Is 30mb/sec fast enough for 8fps?

[FMX]

I found some 4gb cards on Amazon for $20.

Will these be fast enough for my 7D?

[yourdoinitwrong]

Yes it will be fast enough. The internal buffer of the camera will allow the 8fps burst in RAW up to about 16 shots and in jpeg up to around 99 shots (I think). The speed of the card is more related to how quickly the buffer will clear after it fills up. For the HD video you only need about 8MB/s, it's in the manual but I don't have it with me at work to verify.

[anthony11]

The speed of the card is more related to how quickly the buffer will clear after it fills up.
... and thus to how quickly you can take additional shots after the buffer fills, and how slow it is to read the files off the card later.

[hollis_f]

and how slow it is to read the files off the card later.


Assuming the OP means 30 megabytes per second and not 30 millibits per second...


With most USB card readers 30 MB/s will outpace the reader, so no advantage to a faster card.

[PacAce]

Assuming the OP means 30 megabytes per second and not 30 millibits per second...


With most USB card readers 30 MB/s will outpace the reader, so no advantage to a faster card.

LOL Too funny. Is that 1/33 of a bit per second? :lol: ;)

[FMX]

Yes it will be fast enough. The internal buffer of the camera will allow the 8fps burst in RAW up to about 16 shots and in jpeg up to around 99 shots (I think). The speed of the card is more related to how quickly the buffer will clear after it fills up. For the HD video you only need about 8MB/s, it's in the manual but I don't have it with me at work to verify.

Right... but will 60mb/s vs 30mb/s really make a huge difference in how fast the buffer clears... so that I can burst again?

[PacAce]

Right... but will 60mb/s vs 30mb/s really make a huge difference in how fast the buffer clears... so that I can burst again?

Assuming that the actual throughput of the cards are 60 MB/s (not mb/s, btw) and 30 MB/s and the camera can move the data that fast, the the card with the 60 MB/s would take half the time to clear the buffer as the 30 MB/s card would. To me, that would be a huge difference but to someone else, it may not be.

[DDCSD]

Depends on how much you you like to hold the shutter down. I use 15 Mb/s cards in my MkIIn and MkIII and have never run into my buffer and have never had to wait for it to clear.

[PacAce]

Depends on how much you you like to hold the shutter down. I use 15 Mb/s cards in my MkIIn and MkIII and have never run into my buffer and have never had to wait for it to clear.

It also depends on whether you shoot JPEG (which you obviously do) or shoot RAW (which won't allow that kind of sustained bursts without slowing down). :)

[DDCSD]

It also depends on whether you shoot JPEG (which you obviously do) or shoot RAW (which won't allow that kind of sustained bursts without slowing down). :)


I only shoot RAW. Haven't shot a JPEG in about 2 years. Like I said, it depends on how long you like to to hold the shutter button down.

2 seconds is a loooooong time to hold that shutter button down.

I haven't run into the buffer on my 20D since about 6 months after I got it either, and that only has a 6 shot RAW buffer and clears it a lot slower than 30 Mb/s. ;)

[PacAce]

I only shoot RAW. Haven't shot a JPEG in about 2 years. Like I said, it depends on how long you like to to hold the shutter button down.

2 seconds is a loooooong time to hold that shutter button down.

I haven't run into the buffer on my 20D since about 6 months after I got it either, and that only has a 6 shot RAW buffer and clears it a lot slower than 30 Mb/s. ;)

Oops! Sorry. I misread your post. :o Somehow I got the impression from your post that you were holding down the shutter button and shooting a long burst of shots. But now that I've reread your post, I see that i was mistaken.

[DDCSD]

Oops! Sorry. I misread your post. :o Somehow I got the impression from your post that you were holding down the shutter button and shooting a long burst of shots. But now that I've reread your post, I see that i was mistaken.


I was wondering! I do see how easy it was to misinterpret. :lol:

[FMX]

Assuming that the actual throughput of the cards are 60 MB/s (not mb/s, btw) and 30 MB/s and the camera can move the data that fast, the the card with the 60 MB/s would take half the time to clear the buffer as the 30 MB/s card would. To me, that would be a huge difference but to someone else, it may not be.

True... it would be more useful to get some more numbers though.. as in how many seconds it would take to clear out a full buffer with the 30mb/s card. Then I will divide by 2 for the 60mb/s card... like you said... although in the real world I wouldn't think it would be half.

[MT Stringer]

I bought one of the new model SanDisk Ultra 8GB 30 MB/Sec CF cards. Works good so far. After formatting the card in the camera, I tried it out. I good light I fired 42 continuous shots (jpg) at 10 FPS with a MK3 before the buffer filled or whatever because the camera quit shooting and was steadily writing to the card. It took a few seconds before the light went out.

[int2str]

Yes / and no...

You'll the 8 FPS initially, but after the buffer is full you'll notice a difference. And it can actually get in the way if you burst a few shots, pause, then boost a few more, wait and then try to burst a bit more. I've gotten the dreaded "busy" indicator before. Given that the faster cards aren't all that expensive anymore, I'd get a faster card.

Here's a test I did a while ago on the 50D (lower burst rate and smaller files!!; haven't tried on my 7D or 5D II yet):

http://photography-on-the.net/forum/attachment.php?attachmentid=363819&stc=1&d=1241889680

[themadman]

I found some 4gb cards on Amazon for $20.

Will these be fast enough for my 7D?

Fast enough, probably. Large enough.. I dunno. Depends how much you shoot. I shoot 500-800 shots per 3 hour event some times and thats about 8GB-16GB space. I also spread it over two cameras, but thats a different story. Since the 7D has more MP than either of my cameras, it each file will take up more space.

Ask yourself, will I need to shoot more than 200 shots? I don't own a 7D but I am gonna guess 4GB will get you 200-300 shots in raw max.

[That_Fox]

There's a noticeable difference in speed between the two cards. I did a test on this earlier with my Extreme 60MB/sec, I took 18 photos with my 7D at 8FPS, each photo was 24.3MB and it took 8 seconds for it to write all of them to the card. In other words, it wrote at a speed of roughly 55MB/sec. I did the same test with my Extreme III 30MB/sec, 18 photos at 8FPS with each photo being roughly 24MB. It took 14 seconds to write them all to the card, so it wrote at slightly over 30MB/sec. That's a very noticeable difference and personally I'd go for the faster card, I know that from now on I'll be sticking with the Extreme series for all of my new cards.

[hollis_f]

Here's a test I did a while ago on the 50D (lower burst rate and smaller files!!; haven't tried on my 7D or 5D II yet):

Your diagram inspired me to try my 7D with a variety of cards with this result -

http://www.frankhollis.com/temp/card%20speeds%20lablelled%20small.jpg

Note that the two Extreme IV cards were stopped the 11 and 12 second markers, respectively. Damn! Just noticed the 12GB card is Extreme III, not II.

All the cards rattled off the first 20 shots at the same speed. After that there were delays between the shots. Interesting observations are that the delays weren't consistent for all the cards and that shots after the buffer filled always happened in pairs.

[MT Stringer]

Frank, I'm lost. How did you chart your tests? I have several cards I would like to test.
Thanks.
Mike

[hollis_f]

Frank, I'm lost. How did you chart your tests? I have several cards I would like to test.
Thanks.
Mike

Hi Mike,

I used the Voice Memo function on my iPhone to record the sounds, emailed the resulting files to my PC, imported them into Adobe SoundBooth and lined them up. Then just took a snapshot of the display.

[MT Stringer]

Hi Mike,

I used the Voice Memo function on my iPhone to record the sounds, emailed the resulting files to my PC, imported them into Adobe SoundBooth and lined them up. Then just took a snapshot of the display.

OK. Thanks Frank. That may be a little over my head. :confused:

[themadman]

OK. Thanks Frank. That may be a little over my head. :confused:

If you have a microphone attacked to your computer, just get a free audio recording program and hold the mic close enough to the camera to catch the shutter noises.

This is one I have used http://audacity.sourceforge.net/

[htpc]

I like this audio analysis way of "counting"..so did my own test on my 7D with a LEXAR 16GB 300X
this card is in the 24-30 MB/s real world range


with RAW....
:you fire 16 in a row at 8 fps for 2 seconds,
:then fire next 8 in double bursts (2 at a time in fast 8 fps like succession) for 2.4 seconds (bursts every 0.6 sec) (assume buffer now full)
:then fire next x in double bursts (2 at a time in fast 8 fps like succession) as long as you want every 1.4 seconds (buffer stays full)
......when you stop it takes 13 seconds to clear the camera buffer (light goes out)


with jpeg large....
:you fire 160 in a row at 8 fps for 20 seconds !,
:then fire next 20 in double bursts (2 at a time in fast 8 fps like succession) for 4 seconds (bursts every 0.25 seconds) (assume buffer now full)
:then fire next x in double bursts (2 at a time in fast 8 fps like succession) as long as you want every 0.35 seconds (buffer stays full)
......when you stop it takes 10 seconds to clear the camera buffer (light goes out)

there are many reasons to use the 8 fps advantage this camera has, but it appears that if you drop to jpeg quality for those instances, a medium speed card like this lexar should be fine for lots and lots of action.


interesting that I only got 16 in a row before it started to reduce rate while holis_f got 20?
(note when you count the audio there is a small then large sound for each shuttermovement (of course)

cheers
R

[MT Stringer]

Are all of these test done with the camera lens in manual focus? Just seems like a lot more than I got. I stood in my drive and shot my truck just like I would at a football/baseball game and I only got 42 images before the camera (1D MKIII, 10 FPS) bogged down.

Just curious. I have a couple of Kingston and a Transcend along with a couple of San Disk Extreme III I might try the same test. I zeroed my counter so that's how I knew how many shots in the initial burst I got. Then I quit shooting.

Thanks
Mike

[htpc]

I did mine on manual to make sure autofocus and shutter speed did not interfere with card writing. So I just shot my computer screen at about 1/500 just because that is plenty fast enough for this analysis


perhaps a standard test protocol could be recommended...

Was that 42 large jpegs or raw? You need to state that with your camera or else we can't compare since this is a write speed plus buffer capacity question

[MT Stringer]

They were large jpeg; 1D MK3 at 10 FPS with the camera in AV mode, autofocus outside on a well lit day. I don't recall the f/stop or shutter speed. Plenty fast for action though.

[FMX]

Fast enough, probably. Large enough.. I dunno. Depends how much you shoot. I shoot 500-800 shots per 3 hour event some times and thats about 8GB-16GB space. I also spread it over two cameras, but thats a different story. Since the 7D has more MP than either of my cameras, it each file will take up more space.

Ask yourself, will I need to shoot more than 200 shots? I don't own a 7D but I am gonna guess 4GB will get you 200-300 shots in raw max.

100 shots :(... Def gonna need a bigger card!!