A quick and easy Flats light source...

[The Thing]

It fits over my 6" Newtonian. The light source is an electroluminescent string from ebay which runs off 3v batteries. The tube is closed cell camping mat from Tesco which happens to have a silvered side.

A double thick circle of mat forms the base. the EM string was loosely coiled in the base. Two strips of mat about 8cm high were formed into hoops and inserted into the tube with circles of plastic. The hoops also support the diffusion material which is three circles of 'Static Film for Decoration and Privacy', got from Amazon to put of a window to make it obscured.

The discs were cut about 2cm larger than the diameter of the hoop and then slits were cut around the edge to make tabs, these were then folded over the hoop edges as it was inserted in the tube from the rear - no glue needed to hold them in place. The top one (the one you can see) has one layer and the bottom one has two to make sure the EM string is well diffused. Then the string was installed and the base taped into position. Note: more tape will be applied now I know it works!

The little control box takes two AA batteries but I have connected it to a variable power source and the EM string, it turns out, is dimmable. So the next part of the project will be to connect it to an Arduino PWM output so it can be controlled from the laptop. There is a sample flat on my website.

Total cost about £12 if I had to buy it all from scratch.

[Carole]

Amazing the different things people do to make flats, this looks like a really economical one. 

My cheapest was about £12 too, it was a light panel from Ebay for kids to trace over it with paper.  It has points of light, but easily diffused with typing paper.  I cut a hole in the box it was posted in the size of the scope aperture, and it fits over just fine,  Also has a control to increase and decrease the brightness. 

I only had to use that with my Newtonian as it leaks light if done in the day time, but with my refractors I just use the sky and a folded white pillow case to diffuse/dim the light - can't get much cheaper than that, but of course it is not always possible for people to do sky flats and leave their kit up all night.

I still have the flats panel, so if I was at camp say and it was raining the following day so I can't do sky flats, I could still use the light panel.

It was something like this one:
https://www.ebay.co.uk/itm/Portable-A4-LED-Light-Box-Drawing-Tracing-Tracer-Copy-Board-Table-Pad-Panel-M9M5/312652989090?hash=item48cb9202a2&_trkparms=ispr%3D1&enc=AQAEAAADEKvsXIZtBqdkfsZsMtzFbFsbX3WcW5fmB%2Fx7ZbaZTyexVZ2WeZpDOoMD2VSvbGzMN8bLr6A0Ju2UYKyN6eXJZpWVCID6CLHfO%2FMoMXDkgOb7Y32r0sQAVuZ7l1xcztasehspa64bvgLkWFSIcAWcvYiVYamrgmdWnWLD7D%2F5HOEyuJ8DhAXZTXupCCROtKCBKw7dfUL3%2Fvmj1XVoFj4ZqqFBoORhx7MOCxMVLNOUK2xVrTZD9BT8BqjdvvOy2GSOA8sqaKLAeCkFyCQrmNyckT4Lswc%2BcjUuLv%2BpUpLyiZMRhyvn2WXQHZslHxX3uwm9ErUNb5hRjTfre7rJPwVVvR48W6f8JWDBhcyLJECP0UKWRr0P1PangFrMQ%2BLwbZRYJTdoUDYmyoFD4WDQdUlMScp0VMAn5glQZmxfWcdoH41k8Sz2DTexRbSPlLbl%2Bc4E6MuW7ml8mod83BNDMG0J04eHE7F4oyb6%2FOweJFhxDkMjnlMlMIBgO%2FF7zjk2Z5%2FzmW7eFQKOOAlIu1CiRBv1WbTfyP%2Fdbx7rO9uk8QUc9kVHIC6%2FxjBsd56u%2BEZDUySuvrmp8BeFrAoGLgUOcTMA84npHat5IH1Dm4jlX1MhFOPC%2Fxb6P2j9eBJYEhRXdymZ2DPYRlhdryqqQ7lUlN3VyISHo7vtuwaBOhW%2B1k9Jjk2B3KiDlDResEtKaJcE8YE55Mvke6z7npnXERjQunF0CIb0q6lwzdTogbw3%2B6anYpRUx4tKBGQ6GaYETlQO4hTqCNQwCT7h9d0MadSDi12dMmX%2F2WhXQvkqX%2FPlAkbvaNMUrgtIK4R4yxtpFk8ajYceoVZdZUDy6MK6BTPDycMXCiH6eY2H5bYBLRtQS2%2BBQRJ1hoN9GCEH55jV907mm%2FNXxXipbJg5%2BIzRGLjXOey9mKZ6JE8uAAd1SHkvirQ9oHsumtzdnQfSZ6XyIlMoc8%2FHezC8Xaqy9tQYWQ2vk2V4ySOCf38rbsm0%2FjE%2F0yIGYoFxUD3DkFLVci01SSWEEbxPEPx5ZVb5zeTLIMJf8YNLs9I%3D&checksum=312652989090d5fc6229a6a447219bef84f671ae728d

Carole