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Making flats for a small refractor

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#1 descott12

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Posted 30 November 2021 - 05:04 PM

Hello all,

I recently got an ATED60 and I love it but until recently I haven't been able to make flats for it. For my SCT, it is easy. You just point it up and lay an LED panel over the end of the dew shield. But this little refractor is way too small for that and I don't really have a way to point it at a wall with the LED panel hanging vertically.

 

So I got a small LED panel like this one from amazon:

https://www.amazon.com/dp/B09HCKD32V

 

It has a grid of large LEDs so I needed to add several layers of paper and white cloth T-shirt to diffuse the light.

Then a simple 3D print job to allow it to slide over the end of the OTA. And it works perfectly!

 

This panel also is nice because it has on/off and bright/dim switches on the USB power cord.

 

Cheers

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#2 m2434

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Posted 30 November 2021 - 09:09 PM

Cool, not sure how even take light will be though. I used to use uneven lights like that, but with a cardboard light box. You may want to look at something 8-12” deep, with around 4 equally spaced layers of vellum paper.  Glue Styrofoam to the sides inside, and cardboard with a large hole across at each mount point. Glue the vellum at each layer of the mount cardboard. Line the inside, sides with tinfoil.  Last cardboard mount, cut the hole as close to the dew shield aperture as possible so that the light box will rest on it, if the telescope is vertical. Will probably diffuse a lot better.


Edited by m2434, 30 November 2021 - 09:10 PM.


#3 descott12

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Posted 30 November 2021 - 09:54 PM

Cool, not sure how even take light will be though. I used to use uneven lights like that, but with a cardboard light box. You may want to look at something 8-12” deep, with around 4 equally spaced layers of vellum paper.  Glue Styrofoam to the sides inside, and cardboard with a large hole across at each mount point. Glue the vellum at each layer of the mount cardboard. Line the inside, sides with tinfoil.  Last cardboard mount, cut the hole as close to the dew shield aperture as possible so that the light box will rest on it, if the telescope is vertical. Will probably diffuse a lot better.

My first test run was surprisingly even. I used the diffuser that came with the light, 2 pieces of white printer paper and two layers of gauze.  I don't do hardcore AP, just EAA so my requirements for perfection aren't nearly what many would need or expect. But overall, it works pretty well. Certainly better than nothing.



#4 matt_astro_tx

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Posted 01 December 2021 - 02:01 PM

From one AT60 user to another, that's a sweet solution.  Nice job.  I usually bring my rig into the kitchen, put a t shirt over the end, flip on the crazy bright overhead lights, and take my flats.  Seems to work ok for me.  But I really like your setup.



#5 radon199

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Posted 01 December 2021 - 02:33 PM

I use a small LED tracing pad I got on amazon. Takes a usb mini connection and I can plug it into my battery. It is already very diffused because it is side lit, but I add some cloth over the top to further diffuse the light. Haven't noticed any issues and it is very compact and cheap.

 

https://www.amazon.c...RP35Y1X1X5QBC3Y



#6 descott12

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Posted 01 December 2021 - 02:51 PM

I use a small LED tracing pad I got on amazon. Takes a usb mini connection and I can plug it into my battery. It is already very diffused because it is side lit, but I add some cloth over the top to further diffuse the light. Haven't noticed any issues and it is very compact and cheap.

 

https://www.amazon.c...RP35Y1X1X5QBC3Y

That LED pad is huge so you can't really balance it on the end. Do you just hold it up vertically in front of the OTA?



#7 radon199

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Posted 01 December 2021 - 03:07 PM

That LED pad is huge so you can't really balance it on the end. Do you just hold it up vertically in front of the OTA?

Sorry, That was just an example, they come in many different sizes. Mine is an A5 which is 8 1/4" x 5 7/8" or so. I have no trouble balancing it on the end of the dew shield of a 72mm lens when pointed straight up.



#8 descott12

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Posted 01 December 2021 - 03:32 PM

Sorry, That was just an example, they come in many different sizes. Mine is an A5 which is 8 1/4" x 5 7/8" or so. I have no trouble balancing it on the end of the dew shield of a 72mm lens when pointed straight up.

Ah.... I looked around and couldn't find a small one so that is why I cooked up this contraption! Oh well. Looks like I reinvented the wheel.



#9 radon199

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Posted 01 December 2021 - 04:37 PM

I actually like the 3D printed sleeve. In theory, flats should be taken with the least disturbance to the imaging train. Having the fit on ring means that you can leave the scope at the last tracker position and take the flats, with less chance of disturbing any dust motes.

I might make a little clip in sleeve for mine to do the same thing.


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