Continuum Filter First Light

[Graeme1858]

My very good friend Mark kindly gave me a Continuum filter. I've had it a couple of weeks now so of course it's been cloudy. My five hole EFW has only LRGB loaded and the spare hole was calling out for a solar continuum filter. It was cloudy today too but it was thin high cloud and there's a week of rain forecast, I couldn't wait any longer, so I fired up the SCT. I connected everything up in NINA. I know SharpCap is the way to go but with suboptimal conditions I thought a quick trial run would be best done using familiar software. I pulled in the coordinates of the Sun from Stellarium and sent the CGX to slew round to the south west. The slew wasn't perfect but the brighter bottom left corner showed the way to go.

Once centred I had a constant battle with the drifting cloud changing the exposure level. Trying to focus with the image going from barely visible to saturated was tricky. But I did manage to get close to focus through the high clouds. While the cloud thickness was stable I managed a few one second exposures.

I counted nine Sunspots and there's some faint granularity. This is the most fun I've had in ages! And there was an excellent Sun halo too. Can't wait for a proper clear day.

Thanks Mark.

Graeme

[Thefatkitty]

No worries Graeme, and I admire your perseverance! I hear you on focusing too. The Sun can be difficult. For the Ca-K scope I use I focused on the Moon, much easier and was good to go (dedicated scope).

That really came out well despite the conditions! That's my fault though; I cursed your skies.... And you had a halo around the Sun as well? I can't ever get anything passable with that going on, amazing!
Get yourself a clear day and with focus the granularity will really show through.

Glad you're having fun with it. I have some extra Baader film, both 5.0 and 3.8 if you're interested, but the duty you might have to pay scares me!

Keep it up and all the best,

[Bigzmey]

Congrats on the new filter Graeme and kudos to Mark!

I thought continuum produces green images.

[Lady Fraktor]

I love using the Continuum filter, very handy.
Nice image as well

[StarHugger]

Cool you are getting started Graeme, best of luck with those skies !

[Graeme1858]

I thought continuum produces green images.

It only lets green photons through but camera sensor pixels only see photons not colour (frequency). Just as your eyes do, the colour only exists in your brain!

I colourised the monochrome image to orange hues for a true colour representation of the Sun.

Graeme

[StarHugger]

I thought continuum produces green images.

It only lets green photons through but camera sensor pixels only see photons not colour (frequency). Just as your eyes do, the colour only exists in your brain!

I colourised the monochrome image to orange hues for a true colour representation of the Sun.

Graeme

No, there arent any green photons either Graeme

Just narrowband light at 540nm or so, the cameras green filter is isolating the frequency so it is seen as green.

A colour camera is like a spectrum analyzer or prism in that it isolates wavelength by colour similar as the human eye does.

So the rgb's are indeed everywhere, in your phone, tv, paint set, refractor telescope and on and on and on the list goes...

Colour is always representative of fact in any optical measure of any kind so from Starlight to Moonlight revealing gases and minerals otherwise detectable in no other way and at great distance.

You will have to excuse me, I have colour all up on my brain

The continuum filters wavelength is chosen though not for its colour alone but for the 540's ability at better atmospheric steadyness at that wavelength and your refractors green centered colourband.

So colour/frequency is being used here to allow convection cells to be imaged more accuratly with better atmospheric stability in general and in addition fewer optical distortions in particular telescopes.

[Graeme1858]

No, there arent any green photons either Graeme

Excellent explanation Aaron!

It would have been more accurate of me to say that the continuum filter only lets photons through of 540nm.

Graeme

[yobbo89]

I too can just see the faint granulation, maybe need some Better seeing? Should be able to get the details to pop a little more with just that filter, nice test a few sun spots in there

[Graeme1858]

Cheers Rob.

Yeah, less clouds would be good.

We're getting clear skies today, in between torrential downpours and 40 mph winds!

I'll be ready to go with Sharpcap when we get a good hour of blue sky.

Graeme

[messier 111]

nice shot , thx .

[Lady Fraktor]

The continuum filters wavelength is chosen though not for its colour alone but for the 540's ability at better atmospheric steadyness at that wavelength and your refractors green centered colourband.

That should be eyesight instead of refractors.

[StarHugger]

The continuum filters wavelength is chosen though not for its colour alone but for the 540's ability at better atmospheric steadyness at that wavelength and your refractors green centered colourband.

That should be eyesight instead of refractors.

Yes but a more inclusive yes and thanks for allowing me to continue Gabrielle as there is alot more to be said here indeed.

Its actually designed for 540nm...a refractors green centered colourband wich is also the center colour band for most colour cameras and our eyes it just so happens are most sensitive at that band.

So indeed even achromatic refractors will perform well both for imaging and visually with the continuum for this reason.

And it does indeed work quite well for visual as baader has permoted its use also for solar visual with a solar wedge and the proper additional filtering were required per "Your Specific Solar Wedge" Brand/Type/Model

It can almost as well be used with baader solar visual film or other visual solar films but Imho a Solar wedge serves up finer detail and is a much better and way safer option than solar film, so is a aluminum housed properly fitted dual surfaced white light glass filter Made by SolarSpectrum...my opinion.

For imaging with the continuum I suggest a mono camera, unless you are well versed in the extreme difficulties and pitfals of monochromatic colour solar imaging and its methods...

So actually all three, Eyes, refractors and cameras, Its the 540nm wavelength itself thats comes through our atmosphere less thermally discombobulated at that wavelength, and the 540nm frequency is being isolated and utilized here for filtering to take advantage of the steadier atmosphere there at 540nm.

Any green filter in general when added to the eyepiece for whightlight solar will work to a degree and in this order from best to least-Continuum/Wratten#56/Wratten#58...As well a colour camera with its blue and red exposure levels turned to zero will also have a steadying effect for solar whitelight imaging while using proper solar filtration...

In addition green filters also provide good sunspot to convection cell contrast visually and have been known and in use for both Solar visual and imaging applications for decades previous of baaders continuum designing, and it was this known use of green filters and blue and red colour imaging subtraction practices that led baader to its designing the continuum filter but initially for mono whitelight solar imaging is my understanding.


Hope this explains it all a bit better

[Graeme1858]

Excellent verbose clarity Aaron! Thanks.

I've only used it with NINA collecting image files so far. I tried the Lucky Imaging plug in without much success. I need to use the Continuum filter to capture a video in SharpCap so that I can sort by quality and just work with the sharpest ones.

Graeme