My first every mosaic

[batema]

I have captures six panels each being a total pf 45 Minutes through my williams optics 110 and have managed to get them together to have a look. I have only put them together and then flattened, cropped and then on the whole image did a very quick process to see what it might look like.

Can someone head me in the direction of how to process mosaics so I can have a real go at this.

Thanks

Mark

[RickS]

That'll be a nice mosaic, Mark! I've never had time to do more than one frame so I can't offer advice on mosaics...

[mithrandir]

Mark, did you apply flats to each frame before you joined them?

What are you using to do the mosaic? I'd use AutoPano to do the merge (and even to do the flat fielding if the vingetting isn't bad). Others do it in Photoshop, Hugin or Microsoft ICE.

[multiweb]

Cool field. You can get rid of the seam if you use the auto-blend layer mode in PS. Very easy to do. :thumbsup:

[rustigsmed]

auto blend in PS ay :question: might have to check it out!
i've only ever done one mosaic and had some success with Windows Live Photo Gallery, your computer probably already has it.

Good luck :thumbsup:

[batema]

Thank you all. I am looking forward to having a go. Andrew I did a full callibration of lights, darks, flats and bias frames. I then went into photoshop CS5.1, adjusted the size of the canvas to fit them all then started with the top right panel and pasted panel 2 and then moved it with a difference blend and fine tuned the alignment. I then repeated for each panel. I then flattened the whole image and did a couple of curves levels and a high pass filter on all.

Mark

[Ross G]

Good looking photo Mark.

Nice mosaic start.

I'm still trying to drum up the courage to try one!

Ross.

[gregbradley]

Mosaics are hard. Plan it out carefully.
The main thing is to make sure each panel gets the same exposure details as closely as possible and the same conditions, same exact focus, same filters, same scope, guiding etc - all the same as much as possible. Trying to take all panels in one night may cause differences. Approx the same time each night for each panel would work better but may not be practical. 2 panels a night I found workable. 2 hours per panel or less makes sense. How often do you get 4 or 5 nights clear in a row with similar conditions?

Process each panel exactly the same way up to a basic LRGB image. Stretch each one the same amount so one panel is not stretched differently to the rest. Thats what looks like happened here with your image. One is processed differently to the others or was taken under different conditions or exposure lengths etc. Don't try to finish processing them separately. Be methodical and consistent and take each panel to a basic LRGB image, then stitch them and then final process for colour.

Photoshop whilst improved greatly in CS4 is still a weak mosaic tool. It does not do a great job of balancing out the panels nor the overlaps which are often quite visible requiring time consuming fiddling that does not end up with a very good result. Other software is better. Microsoft ICE is free, PTGui Pro is good. You may need to manually stitch some shots as PTGui for example does not like star scenes. You may need to reduce your panel images so the software can handle them easily.

Its easier to get the acquisition right than try to fix it in post processing which is nearly impossible to do. Also allow a bit more overlap than you would think is needed. 1/4 would be a minimum overlap.

Pixinsght is another approach. It would take a learning curve as last I used it the software was complex and you needed to be precise. They have refined it but I have no experience in how it is now. I suspect its still hard to use.

Greg.

[mithrandir]

The alignment is good but I think I can see some frame edges. Try Microsoft ICE and see if it blends better. I use AutoPano Giga which does a good job of blending, but that isn't cheap.

[gregbradley]

Its really only the top left hand panel. Perhaps some curves on that layer only (if its saved still in layers) to match the brightness level.

The selective colour tool in Photoshop set to neutral works well to for matching background colours if they are slightly different between panels.

Greg.

[batema]

Thank you all. I'll have a crack this weekend.

[jase]

Great work Mark. I admire your commitment to stick it out until the project was done. As others have mentioned, mosaics take planning. Without an accurate plan and vision is asking for trouble. I'm afraid there are no free lunches when processing mosaics. Yes there are plenty of automated tools out there to assist with stitching the frames together but I've found them hit and miss. Some suppress the dynamic range in order to achieve the task making the image look rather flat. Other times, they've worked very well. Just need to find what works for you. Looking forward to seeing more.