Originally Posted by avandonk

To save repeating it here Doug have a look at this thread.

http://www.iceinspace.com.au/forum/s...ad.php?t=75344

Bert

Thanks Bert - heaps of great information there.
Cheers
Doug

[Carl]

The best, absolutely best stitching/ mosaic software available is AutoPanoGiga. TThis is the link.

http://www.kolor.com/image-stitching...pano-giga.html

I have created panoramas and mosaics using up to 90 overlaping images and there is nothing that i have seen that compares. Photoshop cannot do anywhere near as good a job as this software. Autopano-giga is a dedicated panorama creating program.

Autopano-giga locates matching pixel patters on each individual overlapping image. You do not have to even number the sequence of images it looks for matching overlapping information.

The software will build a multi row panorama from your images automatically. All you need to do is set a few parameters and locate your images and let the software do the rest of the job ( go and have a glass of wine it is memory intensive). It will even colour balance each image and adjust images so that the final mosaic has an even colour balance accross the entire image. The software even has a stacking function for astro images

This software is not cheap and is industry standard. Check it out.

Regards
carl

[dugnsuz (Doug)]

Originally Posted by Carl

The best, absolutely best stitching/ mosaic software available is AutoPanoGiga. TThis is the link.

www.kolor.com/image-stitching-software-autopano-giga.html

I have created panoramas and mosaics using up to 90 overlaping images and there is nothing that i have seen that compares. Photoshop cannot do anywhere near as good a job as this software. Autopano-giga is a dedicated panorama creating program...

Regards
carl

Thanks Carl - will check out the link
Cheers
Doug