Flat Frame Light Box tagged posts

LED Flat Frame Astrophotography Light Box on the Cheap

LED Flat Frame Light Box

LED Flat Frame Light Box

Call it an impulse purchase but as I checking out at Walmart, I saw this small pack of Christmas Wreath lights as I was putting my items on the counter.  As I looked closer, I saw that it was a single string of 18 small LED lights.  It was only $3.99 and it came with its own power supply, requiring 3 AA batteries.  I thought to myself that this would make a very inexpensive way to power a flat frame astrophotography light frame box.  I had orginally specked out purchasing LED’s and buidling the powering mechanisms from scratch but this system was already complete and I did not even have to solder any of wires.  Having extra foam core from when I created my first light box using an Electroluminescent Panel, I broke out the Exacto Knife and began cutting panels.  As I cut my first panel, I envisioned how this LED light string could be used.  Here is how I created a Flat Frame box using this simple 18 LED string of lights.  Here is what I did:

1.  I cut a piece of foam core to the size I would need for my 90mm Refractor and then I used a hole punch to create a pass through where I could feed the wires and the LED lights through the back of the panel.  I left some slack and some extra cord hanging out of the back of the panel so that I could attach the power supply to the light box using Velcro.

 

2...

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Flat Frame Calibration Astrophotography Example with M13

Flat Frame Calibration

Flat Frame Calibration

A couple weeks ago I built a flat frame light box for my telescope so I can take these really important images so that imperfection (dust, etc.) in my telescope and CCD camera are subtracted from the frame.  At the most basic level, flat frames are used to correct the vignetting and uneven field illumination created by dust and imperfections in the optical train.  In the example above, the photo on the left is not flat frame calibrated and you can see dark circles in many places on the image.  These imperfections are dust motes.  The photo on the right has been calibrated with flat frames, serving two very important purposes:

1.  Removing dust motes

2.  Evening out the field around the corners of the image

Here is the final LRGB image of M13 that is both dark and flat frame calibrated:

M13 Globular Cluster in Hercules

M13 Globular Cluster in Hercules

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Astrophotography Flat Frame Light Box using Electroluminescent Panel

Flat Frame Light Box Made from Electroluminescent Panel

Flat Frame Light Box Made from Electroluminescent Panel

Before I start, I wanted to say that almost 100 flat frames were sacrificed in the making of this light box.  Last weekend, I built myself a Flat Frame Light Box using 5mm Foam Core and an A5 Electroluminescent (EL) Panel.  I image with a Takahashi Sky 90II and an SBIG ST-2000XM and there are dust particles on the telescope as well as the CCD.  I am not going to describe the need for flat frames or how to take them as it is covered in many other articles around the web.  This blog aptly called DasFlatFrame does a good job at describing the need for flats.  I am going to describe how I constructed the light box

Materials Used:

  • A5 Electroluminescent Panel
  • 12 volt inverter (if you want a dimmer panel you can use a 9 volt inverter)
  • 5mm White Foam Core
  • White Printer Paper
  • Vellum Paper
  • White Duct Tape
  • Scotch Tape
  • Cardboard (used to hold the box on the telescope)

Tools

  • Protractor
  • Ruler
  • Exacto Knife

Light Box Construction

Figure out your measurements based on the size of your telescope.  This light box was made for a Takahashi Sky 90 so I figured a 10 in. x 10 in. x 10 in. box would suffice.  For the outside of the light box, I cut 6, 10 in. x 10 in. x 10 in. Foam Core panels.  I cut an additional 10 in. x 10 in. x 10 in. panel for the Diffuser Panel.  The Diffuser Panel and the Rear Panel of the box have rectangular cut outs so that paper and the EL Panel can be affixed on to them...

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