With all the hoo-ha about the new Canon 70d DSLR and its revolutionary video capabilities I decided o give it a try.
To my horror I find that that any footage shot in 25p has a strobing effect when played on a tv set (LED and CRT); there is no issue when played on a pc.
I followed advice from various websites (slow panning, shutter speed at 1/50 etc) but the footage still strobes/stutters when played on tv. In fact any kind of movement produces the strobing effect. To me, 25p is totally and utterly unusable and not fit for purpose.
Am I doing something wrong? Is there a particular workflow? Do I have to convert the footage to another format before it will play correctly on a tv?
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Thread: Strobing from 70D 25p footage
How exactly do you play back the recordings on your TVs? Do you convert the video files at any stage? Is the problem gone if you record in 50p?
Technically, 25p is simply rather stuttery no matter what (well, compared to 50p that is), but it does sound like there is something wrong.
Upload before and after samples. But 25p (and 24p) does strobe, especially with bright, high contrast material. You can see this with any movie shot at 24p. See pan.avi in this post (24p)
and pan60.avi in this post (motion interpolated to 60p):
Is what you're seeing like pan.avi? Worse? Better? Different?
Keep the subject still in the frame and use depth-of-field and motion blur to blur the moving background when possible.
The footage is much better when recorded in 50p. I will download the pan avi files and play them on the tv to see if the problem is similar.
It's not a bug it's a feature. That's part of the "film look" everyone was falling over themselves to achieve a few years ago.
Do check your shutter speed, slower shutter speeds produce more motion blur and can make the stuttering less distinct.
Last edited by smrpix; 13th Jan 2014 at 08:54.
I have played pan.avi and pan60.avi on the TV set. The first one showed a little bit of strobing, barley noticeable. The 2nd one was super smooth.
When I shot 25p I made sure shutter was set to 1/50s. I even tried slower speeds but with not much difference.
This is one I shot in 25p at 1/50s. All the moving objects are strobing on a tv screen:
This one is shot at 50p and shows no strobing at all:
Just to mention that the strobing effect does not show much on a pc screen but is quite profound on a TV screen.
If this is 25p and the way forward then I cannot believe how this is fit for purpose or how can they expect a human being to watch it for any length of time.
The first video is clearly 25 fps. I get a few blurry frames at the start but the rest looks normal. It should flicker a bit on TV, about the same as on a computer monitor. The second was 50 fps and looked fine and should play smoothly on both a TV and computer monitor.
I suspect some problem at the TV or player. How are you playing these videos on your TV? Does your TV use motion smoothing techniques to smooth out film based material?
Try the attached video on your TV, viewed full screen. The top row is 25p, the bottom is 50p. Does your video flicker like the top row of the test video?
Last edited by jagabo; 13th Jan 2014 at 10:02.
I normally copy video files onto a usb and play them through that on a LED tv.
I have played the above fps50.mp4 file. The bottom row is fairly stable but the top row flickers like mad.
The TV does have a motion smoothing option but thats turned off as I dont like that efefct.
At this point I think what you're seeing is normal. The 25p row of fps50.mp4 is about a worst case scenario: High contrast, moderate and smooth motion, no motion blur.
Some things to consider regarding watching on TV vs a computer monitor:
The bigger the image is the more apparent the flicker will be. You can see this on a computer monitor by playing the fps50 video in a small window vs. full screen. Or when playing it full screen, compare the apparent flicker when viewed from very close up vs. very far away.
The brighter the picture and the higher the contrast the more it will flicker. TVs are often set up for a brighter picture than your typical computer monitor. And their automatic brightness/contrast settings will make the flicker even worse.
If your TV or monitor is running at 60 Hz the 50 fps row will show 10 little jerks every second. The 25 fps row will be even more jerky.
Thanks for that. In that case, can I conclude that 25p is really not fit for purpose? I mean how do you control so many different things and shoot a movie at the same time? With such problems, I would just use 50i all the time except the Canon 70d does not have full HD 50i (only has 720p with 50p).
In my case I shoot movies to be edited and played on different TVs, inc old CRTs. So if 25p is so picky and intolerant then there is no point in shooting 25p. I should hang onto my HD camcorder a little longer, I guess.
Here's your 50p video reduced to 25p with some simulated motion blur. It should flicker less (than your 25p clip) on your TV. But this would have been a better shot for 25p than your original 25p video because the camera follows the boat, and the moving background is darker and has less contrast.
As you have discovered, shooting in 25p while retaining a decently low level of flicker/stobe is like taming a monster, and in my opinion it is absolutely not worth it unless you really need that look and are prepared for it.
It is definitely not something you should do unless you are a skilled camera operator, I recommend anyone new to a camera/camcorder to shoot in 50i (25i) or 50p.
So, yes, shoot in 50i, there is nothing wrong with that at all.
Skiller - thanks for that advice. Its as much as I thought. I cannot see working with 25p with so much restrictions and such a steep learning curve.
jagabo - the clip that you provided sill flickers/strobes although not as much as the other 25p clips.
IMO all these clips with strong and even weak strobing are unwatchable. If I had to watch this kind of footage for any length of time, I would probably get a headache.
btw I have a LG 47" LED tv bought about 2 years ago. It claims to play progressive footage natively though there are no settings related to progressive/interlaced. However, some 720p and 1080p MP4 movies that I have played were ok and I did not see any strobing or flicker.
I guess it will be 720/50p for me on the Canon 70d.
Last edited by jagabo; 15th Jan 2014 at 11:59.
btw as far as the so-called 'film look' is concerned, I cannot see any difference between the 25p and the 50p shots. There is nothing 'filmy' about any of the shots I played on the tv.
Last edited by smrpix; 15th Jan 2014 at 19:55.
Could it be the LED tv? I have heard LED tvs are a little prone to flicker etc.
When shooting low framerates like 24~25p, shallow dept of field and slow shutter speeds are your friends. See how this 24p clip shot with a t2i looks on your TV:The memories of a man in his old age, are the deeds of the man in his prime.......
racer-x - I have played the spider24p file on the same tv and it looks great. Although there is a bit of camera shake, I cannot see any strobing or judder at all.
But when I play any of my files any kind of movement, camera or otherwise, produces ugly strobing.
To have simple answer to this, you have to blur the heck out of it to not have strobing, use 1/25 shutter speed - that will make you put ND filter on in daylight, keep your camera steady, keep you object in frame always in the same spot and just blur the rest of the frame, same effect you can get by using shallow depth of field with good lens,.. so you see it is not much practical to shoot 25p if it makes you uneasy to watch any kind of strobing
I think this is a lost cause. So much for the 70D marketing hype! I am going to stick to the Canon HF100 for my videos for the foreseeable future.
As an alternative, I converted some of the 50p footage to 25p. But when I played this it was like stop-motion frames. Obviously I have done something wrong in the conversion process. Is there a special way to convert 50p to 25p?
Any suggested software that might do a better job of converting 50p to 25p or even 50i?