How bad is the chromatic abberation in my photo?

[Jay6879]

I'm curious to see if others see any chromatic abberation, and if so would you consider it acceptable?

I got thjs image using an asi533mc and a Zenithstar 81.

[barbulo]

It looks good to my unexperienced eyes. The overall colour balance might be tweaked if you like (I would leave it as it is) but I don´t see any aberration. Congrats!

[geeklee]

2 hours ago, Jay6879 said:

I'm curious to see if others see any chromatic abberation, and if so would you consider it acceptable?

Really nice image - how long was the integration?  From the UK?

I see a little CA.  The only person that matters whether its acceptable... is you   You could do a little with it in processing but it doesn't detract much from the image - I was enjoying the Iris and dust .  

It looks pushed hard viewed at 100% and there's maybe a slight green cast across the image if you're looking at it again in processing. The latter easy to fix if you wanted.

Thanks for sharing  Hopefully you're pleased with the image, you should be!

[Clarkey]

2 hours ago, Jay6879 said:

I'm curious to see if others see any chromatic abberation

If you look really hard around the brightest stars there might be a tiny bit - but not enough to detract from the image. As @geeklee says - only you can decide if it is at an acceptable level. The star on the right of your image is genuinely very blue anyway - so this blue fringing is to be expected. Even with a triplet it looks similar. Below is a virtually identical image (albeit 'upside down') taken with a well corrected FPL-53 triplet. (To be honest mine really should be re-processed). I do not see a lot of difference.

[Ratlet]

I don't see any myself.

If you zoom in there might be a weird artifact around some of the stars that looks like the Photoshop raw filter was used to removing some flaring, but honestly I only see that because you asked my to looks at the stars.

But trust me, nobody looking at this is going the doing that.  Fabulous image.

[rl]

I'm wearing glasses. If I tip my head from side to side the CA from my specs is hugely worse that anything inherent in your image. Looks like a good scope matched to good processing skills.

[Jay6879]

7 hours ago, geeklee said:

Really nice image - how long was the integration?  From the UK?

I see a little CA.  The only person that matters whether its acceptable... is you   You could do a little with it in processing but it doesn't detract much from the image - I was enjoying the Iris and dust .  

It looks pushed hard viewed at 100% and there's maybe a slight green cast across the image if you're looking at it again in processing. The latter easy to fix if you wanted.

Thanks for sharing  Hopefully you're pleased with the image, you should be!

I'm in Canada, and the integration was around 15hrs. I'd love to see what would be revealed by doubling that time! I'm still quote new to Pixinsight, only been using it for a few months now but i had posted the image during a "debate" on well corrected doublets (of which the Z81 would be considered one) and when I posted that pic the people on the uh...other side of the debate told me it was full of CA which I found bizarre haha.

This was my first go at processing this object beginning to end and I'm definitely going to have another go at it and carry forward what I've learned. I'll certainly consider not pushing it so hard, and correcting the color!

I appreciate all the responses!

[Ratlet]

59 minutes ago, Jay6879 said:

 the people on the uh...other side of the debate told me it was full of CA which I found bizarre haha.

Not wanting to jump to conclusions or indeed name names, but would it have been a 'debate' on a forum that might have a name that possibly sounds like a time of day where the weather would prevent astronomy?

[CraigT82]

I think there is a little CA but certainly not much, it’s a lovely image and I’d be proud of it if it were mine, nice work.

 

[ollypenrice]

Negligible CA. I would never have given it a thought.

However, on my monitor (which is calibrated) I see no green caste but I do see that your blues tend towards magenta, suggesting too little green weighting. Look at the bright star half way down on the right. I had a play with a screen grab in Photoshop and tried to lose the magenta dominance in blue. I also tried to bring out the blue in the Iris and open up the colour in the dust. Basically this meant a lift in the lower brightness reds. I felt that, above the fainter signal, you did have a green deficit.

Olly

 

Edited January 5, 2023 by ollypenrice

[CraigT82]

53 minutes ago, ollypenrice said:

Negligible CA. I would never have given it a thought.

However, on my monitor (which is calibrated) I see no green caste but I do see that your blues tend towards magenta, suggesting too little green weighting. Look at the bright star half way down on the right. I had a play with a screen grab in Photoshop and tried to lose the magenta dominance in blue. I also tried to bring out the blue in the Iris and open up the colour in the dust. Basically this meant a lift in the lower brightness reds. I felt that, above the fainter signal, you did have a green deficit.

Olly

 

Yes I did notice the magenta too, almost like NB stars. Maybe that’s what the CN lot were shouting about.

[Jay6879]

11 hours ago, ollypenrice said:

Negligible CA. I would never have given it a thought.

However, on my monitor (which is calibrated) I see no green caste but I do see that your blues tend towards magenta, suggesting too little green weighting. Look at the bright star half way down on the right. I had a play with a screen grab in Photoshop and tried to lose the magenta dominance in blue. I also tried to bring out the blue in the Iris and open up the colour in the dust. Basically this meant a lift in the lower brightness reds. I felt that, above the fainter signal, you did have a green deficit.

Olly

 

 

Could that have happened from being a bit heavy handed on the scnr?

[ollypenrice]

10 hours ago, Jay6879 said:

 

Could that have happened from being a bit heavy handed on the scnr?

It's the most likely cause. It can be difficult to get the green balance right because it can be too high in the low brightnesses and too low in the high. We know that green is critical, which is why we have SCNR Green, Hasta La Vista Green etc. The other end of the green axis is magenta, which also looks glaringly wrong on stars. Green-Magenta is, therefore very unforgiving.

Have you tried one of the star removal routines possible these days? Starnet++ or StarXterminator. I'd highly recommend them. Once the stars are separated their stretch and colour can be adjusted independently of the rest of the image before they are replaced.

Olly

[geeklee]

The red in the Iris is welcome (and additional blue) but IMHO the lower brightness reds and some of the other image tweaks have pushed the image too far and look almost like colour noise.  For me personally, I prefer @Jay6879's original.

Edited January 6, 2023 by geeklee

[Mr Spock]

I like the original too. Even if there's a slight colour imbalance so what? Who decides what is and isn't right? You could lower the magenta level a bit, but too much tinkering would lose what you have - a really good image.

Looks great to me 👍