Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Early Color Television

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #226  
Old 05-20-2018, 06:37 PM
etype2's Avatar
etype2 etype2 is offline
VideoKarma Member
 
Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
Posts: 1,487
Quote:
Originally Posted by old_tv_nut View Post
Whoa! Look at Tournament of Roses Parade #2, at 01:26 and following, and 01:58 and following. In these scenes, much of the background is neutral pavement. In the 21CT55 there is a 60 Hz blue hum bar moving slowly upward. The CTC-5 also has a hum bar, but it's weaker and different.

Some portion of these effects could be caused by a beat between the TV video and your camera sensor, but I don't see how your camera could cause two different effects on the two sets like that. It seems like there's some hum in the color circuits or the blue matrix/amplifier, which sometimes makes the bottom bluer and sometimes not. The DC restorer *might* be able to take out hum, but then again maybe not, if the time constants are long.

Besides checking DC restorer operation, maybe you should be looking for the hum.
Eagle eye Wayne! I hadn’t noticed the blue bar only the annoying greenish/yellow bar. The yellow bar is definitely from the camera and possibley the blue bar as well. This video was taken with an iPhone X. The yellow bar still shows up in photos taken by A Sony A6300 at 1/30, 1/40, 1/50.

Here are the frames Wayne noticed.



__________________
Personal website dedicated to Vintage Television https://visions4netjournal.com
Reply With Quote
  #227  
Old 05-20-2018, 06:40 PM
etype2's Avatar
etype2 etype2 is offline
VideoKarma Member
 
Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
Posts: 1,487
Quote:
Originally Posted by old_tv_nut View Post
By the way, I thought I caught a brief glimpse on one of the videos (sorry, I can't find it again) of the CTC-5 hue pulling momentarily in the top third of the picture. I have this problem with my CTC-5 occasionally when there is a strongly colored area at the left of the picture, and the horizontal hold is slightly off, causing the burst gate to let in some picture chroma. I haven't bothered to put a scope on it to see if the burst gate pulse is too wide or something.
It’s a CT -7.
__________________
Personal website dedicated to Vintage Television https://visions4netjournal.com
Reply With Quote
  #228  
Old 05-20-2018, 06:40 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
On second thought, the two screens are at different vertical positions in your video frame, and this combined with the camera's rolling shutter could cause different hum bars.

So, do you see any of this hum bar with the naked eye? If not, forget it, it's purely a camera issue.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #229  
Old 05-20-2018, 06:41 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
Quote:
Originally Posted by etype2 View Post
It’s a CT -7.
oops - senior moment
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #230  
Old 05-20-2018, 06:48 PM
etype2's Avatar
etype2 etype2 is offline
VideoKarma Member
 
Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
Posts: 1,487
Me too, all the time.
I definitely see the blue bar in the video, but I can’t see the blue or yellow bar live. Pretty sure it’s the camera. In fact, when shooting the stills in the viewfinder and it’s processing, I can see the yellow bar. I try to mitigate, by shooting multiple shots. I’m using aprature priority, auto white balance and ISO. I’ve tryed different speeds. Seem to get best results at 1/30, 1/40.
__________________
Personal website dedicated to Vintage Television https://visions4netjournal.com
Reply With Quote
Audiokarma
  #231  
Old 06-03-2018, 04:17 AM
etype2's Avatar
etype2 etype2 is offline
VideoKarma Member
 
Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
Posts: 1,487
So I decided to look into the the DC restoration issue today. As it turned out, it was the cameras fault, not the TV. I was not seeing the blue push that the photograph showed. I adjusted the white balance to what I was seeing on the screen. It was set to auto, and we changed it to “shade” which better matched the actual colors on the screen.

The first shot is the one posted earlier and commented on. The second shot was from today after adjustment. All shots original size 6000X4000 reduced for posting here.

The yellow straw hat is influenceing the skin tone.





I’m also posting some test shots from the Video Esentials disk using the new white balance setting.











__________________
Personal website dedicated to Vintage Television https://visions4netjournal.com

Last edited by etype2; 06-04-2018 at 02:15 PM.
Reply With Quote
  #232  
Old 06-03-2018, 10:43 AM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
Very nice
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #233  
Old 06-05-2018, 03:36 AM
etype2's Avatar
etype2 etype2 is offline
VideoKarma Member
 
Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
Posts: 1,487
Smile

Back in the day, I used an analog Nikon 35mm SLR. In those days the camera did not have ISO settings or white balance settings. Film was generally slow, so one wanted a lens with an aperture that allowed the most light to strike the film such as 1.4. You bought “fast” film and high ISO ratings.

I haven’t operated that camera since 1998. Been using cell phone cameras. Recently my wife gifted me with a nice DSLR, mirrorless, APS-C sensor, with interchangeable lens’s. It’s been a learning curve adjusting to all the settings available. Case in point, white balance. What I learned, check the white balance of the subject your shooting. :-)

The “sweet spot” or maximum focus of my lens based on an Aperture of 3.5 is supposed to be about F9. So today, I tried that setting on the 21CT55, but all the shots turned out lousy.

From the old days of analog, shooting through the center of the lens (stopping down or closeing the lens) was usually the sharpest. A lens is curved so you have distortion at the outer edges of the lens. Sony used this anolgy effectively in advertising in 1968 with their one gun, one “lens” Trinitron. I found F16 worked the best for screenshots.

I think I’ve got it right?

I’ve attached two sets of comparison photos. You can see the blue “push” with auto white balance.



__________________
Personal website dedicated to Vintage Television https://visions4netjournal.com

Last edited by etype2; 06-05-2018 at 09:33 AM. Reason: Typos
Reply With Quote
  #234  
Old 06-05-2018, 08:35 AM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 1,191
Some things to worry aboyt using SLRs.

First, focus and saturation. The cameras will generally resolve the
individual dots on a color CRT. This means that using autoexposure, which
generally goes for average brightness, the brightest dots will very often overload,
ruining color rendition in highlights. To avoid this, underexpose or use manual focus
so the dots are just barely out of focus.

Color balance is as you notice a problem. By choosing a setting you may be
able to find one that looks OK. Otherwise, if you camera can save as "raw" files,
you can correct perfectly in software. That's what I do.
Reply With Quote
  #235  
Old 06-05-2018, 10:40 AM
etype2's Avatar
etype2 etype2 is offline
VideoKarma Member
 
Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
Posts: 1,487
Quote:
Originally Posted by dtvmcdonald View Post
Some things to worry aboyt using SLRs.

First, focus and saturation. The cameras will generally resolve the
individual dots on a color CRT. This means that using autoexposure, which
generally goes for average brightness, the brightest dots will very often overload,
ruining color rendition in highlights. To avoid this, underexpose or use manual focus
so the dots are just barely out of focus.

Color balance is as you notice a problem. By choosing a setting you may be
able to find one that looks OK. Otherwise, if you camera can save as "raw" files,
you can correct perfectly in software. That's what I do.
If I understand you correctly, you are saying by defocusing, the camera metering system will read the image differently since it can’t “see” the pixels and hence, won’t “blow up” the highlights? Interesting. I imagine the image will have a softer look. Must try it.

Still not fully comfortable with my camera, but I’m able to shoot “RAW” and need software to use it.
__________________
Personal website dedicated to Vintage Television https://visions4netjournal.com

Last edited by etype2; 06-05-2018 at 10:54 AM. Reason: Grammar
Reply With Quote
Audiokarma
  #236  
Old 06-05-2018, 11:32 AM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
Defocusing slightly doesn't make the auto exposure work differently. When you defocus, insted of imaging bright phosphor dots on some pixels and the dark spaces between the dots on adjacent pixels, you spread the bright dot over several nearby pixels so they see an average brightness that is more like the average that the automatic exposure sees.

Defocusing is tricky to do just enough that it prevents bright pixel overexposure but doesn't degrade resolution. As stated by DTVMcDonald, if you adjust the exposure towards a darker picture, it will help the very brightest pixels not be overexposed. However, if your picture is sharp enough to resolve the phosphor dots, this will mean the picture will look darker on average.

Regarding white balance: if your camera provides a way to save a custom white balance, you could do that by turning the color down and capturing that setting on a black and white image. But I agree with the comment that the best way to handle this is to shoot in raw mode and adjust the white balance in software.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #237  
Old 06-05-2018, 11:45 AM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
By the way, when you say "aperture 3.5" and "f/16" these are contradictory. The 3.5, I suspect, is the maximum aperture of your lens, but you are really stopping it down to f/16.

The best resolution of many lenses is around f/8 or so, but any aperture from f/4 to f/16 is probably good enough to resolve the phosphor dots.

Since you seem to be keeping a shutter of 1/30 second while varying aperture, your camera must be automatically adjusting ISO. Using f/16 may be forcing the ISO higher than necessary, so I woud try f/8.

Your camera seems to be doing a good job, but you might try full manual mode: Set ISO at perhaps 400 for starters; set shutter at 1/30; then see what aperture gives a good exposure. If you can't get a reasonable aperture with ISO 400 and 1/30 second, adjust the ISO to allow a reasonable aperture. The goal is to not use an unnecessarily high ISO, which introduces noise.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #238  
Old 06-05-2018, 11:57 AM
etype2's Avatar
etype2 etype2 is offline
VideoKarma Member
 
Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
Posts: 1,487
Thanks!
__________________
Personal website dedicated to Vintage Television https://visions4netjournal.com
Reply With Quote
  #239  
Old 06-05-2018, 12:08 PM
etype2's Avatar
etype2 etype2 is offline
VideoKarma Member
 
Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
Posts: 1,487
Something bothering me. I have an image on freeze frame. I take multiple shots until I eliminate the annoying yellow band. While doing this, the color balance seems to change with every shot. This was also happening with cell phone shots. Makes me lose confidence in my camera. While it’s not a $4K camera, it’s a decent pro-sumer camera. It’s probably the camera operator not understanding his camera?
__________________
Personal website dedicated to Vintage Television https://visions4netjournal.com
Reply With Quote
  #240  
Old 06-05-2018, 12:24 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
Quote:
Originally Posted by etype2 View Post
Something bothering me. I have an image on freeze frame. I take multiple shots until I eliminate the annoying yellow band. While doing this, the color balance seems to change with every shot. This was also happening with cell phone shots. Makes me lose confidence in my camera. While it’s not a $4K camera, it’s a decent pro-sumer camera. It’s probably the camera operator not understanding his camera?
This may be due to the electronic shutter on your camera. The cell phone is probably a hopeless case if it doesn't give you full manual control.

Does the problem on the Sony appear when you have the shutter speed set manually to 1/30, or is the camera possibly setting a different shutter speed?

The light from the CRT scanning spot is brightest for only a few microseconds, but then trails off at different rates for the three primary colors. The only way to get the same exposure for all three colors everywhere on the screen is to have the shutter open for exactly an integer number of frames of 1/30 second each. If your shutter captures some number of frames plus or minus a fraction, you will see the different trail off of light output from each phosphor color.

Edit: in a camera with a physical shutter, this effect is so abrupt that it will cause a dark "shutter bar" across the part of the picture that didn't get a full frame of exposure.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
Audiokarma
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:31 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.