24p flickering help.

F

fotojoe

New member
hi all,
Shooting tests for the last couple of weeks for an upcoming short. Ultimately it will be submitted to film festivals on dvd.

My problem is not new to some but it's maddening! Its the flickering on pans when the footage is shown on tv's.

Here's some facts: shooting DVX100a, 24 pa, thin.
capturing on FCP4 w/ DV NTSC 48 khz advanced (2:3:3:2)
pulldown. Editing timebase @ 23.98

Tried "print to video" w/ reverse pulldown, also tried to burn a dvd on IDVD from a QT self-contained movie.
Both show horrible flickering on pans. slow or fast.

I need to resolve this asap since shooting will start in 3 weeks.
Will getting DVDSP help since i can choose from variable codecs? i know IDVD wont accept M2V files.
Somehow the conversion is not pulling it back to NTSC for tv showing either from the "print to video" tape or the dvd. please any thoughts. thanx
 
Re: 24p flickering help.

..all i can say is pan slower. try a circular dolly move in the opposite dierction of the pan, it will smooth out the transition.  the ntsc model works great when its handled nicely.
 
Re: 24p flickering help.

oh, did i fail to mention the pans look great when viewed
on the computer screen in FCP4 or as a QT movie.
they fall appart when viewed on a tv.
step...step...step...step... no matter how slow or fast.
 
Re: 24p flickering help.

We're having a similar discussion going on on a french site : DV Forever.

http://www.dvforever.com/forums/index.php?showtopic=7144

I know : "DV Forever" doesn't sound very Frenchy but, you motherf***ers have definitely won the language battle (fortunately, I'm in love with the English language, so I can remain a smiling loser...)

Anyway...

Steven-Marc, one of the gurus on this site, has posted a chart, based on the American Cinematographer's Handbook's recommandations, concerning pans (those problems are not for progressive video only ; rich people have problems too).

According to his approximate calculations, here are the minimum times (for a 90° pan) a DVX-ographer can allow him(her)self before being eaten by the nasty demons of flickering :

Focal length : 4,5    6    7,5    9    11    16,5   19    22    33    40    45
Time (90°) :  10s   14s  18s  20s  25s  37s  50s   60s  80s  90s  100s

Hope it can be useful. If anyone has come up with more precise calculations, we, in France, would be happy to know them.
 
Re: 24p flickering help.

whoa! thats just insane.. those times are way long.. but you must be reffering to the pal model. so im not going to touch it. but on the ntsc 10 sec to go 90 degrees is really excessive. using good camera movement, you should really be able to do it in about 3 secs pretty easily without excessive strobing. espescailly if your doing circular counter tracking as i mentioned above.
 
Re: 24p flickering help.

I think Steven's chart is not making any difference between PAL and NTSC. I think he made his calculation on the equivalence between DVX focal length and 35mm focal length (CCD size vs. 35mm camera window).

I'm gonna ask him and keep you guys posted.

Sorry if I brought any confusion :-[
 
Re: 24p flickering help.

oh! ok. but there has to be an inherant differene betwenn the two , one is 25fps, and one is 24fps, both using different shutter speeds as well. the motion rendering although similar, will be different. but all in all it comes down to the fact that when you shoot progressive, or do anything progressive you should have a progressive display to view it on.. thats why everything from both cams is pefect on the computer, or film out. although the ntsc version looks fine on ntsc sets. after a telecine from 24p, or when just shot in 24pn.
 
Re: 24p flickering help.

I did the calculations once and posted the chart over at DV.com.  Those numbers are faster than what I calculated for NTSC, so maybe they apply for PAL.  Here's what I posted on DV.com:

FOCAL LENGTH / 24P PAN SPEED / 30P PAN SPEED
4.5mm / 15 seconds / 11 seconds
6mm / 18 seconds / 14 seconds
7mm / 21 seconds / 16 seconds
8mm / 23 seconds / 20 seconds
12mm / 36 seconds / 27 seconds
14mm / 50 seconds / 38 seconds
16.5mm / 60 seconds / 45 seconds
25mm / 80 seconds / 60 seconds
30mm / 90 seconds / 75 seconds
45mm / 120 seconds / 120 seconds

Now, to read that chart properly, what it's saying is, if you are on 4.5mm, and you want to pan 90 degrees, with no juddering or stutter, and you're shooting 24P, you have to take 15 seconds to execute the pan.  If you take 15 seconds, the pan will be glass smooth.  Any faster than that, and smoothness will suffer.  That's for 24P.  You can go faster if you're shooting 30P -- at 4.5mm, you can pan the 90 degrees in 11 seconds and it'll still be smooth.

If you're on maximum telephoto, things change: you have to go much slower.  If you want a glass-smooth 90-degree pan, it will take two minutes to execute that pan.

Those are the rules, as established by the combined experience of the American Society of Cinematographers, having shot film for the last 100 years they've figured out the speeds you need to stick to if you want smooth pans.  When people say "pan slower", they're not kidding!

Obviously those speeds are very restrictive.  You can go faster, you just need to determine what level of stutter/judder is acceptable to you.  Fortunately with the DVX, you can hook up an external monitor and see exactly what it looks like (with film, obviously they had to wait until it was developed and projected, which is why they took the effort to devise the chart in the first place).

The key to panning faster is to have a relatively stationary object in the foreground, that you track with.  If you want to execute a good quick pan, follow your subject through the pan.  If you want a really fast pan, then it'll be so motion-blurry that nobody will notice any stutter (think "24" here).
 
Re: 24p flickering help.

..so these are the figures for if your panning to have absolutley no apparent motion blur, or strobe at all? ..
 
Re: 24p flickering help.

Yes, but a 25fps-1/50sec ratio is not that different from a 24fps-1/48sec ratio, is it ?

Why this insistant rumour about PAL giga-flickering issue compared to NTSC ?

Sorry to relaunch the old debate here when Fotojoe is in need for our help, but I don't find my PAL pans this stroboscopissimo.

And you're right, 10 seconds is an incredibly long time for a 90° pan at Zoom zero (I had not realized before posting). Maybe it's for 180°, or maybe the A.C.N's chart is giving zero-flickering-times... I don't know...

As for Fotojoe's problem : have you tried a slight vertical blur on your final cut before burning your DVD ? Might help...
 
Re: 24p flickering help.

the ratio is the same.   but its the frame rate, and shutter speed (granted the shutter speeds are very close, or the same) that will affect the motion rendering . one takes 25fps using  a shutter speed of 1/50. and one takes 24 fps using a shutter speed 0f 1/48 or 1/50.  so the frame rate is the main factor here. and the motion rendering  would be slightly different.
- im not sure what you mean about the pal flicker thing. i think the pal cam works fine , and records beatiful porgressive images. i think that people can only complain about not having a progressive tv to play then on, and the issues of its iamges not playing nice on a pal tv isnt the cameras fault. any 25p camera  or 25p scource played on a pal tv would have the same result .  

at any rate as barys cleared up , in the post above those figures would be for an image with no strobe at all. but its really not a rule to go by , obviosly people pan faster than that all the time, and as he mentions, the key is to have the viewers attention on somthing other than the strobing background. just like in the theatre, if you sit there and look for strobes, youll be sure to find plenty of them, cause they are all over the place, but that means your not paying attention to the film, and watching what you know they want you to look at. i think most people dont notice it in the theatre cause they dont expect it to be there, and never look for it, but they hear all this stuuf about flicker from the dvx,and then sit there staring and desperately searching for it. well of course youll notice it. and then they cant stop looking at it.
 
Re: 24p flickering help.

25fps - 1/50th is only 4% different than the NTSC 24fps-1/50th, so the numbers should be very close.

As for the rumor, you in France would have a better chance of getting to the bottom of it than we over here in NTSC land. It seems like a higher percentage of PAL users are complaining, as compared to NTSC users. And, unfortunately, I don't have a PAL monitor here to be able to check their footage and see if it's the same issue we face here. In NTSC some people gripe about strobing, but they weep and wail when we tell them "move the camera like a film camera." The chart above shows what film cameras deal with. Again, those numbers are for glass-smooth, absolutely-zero-jitter pans. Of course you can go faster, you just have to understand that the faster you go, the more motion artifacting you'll get.

More than anything, quality motion in 24P requires a good camera operator. Pat Kerby (filmmaker58 on this board) shoots a TV show for me every other week: 28 and a half minutes of handheld GlideCam 4000 footage, shot in 24P mode. Pat's been shooting film for about 28 years, and knows what he's doing. He handholds the GlideCam 4000, and shoots in 9-and-a-half-minute takes, all handheld, all 24P -- and nobody has ever complained about excessive strobing! Is there strobing? Of course there is. But the way he frames it, the way he moves the camera, and the way he moves the shots, it looks great and completely masks any problems. The client's thrilled with it, the agency is thrilled with it, and the viewers seem to love it.

It's all in how you handle the camera.

But that's for NTSC. I don't know if there's an actual problem with PAL, I haven't seen PAL footage. But Shai doesn't seem to think there's a problem, and neither does Anartiste, so maybe there isn't one?
 
Re: 24p flickering help.

I don't think there's an actual problem in PAL... Once again, I don't feel that way and I'm quite happy with my baby. There should be no real difference between us and the NTSC world...

Except, maybe, that PAL superior vertical definition makes any strobing more apparent, which should oblige us, PAL users, to be a little bit more careful in our camera movements.

Wealth problems... ;)

Thanks again to you, DVX gurus, for this so generously shared knowledge. May the Force bless you.
 
Re: 24p flickering help.

I agree...there is no specific problem with the PAL...as I have believed all along. I was recently in Paris Disneyland,,and recorded nearly 5 hours of raw footage. while i do not have exact measurements, my assessment of a zero-flicker panning in 25P has almost the same time scales as given by barry and anartiste above...

It is good to see reaching some definitive conclusions over this issue...at last ;D ;D.
 
Re: 24p flickering help.

Merci cousin français pour le site DVforever-forum.

Nice, now I can also go to a french forum to see what's happening out there even if it is PAL.
 
Re: 24p flickering help.

well, i maintain my problem is not in my panning technique,
since they look great on the lcd & on the computer screen.
It all happens when the pulldown is put back going to ntsc.
I think my dvd was the same way because Idvd is incapable of
handling a mpeg2 file (which maintains 23.98 thoughout)
I just ordered VDVSP2 so i can burn true 24p dvd's. I think that may take care of it. any other thoughts?
 
Re: 24p flickering help.

[quote author=iamloser link=board=Events;num=1079975980;start=0#4 date=03/22/04 at 11:28:30]whoa! thats just insane.. those times are way long.. but you must be reffering to the pal model. so im not going to touch it. but  on the ntsc 10 sec to go 90 degrees is really excessive.  using good camera movement, you should really be able to do it in about 3 secs pretty easily without excessive strobing.  espescailly if your doing circular counter tracking as i mentioned above. [/quote]


no way in PAL

these speeds are totally correct to avoid any strobing juddering flickering
footage - believe me
I struggle with this issue for weeks now
 
Re: 24p flickering help.

It seems to me that some people are talking different things here: the displaying device is progressive monitor or interlace TV?!

Ok, my question is: if 24p/25p footage can only be "precise" while watching at progressive monitor (camera LCD or computer monitor etc.), then how to make it looks fine (strobing problem) even on interlace TV? Like any DVDs that was shot in either film (movies) or 24p/25p (Dixie Chicks concert etc.).

Thanks!!
 
Re: 24p flickering help.

[quote author=kfkok link=board=Events;num=1079975980;start=0#17 date=03/31/04 at 18:06:18]It seems to me that some people are talking different things here: the displaying device is progressive monitor or interlace TV?!

Ok, my question is: if 24p/25p footage can only be "precise" while watching at progressive monitor (camera LCD or computer monitor etc.), then how to make it looks fine (strobing problem) even on interlace TV? Like any DVDs that was shot in either film (movies) or 24p/25p (Dixie Chicks concert etc.).

Thanks!!
[/quote]

If you notice on most films or concert films for that matter, the camera is not typically doing fast pans, but the action is moving in front of the camera. I have noticed that the action movements (no matter how fast) in front of a semi-stationary DVX looks fine, even on TV. It's when the camera itself makes quick pans that the problem shows up. I recently shot a dance competition and shot in 16:9 24PA at 24 shutter. I pretty much stayed stationary and only had slow zooms... The footage looks great on both 24P DVD and on NTSC TV even though the dancers were moving very fast.

Andrew
Crystal Clear Media
 
Re: 24p flickering help.

"I pretty much stayed stationary and only had slow zooms... The footage looks great on both 24P DVD and on NTSC TV even though the dancers were moving very fast."


That is absolutely right. If we look at any professionally made film, or any live broadcast, one can notice what APDeib has mentioned. As we know from some of the reviews of this camera, it is not....BASICALLY...a RUN and GUN tool; it is best utilised in a planned, controlled environment. I mean Professional use, for film making mainly.

I think the tendency to be able to 'move' or 'pan' the camera at will or to conisder such use appropriate, is because of totally unrelated reasons. Actually DVX100, due to its size, price range and looks has attracted a very large number of prosumer/consumer customers to its flanks. Hadn't that been the case, the camera though still popular among broadcasters and indie film makers, would not have been the best seller of most camera/electronic stores. One can also feel that while looking at some of the very basic, 'amature' questions raised in the forum, at times. I did it myself soemtimes. In fact, those questions in my view are very welcome....that is how u learn...and actually that is how I have learnt...(whatever I have so far :P).

But nonetheless videography like any other art has its own do's and dont's. As for the panning, I think all the gurus and GODS here on this forum have repeatedly underlined the need to do it 'professionally and in a certain prescribed way....only'.

It is a professional camera. It has to be treated professionally. One should not expect it to perform according to someone's whims or perceptions....specially if they are very 'newbie'.  :o 8) ;D
 
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