Photographing CRTs

[dreadnought]

As you might've guessed the exact title should be "photographing CRT live displays", to be more exact. Taking a photo of a switched off TV box itself is fairly straightforward ;)

When it's on, not so much. Due to the nature of the arcane magic powering these things - what I imagine is a mixture of alien death rays, cosmic background radiation and black hole essence - trying to take a perfect pix of a live CRT screen can be fairly tricky. I was wondering if the resident experts might have any advice.

I found two fairly decent articles on the subject:
-http://www.halfhill.com/video.html
-http://strobist.blogspot.co.uk/2006/04/ ... s-and.html

So basically the golden rule is "shoot under 1/30". Darken the room as much as possible, avoid reflections. Pray to the Phosphor God.

I tried this (bar the last bit). The results vary, seeing as I don' have a tripod - at this exposure speeds it can be tricky to maintain perfect balance while in handheld mode. Also, I suppose the inherent flickery nature of the medium might play a part. Bu that's a lesser problem, I suppose that with a tripod (or at least a makeshift one) the sharpness can be more less brought under control.

More worrying for me was the fact that white balance is extremely difficult to reproduce properly. Basically, the colours you get in the photo seldom match the ones on screen. Not sure how to deal with this (tried lots of different mods, custom one sometimes help). You can of course try and compensate in some post processing program, but that's more of a hassle, especially seeing as you then need to fire up the game and find the particular scene to compare.

I'm using Sony RX100. Mostly tried with shutter at 1/15, f stops depending on the scene (mostly 2-5) and ISO 200. The TV is KV-29F2U Trinitron (contrast: near max, brightness: about 1/3rd) fed RGB signal from RPi3 B.

Some examples (click for the big ones)



Any suggestions on how to improve the results most appreciated. I'm mostly concerned with sharpness & colour reproduction, geometry/framing is more of a "mechanical", easy issue (similarly, these haven't been retouched with usual post process tools).

[coderkind]

I’d be interested too.

How do you find that CRT for gaming by the way? Sharp?

[Tapeworm]

I don't have much advice for shutter speeds and ISO and stuff. Some cameras do offer the ability to adjust white balance--mine does and I just toy with white balance until the LCD matched what I was seeing in real life.

But I do recommend a tripod...those scanlines need to look nice as possible!

Actually, I have the same camera as you (pretty sure...). There is an in camera setting for Custom white balance where you can move an icon across the color balance to get differing temps.

[Josh128]

A few shots of my 27" Sony Trinitron Wega I took a few years ago. Used a tripod and a Fuji 3MP camera. A sharp input /source makes a big difference too.

https://imgur.com/a/0FxFF

[elvis]

avoid reflections.

Back in the 80s and 90s, they used to have a makeshift squarish cardboard cone of sorts that they'd use to eliminate reflections. I tried to find a few shots of it, but nothing turned up in a quick Google search.

It would also help center the shot, and ensure the exact distance from the screen each time.

[nissling]

I'm only using DSLRs for all my photographing. I'd say match the shutter with your refresh rate. For focal lenght, use a normal lens or longer (avoid wide-angle and fisheye). Screen sizes at 20" or higher I prefer to have a larger aperture (3.5-4.5 is usually enough) while smaller CRTs benefit from using a smaller aperture. Automatic focus may work somewhat but manual is recommended to avoid moire. Set the ISO so you get a somewhat bright picture but not too noisy. Set white balance at either 5600° or 6500° Kelvin, otherwise you'll lose too much color.

There are no rules of thumb when photographing CRTs. You have to experience it yourself and get good in order to make decisions for your shots. The suggestions above are mainly for 15KHz. CRTs with higher line frequency are much more difficult to capture.

I'd say avoid kit lenses. Primes are much better when you're on a budget. If you really want to play around I suggest getting a macro lens. The Nikkor 40mm/2.8G (APS-C) is fantastic for its price tag.

[Balladof32]

Hi, do you still have you're f2u ? I have one myself and is there an art to getting any audio out of it in the menus ? I have the 2 correct stereo speakers attached which do work as I can get the test tone from the f2u. Tv is def not on mute and I can't get any audio at all . Tried both and MD and Saturn via the rgb av1 input and nothing :-/ . Thought you might know something I don't .

[Taiyaki]

I'm only using DSLRs for all my photographing. I'd say match the shutter with your refresh rate. For focal lenght, use a normal lens or longer (avoid wide-angle and fisheye). Screen sizes at 20" or higher I prefer to have a larger aperture (3.5-4.5 is usually enough) while smaller CRTs benefit from using a smaller aperture. Automatic focus may work somewhat but manual is recommended to avoid moire. Set the ISO so you get a somewhat bright picture but not too noisy. Set white balance at either 5600° or 6500° Kelvin, otherwise you'll lose too much color.

There are no rules of thumb when photographing CRTs. You have to experience it yourself and get good in order to make decisions for your shots. The suggestions above are mainly for 15KHz. CRTs with higher line frequency are much more difficult to capture.

I'd say avoid kit lenses. Primes are much better when you're on a budget. If you really want to play around I suggest getting a macro lens. The Nikkor 40mm/2.8G (APS-C) is fantastic for its price tag.

These are some great tips.

[strayan]

I have a iPad Pro and it takes excellent photos of CRTs.

Here’s a few examples (I was simply holding the iPad when I took these and didn’t mess with the lighting or anything):

https://imgur.com/a/chlXYJ0

[Josh128]

Its not voodoo, its really just a matter of stability, shutter speed and light sensitivity. Use a rest or a tripod.


CRTs create their images from light emitted from red, green, and blue phosphors excited by a 1 vertical pixel thick (actual thickness depends on resolution) composite scanning electron beam that is comprised of 3 different beams, one for each color. It scans, starting from the top of the screen, left to right, the entirety of the width of visible screen, + small non-visible portions on the far left and far right, then moves down 1 vertical pixel distance and repeats the process until it has scanned the entire screen then repeats the process, continually updating the deflection of each individual color beam, to create the changes needed to update new images as it needs. It scans the entire screen at the number of times per second that equals the refresh rate of the monitor.

The overall scanning speed plays an important part in your eyes and brains perception of a solid image being displayed. The excitation speed (speed at which the phosphors react to being struck by the electron beam and illuminate) and the decay speed ( aka persistence, the speed at which the phosphors darken after the beam has struck them) of the phosphors play an important part in also play important parts in perceived "flicker" and smearing or blurring of moving imagery.

If you consider all this, it makes it easier to look for settings on a camera to capture the images you want.

Closeup of a high TVL VGA monitor:


Full Size: https://i.imgur.com/JpOvj1L.jpg

If you want to capture an image similar to what your eyes and brain perceive, a rule of thumb is: Low shutter speed, medium ISO.
If you want to capture what is actually technically happening on the CRT, a rule of thumb is: high shutter speed, high ISO, and wide aperture.

Heres a couple photos of the actual scanning beam of the same monitor above, taken at a shutter speed of 1/4000 sec. That is still not fast enough to capture a single beam, just as fast as my camera can go. You would need a shutter speed approx. equal to the KHz of your display to capture a single beam scan.

60Hz Refresh

Full Size: https://i.imgur.com/xgdGO5S.jpg

120Hz Refresh

Full Size: https://i.imgur.com/wgS5svvh.jpg