https://www.astrobin.com/dh8m66/?nc=user

This is a two panel mosaic taken last month, RGB from a dark sky sight at TDS, Ca and Ha for luminance from my backyard in Carlsbad, Ca.  Taken with my 130GTX and the QTCC on a 1100GTO-AE mount.
Khushrow

Doing mosaics is definitely an art and is difficult. Especially one with color data. You have done a masterful job.

Three of us local amateurs once made a 9 panel mosaic using small chip ST8 cameras and long focus telescopes (long focus to get high res detail). Getting the RGB data took months, a whole summer in fact. We wrestled with cloudy nights, poor seeing at times, Moon being up and causing gradients, tracking issues, etc etc. After producing hundreds of individual RGB exposures, it was left to me to stitch it all together. The first few tries produced a total mess.

I had to re-shoot the object with my wide-field Traveler scope and a larger chip ST10 to get a single underlying reference image that could be used to place the high res images over the top. Each individual RGB had to be stretched, processed and gradient removed to look like its 4 neighbors before it could be permanently attached. This took another couple of months and we finally had a finished image that could be laser printed on 50" photo paper to produce an image that you could examine with a magnifying glass and see tiny detail. Today, you could shoot this same object with a single chip color camera and get the same result.

We've come a long way, baby!

Rolando

-----Original Message-----
From: Khushrow Machhi via groups.io <kmachhi=yahoo.com@groups.io>
To: main@ap-ug.groups.io
Sent: Thu, Feb 18, 2021 10:46 pm
Subject: Re: [ap-ug] Horsehead Nebula and M42 two panel mosaic with 130GTX + QTCC

If I was processing just the single images without putting together the mosaic then probably 3-4 nights and spending 2-3 hours each night would have done it.  Putting together the mosaic and getting it to a point where I was satisfied with the seams merging took a long time.  I restarted three times before getting to the point where I was satisfied.  And so it took almost a month after I captured the data to my post this morning, working on it 2-3hours each night 4-5 nights a week for the past month.

Thanks, I'll look into that if the need ever arises. Those tools were not available back in the 1980's, so we were on our own. We actually produced two large mosaic images, one of the Andromeda galaxy and the other of the Orion Nebula. We printed them on 50" wide photo paper and sold a limited number to a few amateurs here in the US. I have one of each on the wall in our showroom. The project burned out my two friends on ever doing this again.

Rolando

-----Original Message-----
From: Stuart <stuart.j.heggie@...>
To: main@ap-ug.groups.io
Sent: Fri, Feb 19, 2021 10:29 am
Subject: Re: [ap-ug] Horsehead Nebula and M42 two panel mosaic with 130GTX + QTCC

Rolando, there is now a very useful tool in PixInsight called GradientMergeMosaic which follows your logic: create an underlying rough mosaic and map all the subs to that. The gradient tool built into it does an amazing job of removing the seams and smoothing the transitions.

The most I've done is the 2x2 Veil mosaic I posted in the summer.

Stuart Heggie

http://www.stuartheggie.com/

On Fri, 19 Feb 2021 at 11:15, Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:

Doing mosaics is definitely an art and is difficult. Especially one with color data. You have done a masterful job.

Three of us local amateurs once made a 9 panel mosaic using small chip ST8 cameras and long focus telescopes (long focus to get high res detail). Getting the RGB data took months, a whole summer in fact. We wrestled with cloudy nights, poor seeing at times, Moon being up and causing gradients, tracking issues, etc etc. After producing hundreds of individual RGB exposures, it was left to me to stitch it all together. The first few tries produced a total mess.

I had to re-shoot the object with my wide-field Traveler scope and a larger chip ST10 to get a single underlying reference image that could be used to place the high res images over the top. Each individual RGB had to be stretched, processed and gradient removed to look like its 4 neighbors before it could be permanently attached. This took another couple of months and we finally had a finished image that could be laser printed on 50" photo paper to produce an image that you could examine with a magnifying glass and see tiny detail. Today, you could shoot this same object with a single chip color camera and get the same result.

We've come a long way, baby!

Rolando

-----Original Message-----
From: Khushrow Machhi via groups.io <kmachhi=yahoo.com@groups.io>
To: main@ap-ug.groups.io
Sent: Thu, Feb 18, 2021 10:46 pm
Subject: Re: [ap-ug] Horsehead Nebula and M42 two panel mosaic with 130GTX + QTCC

If I was processing just the single images without putting together the mosaic then probably 3-4 nights and spending 2-3 hours each night would have done it.  Putting together the mosaic and getting it to a point where I was satisfied with the seams merging took a long time.  I restarted three times before getting to the point where I was satisfied.  And so it took almost a month after I captured the data to my post this morning, working on it 2-3hours each night 4-5 nights a week for the past month.