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Electro-luminescent Panel for FLATS

steppenwolf

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steppenwolf

steppenwolf

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One of the bugbears of Deep Sky Images is the taking of FLATS. Whereas DARK frames and BIAS frames are very simple to take, requiring the minimum of user input, FLAT frames have to be taken much more carefully and MUST be taken at the exact same focus and camera orientation as the image data. This means ideally taking FLATS immediately after taking the image data which can often be inconvenient so it is easy to skip this important calibration routine.

To my shame, I often find myself 'forgetting about' the FLAT frames but thanks to Father Christmas, I now have an electro-luminescent panel that was bought from a company called Earlsmann and have just had my first opportunity to try it out.

Taking the flats was simple, I just held the illuminated panel over the front of the telescope and took a series of images yielding about 30% saturation. I then combined these into a Master FLAT frame using 'median' combine with a boxcar filter selected. I then calibrated my image data before producing the final image.

I think the results speak for themselves and I now have no excuse for not taking FLATS in the future.

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Ford Prefect

Ford Prefect

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Hi Steve

Thats just what Ive been doing. Do you have the sheet sanwiched between perspex? ( http://stargazerslounge.com/equipment-discussion/78054-el-sheet-taking-flats.html ) I find it helps difuse the light a bit better.

Note of caution, I’m actually on my second sheet as the connection between the sheet itself and the inverter is fragile and mine managed to come apart at the most inconvenient time i.e. while at kelling this year. :)

Cheers Jon

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steppenwolf

steppenwolf

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and congrats on the Scope Doctor role at S@N mag!

Cheers, Nick!

Note of caution,

Thanks Jon, I heard about this problem and have looped the cable through the Correx backing sheet I attached it to but a timely warning for others.

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MartinB

MartinB

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I have started using just the same, A3 size with lots of gaffer tap around the connection and sandwiched between sheets of polar white perpex. The main benefit of the perspex is it is nice and rigid as well as providing some diffusion. SteveL put me onto the idea.

Finally my flats are no longer the lottery they have been in the past. The sheets aren't perfect and the lighting isn't 100% even but plenty good enough.

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steppenwolf

steppenwolf

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How are you powering it Steve?

Hi Helen, I have used both my AC mains to 12v supply in the observatory and my 12v 'Powertank'. The panel was supplied with an inverter which converts the 12v DC supply from either source to 130v to power the panel itself.

What size did you get Steve...

I am hoping that an A4 sheet will be big enough for the 8"

Peter, unfortunately, the A4 sheet doesn't quite cover the aperture of an 8" Newtonian because of the tube diameter itself. However, if you made up an alignment jig to mask stray light and hold the panel dead centre at the same time, it would illuminate the mirror but I decide against doing this to make absolutely sure that I got full illumination to match that of the real sky.

Finally my flats are no longer the lottery they have been in the past. The sheets aren't perfect and the lighting isn't 100% even but plenty good enough.

Pretty much my own view, Martin - I am not convinced that any lightbox/tee shirt etc. would give perfect illumination but at least now I have a 'repeatable' source of light that is easy and quick to use so I WILL use it!

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  • 2 weeks later...
jacobb

jacobb

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Hi

I've also used a Electro-luminescent Panel for some time now, and for me it's a real timesaver.

It gives me more time preparing an imaging run rather than having to spend the time at dusk taking flats.

I wrote a few words about how I use it on my webpage

Kind regards

Jacob

Copenhagen, Denmark

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  • 3 months later...
Ant

Ant

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nice one guys - thanks for that.

I've just contacted them about getting two A4 sheets - but with an extra 50mm on the length to protect the power supply...

Ant

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ollypenrice

ollypenrice

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Damn, my panel has just stopped working. No luck with checking the contacts etc so I reckon it's a gonner. I bought it here in France and it was sufficiently expensive for me to be reluctant to buy another one. How are others finding reliability? Since I am obsy based I think I will put up with the bulk of a lightbox again. I am quite upset about this. Boo Hoo!

Olly

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Psychobilly

Psychobilly

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It may be the inveter can you hear a high pitched whistling at all when it switched on... The panel material operates as a "lossy " capacitor so is harder to "meter" ... check the output of the inverter with a AC voltmeter set on 1000V range...

The inverter on my Earlsman panel only seems to run properly if a panel is connected no sensible voltage can be measured with the panel disconnected...with it connected the DVM on AC gives a reading of 110V...

You can't get a resistance maasurement from the panel

The biggest problem I have with mine is a really bad intermittent connection on the DC input connector

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Fay

Fay

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I think I got mine from Earlsmann, will have to check, I have sandwiched it with perspex one side & cardboard the other. It runs with 6 batteries. It is very bright & my flats are at a very low exposure, 0.5 for Ha I think.

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