Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 12/24/2016 - 20:01
Anyone on the forum taking Ic flats with the Spike-a-Flat flat fielder?
My EL panel is deficient in the near infrared (it works, but exposures are long). I am looking for a substitute for my remote imaging setup with light control. There is no information on the Spike-a-Flat web site detailing the spectral output. My suspicion is that the LEDs used are near-IR deficient, but I would be pleased to hear otherwise.
Best for 2017, Ed
I'll answer my own question. Spike-a-Flat spectral response is an unknown, but based on several other flat panel sources I have investigated, none offer good coverage in the Ic region of the spectrum, even those custom panels that some sources have been kind enough to provide spectral coverage. It appears that one would have to design their own panel. Near-infrared LEDs do exist, but combining them into a useable light panel is quite beyond my expertize. I am turning back to twilight sky flats.
Ed
I built my own light box using polystyrene, a translucent panel, and incandescent bulbs. It was a trial by error but I finally found some with wattage low enough to allow me to do 1/2 second exposures in B and V; at that exposure time and ISO 200 the red signal is too high (not that I care) and I am sure the near IR signature is still higher: According to Wien's law a 2800K black body has its peak at 1.03 micrometers.
There is information on building a light box in Bery & Burnell's Handobook of Astronomical Image Processing.
Ed:
I routinely use a Spike-a-flat LED flat fielder with CBVRcIc filters. The output is not rich in infrared but if the unit is turned all the way up to its brightest setting, good Ic flats can be acquired within 5-7 seconds using an SBIG ST8XME ccd camera. They sell a USB dimmer for remote applications.
Kevin (aka NJScope)