Slightly OT: bios screenshot capture device

Question

Somebody here (or perhaps on the Framers list) asked about techniques to get good bios screenshots. For those who might be interested, I just came across a good example of screens, and a mention of the video capture device used.
Image: http://www.hardocp.com/image.html?image=MTI5NDcxNTE1M1NNSTgwSDVodGFfM18yX2wuZ2lm
Tool:
Dan_D, forum editor, said:
"They are taken with an old school DVC-80 S-Video capture device using an S-Video output on an NVIDIA graphics card. The AMD / ATI's produce inferior results via S-Video so I never use those for screen shots."
http://hardforum.com/showthread.php?s=a8982caf7410523d9bd17933692b157f&t=1578842&page=2

Answer 1

I don't believe any Windows (or DOS) screen capture app can take a capture at the bios stage, no.
It would require a custom BIOS to do that, because all that is running is BIOS firmware during those screens.
However; historically, BIOS supported the [PrntScrn] key on the keyboard, and would dump a plain text copy of the current BIOS screen to the parallel (LPT) port.
What happens on machines lacking LPT is unknown to me. I have even less clue on what EFI and UEFI implementations do with PrntScrn, if anything.
The usual solution when you need an exact screen image is to use a digital camera.
Use a shutter speed of 1/30 second or slower, to avoid any screen refresh or black-screen-insertion artifacts.
Use whatever focal length provides the lowest pincushion or barrel distortion, usually telephoto.
Use a tripod. Be on-axis. Use the self-portrait timer if you don't have a cable release.
Set a custom white balance using an all-white screen.
Since BIOS displays are 640x480, any Mpixel count over 1Mp will do to avoid sampling artifacts when you crop, de-rotate, resize or otherwise morph the image to the final 640x480.