Light box

[Grierson]

Hi everyone, l have finally decided I must include flats in my astro photography workflow. I am building a light box but I’m undecided as to what to use as a light source. I wonder if there is any concensous on what the best approach is. Any comment would be appreciated. 

[souls33k3r]

I've heard good things about https://www.amazon.co.uk/Huion-A3-Tracing-Adjustable-Lightness/dp/B00IZQZXTE

 

[Grierson]

Thanks for the thought souls, but I was really looking for LED or bulb recommendations for fitting in the back of a box into which will be mounted white Perspex. The whole thing to be slid over the ‘scope shield.

[vlaiv]

Go with led strips - just be careful to get broadband type of leds.

You can just glue the strip on piece of plastic / cardboard and put that some distance behind diffusing material like Perspex. This is how my flat box is made, although I purchased it already made (and was expensive at the time, it would have cost a lot less had I done it myself).

[Grierson]

Thanks vlaiv, could you just elaborate on the description ‘broadband type of leds’. I’ve not come across this as applied to leds.

[vlaiv]

4 minutes ago, Grierson said:

Thanks vlaiv, could you just elaborate on the description ‘broadband type of leds’. I’ve not come across this as applied to leds.

Most leds used to be narrowband - like those red or green leds meaning their light is concentrated in part of the spectrum. For light box you want whole spectrum of light because you will be using it for green / blue / red parts, lum, and maybe even narrowband filters.

Most led bulbs have phosphorous coating to produce broad band light spectrum that we perceive as natural light. There is index that describes how broad spectrum of led bulb is - CRI index (or color reproduction index).

So you want a white led strip that emits as broad spectrum as you can get.

[Grierson]

Thanks for the further reply vlaiv. Now I have decide how many of such leds are needed and where to get them from. I see flea-bay has rolls but it’s not clear what spec. they are or indeed whether the roll can be cut up. Problems. Problems! ?

[vlaiv]

Have a look here:

https://en.wikipedia.org/wiki/LED_strip_light

You need to take into account angle of spread and distance to diffuse cover and space them so that each part of diffuse cover gets about the same amount of light.

[Shelster1973]

Plenty of options available.

Here is one that I put together and has stood me in good stead.

[sulaco]

Hi, I made one with a similar paper thin light panel to these.

https://m.alibaba.com/product/60034600805/ultra-bright-el-light-

I then stuck it to some white translucent acrylic sheet,

Its light and can be mounted to the end of the scope with plastic bolts used for the focus mask. 

I photograph it later for you.

Campbell

 

[Grierson]

Well despite my best efforts to find LEDs sold with broadband specs. I couldn't see any at sensible prices so in the end I opted for an electroluminescent panel. I've not had much chance to try it and initial results produce an orange background to the Master Light Binning in PI. Although this is easy to remove I need to experiment with exposure levels.