Originally Posted by Kayaker72
Is it possible that around 48mbs is the cameras limit, and going from 60 to 90 may just be wasted speed. I guess a question would be is how fast can the camera write if it has all the speed possible in the card.
48mbs could explain why I had 3 less pictures with a 45mbs card. Maybe if I had a 60mbs card I would have seen no difference.
Done..........
....and done.....Thanks for the tip on the price reduction. I checked out a couple of other Sandisk cards and it seems like a pretty consistent mark down when you add each card to the cart. Both 16 GB cards dropped by $6, the 32 GB 60 MB/s dropped by $10 ($89 to $79) and the 32 GB 90 MB/s dropped by $13.
Is it possible that around 48mbs is the cameras limit, and going from 60 to 90 may just be wasted speed. I guess a question would be is how fast can the camera write if it has all the speed possible in the card.
48mbs could explain why I had 3 less pictures with a 45mbs card. Maybe if I had a 60mbs card I would have seen no difference.
Rick,
I'll let one of those that know more answer for sure, but the numbers work out perfectly assuming your files were ~20 MB each. (the 3 pictures would be 60 MB or 3 MB for each of the 20 seconds you shot).
One of the things I found interesting about my test was that each slowed down at 24 shots in ~3 secs (no noticable difference between the 30 MB/s and 60 MB/s cards), which, indicates to me that files are not being written to the card during those 3 seconds of shooting. If they had been, I would expect at least at least a slight difference (I also ran my tests twice, each time coming up with the same # of shots).
Anyway, it definitely seems that something besides the card write speed is limiting shooting speed.
Brant
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Thanks, all! Very useful discussion.
Rick, thanks for the testing! That pretty much answers my question, and supports my observations with the one 'slow' card that I have (a 2 GB Sandisk Ultra that I bought the day I received my 7D, which was 2 days before the UDMA cards I ordered arrived).
Not knowing if/when the prices will return to what they were yesteday, it makes sense to order now - if one needs more memory cards. I'm not sure that I do, but for $100, the 32 GB card is a sweet deal...and if I get the 1D X, 12 fps will fill it pretty fast. So...I just ordered two of them. Interestingly, when you order one, the price in cart is $99.95, but when you order two you get a 'quantity discount', and the price in cart is $99.99. An extra 8¢ doesn't fit my definition of a discount (or anyone's, I would think), but whatever...B&H has been a great vendor, so I ignored the fleeting temptation to stiff them slightly for the non-discount by ordering the two cards separately so they had to pay UPS twice...
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Unfortunately, as of this morning those extra discounts seem to be gone at B&H<span>- cart price is the same as browsing price. Glad I ordered last night!
John,
I think we all got the "quantity discount" last night, because this morning if you put one 32GB 90MB/s card in the cart it's $112 and if you add a second card and update the cart the price drops to $99 each.
Also, B&H is now out of stock on the 64GB 90MB/s cards.
Thanks for the heads-up Bryan and Brant!
Rich
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I liked Rick's test and ended up testing my 30 MB/s and 60 MB/s cards on my 7D last night. The conditions weren't identical as with the cap on I could only get ~4 fps bursts but with the cap off I could get 8 fps. With my 60 MB/s card (which seems to write at ~48 MB/s) I had ~22 shots in 3 seconds and 67 in 20 seconds. With my 30 MB/s card (seems to write at ~23 MB/s) I also had ~22 shots in 3 seconds but I only had 48 shots in 20 seconds. The framing was different than the test I did earlier and the image files were ~18.5 MB. Playing with the numbers and assuming the buffer was full after 3 seconds, the writing speed for the 60 MB/s card was again 48-49 MB/s while the write speed of the 30 MB/s card came close at 28 MB/s.
It does look like there is benefit going from 30 MB/s cards to 45-60 MB/s cards if you are going to use continuous shooting after the buffer is full. But it looks like the current cameras themselves max out with write speeds in the 45-49 MB/s range.
Just some random information I looked up.
Regarding testing when you have the lens cap on, the frame rate will drop in low light and/or high noise. The read/write speeds of the SanDisk card are supposed to be the same according to the specs at B&H, although I would tend to agree with you that write speeds are usually slower, or perhaps the buffer is slowing down the writing to the card, like a bottleneck.
According to the Canon specs the 7D can shoot a maximum burst of approx 15 Raw shots, while the MKIV can shoot a maximum burst of approx 26 RAW shots.
A google search tells me that the MKIV seems to be able to handle cards up to 133MB/s. I'm not sure about the 7D though.
Rich
**Edited:Regarding testing when you have the lens cap on, the frame rate on the 7D will drop significantly (about in half) in low light and high ISO, but not on the MKIV.
I just tried to replicate the test without the lens cap. Yesterday I did the test with the 500mm, this morning I had the 70-200mm L II on. Interestingly, without the cap I got 53 frames in 20 seconds. With the cap on I still got 64. I repeated this four times and same results. I didn't time to burst rate specifically, but it seemed to burn through the burst faster without the lens cap on, but it had a harder time recovering, figure this one out :-/.
Brant
I retested, again this morning. This time I timed how long it takes to write the files. What I found is that to write the 64 files it took right at 29 seconds. It was hard to be exact, but it looks like I am getting 41MBs. I wonder how much this is slowed by camera settings such as shooting in different modes, noise reduction, highlight priority etc.......
I am curious now, since you have a higher rate with your scandisk and 7D, if the scandisk is writing faster than the Hoodman, or possiblythe 7D writing faster than the 1D IV or is it the settings in camera.
The little numbers in the viewfinder list the burst as 23 available. I wonder if this is because of some settings I have in the camera.
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