Lighting distance

[loonsailor]

I'm about to put in a lighting track to illuminate my 4'x8' print viewing/proofing board.  I'll light it with two 50 watt Solux bulbs.  My question is, how far from the board should the lighting track be?  Is there a formula, or rule of thumb?

[BradSmith]

I can't tell you the distance.  Others will probably be able to give you illumination levels that are in the right range.  Those you could measure with your light meter.    Without that, you'll need to tell people which bulbs and what kind of reflector or spot they are in.  Wattage?  Bare bulbs?  Spot bulbs?, etc.  Then maybe they can give you examples of what they have.  But illumination levels are the best way of doing it.  I've seen that data before on the web.   Why not google it and see what you get?

[Czornyj]

I'm about to put in a lighting track to illuminate my 4'x8' print viewing/proofing board.  I'll light it with two 50 watt Solux bulbs.  My question is, how far from the board should the lighting track be?  Is there a formula, or rule of thumb?

You should take the luminance of your display and multiply it by π (3.14...).

So if your display is calibrated to 120cd/m^2, you need about 380lx - one 50W Solux lightbulb should be about 2 feet from the board, and it should be enough for such a small proofing board. With 2 bulbs it's more complicated

[loonsailor]

You should take the luminance of your display and multiply it by π (3.14...).

So if your display is calibrated to 120cd/m^2, you need about 380lx - one 50W Solux lightbulb should be about 2 feet from the board, and it should be enough for such a small proofing board. With 2 bulbs it's more complicated

Thanks, Czornyj.  I assume you mean to multiply by pi, right?

OK, so I dug out my 40-year-old Gossen Lunasix, and I'll go buy some batteries for it.  Although it has only EV on it, I've found a table at http://en.wikipedia.org/wiki/Exposure_value relating EV to luminance.  Would an incident reading be appropriate, or should on attempt to match a reflected reading off a blank sheet of paper to the calibrated screen brightness?  Perhaps they'll be close enough that it doesn't matter.