Please have a look at these and let me know what u think

[lensman57]

Hi,

I am posting a couple of images taken with my Atik 428 EXC.These are just pure stacked data done in PI, STF has been applied and then a Histogram Transformation  so they could be saved as viewable Jpegs, in another words the data has not been molested. Why am I getting the Blue - Green  borders?

Thse are not stacking artefacts and are present on all my captures using the 428 and somehow the flats do not seem to correct these either. They are always Blue-green in colour and I have great difficulty correcting the back ground with them so most of the time I have to crop them out. Has anyone else seen these on other cameras? The camera was purchased last  July from FLO and has seen relatively little use, as I image with DSLR and a 314L+ and a QHY8 as well. I would be obliged for any input.

Regards,

A.G

[JohnC64]

Hi AG,

I get similar "borders" if my alignment/tracking is off slightly.  I end up with round stars on each individual sub as I am guiding, but if i look at the first image in stack and the last image in the stack, i find that there is a diagonal shift in the position of the stars. i.e the good bit in the middle is the intersection of the first and last image rectangles   Registration takes care of this but when the images are integrated, i get noticeable borders around the image.  The give away for this is when looking at the histogram, i get secondary spikes in the histogram. If i clip off the border, the secondary spikes are eliminated.  STF does Accentuate all details in the stacked image to the max so it will make  things look worse than they are when hand processed.  My fallback processing position is to DBE the image and if that doesn't work then Clip out the borders with a dynamic crop.

If the data shown above after  a STF is anything to go by,  you should have some great images there.

Cheers John

[lensman57]

Hi AG,

I get similar "borders" if my alignment/tracking is off slightly.  I end up with round stars on each individual sub as I am guiding, but if i look at the first image in stack and the last image in the stack, i find that there is a diagonal shift in the position of the stars. i.e the good bit in the middle is the intersection of the first and last image rectangles   Registration takes care of this but when the images are integrated, i get noticeable borders around the image.  The give away for this is when looking at the histogram, i get secondary spikes in the histogram. If i clip off the border, the secondary spikes are eliminated.  STF does Accentuate all details in the stacked image to the max so it will make  things look worse than they are when hand processed.  My fallback processing position is to DBE the image and if that doesn't work then Clip out the borders with a dynamic crop.

If the data shown above after  a STF is anything to go by,  you should have some great images there.

Cheers John

Hi John,

Many thanks for your reply, I will surely give the tracking some thought but both of these images were taken with 900s subs and the polar alignment was good, the PhD graph was also as flat as a pancake so the guiding was good. What worries me is the starnge colour of the borders. Another SGL member with 428 EXC thinks that I either have a ground loop problem or something is not right. The images are just a straight histogram stretch with the STF values applied and nothing else. I have now sent these to Atik support along with a master Bias and a Master Dark, the master Bias does show some strange vertival bands but the Dark is clean, I have as yet not had a reply from Atik but it is the first day after the Easter Break. I attach the master files for reference, the bias were taken at the end of session with all the imaging gear in situ, the darks were taken inside only the camera and the computer attached to the power supply. I may take the bias with the camera powered by a ptank and see if the bands appear again. The master dark ( heavily stretched ) is on the left and the master bias ( heavily stretched ) is on the right.

Many Thanks and Regards,

A.G

[sloz1664]

Hi AG

It could be a ground loop problem. I found when I had a GP problem the first couple of lights were very streaky, washed colours on the osc

or they had a black band across the bottom.

Are you get the trembling or static sensation when touching any of your imaging gear. That's the tell tale sign of GL.

I ended mine by earthing my tripod to ground.

Hope you get it sorted

Steve

[lensman57]

leg and sink the other end into the soil

Hi AG

It could be a ground loop problem. I found when I had a GP problem the first couple of lights were very streaky, washed colours on the osc

or they had a black band across the bottom.

Are you get the trembling or static sensation when touching any of your imaging gear. That's the tell tale sign of GL.

I ended mine by earthing my tripod to ground.

Hope you get it sorted

Steve

Hi steve,

Funny you should mention the tingle, I have not noticed it with my HEQ5 but when I had my EQ5 I once thought that I was getting electric shock, I ended up wrapping a piece of copper wire around the leg and sink the other end into the soil and the  tingling was gone , maybe I should try it with the HEQ5.

Regards,

A.G

[sloz1664]

Hi AG 

leg and sink the other end into the soil

Hi steve,

Funny you should mention the tingle, I have not noticed it with my HEQ5 but when I had my EQ5 I once thought that I was getting electric shock, I ended up wrapping a piece of copper wire around the leg and sink the other end into the soil and the  tingling was gone , maybe I should try it with the HEQ5.

Regards,

A.G

That's how I cure my earthing problem

cheers

Steve

[Vanilla]

I agree with what others have said...also... Your photos are wonderful. I'm still learning the ropes regarding astrophotography.  My star photos look like some kind of  Alien ships shaped like fat sausages.

[mbrickley]

Hi AG,

I get similar "borders" if my alignment/tracking is off slightly.  I end up with round stars on each individual sub as I am guiding, but if i look at the first image in stack and the last image in the stack, i find that there is a diagonal shift in the position of the stars. i.e the good bit in the middle is the intersection of the first and last image rectangles   Registration takes care of this but when the images are integrated, i get noticeable borders around the image.  The give away for this is when looking at the histogram, i get secondary spikes in the histogram. If i clip off the border, the secondary spikes are eliminated.  STF does Accentuate all details in the stacked image to the max so it will make  things look worse than they are when hand processed.  My fallback processing position is to DBE the image and if that doesn't work then Clip out the borders with a dynamic crop.

If the data shown above after  a STF is anything to go by,  you should have some great images there.

Cheers John

You could have good guiding for long subs but still get image shifts between the subs. what happens if you stack the images  *without* alignment.... do you get a a trail of stars. If yes then I bet its the fact that the central part is registered on all the images and not the borders. Earth loops are capable of funny effects but more normally would give banding or hash type effects rather than a clear edge effect like this.

Hope this helps