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NEW EF Flatfield Foils deLuxe NEW

The well known EF-Flatfield foils are now also available in a mounted "DeLuxe" version: The foils come in a square size for instruments of various sizes. The frame is made of unbreakable polymer with a special protection around the edge. The opaque frame gives you an even more uniform brightness than the foil alone. Additional to that the foil is very well protected against humidity and moisture and dirt and scratches during transport.
For very fast system you will have to reduce the brightness by placing (some) sheets of paper in front of the foil: The DX frame also keeps this very well.

The EF DX Flatfield Foils give you the ideal and pratical flatfield-source for even the most critical applications!

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Color

The light from the foil looks blueish/white. Most foils from other sources seem to be white to the human eye, but the light is made of discrete emission lines. -Due to this the foils from most other sources at not suitable for narrowband emission line filters! I tested the products of all manufacturers worlwide and selected these foils because they are best for astronomical applications!
The spectrum of the EF is not made of some emission lines (like most foils do!). It has a very broad, continuous emission across the whole spectrum. This fact makes the foils great for narrowband emission line filters.

Spectrum of a bad foil (but still looks white the the human eye!)	Spectrum of a good foil (You get this one here :-) )

Brightness

The brightness of the EF foil can not be controlled electronically. If the foil is too bright for your setup (very fast instruments), you should place one or more sheets of paper or a piece of white plexiglass between the foil and your telescope. The brightness is very even across the whole surface. It works well for the most critical observations, even photometry or spectroscopy.

Power

The foil is illuminated by an external high voltage, which is produced by the "inverter" you have also received. The high voltage is produced at a very low amperage, so there is no danger to you! A normal Wall-Transformer does not work!
Please use the foil only with the supplied matching inverter. Connecting a foil to a inverter of the wrong size reduces the livetime very much!

Exposure Time for Flatfields

There is no universal rule for the exposure time. Due to the focal ratio of your instrument, the camera and the filters the exposure time may vary between 1/100 of a second and 30 seconds. Please look at histogram of the images: You should have the peak at about 50% of the dynamic range of the camera, and no part should reach saturation! If you use special Astronomical cooled slow-scan cameras (SBIG, QSI, FLI, Atik etc...), you should avoid very short exposures, as the moving shutter might cause some gradients.

Look and feel

The EF foils look like a laminated piece of thick paper, with a cable on one side. They are very lightweight but very sturdy! You may use your EF foil directly at your scope: The easiest way is to point your instrument to the zenith and put the EF foil on top of the instrument. (You may also install the foil at the wall of your observatory of course.)
We do recommend that you secure a cable to the foil in a way that there is no force on it.  A very nice way is to stick the EF foil to a thin piece of wood with double-sided adhesive tape. Mounted this way the EF foil is very sturdy and will serve you for many years even with mobile use!

Size	active area	for instruments up to
A1	594mm × 841mm	594mm (23")
A2	420mm × 594mm	420mm (16")
A3	297mm × 420mm	297mm (11,5")
A4	210mm × 297mm	210mm (8")
A5	148mm × 210mm	148mm (5,8")
A6	105mm × 148mm	105mm (4")
A7	74mm × 105mm	74mm (2,9")
EF Folie DX A5	148mm × 148mm	5,5" / 148mm
EF Folie DX A4	210mm × 210mm	8" / 205mm
EF Folie DX A3	295mm × 295mm	11" / 295mm
EF Folie DX A2	420mm × 420mm	16" / 410mm

Delivery:

Each EF Foil is covered by an additional protective foil. There might be some bubbles or greyish haze between the protective foil and the illuminating foil itself. For the best results, you should remove the protective foil.