0 ire or 7.5 ire. Dilima

Re: 0 ire or 7.5 ire. Dilima

An editor friend of mine and I were just having this disscusion on Tues. He told me to shoot 0 setup if you are staying in the digital world. But if you are shooting to go to broadcast (ie Beta) to shoot in 7.5 setup. He told me that most editors would boost the setup to 7.5 if they got DV tapes for intercutting with Beta. If I understand correctly, Jarrred are you saying when the DVX feeds out via analog it does this automatically.
 
Re: 0 ire or 7.5 ire. Dilima

this is gonna get confusing again..

The dvx will add an extra 7.5 ire to its analog outputs if you choose 7.5 setup in the menus. You can test this yourself by hooking your camera up to a waveform monitor and switiching between the 2. If you dont have a waveform monitor kicking around (most people dont) you can see this by just hooking up your DVX to a tv and turning down the lights so most of the picture is dark. When you click setup in the menu you will get a similar effect as you would if you jacked up the master ped all the way up.
 
Re: 0 ire or 7.5 ire. Dilima

Hmmmmm...

There are two conflicting statements in this thread. At least I think they are conflicting. Perhaps I am missing something.

iamloser quotes Adam Wilt saying:

"The AG-DVX100, PD150 and DSR-250 have a "7.5% setup" setting in the menu. Don't use it! It does not add setup to the analog outputs; it modifies the digital data coming from the camera head by boosting the black level, resulting in washed-out blacks, reduced precision, and nonstandard tapes as described above."

Jarred Land then wrote:

"The dvx will add an extra 7.5 ire to its analog outputs if you choose 7.5 setup in the menus."

Mr. Wilt says setup is NOT added to the DVX100's analog outputs. But, Mr. Land says the opposite.

So, which is it?
 
Re: 0 ire or 7.5 ire. Dilima

both are correct,  mr land also says not to use the setup ,,as i quote here:

"Always shoot 0 IRE.  You are shooting Digital and Digital Black is 0 IRE. At the stage that you goto Analog I.E a Television, it will add the Setup to 7.5 IRE for you. If you add 7.5 in the Digital process your analog output will add another 7.5 IRE to the signal and whatever used to be black wont be black anymore."

jarred is giving an example of if you would want to use the setup, and states that the dvx adds setup, which it does.. its just the method that the dvx uses to add setup, which is techncally not  "setup" but gives about the same result. that is why adam says its not real setup.(if i remember correctly, the dvx actually jacks up the pedistal on the digital data, so your digital firewire out will have that greyish black instead of true black..and black should always be black in the digital world.. the analog outputs output the same signal then with the higher black level as well, you can even see the jacked up level in the lcd when you switch between the two,, as jared stated, it looks just like you jacked the MP up.. and basically thats what its doing. so both the digital black, and analog black are jacked up.) but anyway all of this doesnt matter, the fact of the matter is they are both saying not to use the 7.5 setting, and to use the 0 setting.  i think jared was just making a case in point of what happens when you use the dvxs 7.5 setting, and that it boosts the video level by 7.5 ire, he wasnt saying that it should be used at all.

so heres your answer USE O  all the time.

even if someone wanted somthing in 7.5 they can change it themsleves..
 
Re: 0 ire or 7.5 ire. Dilima

Let's get some of the facts straight here so we are all speaking the same language:

IRE is an analog measurement of a digital signal
NTSC in US for broadcast uses set up which is 7.5IRE. 99% of all monitors in the comsumers homes are analog.
PAL and NTSC-J (Japan) use 0IRE
What you shoot and what your correct for are very different matters.
The only consistent standard for PAL and NTSC for 8 bit formats is that SMPTE defines black as 16RGB and white as 235RGB for television.
Film and other computer based streaming formats use a 0-255 RGB as the full scale.
When deliverying for NTSC broadcast, the blackest legal black is 7.5IRE (16RGB), the whitest white is 100IRE (235RGB).

Shooting Setup at 7.5 and master pedestal at -8 will give you the exact same black level on the recorded material as shooting 0 Setup and -6 Master pedestal. THE SAME!

As mentioned earlier, there is not even 2.5IRE difference between the 0 and 7.5 setup as excpected, this has been corrected on the new "a" version.

If you are monitoring on the set, and the environment it is set in will affect the image far more than what the set up is set for, a properly set up analog monitor expects set up (this black at 7.5).

But since shooting is all over the map depending on condtions and this being uncorrected for legal broadcast, the viewers must adjust their approach to the material. In broad daylight which washed out the image on the monitor, you may feel compelled to keep loweing the MP and set up to make nice rich blacks in the set but then realize in post in a real environment you lost a ton of detail in the shadows becuase of the crushing of blacks on the set.

Knowing that 16RGB is the international SMPTE standard for black, the following settings will give you black at 16RGB (original camera):

Setup 7.5 and MP = -8
Setup 0 and MP = -6

Everything else will give you more or less shadow detail and changing those will be based on creative decisions, the look and feel etc.

I say pick one or the other for Setup amnd learn how MP affects that image. I shoo with 7.5 setup because it gives me more room at the black end before the sensors cut off completely. See my chart at:

http://www.24p.com/dvx.htm


Michael
 
Re: 0 ire or 7.5 ire. Dilima

while this is very true for the dvx, since its setup option only changes the black level, instead of the actual ire luminance values to give the same result..does it hold true for other cameras? i would imagine so since on a camera with real setup, your digital black from the 7.5 setup setting should still be pure black when viewed at 0 ire, unlike the dvx from which the black level will still be grey when viewed at 0 ire since it was changed , so you could still shoot in either one then, and be fine. it all comes down to post with the dvx.
 
Re: 0 ire or 7.5 ire. Dilima

Michael. just so I'm clear on this, if I'm using a production monitor for adjusting my lights I should add setup. And set the camera to 7.5IRE and lower the MP?
 
Re: 0 ire or 7.5 ire. Dilima

The setting I showed for 7.5 is the proper setup for analog monitors, so yes, if you have an analog monitor on the set, start there. But this assumes a properly calibrated monitor in a proper viewing environment. All dark is not good either for a monitor (it is for projection). As you would guess, there is also a SMPTE standard for viewing environments... and color correction decisions.


Michael
 
Re: 0 ire or 7.5 ire. Dilima

.. jareds pics are a great reference for seeing how the setup on the dvx effects the image.  and just to try to clear up any confusion i may have cause with all the "dvx improper setup thing" ill try to explain it simply here as well.

ok.. the setup is supposed to affect the IRE luminace values of the video. the dvx setup does not do that. instead it changes the actual color information, to change the colors so that they look like they are being displayed with more luminence(brighter)  (basically it adjusts the master ped black level. so basically its like the difference betwen turning the brightness up on your tv till the black shows up as grey..which is proper setup.. or just playing a grey signal through your tv while you leave the brightness the same.. dvx setup.  they both look the same, and give off the same signal at this point, but with proper setup, when you turn the brightness back down/or play it in a 0 setup environment, the black will be black..-like a dvd is black on pc-grey on tv-, but  the grey signal played at any brightness will always be outputting a grey signal..even in a 0 ire viewing )  in other words  if you add 7.5 IRE brightness to  black. it would then be brighter than black, and show up as a greyish tone. and every color , and such would be shades whiter due to added brightness. but the dvx doesnt add setup brightness which actually makes the image display brighter, what it does is cheat. it just changes the actual colors, to the colors that would be showing if the image were displayed brighter. so in other words with real setup, your digital black would stay black, but when displayed with setup, it would show up grey.. then when you display it in a 0 setup enviropnment it will go back to black, cause the setup is only affecting the brightness/luminance of the display. think of a dvd.. they all have 0 ire setup,, and therefore when they are shown on a computer monitor whic has no setup.. the black are black(your monitor must be calibrated)..and when you watch it on a tv.. the blacks are somwhat greyish..and not completely black from the added 7.5 IRE brightness. but if you record somthing with the dvx 7.5 "setup" it doesnt touch the brightness values of the video, it just changes your black to that greyish color so that it looks that same as if it were being played back brighter. so when you watch somthing done like that on the same computer monitor wich has no setup, your blacks will be that grey color instead of black like thay should be. anyway as micheal said on the dvx you can use either one.   again since the "setup" is only changing the master ped black level, and not the actual luminance values, you can get the same exact signal in either method by adjusing the mp accordingly.    for my own personal purposes, i just leave it in 0 at the -6 setting for MP.

i probably just confused alot of people even more .. but oh well. i can think of how to explain it any better right now. sorry.
 
Re: 0 ire or 7.5 ire. Dilima

You will also see in Jarred's hard work with all the settings, that the 7.5/-8 and the 0/-5 are nearly identical.
 
Re: 0 ire or 7.5 ire. Dilima

Jarred when you a shooting on set with a Sony 8045q monitor do set the DVX100 to 7.5IRE ?
 
Re: 0 ire or 7.5 ire. Dilima

i never ever set the DVX to 7.5 setup. Hey how is that monitor working out for you? If i recall right you got a great deal on it right?
 
Re: 0 ire or 7.5 ire. Dilima

No I got out bid so I'm looking at buying a new one that has been calibrated . That comes in this cool hardshell case. Check on e-bay under sony pvm 8054q to see what I'm thinking about buying. Tell me what you think.
 
Re: 0 ire or 7.5 ire. Dilima

good because ive been seeing alot of hooped monitors lately, albiet from rental houses that have been well used. I like that hard case petrol makes, even though it costs almost as much as the monitor does.
 
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