I've been pretty happy with my XL-1. The one "complaint" I have is that the black levels seem to be crushed quite a bit. I've seen on related threads that the XL-1s can set set-up level. Is there any way to adjust black levels on the XL-1. If not...is there any other recommendations for reducing the contrast?

I'm considering shipping it to Canon for inspection (which I know some folks will suggest anyway). I'd love it if the black levels could be boosted a bit.

-Don

Don,

Would a -3dB gain setting help you? I know that many of us use that as our standard setting since the XL1/1s factory settings tend to be a touch hot.

Canon being a Japanese company uses the super black standard. In the USA we use 7.5 ire black (for whatever reason, I tthink super black looks richer).

The XL1 black level is 0 IRE, however the XL1S allows you to adjust the set-up level in the camera menu. Hope this helps,

Thanks Ken I will try the -3db gain. That is sure to help a bit.

I guess I'm wondering if theres a way that the Canon folks in NJ can boost the black level a bit.

BTW: The suggestion of -3db makes me think of the "spotlight" mode. Does anyone use this? I usually stay in full manual.

(I'm pshched that I just landed a job teaching video production at a college that has....XL-s and GL-1s! This camera has been my hobby to this point. I'm sure I'm going to be getting to know the XL-1 much more this year)

That's great news, Don! Congratulations. Of course you'll send your students over here for extra-credit work. ;-)

Actually Don, Ken isn't kidding at all, your students will be more than welcome here. We can set up a special forum just for them with you as a moderator, or a special account to give them access to all the boards here. Hope this helps,

Ken:

Please help me understand this. I thought that the gain setting is similar to the ASA setting, that it is adjusting the sensitivity of the chips. Thus a mid-level (i.e. plenty of light) exposure of the same scene under different gain settings should have similar gray scale values, the main difference being that the lower gain setting will require the aperture to compensate.

Now how does that effect the baseline black level? Shouldn't that remain constant at 0 db regardless of the gain setting? I have seen that at high gain settings the image appears more contrasty, but I think of that as being a function of increased gamma, wherein the blacks and whites remain constant (0 and 100 ire) but the intermediate points are more steeply stepped.

Charles,
Fundamentally the only action that will change the camera's true black level would be...well...changing the black level setting.

(I'm no true video engineering tech but here's my best shot at an explanation.)

I believe that the XL1/1s' AE control would be the closest analog to film's ASA/ISO adjustments, although the analog is somewhat loose. That is, by making AE adjustments you're essentially adjusting the relationship between shutter speed and iris, much as the setting on a film camera performs this function. In a rather metaphorical sense, therefore, you can think of the AE adjustment as an intervention -in front- of the CCD.

I don't think that the gain control has a direct analog in the film world. Rather, it's closest analog may be in the radio world since its setting adjusts the strength of the signal coming from the CCD block. Higher settings=higher signal strength but more noise. Lower settings=lower signal with less noise. Gain settings, however, will not have an effect on the camera's shutter/iris behavior. That is, by the same metaphor above, the gain intervenes -behind- the CCD block.

I've seen people use both AE and gain to very effectively tweak their image to taste. Since the XL1/1s tends to shoot a bit hot, with somewhat noisy blacks, many folks just leave their gain set to -3dB as standard. Ozzie Alfonso's friend who shot those two Las Vegas shows ( http://www.dvinfo.net/conf/showthread.php?s=&threadid=2273 ) reportedly used a Sony DSR-PD150 with his gain set to -5 (!) for most of the shots. And the results were remarkable, although it's a different camera and DSP.

So, while gain does not change the camera's true black setting, by reducing the signal noise it can produce an -apparent- deepening of black levels and, by visual relationship, slightly higher contrast. When you get a chance, it's fun to set-up some test shots for these various settings.

Hopefully someone with more knowledge than I will correct and/or modify my explanation.

0 dB is the minimum gain on a PD150

Noise will begin to appear with added gain, which may appear to raise the black level but it's just noise.

Not that my NLE is a true waveform monitor, but on an xl1S and a pd-150 it indicates about 5 IRE with no setup added. Everybody says it's really zero in the digidomain, but noise or whatever, it shows to be that.

Both appear to be just a tad under 7.5 IRE with the PD using the 7.5 setup level and the xl1S at +1 setup. I think it's around 9 IRE at +2.

I just wanted to thank everyone for the input on this thread. As time allows I do plan on spending more time on this board. Chris & Ken..when fall comes around I do plan on having my vid prod students use the board. Thanks for the "invite".

Regarding my original post to this thread: It seems that is all I can really try to bring the black level up a bit (or at least appear that way) is try shooting in -3 db. I am going to try this asap. It seems there's no way for the facory to set the black level on the XL-1 (?). Thanks again for all responses.


-Don B.

The gain setting is, indeed, just like the ISO/ASA rating for film speed. Changing the AE setting is equivalent to changing the ASA dial on a still camera, but, leave the same ASA film in it. The AE setting just biases the light meter plus or minus, while the gain actually changes the sensitivity of the CCD to light. Neither have a direct effect on black level, except for the noise generated as explained by Ken.

The DV standard requires 0 IRE for black. That is a given. Adjustment to black level for NTSC standard has gotta be done in post.The "Black Level Adjust" on the XL1s is more than just pedestal.

Bill:

Please expound on the statement "The Black Level Adjust on the XL1s is more than just pedestal". What else does it affect/what exactly is it doing?

Don:

I had thought that the reported effects here of going to -3db were to improve the noise characteristics rather than raise/lower the black level.

One thing that comes to mind for your dilemma is the use of filtration such as Tiffen's Low Contrast filter, which will elevate the black level. There is a slight softening or blooming of highlights with this filter, which can actually be a desirable effect. I'm a fan of their Ultra Contrast filter which transfers some of the highlights into the shadows, effectively increasing the dynamic range of the camera by as much as a stop, and they don't have the blooming characteristic of the Low Cons, but they have to be used with care. Check out tiffen.com, they have some pictures that demonstrate those filters in use.

I will tell you what I know, which admittedly isn't much. I don't know the exact details of the "Level Adjust" on the XL1s except that it isn't true pedestal. At nominal, according to my Vectorscope, the IRE is 0. At negative settings, the black level remains at 0 IRE. At +2, the black level is about 7.5 IRE, at +3 it's 16 IRE. At intermediate settings, the black level remains at 0 IRE. The Level adjust seems to also adjust the contrast of the image so that, in addition to pedestal, it's adjusting the "bandwidth" of the entire signal range. All this is the result of testing I did with my XL1s and a vectorscope, so, take it for what it's worth. In order to view images, I had to download into my NLE, so, there's some effect of the image decoding by the NLE codec before I can view it.

As I said, the DV standard is for black to default to 0 IRE. If the XL1s allows you to vary from DV standard, what happens when you try to lay the signal down to tape? The camera's codec, which I assume is according to DV standard, will crush or stretch the measured black signal to 0 IRE. Why, then, did Canon provide this adjustment. If anyone can shed uhhhhhh, light, on this question, forgive the pun, I'd be interested.

Here is some other ramblings that might help:

- DV range for IRE is 0 to 115(120 for some cameras) That is the equivallent to RGB 16,16,16 and around 255,255,255

- Broadcast standard NTSC IRE is 7.5 to 100. That is equivallent to RGB 36,36,36 and 235,235,235.

- Super Black is actually below 0 IRE and is equivallent to RGB 0,0,0. That is what many title programs use for keying.

- As Bill said, the black level adjustments like a contrast control. It will raise your black levels of the video. A good adjustment for bringing detail out of shadows. What it does not do is raise the pedestal (or blanking) of the signal which will remain at 0 IRE. That can create problems. Though your black levels are within broadcast spec above 7.5 IRE broadcast also has the blanking level at 7.5. Your best bet with DV is to shoot your 0 to 100+ IRE and color correct in post, raising the black levels and pedestal all at once. I find once I bring the video signal into spec it smooths out the picture and actually adds to the color saturation.

So back to the original question about lightening darks, you might also consider a simple proc amp.

(As a side note about color correction and broadcast spec. We have had TONS of discussions about IRE and NTSC standards, and I know we all are learning and trying to do things right. The funny part is I just received several PSA's from the foerest service, local wildlife agencies, state parks, and others for this season of show. All were produced by highend production and post houses. Guess what? More than 75% had illegal IRE levels, going down to 0 and well above 100.) The biggest culprit was graphics. Thought you all might get a chuckle.

How about PAL? If I remember correctly PAL is 0 IRE. That is
16,16,16 or 0,0,0? It is a real bummer that everything is so
geared towards NTSC (not pointing fingers at anyone here).
Try to find a guide about how to calibrate a PAL monitor. There
are plenty for NTSC ones.

Az,
You are saying, to shoot at 0 ire and then correct in post? And as far as graphics, how do you know when you are creating broadcast safe? Alot of what I do will never be broadcast, but at the same time, I use alot of graphics in all of my projects. Is there a color safe chart somewhere, or perhaps an NLE feature?
Keith

Rob,

Yeah, PAL is a different animal. Most the information I liked to read about was at the Tektronics (http://www.tektronics.com). They have been the only WF/VS I have used. Thye have information for PAL and NTSC

Check out:
http://www.tek.com/Measurement/cgi-bin/framed.pl?Document=/Measurement/App_Notes/indexes/video_audio.html&FrameSet=television

Capt,

For DV and editing I just stick with 0 IRE. It is what the camera and digital edit systems work in. I also found the XL-1S likes to have that whole range (0-115) to make video. I have tried kicking up blacks and clamping down whites to be 7.5-100 and it looses the color saturation and doesn't seem to "pop" out the images. Just seem light and flat. Now all that might be different if you have correct lighting, but I do mostly run and gun.

Anyway, so correcting in post is an option, but I would think the best bet is to use a proc amp when you make copies. Shoot in 0, edit in 0, master back in 0. Then, if you go analog use a legalizer or procamp to correct.

As for making safe color, that is where the RGB values come in.

0 IRE is RGB 16, 16, 16. That is black. When you create grapihcs none of the RGB numbers should go below that. If you created a graphic in Photoshop with black letters and you just click the black in the color pallete you would be using illegal colors. That black is 0, 0, 0. Or say you wanted yellow and you go to the swatches and pick the second color of the first line. If you check the RGB values you will see they are 255, 255, 0. Again, an illegal color. Just remember 16 to 235

Also, when you use grapihcs or pictures from other sources or that you scan in you have to bring them into spec. Open the item in Photoshop. Choose levels under the Image menu. Look at the histogram and see if it is too black or too white. If it need correcting then in the output levels type in 16 for the low and 235 for the high. That corrects each of the RGB at one time. Might look washed on a computer screen, but is fine for TV.

I had examples on my website, but I have to organize them better. I have a few hours before the next production is scheduled so maybe I'll work on that really quick and post it.

AS for a color safe chart, I know I saw one at a station I used to visit, but haven't looked for one since.

I have to laugh. Everytime I meet a broadcast engineer the first thing out of my mouth is, "Hi, Michael Rosenberger. What RGB values do you use for an NTSC safe red?" :)

For those of you interested in producing broadcast legal video, Vegas Video 3 has a number of filters to perform this function. One manual way is to play the video and watch the histogram. The histogram will tell you if you ever exceed 0-100 IRE. VV3 also has an internal filter called "broadcast color". This filter will remap the video signal to ensure that all values in the recorded clip stay within the NTSC reqmts. This is really the easiest way. Simply clamping the limits will NOT work, because it will blow out the highlights and crush the shadows. The right approach is to REMAP the entire luma to fit in 16-235 RGB as Azsportsman says. All DV cameras record 0 IRE by specification(default). In order to go legal, YA GOTTA fix this in post. There is NO OTHER WAY....unless you have a proc amp and vector scope/waveform analyzer.

An analogy can be made to audio recording. In digital audio recording, sound levels typically run -24 to 0 dB. Broadcast stations wil NOT broadcast any video in which the audio exceeds 0 dB, because anything over 0 dB will be clipped, resulting in distortion. Any audio signal below -25 dB gets lost in the threshhold noise. Gets complicated doesn't it...hehehehe.

> VV3 also has an internal filter called "broadcast color".
> This filter will remap the video signal to ensure that all
> values in the recorded clip stay within the NTSC reqmts.
> This is really the easiest way.

NICE! Haven't played with VV3 enough. To do the same thing, the external video legalizer we used (SDI) was over $1000 itself. And VV3 is what, $600?

Working on examples for RGB to IRE values using WF and VS and should have a page up in an hour. Also throwing in a quick example of checking and correcting histograms for scans and grapihcs in Photoshop.

I know I sound like a salesman, michael, but I can't say enough good things about Vegas Video. There's as much to getting the audio tweaked, trimmed and legal as there is to the video. VV3 has a really nice set of audio compressors, expanders, and noise filtes to help out.

Here is the link for RGB and IRE tests. PLEASE let me know if you would like to add to it, or think of better wording and examples. Thanks

http://www.azuho.com/waveform/ire.html

Bill,
As for VV3...I am a die hard Canopus user. Not that I enjoy editing in Premiere or StormEdit, just the functionallity of the Canopus hardware, realtime capabilities and the quality of the images. My preferd interface has been FCP since its inception

PS - The page has graphics so it may load slow.

checked your webpage.....good someone has that info up and available. That agrees perfectly with my own procedure except that I'm using a software vectorscope/waveform analyser.....synthetic aperture's Video Finesse. The VF software will do in the video stream what you're doing in Photoshop with the histogram. The problem with doing a single image frame is you never know what frame in the stream has been missed.

A few more notes: I set my zebra to 90% and stay religious about eliminating zebra during my image capturing. This keeps me pretty assured I don't exceed IRE100. The pedestal can be reset with Video Finesse in such a way that the sharp corner of the knee can be rolled off. Gives a much more natural look to the shadows without crushing them. Unfortunately, Video Finesse only works on premier.....not on vv3...yet.

That is just the sum of all the questions I have had to ask over the years and reading forums and articles. Still don't completely understand the ENG side of video (SC, Burst, yadda, yadda, yadda), but I use those basics to make sure I am on the "level"...pardon the pun. Trust me, in my earlier years I had enough tape to stretch from my house to your house returned to me for having something wrong.

Hell, I still find myself making mistakes. The good part is I know they are mistakes and I know how and why to correct them.

Need to get back out to NM. Been craving red chili beef or pork. The stuff I had in Farmington just didn't cut it. You know a spot? How's Red River? :)

I usually set zebra to 100 anymore and look for VERY slight crawl in the hot spots. Like I said, everytime I cut down the high's it seems the XL-1S looses it color saturation. So keeping it on the hairy edge of 100 keeps the color I like and is easy to correct, or just clamp if it is just dribbled peaks.

Canopus used curves, allowing to bring up pedestal and lower whites. It also gives a knee adjustment to shift highlights or shadows. I admit, I need to play with it more to really understand how the adjustment effect picture quality. Sometimes I just put it to spec and I end up with clips that are good, but could be better with specific tweaks.

I tried the Finesse and one other, but I have to render the output. With doing a show every two weeks I just don't have that kind of time, and Canopus allows me good control in realtime.

Michael...

Understand what you're saying. I vascillate between 90 and 100 on the zebra. Some people set it to 70%, which I think is way overkill. I guess they expose for skin tones and not hi-lites.
Anyway, OT.....ummm, Red River is considered the "Texas of New Mexico" because there's so many Texans there. Mex food is pretty watered down. For my money, any little hole in the wall place in Santa Fe, Taos....if you want awesome scenery and out of the way...try Chama or Cimarron.
BTW, you've got your own extraordinary cuisine at the TeePee on Indian Scool Rd. I lived in Tempe for 12 years and know Phoenix well. If you want good adovada(red chile pork) try Rancho de Chimayo just north of SF, or (editted) Blue Corn Cafe in Abq or SF. Also a drive-up place in ABQ called Stuffy's has dyn-o-mite adovada in a sopapilla.

the 70% on zebra is great under studio settings, but I can't see through all the zebra crawl when shooting in super sunny Arizona.

I used to have a girl that worked for me that made carne adovada. I used to say "make me that 'car in nevada' stuff." It was real nice and spicey like too. She was from NM, Sante Fe area. That's why I asked. Heard of Red River from someone else.

I lived at the apartments across from the Tee Pee for over a year. Did get my fill of food.

They started that Hatch Valley company, but I was never too impressed. There is a place called La Pinata on Thomas and I-17 that is a good bet too.

I used to get down Hermosillo, Mex. on shoots often, so I am spoiled. Some of these Americanized Mexican food places just don't cut it.

Anyway, thanks for the heads up on the eats. I end up in NM every few months and hopefully will get to try it. That adovada in a sopapilla sounds FABULOUS!

If you, or anyone else for that matter, gets out my way, be sure to let me know. It would be great to meet some of you guys, and test some of NM's finest. Hot and wet....a great combination.

I'm drooling!

Same here, always ready for ________ and a beer. (Fill in blank with your favorite food. I'm not picky...'cept about making sure there is a beer part.)

Hello,

As a newcomer to digital filming (my camera doesn't even arrive until next week) I wanted to say thanks for all the explanations you fellas have shared here. Special thanks to Azsportsman for the website tutorial. Idiot newcomers like myself need all the help we can get and the pictures help.

I certainly knew there would be a lot of obscure stuff to have to learn about, but some of the technical aspects just make my head hurt. It's good to know that there are people out there willing to share their experience.

Obviously I'm trying to get on your good side because once I start filming I will have a lot of stupid questions to ask you all. I apologise in advance :)

Adrian

Adrian -- there are no stupid questions in our community... have no fear and post anything you want to know. Be sure to browse the boards with the Search tool at the top of the page, you'll be surprised at all the hidden lore you'll find.

;-)

Regarding setting the zebra at 70% for skintones:

There's so much great discussion on this board about achieving a film look with digital (so much so that there is a whole separate category for it, and I should probably post this there as well). My feeling is that skintones should be kept below 60% and more like 50% (%=IRE) to achieve a film look, if that is the desired effect. Washed-out skin tones is one of the curses of video. I tend to expose a solid stop under whatever the camera meter considers proper exposure, to achieve better saturation.

I don't claim any knowledge of shooting digital for film, so I may be off here, but 50% seems super low for skin exposure. I was taught, again for video, that 70 to 80 IRE is about right depending on lighting. Should be getting no washout or highlights in that range. On our expensive cameras we had dual zebra and set one for 75 and one for +100 to check skin and overall highlights, respectively.

A good link for exposure for DV filmaking is here
http://www.geocities.com/Hollywood/Location/5272/expose01.htm

Good Luck.

If you're using an XL1, probably your best bet is to adjust black level in post, if it needs adjusting. I use Apple's Final Cut Pro on a Mac and find I can do a great deal to improve detail in black/shadow areas using the "proc amp" filter, the contrast filter and color balance. Mainly, what is commonly needed is to reduce overall contrast. Proper tweaking can result in an astounding improvement of your video footage. The proc amp filter allows you to adjust black and white levels independently. Proper use allows you to minimize the blown out white effect and crushed blacks. One of the delightful qualities of High Definition TV is the greatly improved contrast ratio. To imitate this with a 1/3 inch chip DV camcorder requires a little post production "magic".

Michael:

My preference for a lower exposure for skintones came out of a dissatisfaction with standard video footage. I too was "taught" years ago that skintones should peg at 70 IRE, and came to feel that was just another rigid engineering concept. In the film world, no-one ever recommends a "proper" exposure for skin tones, it is purely an aesthetic choice and one that should be made based on the look of the individual scene. A reduced exposure on faces will add saturation and create a richer look. When I referred to washed-out here, I didn't mean blown-out i.e. over-exposed. I just feel that a classic exposure of skintones on video nets an image that is actually a lighter tone than the face appears in person, which is to me not as flattering (unless the intention is to purposely achieve this effect).

Good stuff Charles.

I did think that when you said washed out you meant blown out. Thanks for the clarification.

Again, how video transfers to film is WAY beyond me. All things being equal with lighting I don't see why you couldn't go as low as 50 IRE. I brought up the 70 mark as a point of reference for most wedding, event and other situations were lighting is not so controlled. Trying to set IRE to 50 for skin would under exposed the picture as a whole in most cases for video on a TV.

It is the curse of video, but with larger chip cameras you can compensate better. Especially if the camera allows skin tone detail and chroma adjustments. With the Xl-1S, well...there are some pasty looking faces at times.

I haven't experimented too much with frame mode on the XL-1S, but I think it is also forgiving and seems to like the lower exposures for rich color and even video. Shot a whole fly fishing piece at Lee's Ferry on the Colorado River like that and in the clients words, "wow!"

Charles,

I tend to expose a little bit lower than the what my meter is
telling me as well. Gives a much better look imho. Now I only
need a (field) monitor to truly judge my images. I was wondering
though, your saying that you go a full stop below what the
meter is telling you. Which camera/lens settings do you change
and how do you know it is a full stop?

Thanks!

Rob:

I haven't done it mathematically in years--my old Betacam method was to zoom in on a closeup, press the momentary auto exposure button on the lens, then stop down to taste from there. With the XL1, I have the B&W viewfinder set up in a way that I trust the image it presents, and I dial in the exposure based on that (on the manual lens). I think that in general, I tend to prefer an exposure that is about a stop down from what the video cameras think is good. I suppose there may be something I could do with the exposure adjustment dial on top of the camera, biasing it to meter under a stop, but I never seem to use the camera's meter as it is.

I don't know whether I should chalk all this down to experience or laziness, but it seems to work out fine in the end...!

The benefit of experience is an "accute and unwaivering sense of accuracy," I would say.
:)