No announcement yet.

Lamps and color reproduction ...

  • Filter
  • Time
  • Show
Clear All
new posts

  • Lamps and color reproduction ...

    Finally got around to posting ...

    The question is, can the lamp you use whether halogen and Xenon (for examples) actually effect color reproduction on screen?

    I ask as when I take photos with my camera of my projections, when the "white balance" is on, a faded print tends to actually look better than it is ...

    So, if this could be a possibility, what would then be the best lamps to use for proper color reproduction on screen?

  • #2
    There are several things that can affect color when taking photos of projected images. I'm no expert, but I have learned a bit over the years. Bulbs have a CRI (Color Rendering Index) associated with them. I don't know the technical meaning, but I do know it relates to how accurately the bulb's light shows colors. 100% is the ideal, which many projector bulbs claim. I'm not sure if our eyes can easily detect differences if the CRI is a bit lower (90%, 95%), so it isn't something I worry about.

    White balance (WB) is probably the most important factor, as you've seen. The auto WB setting might be "cooler" or "warmer" looking than what the projector's image is, and that might make the color look better to you. In shooting video of my 8mm films, I have a bit of a dilemma as to whether I should honor the projected image, or try to make them look as good as they can (to my eyes). For now I'm setting a manual WB at the same temp (K) as the bulb, but I'll probably fool around with WB in post when I get around to editing my results.

    Other things that can affect color when shooting photos of projections include exposure settings that might make the image brighter or darker (ISO, f-stop, shutter speed), but they won't have as dramatic effect on color as WB.

    I hope that answers your question, rather than confuses the issue.


    • #3
      Comparing halogen lamp from a reputable brand (Osram for example) with a no-name brand bought dirt cheap from aliexpress, they're probably different. The branded ones will look more "white" although both rated at the same color temp.

      But for taking a snapshot from a projected image, just set the white balance with the blank screen (lamp on, no film projected) first. The rest will be fine regardless of the lamp's make.


      • #4
        I recently saw some shots in Steve Osbournes magazine of the difference between a Hallogen lamp and a incandescent lamp, and the color difference was quite striking!


        • #5
          Of course, if you are in a really dark room your eyes compensate more than you might think, after all white looks white in candle light as well as shade when the sun is out. Often I find the colour of a reel looks better at the end than the beginning as my eyes & brain compensate.


          • #6
            From what I heard from several people, Xenon lamps have an effect on faded prints and restores a little bit the colours.


            • #7
              Yes, xenon lamps have a higher color temperature so they add some blue to the image.

              Steve Osborne asked me to mention that the new Super 8mm releases are color balanced (timed) in the lab for 3300K so that they will look their best on the majority (non-xenon) of Super 8mm/16mm projectors. This is different from back in the day when 35mm theatrical releases were graded for a temperature of 5400K, the standard in cinemas.



              • #8
                I have an Eiki EX-200OA and its xenon lamp has a light output of around 6000'K. And, as Doug says, the lamp has quite a blue content. This is excellent for an Eastmancolor print which is losing its colour.




                • #9
                  Here are three images taken using a Photo Research spectroradiometer. You can easly see the color difference between a Incandescent, Xenon and HIT lamp used in our S8 and 16mm film projectors. Lower color temperature results in more red which can be seen in the Incandescent lamp. The higher color temperature results in more blue. All HIT/HID lamps have a spike in green and yellow.
                  Attached Files


                  • #10
                    I worked designing lamps some years ago, I can say the following: all halogen and xenon lights have a CRI of 100%, that means they can reproduce all colors correctly. But CRI is different from color temperature, halogen lamps usually have hot color, meaning they tend to tint to yellow, being the opposite of fluorescent lamps that tend to give cold light which tend to tint towards blue, obviously there are exceptions to this. What WB does is try to get rid of the natural tint, to give real white, not white + yellow or white + blue. Xenon lights can give a more realistic white (less yellow than halogen) that's why they are prefered for professional projectors. On the other side LED lights and flourescent lighting are far from a CRI of 100%, which is pretty undesirable because that means they cannot reproduce all colors. LED lighting has become better in time. I don't know the last information, but the best was about 90% and standard LEDs are about 70%, pretty lousy.


                    • #11
                      The film lab I used to work at printed all the Disney 16mm prints for the armed forces in the 90’s. They always made 2 prints, one timed for halogen and the other for Xenon. And Disney sent someone down to sign off on every print after printing to check for quality and color. So Disney definitely believed there was a difference. Animated films shown with a Xenon or HTI light are particularly stunning. Strange thing though is that I was watching a Abbot and Costello short and the xenon and the HTI made the image seem a little washed out? I then put it on an Elmo ST1200 and it looked better!
                      Attached Files