Advice for the DXC-M7 Camera?

[sdsw4]

After a year of troubleshooting, I finally fixed my Sony DXC-M7 camera. Turned out to be a bad oscillator that threw me in for a spin (didn't think VCXOs could go bad, but this one did). Sadly required the sacrifice of a perfectly good DXC-151A, but it wasn't in vain.

The camera itself works fine. Actually is a breeze to work with while shooting and feels like a lighter (subjective) but more advanced DXC-M3A.
But there's just one problem: The color balance is atrocious! Unlike the M3A, if I'm not shooting in broad daylight or with space-heating halogens, this thing simply won't balance well.

In the above, illuminated with a 150w equivalent 2700K LED. Camera was in the 3200K filter, then auto-white balanced with +9dB gain and component captured. Despite this, I still had to post-color correct just to at least make myself look more "correct" and not look like a lobster.
Meanwhile, the M3A: hit white balance and it's perfectly balanced on the first try.

With that being said, it's still a powerful camera. But that color balancing is a problem, which leads to the actual question:
For those who have had experience with this camera, what are best practices for using this camera in different environments? The manual gives best practices, but rarely do I expect this camera to be put into "best practices."

[Alex KL-1]

Really the spectrum light of a lot of LED's leaves a lot to be desired. Forcing a extra white balance etc.
Besides some extra issues, like the gamma+color balance predicted for monitors of it's era.
Some cameras will be more fussy anyway about it I presume.

[Dave A]

Do you have the CCU-M7? I have a CCU for my M3 and it helps a lot.

[ARC Tech-109]

Glad to see you got it going, I know you fought with that VCXO for some time.

So my experience with the M7 was just as lacking as what you're dealing with now. First generation CCD that had challenges with the white balance that seemed to defy all the best practices short of kilowatts of halogen lighting or direct sunlight, they just washed the deficiencies out... there was a reason I stuck with that M3A, the M7 was abysmal.

As Alex pointed out standard LEDs have a much different spectrum than a black body radiator (tungsten) that look may "right" to the human eye have subtle but distinct non linearities that a camera will pick up on, professional LED lighting has compensations for these differences. Both my D-55 and DVW-790 will pick up the slight differences of the consumer white LEDs showing them as a white balance error.

150 watts isn't really enough for the M7 be it true power or equivalent, 4x this would be more of what the camera really needs to stand out. Most of the power in the key light with 2/3 that in the fill and back lights spaced 4-6 feet out from the subject using a 3 point layout. Years ago I used cheap umbrellas that I shot with silver paint on the inside to make soft lights out of, I powered them with those yellow halogen work lights from Menards and used spring loaded woodworking clamps to hold them in place. Most of my interior work was done using these and they were 3000K so the camera would balance without a problem.

In your situation I'd recommend a soft key light just to your right at 300 watts 4 feet away and a fill of equal power to your left but higher up and 6 feet away for that particular scene. To make a soft key aim a scoop or medium flood light at a white bed sheet keeping it 3 feet away with you 4 feet from the sheet and do the same for the fill but have the light up higher to both fill in the side shadows and give some depth. If you're going to use LED I'd recommend going with those adjustable "paddle" or panels used for garages or large areas and not the COB style unless you have a large scoop given their dispersion. The paddles are going to be some 4100K so you will need to filter for these possibly run in 5600K mode and see if it will balance down. The problem with LED is the "equivalent" is somewhat subjective and seldom accurate. is it 150 watt equivalent to a bare bulb or reflector? Modern solid state 48" T8 fluorescents seem to do well if all the tubes are from a matched lot and the same age, again they're 4100K and need to balance down (or up) but I've used them in a pinch.

I sent you a message this morning, let me know if you got it as I've changed phones.

[sdsw4]

Originally Posted by ARC Tech-109

Glad to see you got it going, I know you fought with that VCXO for some time.

So my experience with the M7 was just as lacking as what you're dealing with now. First generation CCD that had challenges with the white balance that seemed to defy all the best practices short of kilowatts of halogen lighting or direct sunlight, they just washed the deficiencies out... there was a reason I stuck with that M3A, the M7 was abysmal.

As Alex pointed out standard LEDs have a much different spectrum than a black body radiator (tungsten) that look may "right" to the human eye have subtle but distinct non linearities that a camera will pick up on, professional LED lighting has compensations for these differences. Both my D-55 and DVW-790 will pick up the slight differences of the consumer white LEDs showing them as a white balance error.

150 watts isn't really enough for the M7 be it true power or equivalent, 4x this would be more of what the camera really needs to stand out. Most of the power in the key light with 2/3 that in the fill and back lights spaced 4-6 feet out from the subject using a 3 point layout. Years ago I used cheap umbrellas that I shot with silver paint on the inside to make soft lights out of, I powered them with those yellow halogen work lights from Menards and used spring loaded woodworking clamps to hold them in place. Most of my interior work was done using these and they were 3000K so the camera would balance without a problem.

In your situation I'd recommend a soft key light just to your right at 300 watts 4 feet away and a fill of equal power to your left but higher up and 6 feet away for that particular scene. To make a soft key aim a scoop or medium flood light at a white bed sheet keeping it 3 feet away with you 4 feet from the sheet and do the same for the fill but have the light up higher to both fill in the side shadows and give some depth. If you're going to use LED I'd recommend going with those adjustable "paddle" or panels used for garages or large areas and not the COB style unless you have a large scoop given their dispersion. The paddles are going to be some 4100K so you will need to filter for these possibly run in 5600K mode and see if it will balance down. The problem with LED is the "equivalent" is somewhat subjective and seldom accurate. is it 150 watt equivalent to a bare bulb or reflector? Modern solid state 48" T8 fluorescents seem to do well if all the tubes are from a matched lot and the same age, again they're 4100K and need to balance down (or up) but I've used them in a pinch.

I sent you a message this morning, let me know if you got it as I've changed phones.

Saw your text!

But if it's one thing I noticed...
Videokarma will tell me how to wire and drive a tube-camera the right way. Down to the coils in a DIY camera.

While another lighting-centric board will tell me the exact lighting setup that was used, down to the exact bulbs, wattage and voltage drop per bulb for maximum efficiency.

That being said, finals are coming up but I'll take everyone's feedback into place. I have period-correct fluorescents/CFLs, ballasts, incandescents (in this case deemed 'Iodine Lamps') and practically what's needed to make the neighbors file a light complaint. Stay tuned!

[ARC Tech-109]

Neighbors will get over it, mine have become numb to the what I have going on around here and never complain knowing I'm right there to give them a hand. Never a complaint from me when they want to party late or tune his Wissota modified the friday night before the races. Good folk in this small town that are not exactly politically correct or into others business. Earlier this year I did a high speed run on the neighbor kids' Hayabusa for the camera... three runs at 10,500 and 130-something miles/hr and no one complained. Lights wouldn't even get noticed.

[Tube TV]

With older cameras the more light the better is the rule of thumb I go by. I too have had nice white balancing for CCD cameras with 48" fluorescent lights. How does it do if you shoot a SMPTE color chart? Is there a color that shows up more heavy than others?

To me the lighting in this picture looks a bit low for good color reproduction from a camera this age. I would aim for at least 200 to 300 lux minimum if I wanted accurate color. Judging by how bright the monitor is in the background this was shot at below 100 lux.

There's a lot of other factors that come in to play as well. Colors show up much brighter and warmer on CRT and whites show up whiter compared to LCD. Also LED lighting was not around back when this camera was made.

[ARC Tech-109]

sdsw4: I came across two other tapes made with the M3A in my collection and will post a couple of caps in the next few days so you can get a better "feel" for what it was like in the glory days. Tapes are 3/4SP originals and I will do the grabs as hidef jpegs straight into the Tricaster.

[sdsw4]

Oh nice!

Also, yeah I did know it needed a metric ton of light, just needed stands.
This time I added a daylight 400w equivalent, and now it balances a whole lot better, and I can bring the gain to 0.
I will buy another socket and 400w bulb in a bit and see if I can tape it to another tripod for the right side. Should provide enough light at that point.


But now I have to deal with the atrocious bloom...