DIY large inexpensive flat field panel

[Demonperformer]

Just got one of these Biard panels for use with the 8" scope - guess now I will need to get a more solid dewshield than the piece of 3mm thick yoga mat I have used up until now or it changing shape will mess up my flats. [The yoga mat has performed admirably up to now.] I'm thinking that, at the end of a session, I can rotate the mount so the scope is pointing straight up and then just sit the panel on top - saves building a light box.

One (possibly stupid) question: the power box comes with two bare wires, which I am going to have to attach to a mains socket. That's fine, but do I need to worry about getting the right wire connected to the right plug pin, or shouldn't that matter. I ask because I am reliably informed that wiring some electrics up the wrong way can fry circuit boards, etc.

Thanks.

[angryowl]

1 hour ago, Demonperformer said:

Just got one of these Biard panels for use with the 8" scope - guess now I will need to get a more solid dewshield than the piece of 3mm thick yoga mat I have used up until now or it changing shape will mess up my flats. [The yoga mat has performed admirably up to now.] I'm thinking that, at the end of a session, I can rotate the mount so the scope is pointing straight up and then just sit the panel on top - saves building a light box.

One (possibly stupid) question: the power box comes with two bare wires, which I am going to have to attach to a mains socket. That's fine, but do I need to worry about getting the right wire connected to the right plug pin, or shouldn't that matter. I ask because I am reliably informed that wiring some electrics up the wrong way can fry circuit boards, etc.

Thanks.

Regarding the wiring of the mains AC connection from experience, the left pin on the plug is neutral (blue wire usually) and the right pin is live going through the fuse (brown wire usually) in the case of a fused plug. I don't think reversing the order can fry the circuit/appliance, but generally it's safer wiring it this way.

[angryowl]

The panel and inverter from elwirecraft.co.uk arrived last week and did some quick tests of 100 frames each on the narrowband filters. The panel is A3 size and I got the dimmable version of the inverter. 

Duration for each filter are as follows:

Ha - 0.22s

SII - 0.4s

OIII - 0.035s 

Luminance - 0.003s

The above exposures result in images with roughly 15k ADU for each channel. 

Very pleased as these tests were done with the panel at its maximum brightness and it's still not completely saturated the Luminance channel which passes most of the light.

And the final master flats which were dark and bias subtracted:

Ha

SII

OIII

When taking the flats I tried to re position the camera the same orientation it had during my last night out and applied these master flats as a quick test to the data from that night and I am very pleased with the result.

I'm thinking of gluing the EL panel to a thin sheet of plastic or aluminium to keep the weight down and then devising a mounting systems to allow fastening to the dew shield.

[coatesg]

They look pretty good! A good rest of the panel uniformity is to rotate the panel 90 and 180 degrees, and retake the flats at each orientation at same temp/exposures. Then subtract one flat master from the other - you should land up with uniform noise - any gradient will indicate lack of uniformity.

[angryowl]

2 hours ago, coatesg said:

They look pretty good! A good rest of the panel uniformity is to rotate the panel 90 and 180 degrees, and retake the flats at each orientation at same temp/exposures. Then subtract one flat master from the other - you should land up with uniform noise - any gradient will indicate lack of uniformity.

Never really thought of doing that... That sounds like a very good way of checking uniformity. I'll do this tonight as I have a clear forecast and see what it'll show.