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Old 01-05-2020, 10:20 AM
AnakChan (Sean)
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LED Light Box Tracing Board for flats?

I need a large flatpanel for flats. My Takahashi 250CRS has an electronic focuser, meaning I need to take my flats immediately prior to takedown. If I disconnect the electronic focuser remote, or remove its batteries, I believe the focuser will reset its position. Yes I could takedown and leave the focuser remote and its battery in place and do flats later when I wake up, but it's just a waste of batteries, or worse, prone to error if I accidentally touch the remote during takedown.

I saw this on Gumtree and am wondering if this would be a good candidate for taking flats :-

https://www.gumtree.com.au/s-ad/sydn...pad/1193819599

It seems there is some control of brightness adjustment and seems it'll run off USB power.

Anyone tried this? It seems much cheaper than dedicated astro flatfield panels.
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Old 01-05-2020, 10:43 AM
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multiweb (Marc)
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I have one similar to this. There is a touch switch that if you hold dims the panel from full to nill. So you can vary the illumination and adjust your camera exposure accordingly.
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Old 01-05-2020, 10:46 AM
AnakChan (Sean)
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Cheers Marc. So you're happy with yours? i.e. the light is very even and it works well enough for lights?
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Old 01-05-2020, 10:47 AM
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multiweb (Marc)
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Quote:
Originally Posted by AnakChan View Post
Cheers Marc. So you're happy with yours? i.e. the light is very even and it works well enough for lights?
Yes. It does the job beautifuly. I plug it in a free USB port on the mount hub and that's it. I got an A3. size. Covers all from my C11 down to FSQ.
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Old 01-05-2020, 11:01 AM
AnakChan (Sean)
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Cheers! I'll reach out to seller then. You've saved me $222+ as I was about to go for the Hercules Flatfield Panel which is $291!.
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Old 01-05-2020, 11:12 AM
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The_bluester (Paul)
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What kind of focus control does it use? If it is a stepper or has an encoder so that you can arrive at a specific position repeatably you should be able to get away with "Parking" the focuser and then if for instance it was at 10,000 steps when in focus, power it up and go to position 10,000 and have it in the right place to shoot flats.

Aside from that, I built a flat panel out of a tracing board very similar to that and built the Aurdino controller for it after removing the internal circuit that controls the brightness. It work very well and means you can shoot heaps of flats consistently to average the read noise.
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Old 01-05-2020, 11:25 AM
AnakChan (Sean)
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I don't know what kind of focus control actually. I think it's stepper? It can be ASCOM controlled (but I'm using an ASIAir Pro, and I'm an all MAC user). You've raised a good point worthy of investigating. I'll try to dig into it a little more.

Edit: Confirmed it's a stepper.

Last edited by AnakChan; 01-05-2020 at 12:08 PM.
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Old 01-05-2020, 06:42 PM
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Outcast (Carlton)
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Don't mean to hijack your thread Sean but, been meaning to ask a question about light boards for a while now...

I bought a cheapy A4 tracing board off e-bay, the ad looked good, seemed like it would do what I was looking to do but....

when it arrived & I fired it up.... well, I'm not so sure it's suitable anymore... looks great when it's off but, when you fire it up it has this grey dot pattern due to a film of something adhered to the base of it...

I've stretched a t-shirt over it to see if I can get more even lighting texture but, then it shows up the weave in the t-shirt...

Photo's below... can anyone advise if this will work or did I buy a dud... only cost me like $20 so, it's not like I blew the bank on it...

First pic is light off, second with light on full brightness. Second pic looks worse than it is in real life but... it's not an even white brightness across the screen... there is a grey dotted matrix pattern...

I can't afford 'the real deal' astro flats panel & I don't need an A3 version as I'm only imaging with up to a 5" scope... so, if anyone has any links to an A4 version that will do the job, will be much appreciated... assuming of course that this one isn't up to the job...

Ignore the shadows... that's just my fat bod in the way...

Cheers
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Old 02-05-2020, 02:30 AM
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lazjen (Chris)
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I've also got one almost exactly the same as the link posted. It works well.

Carlton: that's a very bizarre panel. If you could get some white acrylic to go over it, it might diffuse it to make it work?
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Old 02-05-2020, 07:13 AM
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Outcast (Carlton)
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Carlton: that's a very bizarre panel. If you could get some white acrylic to go over it, it might diffuse it to make it work?
I agree... I think they've used this 'dotted matrix' thingy to diffuse the light for tracing.. it would work okay for that, I think but, not for the use I intended...

I think I'll get my hands on something else.... I did a bit of googling last night.. should be able to get something reasonable for around $50

Cheers
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Old 02-05-2020, 09:50 PM
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Carlton, if the panel is placed at the front of the scope which is focused at the infinity (i.e. a normal imaging focuser position), wouldn't the panel be completely out of focus and hence the matrix invisible?
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Old 03-05-2020, 06:44 AM
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Carlton, if the panel is placed at the front of the scope which is focused at the infinity (i.e. a normal imaging focuser position), wouldn't the panel be completely out of focus and hence the matrix invisible?
That is indeed possible, I haven't actually given it a run yet...😁

Been too busy fretting over whether it will or won't work...

I'll give it a try next imaging run & see what the subs turn out like...

Cheers
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Old 07-05-2020, 04:27 PM
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turbo_pascale (Rob)
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I used something that looks very much the same and made a panel I could automate the flats with with SGP. Admittedly, I just use the tshirt flat with this light box, because I don’t do them all the time (I’m on a pier in a dome)

Video on what I made here: https://youtu.be/2RQyRsJflmY
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