How do I use Blue Gun?

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Denniscasey

Well-known member
I just got 5 inch LCD external monitor for HMC40 and it provides Blue Gun feature. I don't know what this is supposed to do or how I would use it to help compose video shots?
 
Blue gun is useful in calibrating the monitor for proper image rendering by eye when connected to a known good source that can output standard (e.g., SMPTE) color bars. Once bars are displayed on the monitor, do the following with the blue gun feature still disabled:

  1. Turn down the Chroma (sometimes Color or Saturation) all the way.
  2. Adjust Brightness up or down until the the pluge bars (thin vertical ones in lower right corner) seem to match. The brightest bar, which is the 11.5 IRE one, will remain visible and will never match its neighbors.
  3. Adjust Contrast to further tweak that brightest bar until it nearly becomes invisible to the eye, but still is differentiated from the darker bars (matched 5 IRE and 7.5 IRE) as slightly more visible. The white square in the lower left of the field should not bleed into its neighbors, but should not appear to be gray. Some people will use a white card or foam core chip to reference "white" to their naked eye. I've never found this useful, but many prefer to have a piece of white paper to reference white.
  4. Turn Chroma back up to "unity" level. There may or may not be a green highlight in your Chroma display bar when you hit unity. Most production monitors do. Older monitors, without on screen display (OSD) would simply have an easy-to-find detent-style positive position on the knob that would be at unity.
Now is the time to engage "Blue Only" or "Blue Gun". The following is for SDI input and HD Component. Y/C is different.

  1. Adjust Chroma again so that the tallest bars on the monitor show no differentiation in gray quality between the top and the bottom of the bar. Imagine they are a total value of 10, with 0 at the bottom where the pluge bars are, and 10 at the top edge of your monitor. When the Chroma is slightly off, you will be able to detect an actual line of separation of these bars between segment 0 and 1. The difference between top and bottom should not be discernable.
 
Thank you Erik. Taking me a while to learn all the features of HMC 40 but I think I can get it to display color bars on external monitor (which uses HDMI input)--are those the correct type to allow me to follow your methodology?
 
It depends whether the camera outputs RGB or YUV calibrated data. Someone else may be able to answer this. If RGB, then you would be good to calibrate as per the instructions above.

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I believe RGB mostly used for computer monitors and YUV for broadcast color space so I'm thinking HDMI output from HMC40 is YUV?
 
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