Very Nice, The only thing I would recommend is to be careful when adjusting the Curves or levels so you don
Very Nice, The only thing I would recommend is to be careful when adjusting the Curves or levels so you don
Originally Posted by tkerr
Yeah, you are right. I have to fix the blown highlights. As for the blacks, I just like them that way. I know some people don't, but don't like seeing a greyish background.
Don't I need DPP to convert the .cr2 to .tiff? DSS won't work with .cr2 files, will it? And I like to do some 16 bit processing before going to gimp. Gimp only handles 8 bit files.
Ahem. No. Not this time. The AP really doesn't require flats. This weekend I'm going out again, and I'll take some shots with the Edge HD, and I'll try doing it right (or at least, a little more right) []
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Yeah, you are right. I have to fix the blown highlights. As for the blacks, I just like them that way. I know some people don't, but don't like seeing a greyish background.
You can adjust the shadows so the sky is still dark without over clipping. And provided you got enough image data in the first place you will leave faint subtle details intact.
Don't I need DPP to convert the .cr2 to .tiff? DSS won't work with .cr2 files, will it? And I like to do some 16 bit processing before going to gimp. Gimp only handles 8 bit files.
DSS works fine with CR2 files. It did have some problems with RAW Files from the T1i and T2i cameras, but last I heard that has since been fixed.
I haven't used gimp in a while, but I thought that it did allow you to load 16 bit tif files and do some editing at 16 bits now. Might be wrong.
Ahem. No. Not this time. The AP really doesn't require flats. This weekend I'm going out again, and I'll take some shots with the Edge HD, and I'll try doing it right (or at least, a little more right) [img]/emoticons/emotion-1.gif[/img]
Flat field calibration isn't only to correct optical errors/artifacts or uneven filed illumination that might be caused by a telescope or lens system. What About your camera? Flats are also used to correct for variations in the sensors pixel to pixel response, or artifacts on the sensor such as dust motes.
http://www.cyanogen.com/help/maximdl...alibration.htm
http://en.wikipedia.org/wiki/Flat-field_correction
When stacking with DSS or any astroimage stacking software you really should use Darks, Bias, Flats and Dark Flats for a properly calibrated and stacked image. The quantity of each depends greatly on the SNR of all your Light Frames. But it is often otherwise recommended to use a 1:1 ratio for each.
Didn't know or expect that. Thanks! Srue simplifies things
Well, the one installed on my computer does not allow 16 bits, but it has been a while since I updated. I'll get a new version and see. Here's hoping...
To be honest, whenever I've tried to get DSS to do anything other than light frames, it has not worked for me. I get funny streaks in the image when I use darks, and I get strange radial patterns when I try flats. Perhaps my flats are uneven, perhaps I am using the program wrong, or perhaps DSS isn't working properly. In any case, I get better results when I use in-camera noise reduction and no flats.
As I said, though, I try again this weekend. I won't do any in-camera noise reduction and will take some darks during my session.
I appreciate your suggestiions.
Make sure you shoot your darks at the same exposure that you shoot your light frames. I usually shot some just prior to my image run and some immediately after.
The problem with using in camera High ISO or Long Exposure Noise reduction is that it might also remove some stuff that you want to keep. Such as small smudges that are galaxies or nebulae in the background, and more often small stars that belong in there.
I was pretty careful when I used to shoot darks: I
Well, close but not exactly the same, nevertheless, there are advantages to shooting Darks vs using LENR. Time!
Using LENR doubles your time for each exposure, and that is time you could be using to gather more Image data(Light Frames) instead.
When shooting Flats I hang a white sheet in front of the telescope and light it up with a couple white lights. That way I am assured that I get even illumination rather than changing illumination like you get when shooting the predawn sky for them. One of these days I'll get around to making a light-box to fit over the end of my telescope.
Additionally, if you don't make sure you are get the exposure right on your flats they can do more harm than good. (35%-50% of full saturation) Also shoot Dark Flats!
The Work Flow for DSS when you use all the files necessary for image calibration and stacking. Lights, Bias, Darks, Flats and Dark-Flats
The Master Bias/Offset is created from all your Bias frames.
Next the Master Bias/Offset is subtracted from your Darks and a Master Dark file is created.
Then the Master Bias/Offset is subtracted from your Dark-Flats and a Master Dark-Flat is created.
Then the Master Bias/Offset and Master Dark-Flat is subtracted from all your Flats when creating the Master Flat.
Finally the Master Bias/Offset and Master Dark are subtracted from each light frame and the results are divided by the Master Flat then stacked into your final image stack which you will save for post-processing.
When you use The cameras LENR it's essentially creating and then subtracting a Dark Frame from your light frame. But that doesn't remove all unwanted noise or artifacts that using bias darks and flats will.
When you provide DSS with everything it will work and put out a good quality stacked image.
Ade, I hope you're still following all this and taking lots of notes. I'm completely baffled. Do you think"shooting darks" means "leaving the lens cap on"?
I think I'll leave the experts to get on with it...
That's exactly what it means [
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