Sandisk Memory Cards

[Kayaker72]

Rick,


That is what I am beginning to think. I had expected the 90 MB/s card to come in similar to the 60 MB/s card, expecting the limitation was the camera and not the card. But that doesn

[Richard Lane]

Hey Brant,


Something must be wrong with the card or testing. Did you try to reformat the card and run the test again?


Rich

[Kayaker72]

Hi Rich,


I formated before testing, reformated between each test, and ran each test twice. I know, something seems off. Initially I wasn't planning on retesting my other two cards, but I did because I wanted to see if they had similar results as before and they did. I'll do the test again tonight to see if it is different. Maybe the new card was cold as it had been sitting outside? Maybe cards need to be "broken in" a little? I am open to suggestions as I was expecting 40-50 MB/s and got 16-18 MB/s.


Thanks,


Brant


EDIT---I was just re-reading this thread and Rick has run a 16 GB card....the linear relationship predicted 51% efficiency at 16 GB...Rick got 51, 56, and 64 MB/s on a 100 MB/s card on the 1DIV. That's four points on the trend line....still, not great, but it is getting there. I'll re-run my new card tonight.

[Richard Lane]

Brant,


How are you calculating your Write Time (sec)? I think your numbers (23sec and 45sec) sounds too high.


Rich

[Kayaker72]

Hi Rich,


I am assuming the camera starts to write the second I start shooting (there is a very slight lag to the red LED/access lamp going on) to when the Red LED/access lamp is off. So those times include the 3 seconds and 20 seconds (respectively) of shooting.


I agree, I am surprised by the performance of the 32 GB 90 MB/s card. As you said, I may have just received a bad card.


Thanks,


Brant

[Richard Lane]

Something is wrong with your data. How can it take 23 seconds to write a 3 second burst? I think you have a bad card.

[bob williams]

I am open to suggestions as I was expecting 40-50 MB/s and got 16-18 MB/s.

Brant, One thing Dawned on me---Maybe we are mixing apples and oranges and expecting the same results:


On my test, I only timed 15 seconds andwas getting some significant buffer lag by the end of the test.


On your test, you did 20 seconds, so I can only assume you exprienced the same the last few seconds of the test.


Now your total calculationsmost likley included those "slow moments" when you are only getting one or two shots off per second


With your test being 20 seconds long you had 5 more seconds of "slow" to throw into your calculations, which would reduce the overall calculated speed.


My suggestion is for two or three of us to use the exact test parameters (or as close as possible) and then see what happens---My guess is they will probably be fairly close.


The other thing I noticed is that I reported an average "per file" size whereas you reported the sum of all the file sizes. If assumptions andreverse math is correct you were getting individual file sizes around 18MB per file and I was getting around 20 MB per filewhich tells me weprobably haddifferent camera setups.


If one of our science based forum members are willing to design a test we can all do, I would be more than willing to participate


Bob

[Richard Lane]

I also received my 32GB 90MB/s SanDisk Extreme Pro CF card.


With the 7D, I just shot 70 raw shots which totaled 1.31GB of data for 20 seconds and the red access light stayed on for an extra 7 seconds after I stopped shooting, for a total of 27 seconds.


I ran the test 3 times with similar results.


1310MB/27sec = 48.5MB/sec.

[HDNitehawk]

@Bob , my first tests I was getting larger file sizes. Once I turned off the Auto ISO I didn't have that problem.


If you were going to compare from one person's 7D to the other, the simplest way to match settings would be to go in to the camera and just restore it to the default settings. That way everyone would start with the same setting.


One problem I see, is if you are doing it without the lens cap, each of you will get different results. I noticed this with the 1D IV, I did a series without the cap and I was outside. A bit later I did another series and got different results, the only difference was the lighting. It was outside and the sun had gotten lower in the sky. When I did tests with cap on the results were consistent from one test to the next.


It would be interesting to see if everyone that bought one of the "on sale" cards, get the same results.


@Brant..I talked to Hoodman earlier, explained what I found on the testing (16MB vs 32MB). They said it is possible the camera takes longer to write to the larger card. They took my phone number, camera type info and told me they were going to check it out themselves. Odd though they said they had not heard this scenario / complaint before.


Even if that is the case it sounds like your card is really slow.

[Richard Lane]

7D with 32GB 90MB/sec SanDisk Extreme Pro CF card:


In a 3 second burst; I shot 22 RAW shots totaling 408MB. The red access light stayed on for 5 seconds after I stopped shooting for a total time of 8 seconds. I ran the test 3 times with similar results.


408MB/8sec= 51MB/sec