AJA Video Systems Forum
Down Convert Distortion
Down Convert Distortion
by Matt Dufilho on Jan 11, 2011 at 9:58:25 pm

Here's my situation:

Seeing a slight widening distortion on video as seen in my CRT monitor fed by KonaLHi RGB outs. This is seen in the "Crop" and "Letterbox" downconvert settings in the LHi Control Panel settings, with the aspect on the CRT set to 4:3. However, when the downconvert setting is changed to "Anamorphic" and the CRT setting is changed to 16:9, it looks perfect.

Questions: Can I view a full-screen, 4:3 crop image (center cut) on this CRT without this slight widening distortion? Does this have to do with the PAR?

Here are my current LHi settings:

Buffer: 720p59.94

Downconvert secondary: 525i29.97

Any help or advice would be greatly appreciated.

Re: Down Convert Distortion
by Matt Dufilho on Jan 12, 2011 at 3:44:19 am


My CRT (Panasonic BTH1390YN)seems to have a slight green cast when compared to the video on my LCDs. Tried adjusting the chroma and phase knobs, but these are disabled with RGB input.

Did I just buy too old of a screen? Any ideas?

Re: Down Convert Distortion
by Bob Zelin on Jan 12, 2011 at 4:03:40 am

yes -
throw out your CRT. It's over.

mismatch in the black "gains" is what causes the green tint. Are you going to pay for a monitor calibration at this point ? Of course not.

Bob Zelin

Re: Down Convert Distortion
by Matt Dufilho on Jan 12, 2011 at 4:09:19 am

Thanks, Bob. Not that I like what I hear...but hey...the truth hurts sometimes.

What do you think about the "distortion". Is it the PAR?

Re: Down Convert Distortion
by Michael Sacci on Jan 12, 2011 at 6:30:39 am

[Bob Zelin] "throw out your CRT."

NEVER, they will have to pry my tube out of my cold dead hands!

Re: Down Convert Distortion
by Matt Dufilho on Jan 12, 2011 at 2:41:08 pm


Do you mean that there's something wrong with the screen, or just that it would need to be calibrated?

Re: Down Convert Distortion
by Bob Zelin on Jan 16, 2011 at 10:06:36 pm

listen, I googled Panasonic BTH1390YN, and nothing comes up. Are you sure this is the exact model #, or is there a typo in the text.

you open up your monitor, and with a non conductive screwdriver, you feed NTSC black into your monitor, and adjust the black gains (R G B) until your green hue goes away. Leave your G alone, and adjust R and B until you get true black. Increase your brigtness so you can see what you are doing.

How you can do this by eye, without a calibration probe is beyond me, but hey, if you have a monitor that is worth $200 bucks, and you want to give it a shot, what the heck.

Bob Zelin

Re: Down Convert Distortion
by Jim Wiseman on Feb 22, 2011 at 3:03:35 am

You can get a pdf of the BTH1390Y at this URL:

I have two of them, and they are great for standard and 16x9 NTSC and PAL, SMPTE and Beta 00 and Beta 7.5 levels, cross pulse, blue only,750 lines, etc.

Worth saving.

Jim Wiseman
Sony PMW-EX1,Pana AJ-D810 DVCPro, DVX-100, Final Cut Studio 2 and 3, Media 100 Suite 1.6.1, AJA ioHD, AJA Kona LHi Avid MC, Hexacore MacPro 3.33 Ghz, Macbook Pro Core2Duo, G5 Quadcore PCIe, Media 100i/XR

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