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 Processing with Images Plus and Canon 350D
 
woodwizard
post Jul 14 2006, 01:10 AM
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Added the below process for taking flats and adding to calibration process.

Take at least 10 flats, 20 or 30 are better.
Set the iso at 200 and adjust the shutter speed until the exposure meter in the viewfinder reads midpoint...neither over nor underexposed. Exposure time will vary depending on the light source.
Take your flats and RAW convert them in ImagesPlus.
Average Combine your flats and save as MasterFlat.
Display combined image and Click on COLOR on the toolbar.
Click on Luminance and Gamma
Click on APPLY. Your MasterFlat will be automatically converted to grayscale...very important.
Save image and add to your calibration setup menu.


PROCESSING WITH IMAGES PLUS

Open--File Click on--Canon DSLR Raw file development-- This brings you to the Raw File Conversion Menu

Build MasterDark--Select your dark frames from "Canon Raw File
Conversion" window "Open"
Select output file type--Lossless 16 bit FITS
Select white balance type--Canon WB
Select Converted File Output--Choose a file to save your coverted
files
Press--"Convert"...Raws are converted to FITS
Press--"Combine"...New window opens
Select Combination Method--Usually average or median
Select-- Combination Image Output Directory (Same as
Converted Files)
"Combined File Name" type MasterDark
Press--"Combine" to combine Darks
Press "Done".....back to "conversion" menu
Press--"Select New Input"... Select all your light frames
Press--"Convert"

From top menu press "Calibrate Images"--Select "Setup"...
Calibration Setup Menu
Select--"Color"
Select--"Standard Dark"
Press--"From Disk"....Click on your "MasterDark"
Press--"Done"....back to Raw conversion menu

Press--"Calibrate"... Light frames are dark frame calibrated
From here you can press "Grade" and check focus quality of your
images... select the files you want to keep
Press "Align TSR"

TSR Menu--Press"Correlate"
Press--"Translate+Rotate"
Check off "Common Point Or Star"
Click on image to make it active
Frame a star in the box cross hairs...hold down "shift" key press
enter...star is selected
Click onTSR Menu--Uncheck "Common Point or Star"...Check
"Common Angle..."
Click on image to make it active
Frame a star in the box cross hairs...hold down "shift" key press
enter...star is selected (the two boxes should be at
selected at opposite sides of the image)
Press--"Align" If all images don't align change the "Correlation
Parameter Setup values higher
Under"Combine"--Press--"Aligned"

Combine Files Menu--Select combine type...start with "Average"
then experiment from there
Select output directory
Press--"Combine"...THE FUN PART
Press--"Display Combination"
Your final image is displayed...From here just go into Digital
Developement and have fun!!!
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Ron Walker
post Jul 14 2006, 11:17 AM
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OK, there are some really dumb people out here (OK me) that need instruction from square one.

What is a flat, and how does the dome come into use in making one?

I'm guessing that it is a very evenly illuminated frame that is used as a constant for some reason or another.
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woodwizard
post Jul 14 2006, 01:20 PM
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Taking Flat Fields: Flat fields are used to correct for noise in the optical path of the telescope system. The use of a flat field is essential for a good image. Keep these ideas in mind when creating a good flat field.
It must have even illumination.
It must be taken with the same optical setup as the image you are going to apply it to (don't change the focus).
It should be about one-third to one-half the saturation values for the camera.
Multiple exposures (8 to 12) should be taken and averaged using the median filter.
Take separate dark frames to use with the flats.
Take flats for each color filter for color imaging.
Check the pixel value across the image. The image should have variations of only 5-10 units.
There are many ways to achieve a flat field, and I've outlined a few below.
Dome Flat: Close the dome and with the lights on take an image of the painted white image of the shutter. Move the telescope a small amount to different parts of the shutter for averaging out irregularities. This method is good if you need to change the focus of the optical system during the night.


Sky Flat: Work this one in twilight before the sky gets too bright. You will need to change your exposure to compensate for changes in twilight brightness. You need a similar average value for each exposure. Be careful about getting faint stars in your images as well. Move the telescope slightly so they average out.


T-Shirt Flat: This can be done in twilight or the daytime. There is a white cloth, and a rubber band in the observatory box. Place the cloth over the front of the telescope pulling it tight. Secure it with the rubber band and place the dew shield around the telescope. Point the telescope toward the ground and take your exposures.
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woodwizard
post Jul 14 2006, 01:22 PM
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Flat frames: http://www.njaa.org/research/masterdark/page10.html
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NeoDinian
post Jul 14 2006, 01:23 PM
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You're basicly right about the flats... Flats are (if I remember right, Im still learning also) "Even" illumination. When using these, they help remove dust motes that your camera may have... I belive you can also use these to help remove gradients... not sure though... Using the dome may be a great way to achieve Flats, as you can use a light source outside the dome to make the Poly "Glow" evenly... (IMG:http://www.observatorycentral.com/style_emoticons/default/smile.gif)

Darks are long exposures taken for the same duration as your Subs, that are used to remove "Hot Pixels" caused by the CCD (or CMOS)...

Subs are your standard exposure images...
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woodwizard
post Jul 14 2006, 01:23 PM
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Dark Frames: http://www.njaa.org/research/masterdark/page07.html
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Ron Walker
post Jul 14 2006, 04:16 PM
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Thanks Tom and Neo, things are starting to make some sense now.

I'm wondering if it would be worth while making a light source from a piece of translucent white Plexiglas. It would be placed directly over the telescope tube and then illuminated with a very even light source, perhaps a second sheet of white Plexiglas a few inches from the first. Should make for a very evenly illuminated source.
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Mark Cislo
post Jul 14 2006, 05:37 PM
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Tom :smt023 :smt023 :smt023 :smt023 Thanks a lot! Keep the info coming!!!
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woodwizard
post Jul 14 2006, 07:08 PM
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Light boxes:
http://www.gregpyros.com/html/light_box.html
http://astro.hcadvantage.com/Articles.aspx
http://www.gushie.demon.co.uk/LightBoxPlan.htm
http://www.gregpyros.com/astrovideos/html/..._light_box.html
http://www.telescopes.cc/forums/index.php?topic=177.0;imode
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