Will these fit these? Another electrical question

[[1ponders] (Paul)]

Does anyone know if these LED packs fit into these

[Dennis]

Hi Paul

Methinks that any LED array such as these, which appear to be designed for modern, flush, down lighting, will be way too bright for the relatively small volume of a light box, given the sensitivity of our cameras?

Cheers

Dennis

[[1ponders] (Paul)]

I'm just throwin' ideas out there Dennis. I followed Eddies design, didn't like the colour of the bulbs so I thought I'd try to find something whiter and these turned up.

I actually looked at these the other day when I bought the halogens and thought that maybe they wouldn't have been bright enough. I have 2mm white perspex to get through.

What would your suggestions be for lighting?

[Dennis]

With 4 torch bulbs (3V 1A) my light box has 2 sheets of 2 or 3mm(?) opaque Perspex and a x2 Neutral Density theatre lighting filter sandwiched between them and that gives me 1/2 sec exposure for the ST7 and C9.25 combo.

Cheers

Dennis

[[1ponders] (Paul)]

Right, I gotcha now. Might need to include a dimmer switch in the setup then

What would you suggest for whiter/cooler bulbs?

[Dennis]

Hi Paul

I'm still researching the design for my Tak Mewlon light box and I haven't come across anything yet. I might look at those 3mm super bright LEDs if their emission spectrum matches daylight and if I can somehow modify their narrow beam to get a wider more evenly illuminated spread.

I am thinking of fitting an aluminium plate that has been sanded using an orbital sander with fine sand paper at the bottom end of the light box, as I read somewhere that this will produce Lambertian Scattering, which should produce a more evenly illuminated reflection back down the light box into the opaque Perspex.

Cheers

Dennis

[[1ponders] (Paul)]

Let me know how you go?

[Dennis]

Hi Paul

Will do. I'm even considering mounting a series of x4 each White, Red, Green and Blue LEDs on a mounting ring, so I can switch between them for taking flats with the LRGB filters. However, that may be getting a little too fancy so we'll see how the design unfolds before I make any further bold, or rash, claims!

Cheers

Dennis

[bojan]

Hi Paul,
white LED's may have unsuitable spectrum, as the "white" light is generated in similar way neon tubes use.. White LED is actually generating relatively narrow blue band, and this is radiated into fluorescent material to produce the lower parts of the visible spectrum, but the result will not be uniform....
Just two cents from my side...

[[1ponders] (Paul)]

All donations gratefully accepted bj.

[Dennis]

I am experimenting with White and RGB LEDs to see if I can produce LRGB flats with approximately the same photon counts, using similar exposure durations for each flat. With my current torch bulb light box, there is a significant variation between the L and the RBG flats in terms of exposure duration. The torch bulbs produce a predominantly yellowish light.

Looking at the transmission vs. wavelength graph for the SBIG RGB filters, their transmission efficiency appears optimized for the following wavelengths:

R 615-660nm
G 480-550nm
B 425-500nm

The Jaycar catalogue specifies the wavelengths for RGB LEDs as:

R 625nm
G 525nm
B 470nm

So, using the RGB LEDs may seem okay for taking RGB flats? This project is more of an interesting experiment, as I have time on my hands due to the cloudy weather up here in Brissie! So, if it doesn’t work out, the few $’s spent on LEDs won’t be a great loss.

Cheers

Dennis

[[1ponders] (Paul)]

Don't want to do my uni project while your at it do you Dennis. I mean if you've go some time on your hands

Let me know how you go, I may even be able to use your results

[Dennis]

Originally Posted by [1ponders]

Don't want to do my uni project while your at it do you Dennis. I mean if you've go some time on your hands

Ha ha ha – who, me? I isn’t smart enough mate!

[[1ponders] (Paul)]

I think you might be mate

Besides I think you'd enjoy it. I'm testing a number of consumer grade low end CCD cameras to determine their effectiveness for scientific measurements. Dynamic range, S/N ratios, how long before dark current ruins you and sensitivity. That sort of stuff. Right up your alley really