Teams / DSLR Documentation and Reduction

DSLR Documentation and Reduction

Citizen Sky
We will discuss how to get the best results from a off-the-shelf DSLR camera or point-and-shoot camera by creating guidelines on how one can characterize a camera and create low- and high-level tutorials for various software packages. These documents will be contributed to the Citizen Sky Website.

Tutorial DSLR Finder Chart

By Bikeman on February 24, 2010 - 4:20pm
Teams:

A finder chart with all the check and comparison stars from the Beginners Tutorial Reduction spread sheet.

For the curious: derived from a photo taken in mid February 2010 with an Olympus E 420, f= 55 mm, f/4, 9  x 8 sec, ISO 400, defocused.

It shows stars in the field down to approx 8 mag.

Attached is the ready-to-use PDF version.

I checked the star labels by putting a printed page over a flat screen showing a Stellarium view of the field, so I'm pretty confident they are right :-)

I also attached  an editable  version (OpenDocument Graphics format, created with StarOffice).

Finder Chart ideas

By Bikeman on February 22, 2010 - 7:06pm
Teams:

I thought it might be helpful for beginners to have a finder chart that shows all the stars mentioned in Brians spread sheet and which looked a bit more like an actual DSLR image of the field.

This is harder than Ihad expected. If you add too many annotations, it somehow destroys trhe overall impression of the field .

I'm also not convinced whether a normal or negative image should be used. Negative is definitely more user friedly for printing.

Anyway, attached are a few of my ideas, please let me know whether any of those might be useful (my favorite is the multi-page one).

CS
Heinz-Bernd

IRIS tutorial review

By Bikeman on February 21, 2010 - 6:22pm
Teams:

Hi team!

I made a test run of the Iris tutorial with the sample images that Tom donated. I had a few problems so I changed the tutorial a bit, especially at the point when you extract the green channel.

I also made some screenshots that I sent to Brian in a ZIP (you can't attach ZIP files here and I was too lazy to attach each screenshot individually).

CS
Heinz-Bernd

Sample Data Posted

By bkloppenborg on February 20, 2010 - 10:47am
Teams:

Greetings,

The sample data for our tutorials has been posted online. Tom has kindly provided the files for our use.

http://www.citizensky.org/sites/default/files/DSLRPhotometry/data/sample...

Size is 74.8 MB, files are in .cr2 format.

Brian

Simplified Reduction Method

By bkloppenborg on February 16, 2010 - 1:17pm
Teams:

All,

I think I have a simplified version of the Excel reduction sheet ready to go. I think the math behind it is sound (see attached PDF), but I would like someone else to check it to make sure I didn't neglect anything.

For this introductory-level reduction method, air mass correction is absent, but then again the difference over the field-of-view of a DSLR camera should be small. This would simply correct the instrumental magnitudes going into the equations anyway so I think it's fine.

Let me know what you think,
Brian

Moving Documents to main website

By bkloppenborg on February 9, 2010 - 10:00pm
Teams:

Hey everyone, I thought I would update you on the progress of moving the documents over to the main CS website. Thus far I have the basics uploaded and the AIP4WIN tutorial is ready to go. Within the next few hours I hope to get the IRIS and MaximDL tutorials finished.

Sometime tomorrow I'll be using Python to crop some images provided by Tom to use as sample data (80 MB of files to download for a tutorial seems a little hefty).

The Excel file will follow shortly thereafter. I'll have the webmaster add a link to the drop-down menus at the top of the website once the tutorials are finished. After I get them uploaded, I'll blank out the tutorial pages and we can start on the intermediate tutorials.

Brian

New version of IRIS

By Bikeman on February 5, 2010 - 5:54pm
Teams:

Hi!

Brand new:

http://www.astrosurf.com/buil/us/iris/iris.htm

Version 5.58 now has a command that does batch conversion (RAW => CFA FITS )

CS
HBE

Overview of Reduction Packages

By bkloppenborg on February 2, 2010 - 7:33pm
Teams:

Needs a general introduction...

IRIS

Iris is a general purpose astronomical image processing software suite by Christian Buil with both English and French translations that runs on Windows, and under WINE in Linux. It is very full featured, updated frequently, and has a modest number of "how to" articles written for it.  The program is free to download and use.

Where to get it:
The download and installation instructions can be found on Christian's AstroSurf webpage.

AIP4WIN

AIP4WIN comes as software bundled with the book The Handbook of Astronomical Image Processing written by Richard Berry and James Burnell.  It is a very through book that discusses image analysis, astrometry, photometry and spectroscopy.  The bundle sells for $100.00

Where to get it:Read more

New version of AIP4Win?

By Bikeman on January 31, 2010 - 5:56am
Teams:

Hi!

I just saw that even tho the text here

http://www.willbell.com/aip4win/AIP.htm

refers to AIP4Win 2.3.0, it actually links to a ZIP with version 2.3.1.

I know that Richard Berry wanted to change a few things wrt DSLR raw extraction as reaction to feedback in the forum.

CU
HBE

Logo

By bkloppenborg on January 29, 2010 - 12:02pm
Teams:

I just realized that we don't have a team logo (it's just the blank CS logo at the moment). Anyone care to submit something? Just attach to a reply to this message.

Brian

Excel Reduction

By Tom Pearson on January 29, 2010 - 10:02am
Teams:

Excel Reduction: Introduction

This page is for varios Excel reduction techniques.  Upload your Excel sheet and give a breif (one-paragraph) introduction to how it is used.  Just plug in the general formulas, don't lock any cells (yet), and make it easy to use by someone with a little Excel experience.

We'll evaluate which we think is best for the general public and whichever we think is best will be used as our "standard" reduction sheet.  Brian will modify the worksheet to include the equations for full uncertainty analysis before the sheet is added to the general CS website.

Please name the files by your username without spaces (i.e. bkloppenborg.xls) and add a new section to this page following the examples below (note, you'll need to rename your file on your computer before attaching it to this page).

Heading 2 (filename.xls)

Read more

Choice of Equipment / Requirements

By Bikeman on January 27, 2010 - 3:05pm
Teams:

What you will need



You will need the following things to perform good variable star photometry with digital cameras:

 

- The camera itself: while this tutorial is focused on DSLRs, any digital camera will do as long as it meets the following criteria (all popular DSLR cameras, even the cheaper entry-level models, will meet these requirements):

-- you can extract images in so called RAW format, and the format is supported by one of the software packages discussed in this tutorial (..........). Working with JPEG images will not give good results.

-- you can focus manually. Auto-focus will not work very well on the night sky most of the time

-- you can manually select a shutter time [exposure time ??] of several seconds.    Read more

How to size the aperture (Generic)

By Bikeman on January 27, 2010 - 2:17pm
Teams:

(This content is pretty generic in that it can be used with any of the tutorials for aperture photometry software)

Aperture Photometry: Setting the aperture size
In order to compute magnitudes for stars from images, the software needs to know which pixels of the image should be considered to belong to a certain star. This is not trivial, because to get better photometry results, you often want to spread the light of a star (especially for bright stars) across many pixels by slightly defocussing, so the star in the image often will be a disc of several pixels across. Just how many pixels is something you can tell the software.

Even thoses pixels will not contain the light of only this one star, but also some "background" light coming from far away stars from the same direction or from the glow of the athmosphere in the night sky. Read more

My way of maximDL

By Huberthautecler on January 27, 2010 - 11:24am
Teams:

Hi, this is may way of using MaximDL.

Can someone check this out?

regards, Hubert

Open MaximDL.
Select File – open : select the files you want to analyze.
After the files are opened select Analyze – photometry
You get two boxes open : one information box and one photometry box.
In the photometry box you see the image list with all the selected images.
You can also see “tagged objects”. (Here comes the object you want to analyze).
Click on the “mouse click tags as” and select new object.
This new object will be Epsilon Auriga.
Click on Epsilon Auriga.
In the Tagged Object box “obj1” appears.
Then in “mouse click tags as” click on new reference star.
The reference star is the comparisonstar you will use. In this case it is Eta Auriga. In the “ref mag” box you give the magnitude of the reference star after selecting the reference star. In this case 3.172. Read more

Camera Characterization

By bkloppenborg on January 26, 2010 - 10:47pm
Teams:

These are the essential parts of charaterizing a CCD camera, perhaps they apply to CCDs as well.  Edit as you please.  (I can dig up a few references on CCD characterization if anyone needs them, Brian).  We might also want to reference these pages:

http://www.astrosurf.com/~buil/50d/test.htm
http://www.astrosurf.com/~buil/400d/400d.htm
http://www.astrosurf.com/~buil/eos40d/test.htm
http://www.astrosurf.com/~buil/nikon_test/test.htmRead more

Camera Characterization

By bkloppenborg on January 26, 2010 - 10:40pm
Teams:

Has anyone fully characterized their DSLR camera? I think this is an important step in getting good data. I've created a Wiki page for this topic and would greatly appreciate anyone who could fill in the blanks.

What about Fitswork?

By Bikeman on January 25, 2010 - 7:12pm
Teams:

Hi!

I just read the draft tutorial for IRIS and that made me realize how user-unfriendly IRIS is for importing and calibrating raw images, while the aperture photometry part is quite nice IMHO.

(also in AIP4WIN, it doesn't seem trivial to extract the GREEN channel from the raws without AIP4WIN white balancing the image IIRC.)

So, what about the following procedure:

Instead, use FITSWORK http://freenet-homepage.de/JDierks/softw_en.htm to

* extract RAWs
* calibrate raws

maybe even stack images

then save to FITS file

and do the aperture photometry in IRIS.

The advantage would be that many people who are interested in astronomy and own a DSLR may be familiar with Fitswork already, and for those who aaren't, it's quite user friendly IMHO.

CU
Heinz-Bernd

Excel anybody?

By Bikeman on January 24, 2010 - 2:54pm
Teams:

I wonder whether it could be useful to have an Excel sheet accompanying the tutorials.

The one I dream of would do calibration (Color coefficient), magnitude computations and statistical quality measures (SD).

It would have a range of data (B-V and mag) for comparison stars ready for use. You would just enter the instr. mags next to the comparison stars and the Excel sheet would do the rest.

What do you think? Any Excel gurus here?

CU
Bikeman

IRAF Tutorial

By bkloppenborg on January 24, 2010 - 1:03pm
Teams:

Anyone want to take on IRAF?  It's a classic tool and is very powerful!

IRIS Tutorial

By bkloppenborg on January 24, 2010 - 1:03pm
Teams:

For easiest use download the last version of IRIS 5.58 (especially for any Linux user because the new command convertraw is essential to load raw images).
Then you can install it very easily either to Windows or Linux (using wine).

Note: when you will be loading series of images the IRSI will pause for some time to read, trasform,calculate and save the images (depending on the number and the computer of course). Only the final output will be visible but that does not mean that IRIS has rejected the rest (you specify a working directory and the program will look into this according to the input you give). Read more

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