Ad Astra Observatory

On Apr 3, 2008, at 8:44 AM, Jimbo S. Harris wrote:

> At 08:09 PM 4/2/2008 -0700, you wrote:
>> Detail, Detail, Detail.
>
> The image is bigger in Kate. With a little luck and a lot of time-on-
> scope, I can probably make some pretty images.
>

> J
>
>> Do you have your camera set for B&W. They will do that you know.
>
> Um. I can’t conceive of how that would have happened. But I’ll check.
>
> My normal image processing process goes:

> – Process->set calibration (so far I’ve only successfully used darks
> shot at the same time as the lights. I think.)
> – darks
> – bias (shot awhile ago)
> – flats (only did this once; then I cleaned the CCD and put

> it on a new scope so I need to reshoot them)
> – Process->create master frames
> – File->Save and Convert all
> – pick the new folder
> – make sure “do calibration” is checked

> – save to new “cal” subdir
> – RGB->Convert Color (needs to be done because it’s RAW)
> – this has different weights for the different colors. They
> are cached, and are set up based on a dark-subtracted image

> – this has to be done manually (a 5-keystroke process) for
> each individual image
> – File->Combine…
> – select the “cal” images
> – median combine

> – this takes about 20-30 minutes of hard CPU and disk
> thrashing to combine 40 frames
> – the output is a “0XX.fit” image
> – File->Save (the FIT)
> – File->Save As… (PNG)

> – screen stretch
> – gamma 0.6
>
> Then I have a PNG that I can take into photoshop. A tiny amount of
> levels, curves, and unsharp, crop it, and that’s the ballgame.
>
> So. Problems that I noticed on this M51 set:

> – the set calibration worked fine but the master frames wouldn’t
> apply to the raw images.
> – I have to check to see if I’m shooting in Developed Color
> again, but I’m pretty sure I’m not, because the “Convert RGB” thing

> was not greyed out.
> – I tried both calibrating with “save & Convert” and also by
> doing “Process->Calibrate”. No dice.

/*

This has happened to me when the camera read outs were not the same.
The sized of the image must match in Max or it will not subtract or
add the image. For me this turned out that I had mixed up my
calibration directory and had some images that were not the same pixel
count on X and Y, so it would not subtract.

*/

>
> – When I did the color conversion, normally the frames come out a
> very junky-looking brown (because the colors are all stretched out),
> which fixes itself during combine.
> – this time, the frames came out very blue, which was
> worrying me but I figured it would come out in Combine, but it seems
> not to have.

> – I would have just run the color conversion over again, but
> since the calibration hadn’t worked, I had inadvertently overwritten
> my original RAW frames, so I’m sad now.
> – The combine worked, but the background was all out of whack.
> – I think there may have been some clouds shooting through

> during the run

/*

As you know, I get really bright images when there are clouds and some
light get through. When there are real clouds, I get only the bright
stars, that are used to give pin point coordinates, but there is not
image, no photons from the DSO.

*/

>
> – also I’m now a believer in dark frames. If I could figure
> out how to apply darks to the images I want, I would be in great
> shape.
> – So when the 0XX image came up, it was monochrome-looking (which is
> to say that it had R, G, and B color data, but I think they were all

> the same).
>
> The flow of calibrate, then convert, then stack, is how the manual
> told me to do it, and it’s worked before. I really think that I
> should have been able to apply the darks.
>
> It looks like it would have been a pretty image if it was in color

> and/or the background wasn’t screwed.

/*

You were commenting about the LRGB instead of RGB. The issues you
have above is why I shoot the L layer. The back grounds get adjusted
really dark and strange sometimes, and I can use the white balance and
the brightness to make the backgrounds acceptable. I also assemble
the RGB, the create a synthetic L layer that I can add and adjust up.

Just some ideas. Your color stuff is way over my head, but I think I
got it. You have good images coming out. They are just getting
better. You do have me fixed on staying with what I have until you
and others figure out the fine details. Your processing flow is right
on, and very text book.

In Sun Light Today.

A

*/

>
>
> J