Led vs spiral fluorescent equivalents

I'm setting up a shadow box. Mark recommends a 20 watt spiral fluorescent lamp... a bit outdated now. I tried a 450 lumen 5 watt led lamp and was not impressed.

I've found a useful set of tables showing roughly what output led lamps give compared to fluorescent and other lamps.

This shows I should be aiming around 1200+ lumens 12+ watts with a dimmer switch. 

Here's the link.

I hope this sheds some light 😖


  • heartofengland

    1200 lumens is way too strong for a shadow box. The highlights and shadows on the subject will be burned out.  Two dimmed and switched 450s sound about right, ideally on adjustable mounts.
    Such a strong light would need good aperture and filtering to control the glare.

    Fluorescent has a very spiked and uneven emission of the light spectrum, can overheat and often flickers.
    LED by contrast is even emissions and runs cool without flicker (use a digital dimmer).

  • Thanks @dencal
    I've got some internet bulbs on order after the local shops offered only dim daylight non-dimmable😕. Update to follow.
  • Here are 3 different bulbs:

    450 lumen 4000 Kelvin

    1320 lumen 4000 Kelvin

    1320 lumen 6000 Kelvin

    I adjusted my phone camera each time to match the wood as closely as possible. 

    Basically, I'm glad I went with the 1320 lumen bulbs. They work well with the dark composition. They are dimmable for when I do lighter compositions. Plus they were £3 each which is no real difference to lower powered bulbs.

    The difference between 6k and 4k is not huge. The 6k makes the board a little greyer. The 4k bulb white balance was 5k on my camera so maybe the tolerance is not that tight.

    The 450 lumen will be going back. I thought it was just my bad eyesight that couldn't pick out the bottle neck. I just needed a brighter bulb.

    A big learning point was how badly the camera dealt with the blacks compared to my eyes. In real life the backdrop is more evenly and brightly lit with less shine. This supports my decision to move from photos to life where possible.
  • heartofengland

    Astonished at how dim all these bulbs look.

    I set my 450s into the base of an inverted shiny metal bucket, this shines through apertures and filters on the top of the shadow box. Mine had only about half the vertical height of this pictured SB.

    But good work setting out the experimental comparison.


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