DIY Cheapish Self Powered Flat Panel

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nexusjeep
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DIY Cheapish Self Powered Flat Panel

Post by nexusjeep » Fri Jan 18, 2019 12:57 pm

Not sure if people normally do this type of post but believe it is imaging related, I recently bought a new telescope so my previous flat panel was no use as it was too small and the new one needed to be 180mm - 200mm to cover the end of the scope. So I thought I would do a bit of DIY the panel is built from the individual bits listed below so for £54 I have an adjustable brightness self powered flat panel that I can put over the end of the scope after removing the bahtinov mask to take flats as I refocus for each filter. I had some vinyl sheet laying around so used this to cover the rest of the sketch pad to reduce the stray light.

I have tried it with my LRGB + Ha, Oiii and Sii filters and get a nice flats curve with each.

Huion Thin A4 LED Tracing Panel USB powered £30
200mm x 50mm deep aluminium cake tin £5
Anker USB Battery £12
10 x 12 foam strip to line the inside of the cake tin £7

Cheers
Nick
Attachments
Flat Panel 2_proc.jpg
Flat Panel View 1
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Flat Panel 1_proc.jpg
Flat Panel View 2
Flat Panel 1_proc.jpg (75.44 KiB) Viewed 1000 times

BlackWikkett
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Re: DIY Cheapish Self Powered Flat Panel

Post by BlackWikkett » Fri Jan 18, 2019 9:43 pm

Hi nexusjeep,

I use LED tracing panel for flats myself. Never though about doing this but this looks great. Well done!

Do you use anything between the LED panel and the scope to defuse the light? I use t-shirt which seems to work well for me on my RC 6.

-Wikkett

nexusjeep
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Re: DIY Cheapish Self Powered Flat Panel

Post by nexusjeep » Fri Jan 18, 2019 10:38 pm

Hi
Sorry forgot that bit I do have an extra layer in front of the panel I had some sheets of opal acrylic that I purchased a while back I have one piece in front of the screen to reduce the power. It's from EBAY similar to the one below. Also the foam grips the dew shield and the battery is attached via double sided tape so I can fit it then get the laptop to sort the timings without having to hold it.

Cheers
Nick
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opal sheet.JPG
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turfpit
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Re: DIY Cheapish Self Powered Flat Panel

Post by turfpit » Sun Jan 20, 2019 1:08 pm

I built this for my 66mm refractor. Hangs over the end of the scope, battery powered and can be used in the field.
flat-panel-on.JPG
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100mm EL panel + inverter = £14. 2 pieces of 2mm plasticard, nuts, bolts, washers, plastic rod, Gorilla Glue around £20 total.
https://www.ebay.co.uk/itm/10cm-EL-Pane ... rk:39:pf:0

I have a similar panel for my C8 which cost around £40 for the rectangular panel. Inverter had to be 12v powered.

This company http://www.earlsmann.co.uk/lighting-com ... el-panels/ provides panels plus suitable inverters and have been very helpful.

Dave

nexusjeep
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Re: DIY Cheapish Self Powered Flat Panel

Post by nexusjeep » Sun Jan 20, 2019 10:10 pm

I had an Aurora Flatfield EL for my ED102 prior to selling it after buying the new refractor, but unfortunately it was too small hence the reason to look at building an alternative. The one issue I found with the EL panel was the brightness as depending what I was shooting flats through I had to spend time putting things in front of it to dim it. So for L exposures I had to really dim it down and even on narrowband I had to do the same also holding it over the end of the scope was a pain at least yours hangs on it.

What I have done with the new one is use the opal Acrylic to Dim it so that on the led panel on its dimmest setting it gives me around 0.8 sec exposures on L and if I turn it to the brightest I get 2.4 sec exposures on the worst narrowband filter with the ASI1600MM and new scope so it means there is no fiddling around. The other thing is that the cake tin with the neoprene foam is a good seal to the tube so technically I could shoot them in the daylight although even then I still turn the light off in the observatory. The other plus side to the cake tin / sponge is the grip means that it is secured over the end of the scope if I use it during a session even if it is quite windy.

Thanks for sharing yours as it will be useful info for others.

Cheers
Nick

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turfpit
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Re: DIY Cheapish Self Powered Flat Panel

Post by turfpit » Tue Jan 22, 2019 9:43 am

Nick

I aim for around 40% on the histogram for my flat exposure.
  • Mono flat ~16.7ms
  • Colour flat ~78ms (I use Luminance channel, don't care about colour balance)
  • Ha filter ~15s
  • For my 8" panel, exposure is ~250ms
The panels I use have worked without any dimming material placed in front.
I did have the pegs broken off once when the wind caught the panel. I have a mark2 in progress - EL panel between 2 plasticard sheets (one with hole in, 25mm stand-offs to a third plasticard sheet which fits over the scope.


Mono flat 16.7ms exposure, Atik 314E
flat-frame-mono.JPG
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Colour flat 78ms exposure, Altair 183C
flat-frame-colour.JPG
flat-frame-colour.JPG (59.86 KiB) Viewed 912 times

Dave

nexusjeep
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Re: DIY Cheapish Self Powered Flat Panel

Post by nexusjeep » Tue Jan 22, 2019 11:11 am

Hi Dave,
I tend to shoot my flats for a little longer duration than that just force of habit especially if we have the Nikon D7500 on the scope as it has a mechanical shutter. Hence the reason for dimming it down, also I found that the sensor calibration was unhappy in Sharpcap if I had too bright of an illumination as it would fail on one of the steps as there was insufficient range when it was adjusting the settings for different readings.

At the moment it would just be nice to be able to shoot something that would require the us of flats other than photos of clouds.

Cheers
Nick

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turfpit
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Re: DIY Cheapish Self Powered Flat Panel

Post by turfpit » Tue Jan 22, 2019 11:39 am

Nick
At the moment it would just be nice to be able to shoot something that would require the us of flats other than photos of clouds.
Agreed :)

Surely the generation of a flat frame relies on a (more or less) centralised histogram? Below is an extract from the Nebulosity 4 manual. I have put my trust in Craig Stark. Works for me and a gives a systematic and repeatable way to obtain a flat. This technique works across multiple capture programs and operating systems using the most basic functionality of the capture program (histogram and exposure setting). Works for me but as always, to anyone reading this, YMMV.

As always with this stuff, it is easy to find 5 conflicting statements on the internet about any aspect of astrophotography.

Dave

flats-Nebulosity-manual.JPG
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nexusjeep
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Re: DIY Cheapish Self Powered Flat Panel

Post by nexusjeep » Tue Jan 22, 2019 12:03 pm

Hi Dave,

Not disagreeing just like to let everything settled so tend to like the exposure in the higher 100's of microseconds also I have placed a link below were a comparison of flats for ADU readings from one end of the spectrum to the other was done and using ADU values from 5,000 to 60,000 (16 bit) he found that between 15,000 ADU and 50,000 ADU there was very little difference in flat frame quality his final decision was to aim around 35,000 so just to the right of centre as it gave the best average between time / quality. My flats on the histogram have a symmetrical shape and I adjust the time so that the spike is centred between 47% to 53% for the monochrome camera so in the same ball park mine would just consume more time to take but will achieve the same effect.

http://www.darkhorseobservatory.org/ind ... egoryID=62

Cheers
Nick

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turfpit
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Re: DIY Cheapish Self Powered Flat Panel

Post by turfpit » Tue Jan 22, 2019 1:05 pm

Nick

Thanks for the link, an interesting article targeted at very advanced/experienced imagers. If I had come across it when I was first looking into flat frames, it would have saved me a lot of time as I would probably have given up and sold all my equipment :lol: . This must be one of the 5 conflicting statements about any topic that I mentioned in my previous post ;) .

My response, with the included histograms, was an attempt to help those who are newer to the hobby by showing a simple, systematic and repeatable way to achieve a reasonable flat frame. The information referenced in my post is from the creator of Nebulosity - world class image capture and processing software supported by a wealth of professionally delivered tutorial material on the Stark-Labs website and YouTube.

Dave

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