Astroimage processing

Re: Solar Image Proccesing

chipdatajeffB — Fri, 11 Sep 2009 20:50:21 GMT

pdwhitt:

I have the Thousand Oaks solar filter. I also have hydrogen alpha and hydrogen beta filters for nebulae imagining. Will the h-alpha or h-beta add an detail to solar images?

Paul: No those won't add detail to the white-light image. It won't hurt them if you have the Thousand Oaks filter in place over the aperture, but if you remove the Thousand Oaks filter you'll destroy the nebula filters.

The nebula filters are meant for nighttime use and won't stand the energy of the Sun.

A solar h-alpha filter is very different and much lower bandpass. The detail comes from narrowing the bandpass in such a way as to capture the Doppler shift of the h-alpha features and a simple glass filter (plane, and coated for specific frequency) won't do that.

Typically, the h-alpha filters used for solar viewing and imaging are what are called etalons.

Re: Solar Image Proccesing

pdwhitt — Fri, 11 Sep 2009 20:05:46 GMT

I have the Thousand Oaks solar filter. I also have hydrogen alpha and hydrogen beta filters for nebulae imagining. Will the h-alpha or h-beta add an detail to solar images?

Thanks,

Paul in East Texas.

Re: Solar Image Proccesing

chipdatajeffB — Tue, 28 Apr 2009 14:47:32 GMT

I meant the whole set of things you're using to make the images.

You mentioned the scope and camera/eyepiece combo, but it would help me to know specifically which solar filter and whether you're using any other filter at the camera end.

Right now there is practically zero photospheric detail to see in white light. That will make it more difficult to get a precise focus. And that, in turn, will make exposure absolutely critical.

So, if you're not seeing any detail, then:

Realize there's not much to see right now anyway.
Work harder on getting precise focus.
Take lots of images and stack them to show what detail there may be.

I'm thinking you're probably NOT using a polarizer. Do that, as it will make an obvious difference.

If you're not using a Baader white-light filter, consider trying that. You can buy the material and make your own filter very inexpensively (it's about $20 for a sheet large enough for an 8" aperture).

A continuum filter is a couple hundred bucks, but a polarizer is only about $30 at a camera store. You can also use a skyglow filter to good effect photographically, but I don't think you'd see an appreciable difference visually. Use it in combination with a polarizer.

With a polarizer, you want to be able to rotate it to see the best angle for good effect. An easy way to do that is to screw it onto the eyepiece barrel and then rotate eyepiece and camera as a unit. The idea is to rotate the polarizer relative to the incoming sunlight. This will not only affect your exposure (rotating it will darken or lighten the image) but will also interact with the small amount of polarization applied by the white-light filter to produce heightened contrast for granulation.

Re: Solar Image Proccesing

TilburyN — Tue, 28 Apr 2009 14:25:20 GMT

What do u mean by setup sorry im new to this still

Re: Solar Image Proccesing

chipdatajeffB — Tue, 28 Apr 2009 14:16:48 GMT

If you'll send me an email requesting it, I'll send you a tutorial (I'll have to look, but I'm pretty sure it's a PowerPoint file that'll get through most email systems without being too large).

If you're processing a whole-disc image of the Sun in h-alpha, limb-darkening will be a major factor in processing. If you're processing a higher-magnification image and the area is not near the limb, it's a good deal easier.

For whole-disc images, you may also run into Newton's Rings, especially if you're using a DSLR or other small-pixel imager.

In my experience, white-light images are even harder to process. That's primarily due to exposure. Especially if you are doing low-res (low magnification) imaging, it can be hard to find enough detail for the software to use in processing.

What filter are you using? If you are using Thousand Oaks or similar filter material, you will get good contrast on large features, but you'll miss smaller features like granulation. If you're using a Baader TurboSolar film filter, you'll start to pick up finer detail. And if you add a continuum filter and/or polarizer at the camera end, it will get even better.

Tell me more about the setup you're using.

Re: Solar Image Proccesing

TilburyN — Tue, 28 Apr 2009 14:11:38 GMT

ahah sorry

it was threw a 130slt telescope with a white light filter it was taken with a 300d with a 1 sec exposure i took 4 shots, um used a 25mm eye peic with 2x barlow

Re: Solar Image Proccesing

Kevin Bozard — Tue, 28 Apr 2009 12:48:02 GMT

TilburyN:
How do your proccess a solar image?

That depends on how you're capturing that image. Can you give us more info on the equipment you're using? We can better answer your question if we know how you're acquiring your image. Through a telescope with a white light filter? With a Coronado PST? With just a camera, or by some other means?

Solar Image Proccesing

TilburyN — Tue, 28 Apr 2009 09:16:50 GMT

How do your proccess a solar image?