Author Topic: Canon 60D: Do cards affect quality?  (Read 4216 times)

tubecamera

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Canon 60D: Do cards affect quality?
« on: December 23, 2014, 07:02:21 PM »
Any truth to what I was reading on a Vimeo posting that unless you are using the faster SD cards (i.e. Sandisk Extreme) you are losing video (data rate) quality?


Walter Schulz

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Re: Canon 60D: Do cards affect quality?
« Reply #1 on: December 23, 2014, 07:12:24 PM »
Loosing = Not able to use higher quality

Maximum data write rate for 60D's card interface is about 40 MByte/s. This will allow RAW/MLV recording in 720p24 until the card is full = continuous recording.
Cards not able to write with such rate will either do
- shorter durations (= number of continuous frames)
or require
- lesser resolution
- lower frame rate
for continuous recording.
Data rate (MByte/s) = Vertical pixel number x horizontal pixel number x 14 x frame rate / (8 x 1024 x 1024)

Clear now? It's the same for other cams recording uncompressed RAW. For a given resolution and frame rate you get data rate required.

And if you refer to something you found elsewhere it would be just fine to add a link so we can tell what you understood and the things actually meant in the original source.

 

tubecamera

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Re: Canon 60D: Do cards affect quality?
« Reply #2 on: December 23, 2014, 07:30:48 PM »
Let me clarify and try this again.

I shoot 1080/30P with my Canon 60D for the most part. I do not use RAW at all.

My cards are 16gb Transend SD Class 10's.

I rarely see the white "overload" boxes on the right side of the screen showing I'm close to reaching a data rate limit. My last shoot was 3 hours of interviews with no issues at all. Cards held around 45 minutes or so in 12 minute clips.

So from this can you advise if I should be using the Extreme version cards. That is, is it likely I am suffering a quality loss with this set up?

Thanks!

dmilligan

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Re: Canon 60D: Do cards affect quality?
« Reply #3 on: December 23, 2014, 07:32:23 PM »
60D is limited to ~21MB/s. Continuous 720p raw video is not possible. Best you can do is about 20-25s.

Walter Schulz

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Re: Canon 60D: Do cards affect quality?
« Reply #4 on: December 23, 2014, 07:38:39 PM »
Of course you're right. I tend to mix up 60D/6D, I suppose.

dmilligan

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Re: Canon 60D: Do cards affect quality?
« Reply #5 on: December 23, 2014, 07:40:50 PM »
In non-raw video, card speed does not affect quality. Either your card is fast enough and recording is continuous, or it's not fast enough to keep up and recording stops.

Also, ML lets you adjust h264 bit rate. There's not much evidence that increasing it will improve quality very much, but lowering it means you could record continuously for longer on a slow card.

Fast cards (faster than the 60D's max of 21MB/s) are not totally useless however, because if you have a fast card reader you can transfer files to your computer much faster (I have a 90MB/s for this reason). IMO the relatively small price difference you pay for faster cards is worth simply being able to transfer files to you computer several times faster.

Walter Schulz

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Re: Canon 60D: Do cards affect quality?
« Reply #6 on: December 23, 2014, 07:46:41 PM »
Tubecamera: Please give a link to the vimeo post you are referring to.


tubecamera

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Re: Canon 60D: Do cards affect quality?
« Reply #7 on: December 23, 2014, 07:53:57 PM »

see posting by "Lucas"

Thanks for the help and the clarification.

Walter Schulz

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Re: Canon 60D: Do cards affect quality?
« Reply #8 on: December 23, 2014, 08:07:56 PM »
You can calculate your data write rate just by:

File size/duration. Should be about 5.5 MByte/s if you use pure Canon style. That's why the 12 min break sets in. Maximum file size when using native Canon is 4 GByte. 12 min = 720 seconds.
720 x 5.5 = 4000 (rounded). Fits.
And as dmilligan pointed out a faster card would make no difference in the cam but may do when used in a card reader.

tubecamera

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Re: Canon 60D: Do cards affect quality?
« Reply #9 on: December 23, 2014, 08:33:20 PM »
So this Vimeo poster is full of beans, I assume?

Walter Schulz

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Re: Canon 60D: Do cards affect quality?
« Reply #10 on: December 23, 2014, 09:36:46 PM »
Well, there have been rumours about troubles with early Transcend Class 6 and even Class 10 cards and breaks when used for h.264 recordings. Cannot confirm this because lack of such a card and never looked for a reliable source. And that was years and years ago. Never used a card failing that criteria.
But I never heard anything about quality loss with slower cards. AFAIK (and dmilligan agrees) cam will just stop recording.