did you discard the G and B channels? they'll almost have no data so just use the R.
Yes, I used only the red channel, with two differents process: wide and center.
See, alistairsam. I didn't try, yet, to process the RGB image as normally I do. Only to compare them.
But You can see that the image from stacking process hasn't many color informations. The original CR2 photos have few red information, too.
It seems that the H-alfa helped to fill with some real red information. It is not an artificial manipulation in Photoshop.
As I told in other post, any help ... is a help
I don't dream with good color photos from Canons. But I would like more faint nebulas informations without corruption by light pollution. Or artificial colorization with graphic process.
I can not buy a good mono camera. Price in dollar plus 120 % in dollar for tax in my country. And with 2.5 in cambio... out of reality. At least to me.
My photos never will show the quality of those I see here. But I want more informations from and about the objects that I shot.
Interesting test Jorge. I found the Ha sensitivity of my unmodified Pentax to be extremely poor even with a fairly wideband (30nm) Ha filter. Ended up getting an old full spectrum modified Nikon D70s that responds much better to Ha. That filter in the camera really has to go to get decent Ha shots.
Theoretical response of original filter and my others. 25% of transmission in H-alfa region.
If you want a photo with visual impact ... it is poor. But to obtain information about the object, with DSLR that work with ISO, you can some result with it and total time of exposure.
I think the major problem is that you haven't 100% of pixel to catch the information as mono camera has. But there is improvement when the capture is HalfaRGB.
Mask and HDR can enhance this improvement. This will be the goal of my tests. I never did process with narrowband filters. I am just trying and learning about this task.
Nevertheless, the correct solution is:to buy a good mono camera, a good Halfa filter and go to a site with good dark-clear sky. Easy, no ?
And now, the process without help from Halfa filter. I used similar method to process, enhance with HDR the red channel and superpositon. But from same file.
This photo was processed in Photoshop CS3 to enhance details, and it needed noise filters. Perhaps because of these filters, some details are less sharp.
Note: the first photo, more red, wasn't processed. Only curve and level to adjust de black in background was applied.
As the originals CR2 didn't come with much color informations, these tests aren't conclusive. But, it seems that with Halfa I don't need intense adjustment of curves, and inherent noises by it. And it seems to be a little clipped, too. If confirmed, the Halfa filter is positive.
As soon the sky is ok, I will continue with tests, and with another body. A faint nebula, for example, will be a good object.
Nevertheless, the correct solution is:to buy a good mono camera, a good Halfa filter and go to a site with good dark-clear sky. Easy, no ?
That would be the ideal, but a full spectrum DSLR can still take excellent Ha pics even in light pollution or bright moonlight. Ha even sees through smog to some extent. It's a great way to image nebula when the odds are against us!
As I said, I hope to obtain more red information free from interference of light pollution, and with less work in curves.
I know it will not act as a perfect Ha filter. But if it enhance the quality of information... it will be doing what I need.
About Canons, I didn't believe in "APOD" photos with them. See the stars, they haven't the same shape and sharp appearance as those with a good astronomic camera.
But, for who intends to register the object... they will work well. I have some photos of star cluster with better resolution than many others photos that I saw in Internet. For me, some ones are reference to these objects. At least, up to now, while nobody capture them with a better camera.
But, as the photos in Internet, they aren't beautiful ! They are images of content and not of visual impact.
