Originally Posted by KenTech
Even if you have only a film camera whose light meter you trust, you can do quite well -
Great idea! It also occurs to me this would likely be a good method to use to "double check" and perhaps improve my white level "balancing" among different inputs/soures with SPIC/etc, and make any adjustments as necessary. Given of course a suitable level of white on screen from test pattern(easy enough to do for MS, and for inputs I can hook up a DVD player).
Anyhow -- Ok -- I found this to be easy enough, except for documenting my results in this post! I tried this with the light meter on my trusty Canon FTb SLR, using 50mm Canon FD lens(note to self - although it's fine now, need to get a new battery for the light meter soon!). In this application, It's light meter(uses CdS photocell/coupled to shutter speed, f-stop+film speed) uses Full aperature Metering, but with a central area metering system, which measures the center 12% of the frame or "picture area". You can see the 12% area of measurement directly in the viewfinder. As suggested, to take the measurements I used 1/15 shutter speed, ASA 100 film speed setting.
For the test pattern, I used DVE chapter 12, #12 "window" pattern, which is labeled "100% amplitude"(100 IRE I presume), and set the camera such that the entire metered area was "covered" with the white from the test pattern, with the TV set for "full" mode(test pattern(including all the black in the test pattern uses the entire 16x9 screen). I believe this results in somewhat close to about 20~30% or so of the screen area. I didn't double check it to make sure, but I hope it wasn't too big of an area of the screen to the extent ABL kicked in. *Update 02:45UTC Mon* : I just confirmed the below measurements with "Pluge+grey" pattern from DVE.
TV settings used: Other than the differences in Picture slider noted farther below, The following relevant settings were used for TV : 2170P-1 - RDRV~BCUT 33-17-9-22-17-11, Brightness slider at 31. SBRT=29(factory adjusted default was SBRT=28). 2170P-4 SPIO at factory default value of 10. Since I was using 480p via component video input from DVD player, I have 2170P-3 UBOF=0 for this source(note: I have UBOF settings ranging from 0~5 to balance black levels among different sources/inputs/etc, just so happens 480p from my DVD player needs the lowest setting). I have 2170P-4 SPIC=6 for this source, SPIC ranges from 0~6 to balance white levels among all different sources/inputs. This DVD player at 480p just happens to need the highest SPIC value, for 480i from the same player to "match" this it needs/is set at SPIC=0, as do most other sources. Also, of some slight relevance here are my following current settings for CBGN~YGN, which I adjusted necessarily to correct for a color imbalance for 480p/720p+1080i vs. everything else as discussed earlier in this thread, as well as to lower luminance slightly for 720p/1080i from ATSC tuner, given that I "need" SPIC=0 for those to balance among sources, and can't go any "lower" with SPIC!. Current settings at left, factory defaults in parenteses :
CBGN = 4 (4)
CRGN = 4 (5)
YGN = 4 (5)
GAMM was set at 0, GAMR~GAMB also all at 0, the default for GAMM=0. BLK also at 0. ABL settings for all pic modes were adjusted per Ken Tech's recommendations early in this thread for "customizing" pic modes involving related ABL settings, without looking it up in my notes If I recall correctly, those are the pro pic mode ABL defaults. Any other relevant settings involved for Black/white levels match service manual listing for "pro" Picture mode defaults.
------------------------------------------Light meter measurements
- assuming the measurements are actually quite close to "reality", what I'm measuring seems very much to match what I "expect" I've noticed with my eyes ..... :
Follows is what I measured, listed by "picture slider" setting, unless otherwise notided, the below F-stop readings denote the f-stop setting on the lens required so light meter needle is directly in the middle(or more or less) of the ring, which is "attached" via a apeture signal level+pin to the FD lens, and "moves" inside the viewfinder accordingly with different F-stop settings :
KD34XBR960 -- Current, preferred settings, as noted above, and with picture slider at 23 :
f/4.8~5.2(note there is no label on the lens for this f stop setting - it's in between f4.0 and f5.6 - perhaps the "notch" is a little closer to F 5.6) - According to the info you provided, that would seem to put EV in the range of about 8.4 to 8.8 or so. and, according to your notes and the chart, EV 8.4~8.8 is considered "THX standard" for movie theatres. This setting for "screen brightness" is preferred by me in the sense my eyes *do* seem to like it ....
Honestly, anything brighter given a dim room(with ambient light source behind the TV matched to around the ambient light reference from DVE, mostly being reflected off the walls) Is quite fatiguing to my eyes after more than a few minutes of viewing. Anything dimmer appears "too dim". In fact, even in the daytime with "too much" ambient light of the wrong kind involved, it's more than bright enough, to the point of actually being a bit surprising(to me anyway) given what I've experienced in the past with direct-view CRT's in this regard.
Picture slider at "31" :
f5.6/EV 9.0/~20FL per your chart/Info. It seems a little too bright for my preferences on this TV.
Picture slider at "44" :
Approx f6.8(in between F5.6+F8.0 - there is no label for the actual value on the lens) - This is the target value you suggest for EV around 9.6, as you suggest something around 30FT lamberts -- but, to my eyes, this is just way too bright for me .... but, I suppose to a certian extent it's a matter of preference more than anything else ....
Picture slider at "53" :
f8.0, EV of 10 per your info. Certianly way, way too bright.
Additional measurement on another TV : Note I measured with the same test pattern via the camera's light meter on another set I use(Toshiba 34HF84 - also 34" "HD" 16x9 direct View CRT) with my preferred settings set up for that TV. This measurement resulted in f-stop of somewhere right between about f4.8~5.2(again no label on the lens for that one - I probably have documentation on the lens somewhere which would tell exactly what it is) and 5.6, so, the "needle" for the meter would be "closer" to "in the middle of the ring" given say a ~f5.2~F5.4 setting - Which I'd think should be in the range of 8.6~8.8 EV or so. Not surprisingly, very much along the lines of what I prefer "screen brightness" wise on the Sony .....
, I know that Contrast = 31 gives me an accepable 30ft-L screen brightness.
Well, not meaning to be "contrary"(at all, so please don't take this the wrong way!) here, as each to his own, and what is preferred by YOU is of course the important thing in your circumstance ... However, just to comment on this from my "perspective" ---- according to my "measurements" as noted above(if correct, and I suspect they probably are, or are close enough given the results I've been consistantly getting from exposures with this camera+light meter for many, many years, although I've never actually compared it with another light meter ) : I don't think with this set(or any other) there is any way anything that bright would be acceptable to my eyes, they would become easily, and quickly fatigued with that much "brightness".
I can also just as easily remember Pic slider="44"=30FT lamberts as I can "31" for EV 9.0, or "23" for my preferred settings -- Which again, evidently are right along the lines of the "THX standard" per your chart - which, although as you say it applies as a standard for movie theatres(presumably not necessarily Direct View CRT's), I find it interesting, perhaps especially as it also seems to "match" my results from the THX optimizer "contrast" setting screen - which is admittedly, not a "precise" way to the "picture slider", and is only one of many other references I've used to set "white levels" and/or "contrast".
Of Most importantance to me is not conforming to any sort of standard for screen brightness in "foot lamberts" - Instead, for me is that white level/screen "brightness" are such that 1). an excellent picture results(a film-like, very "detailed" pic or whatever you want to call it) and #2). that watching a few hours of TV doesn't become fatiguing on the eyes in a "dim" room enviornment because it is "too bright", But, OTOH, not so "dim" that the pic appears "dim" or "lifeless". Generally, seemingly equivilent to striving for a similar effect "on the eyes"(but not quite as pronounced) when going from a very dark scene to a very bright scene as one gets when they go outside on a bright day after being in a darkened room(such as a movie theatre).
I could of course redefine the DRV values for a mid-range slider setting of "31" to be the "same" as my current preferred "23" setting(EV ~8.4~8.8), although I suspect I'd probably be getting awfully close to "0" for BCUT, which wouldn't work very well for experimentation purposes, including using the Offsets ... And again, I really don't see any reason for me to do this ....
A reminder: Different models of the DA-4 chassis and different copies of the same model will end up with different settings, so anyone's suggestions are very rough!
Definitely! VERY rough! Especially perhaps as it seems what some of us prefer "screen brightness" wise apparently differs. Black levels OTOH are easy to "talk about", and in my experience, fairly easily to set "properly" with a pluge pattern(such as the DVE Pluge+grey or white, or THX optimizer black level test with the "drop shadow").