Jupiter image - blueish Cresent tinge

[Startrek]

Took a quick 59 sec video of Jupiter on Monday morning at around 4.00am
Altitude was around 29deg so seeing was average , planet was jumping around a bit
Stacked 1500 frames AVI file ISO 800 in Autostakkert 3 and processed sharpened in Registax 6
Ended up with a “blueish crescent tinge” on the sky side of the planet.Tried to remove it in R6 with RGB align but ended up with a blueish tinge on both sides
Any ideas how to mask it or remove it in R6 ( I don’t use PS or PI )
Assuming this is at atmospheric artifact ??

Thanks in advance

[mental4astro]

Martin,

This looks like chromatic aberration to me - blue on one side, red on the other. Were you using a barlow with your Newts?

[Mickoid]

I tend to agree with Alex here, Martin. If your eyepieces or Barlow's are not up to scratch optically, their faults will manifest in resulting aberrations like this. Best way to remove it would be to use the defringing action in Registax. It will create a soft mask around the perimeter of the planet and help disguise the CA. Good on you for getting out there so early while Jupiter is quite low in the sky. It's still a nice result. :thumbsup:

[Startrek]

Alex
I used a 4 x Televue powermate with my canon 600D
Mick
Do you mean Denoise / Deringing feature , there’s no defringing on Rx 6
I tried denoise / deringing on both dark and bright side and didn’t do anything

Funny thing I have some single unstacked unprocessed images of Jupiter from last year when it was up between 65 and 80 deg and used my 4 x powermate but no blue crescent tinge ???

Looks like tonight might ok so may image Centaurus A for a few hours and then Jupiter at 4.30am again, I’ll try my 2.5x , 4x and 5x powermates and see what happens , also at different exposures

[mental4astro]

Could be due to collimation not being schmick as is should be. Or the weight of the camera causing a misalignment through the focuser - a DSLR is much heavier than any collimation tool. Elevation isn't the thing. I doubt it is atmospheric as the whole image would be affected. Something is not quite right with the optical train. I could be wrong, but my first thought is not atmospheric.

If this wasn't seen last year, then something's changed.

Where change in altitude could be a factor is how the different position of the OTA is somehow affecting the stability of the camera in the focuser.

[Startrek]

Makes logical sense Alex
My collimation is not perfect but good enough for my DSO imaging. I use a Cheshire for the secondary and 2 different lasers for the final check of both. I use a small metal rule to check alignment of the spider vanes
I need to replace the original primary mirror springs as they are next to useless When I get back to Sydney next week, Better Springs at Winston hills have the new springs I need
Thanks

[Mickoid]

If you're using Televue Power mates then CA is usually not an issue, they ( Televue ) have very good optics, so again, Alex may be right with something not aligned properly in the optical train. As for the defringing function, yes, you're correct, I meant to say deringing. I've just had a haircut so I must have been thinking of that! :lol: You can adjust the amount of deringing but you've probably given that a try as well. If that fails to remove the false colour, I will sometimes create a mask around the the planet in PS by using the Magic Wand tool with a tolerance of around 10, click in the black background, feather it with a value of around 50 then fill the selection with black. There's a bit of experimenting required with this method and you'll need to get yourself a copy of PS or similar image editing software. Good luck!

[Saturnine]

Martin
The image reminds me of what mine looked like when I first started planetary imaging with an 127mm Achro refractor. Getting that fringing when using an Newt, Televue Powermate dslr combo is a bit strange. Could only come from collimation, focuser alignment problems but even if your collimation was out a little I would suspect that it is more a focuser issue, as Alex noted, where the camera , powermate set up at an angle, is twisting the drawtube enough to cause the alignment to be less than desirable.
A lighter weight dedicated planetary ccd camera would not be so demanding on the imaging train, but that is more expense. Always more expense involved in anything to do with astro imaging unfortunately but many people have taken video of the planets with similar equipment to yours and have not had the fringing problem. Comes back to weight , alignment issues it seems.
I was also out at that time of the morning taking Jupiter for the first time this year, the seeing was pretty ordinary, rippling and jumping around.

[Saturnine]

Should add that it was a stack of 400 from 2000 frame video using an 127 triplet refractor, 2.5 Powermate and ZWO290mc.
Which also gets me wondering whether, because of the crap seeing, that maybe trying to stack too many frames could cause alignment problems in the stacking and processing, thus causing the colour fringing.

[skysurfer]

True, but not caused by optical errors in your telescope, but our atmosphere, although when 29º high it wouldn't be that bad. Even the best Newton or Takahashi will show these errors.
Yesterday morning at 3:30 I viewed Saturn (only 15º high) and saw clear blue on bottom and red on top.
An hour later (when is was 30º high) it was almost over.

For low objects (if you cannot see them higher in the sky) a dispersion corrector (https://www.teleskop-express.de/shop/product_info.php/language/en/info/p10721_TS-Optics-ADC-Atmospheric-Dispersion-Corrector.html) can be an option.

[xelasnave]

A nice image Martin and the little bit of blue tells us the probable position above the horizon...whats not to like☺.
Alex

[Startrek]

Thanks all
As I said the planet was jumping around a fair bit so stacking 1500 frames might produce a problem on the edges ?
Could be a combo of both to much stress on the focuser tube and atmospheric dispersion in the stacked image
Need to do more imaging on Jupiter and try a few things ( not a great time now to do that - 3.30am to 5.30am plus it’s low )

[Startrek]

I think I may have found why my Jupiter image had a bluish crescent tinge on the top side
Found a YouTube clip on Registax 6 and he mentioned about a bluish tinge on the top side of the planet when you image at lower altitudes
“The atmosphere bends the light at low altitudes to cause this effect”
See attached
Has anyone seen this ?

[sil]

Bends the light is the key problem in your image, well splits the light. caused by atmosphere? maybe. Caused by refractive optical elements (clear glass)? likely, Caused by flexing in your optical train? possibly.

A compounding of all the above? probably.

Not likely one solution to cure everything but many things to work on to reduce it. Its a cyan/yellow separation. It there in all camera lenses to varying degrees. No nikon or canon lens does not have it, at any price. You need to work on everything advised already in the thread and the effect will remain but hopefully reduced. More contrast the more its pronounced, so capture under exposed as well .

[Startrek]

Steve
Good analysis and evaluation
The only refractive optical element ( glass ) in my set up is the televue 4 x Powermate with Televue t ring adapter
My Canon 600D body with adapter screws into the powermate and then into the 2” focuser of my 6” f6 newt
I’ve never heard of a Televue powermate with optical issues or the cause of optical issues
I’ll suppose one could put it down to atmospheric distortion or similar at lower altitudes and leave it at that ?

[gb44]

I wonder if you could test an atmospheric dispersion corrector? Maybe Bintel would be a help with their product?

https://www.bintel.com.au/product/zwo-atmospheric-dispersion-corrector-adc/?v=6cc98ba2045f

GlennB

[Startrek]

Glenn
I have a better solution, don’t image planets at such low altitudes as there’s too much atmosphere to get through
I imaged Jupiter twice last year at 65 to 80 deg and no issues

[gb44]

Cool. Defeated...:(

But what about Venus?
Have you seen the detail in it's clouds? Look at Niall MacNeil's pics in astrobin.
https://www.astrobin.com/395229/C/#c320634

GlennB