? about Canon t4i

[Kevin Lewis]

I've had this camera for a few months now but for the first time, I shot some test footage at 24fps. The footage appears to be really jerky and in my opinion unusable. i ve heard people complain about this before but I cant help but wonder if its a camera setting. I've seen plenty of videos with this camera in 24fps mode and they seem fine. I also notice that if I point the camera towared a television, there is lots of flickering and rolling of the screen. My other camera is a Canon XHA1, and I do not have this problem when shooting 24fps. Any thoughts? Is it possible that it only looks like this in the viewfinder but wont actually record to dvd in the same fashion? I dont have immediate access to my system so I am unable to test it at the moment.

[Donald McPherson]

If you are shooting at 24fps then of course the television will not match as it's 25fps pal land and 30fps ntsc land so there will be a mismatch.

[Panagiotis Raris]

you have several issues creating this scenario.

One, frame rate; at 24P it may be slightly out of sync with your TV at 30P/60P. Two, CMOS rolling shutter, this, depending on shutter speed, could be a major issue. try shooting at 1/24 or 1/28 (below 1/30 second).

If/when magic lantern works on the T4i (i dont know), that could alleviate the flicker as it would give you more frame rate options (possibly).

24FPS should not be very jittery; what are your shutter speeds, ISO, and type of television you are filming (ie CRT or LCD, refresh rate, interlaced or progressive, etc).

shooting a CRT under fluorescent lighting is my 'torture test' for setting up an interior shot; i have some presets that work but only for a Magic Lantern enabled camera, but perhaps we can get yours close enough.

[Kevin Lewis]

Thanks for the input. I found out what the problem was. I was connecting the camera directly to the TV via hdmi. It seems that the tv has problems reading the raw mov 24p file. Once I rendered in Vegas and play via dvd or file, the problem goes away. I still have the issuie when pointing at a tv but perhaps it has to do with the light source of the tv. Panagiotis: is flickering under flourcent lights an issuie if your are using professional flourcents or only when using under household flourcents?

[Panagiotis Raris]

can be both, but primarily household. It is related to shutter speed, which is related to framerate, but caused by alternating current and shutter speed being out of correct sync or limits. I dont use fluorescents for 4 reasons; one is cost for a nice comparable setup, two is they are all inherently soft lighting, three is simply mercury, and fourth is bulkiness.

(i did not realize you were reviewing it on a television, that could cause it unless its a 120hz model and only some do it right. i assumed you meant the image on the dslr screen was flickering or you were filming a tv and it was flickering or banding)

In the USA, A/C is 60hz, in Europe, its 50hz. Find some fluorescent lights and record at different shutter speeds, at any framerate. or change the shutter speed while recording; you will notice brown bands moving down from the top of the image field; the speed varies with shutter speed; you have to either expose for longer than 1/60 sec (say in 24P mode) or attempt to synchronize it perfectly and not move the camera vertically at 1/60 sec or damn near close via Magic Lantern (there are options and its a pain to figure out).

This is why i always drag 650 watt tungsten lights with me or rent LED's; no A/C flickering. and with 3 or 4 650w lights on, you can overpower any fluorescent setup, or at least eliminate the banding effects. Plus all the fluorescent lights in most homes, factories, buildings, etc are not the same color temperature, or there are slight variations that create havok with trying to set up a properly white balanced shot.

For instance, i did some work at a restaurant with fluorescents in the kitchen; some were 'cool white' 5000k, others were 'warm daylight' 3500k or something like that. Because of how the human eye/brain works, we 'see' people differently than a sensor, and have more dynamic range. Whereas i saw my subjects to have a slight greenish caste, my camera's sensor saw green hued skin and pink shadows, or the inverse, because of the different kelvin temps on various fluorescents, depending on which light was hitting where. Hence i bring in my own lighting; at 3200k, i know where my baseline is. Its hard to explain, ill post pictures later.

since i shoot mostly indoors, and everyone has latched on to fluorescents, i chose to try and figure out the best settings for fluorescents, and for properly shooting an old CRT screen. plus i was bored and it was a challenge.