Author Topic: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i  (Read 5235 times)

IndyP

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Hi everyone,
   I recently tried recording 30 minute segments by lowering the bit rate to 0.4 and using movie restart while monitoring the CMOS temperature on my Canon T2i. I did not notice any apparent difference in video quality, and during the 1 hour 15 minute of continuous recording, the CMOS temperature remained at 12C - 53.6 degrees Fahrenheit.

Note: While recording at the default bit rate of 1.0 at the same location, same time, and same approximate ambient temperature, the CMOS increased from 12C to 17C - 53.6F to 62.6F

  Can someone who has done a little more testing of image quality and CMOS temperature while recording at 0.4 give me some input as to what you have found.

Thanks

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Re: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i
« Reply #1 on: March 13, 2013, 01:53:51 AM »
If you drop the quality it will record longer? Maybe bytes written factors into max filesize somehow. .4 * 30 is about 120min. I've written 8gb files that last less than 30 mins with no stopping so its only one additional variable.

If you're willing to take the quality cut of .4x then I guess do it. Testing continuous recording I recorded at very low rates and the cmos doesn't heat at all, on tested cameras (6D/600D) it didn't record more than 30min. Video is unusable quality, looks like a webcam. 30 minutes was like 10mb or something. .4x is somewhere in between that and stock.



ilguercio

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Re: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i
« Reply #2 on: March 13, 2013, 03:11:54 AM »
Until now, the only way to record longer seamlessly is to change FPS with override.
But i bet you noticed that already, it's a consequence of changing timers.
So if you start from 30fps from Canon menu and set them to 15 from ML you should be able to record for an hour.
Op said he used movie restart.
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Re: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i
« Reply #3 on: March 13, 2013, 03:23:09 AM »
Continuous recording? or repeated recording with restart? I recorded pretty much all night with timer slowed down to .5 fps and quality at max. The camera didn't give any warnings but did get hot.

ilguercio

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Re: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i
« Reply #4 on: March 13, 2013, 03:28:50 AM »
Continuous.
As far as i can understand, FPS override is possible because timings are changed. That's what allows a longer continuous recording.
If you recorded all night at 0.5 fps then you know already :)
Canon EOS 6D, 60D, 50D.
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Proud supporter of Magic Lantern.

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Re: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i
« Reply #5 on: March 13, 2013, 04:22:21 AM »
I thought he meant he turned on movie restart and instead of restarting it recorded for 115 mins when rate was dropped.

Misread



IndyP

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Re: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i
« Reply #6 on: March 13, 2013, 05:10:14 AM »
Thanks for your input guys. Just to clarify, the 1 hour 15 minutes of continuous recording produced three files with movie restart switched on i.e. ( two 30 min and one 15 min file ).

However, if the quality of CBR 0.4 footage lies between unusable and stock, it is hard to notice without any proper testing. Is it possible that just like increasing the CBR to above 1.0 is supposed to increase video quality, in reality, (according to most of the forum topics on the subject), it is not noticed by most people?

Sometimes in our quest for the best, much time can be spent in doing so when in reality, it cannot be perceived by the eye, or in the case of audio sampling rates, by the human ear.

What I was really hoping for was someone who has done some testing with side by side comparisons of footage shot at CBR 0.4 versus Default 1.0 and higher.

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Re: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i
« Reply #7 on: March 13, 2013, 05:38:31 AM »
With perceptive difference you have to consider one more thing, delivery format. Might look fine on youtube and a small screen but not when projected/enlarged/posted, etc.

Do some tests and put them up.

TompDog

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Re: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i
« Reply #8 on: January 26, 2014, 09:48:49 AM »
I would love to get a follow up on this IndyP!

-TompDog

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Re: 30 min Recording at CBR 0.4 / Image quality / CMOS temperature on T2i
« Reply #9 on: April 04, 2014, 01:27:50 AM »
I also had a hard time finding comparisons of CBR 1.0 vs CBR .4 So, I just made one.

I used  a Canon T2i with a zoom 100-400 lens. The difference in quality is pretty noticeable - the blue lettering is deeper and the specks along the wall are clearer with a CBR set at 1.0. I adjusted no other settings, so if that's something one should do, let me know.

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