Light box for SW 200P

[Gina]

I have a dead monitor but I think it's the back light that's gone - it's just DEAD!

[Gina]

I've ordered some foamboard and a circle cutter from Amazon.

[yesyes]

I think i know what my next project is going to be now. Thanks.

I do have a spare dead 23in monitor here and with the lcd off it looks to light up real nice but it needs a video input from a pc to turn the back light on.

This can be modified so that the backlight is on even without video input. I've done that for one SGL member. All that was needed was 2 resistors.

I can help you with that if you want...

[DrRobin]

Hi,

I am thinking about something similar and came across these A3 LED panels for posters and advertising.

http://www.ledsignsandlighting.co.uk/light-sheet-aluminium-frame-p-160.html

I don't know how flat they will be, but wonder if anyone has tried them?

Might give one ago there are £57 + VAT for an A3.

[Gina]

Daylight and a white T shirt is cheaper

[DrRobin]

Hi,

My LED picture frame arrived today, so I gave it a go to see how well it works. The pictures below were all taken with a 600D and APT. All pictures have been adjusted to show maximum contrast and any artifacts.

The first is through an ST-80, notice that it can't fully illuminate a 600D;

The second is through a C11;

The third is also through a C11 with the panel rotated by 90 degrees;

The fouth is through a C11 with the panel rotated by 90 degrees and the camera rotated in the telescope by 45 degrees.

It looks pretty flat to me. There is a slight difference in illumination across the frame on the C11, only to be expected and there is also a dust spec in the lower left, which is in the same place even after camera rotation, so it must be on the camera chip. Before the contrast is pushed it the c11 looks very uniform.

The other differences are the same in all pictures and is probably readout noise.

To me, it looks like this is going to work well, but any comments would be welcome?

[Gina]

What angle are the "reflectors" - the triangular pieces at the back - to the back panel?

[Bizibilder]

The triangles were 60° (equilaterals) that were fitted into each corner - I assume they ended up at "45°" (if that makes any sense) as they are placed across three mutually perpendicular planes! Each triangle was sized so that they almost met each other along the ends of the box.

Or, in English: I bunged a decent sized equilateral triangle of foamboard tight into each corner .

[Gina]

Thanks Yep that answers my question Was your box more or less a cube? Looks like it

[Bizibilder]

For the 200P (and 120APO) the box is roughly 11" square and 17" long, the smaller one for the ED80 is 7.5" square and 23" long.

[fwm891]

Can you substitute a stepped pot covering the 10K range so you can get repeatable settings?

[Bizibilder]

You don't really need it repeatable as you take a unique set of lights for every imaging session. The DSLR sets its own exposure by using the Av setting. Not sure about CCD's as I don't use one.

[fwm891]

I used foam board for my light panel but there's no 'dimmer' involved (unless you count me )

I also used foamboard as a lens shade for my MN190 painting it matt black on the inner faces, its very light, very effective but does require sealing with something otherwise the dew gets into the exposed foam-core edges

[DrRobin]

Hi,

If you use LED or a normal filament bulb, you could use an off the shelf (PWM) light dimmer to reduce the brightness. LEDs and ordinary bulbs are fine with PWM dimmers.

If it is a Halogen bulb, a dimmer will shorten the life, unless it is a dimmable Halogen. Generally flourescents are not dimmable, unless you get the special type, which tend to be expensive.

But as Bizibilder points out most cameras set their own exposure so it doesn't really need to be dimmed. Same for a CCD, just take a faster exposure or turn the gain down until the histogram is around 80% of max.

[fwm891]

The problem with dimming normal bulbs is they change in colour temperature so if your shooting flats for a particular colour (RGB) which will alter the transmission through a given filter. Dim when shooting through a blue filter and the colour temp goes towards the red end of the spectrum - therefore response changes - shooting red filter and you get the reverse OSC camera chips especially will then record different pixel response patterns...

[Bizibilder]

I only put the dimmer on mine as I wasn't sure how bright the LED's would be when i had finished!!! I can now confirm that it is an optional extra!