OT: Advice re SDXC cards for Sony’s AX100 camera

Dexcon wrote on 8/6/2014, 1:48 AM

I’m hoping that forum members who already have an AX100 might be able to give me some advice about the appropriate SDXC cards to be used with the AX100 - I’m likely to be getting an AX100 in the next few weeks and would like to know the best SDXC cards to get but with cost in mind.

From what I understand, the data rate speed usually given on SDXC cards is the read speed in MB/s (megaBYTES per second), but Sony gives data rate requirement as 60Mb/s (megaBITS per second) for recording 4K at 30p on the AX100 using a class 10 SDXC card up to 64GB. From a couple of online calculators, 60Mb/s = 7.5 MB/s. The Wikipedia entry for SDXC cards shows that the minimum write speed standard for a class 10 SDXC card is 10 MB/s. Therefore, my conclusion is that any class 10 SDXC card up to 64GB can be used for 30p 4K on the AX100 regardless of whether the read speed given on the card is 30, 45 or 95 MB/s (e.g. Sandisk Ultra, Extreme or Extreme Pro).

Am I on the right track or is there something that I’ve overlooked or not properly considered? And does the read speed have any advantage other than the length of time that it will take to transfer data from the SDXC to a portable HD or computer via a USB connection with the AX100?

Any advice and/or experience anyone has with the AX100 will be much appreciated. Thank you very much in advance.

Cheers

Conrad

Comments

OldSmoke wrote on 8/6/2014, 9:14 AM

I use two of these for my AX100

You may not need the 64GB version but at least 32GB if you intend to shoot 4K. Please do not buy cheap SD cards! Nothing is worse then coming back from a shoot to find out your SD card has some kind of problem. You should also use the HDD backup function, specifically if you use smaller SD cards.

John_Cline wrote on 8/6/2014, 3:37 PM

I have had flawless performance from the higher-end Delkin cards, either their "400x" or the "633x Elite" models, they perform as well as the Sandisk Extreme cards but cost a bit less. I second Old Smoke's advice, do NOT use cheap SD cards, that's just begging for trouble.

OldSmoke wrote on 8/6/2014, 4:04 PM

John

Are you sure those Delkin will work with the AX100 recording 4K at 60MB/s? From what I read at B&H website their write speed is well below 60MB/s.

John_Cline wrote on 8/6/2014, 4:26 PM

Yes, I'm sure. The AX100 records at 60 megabits/second, which is 7.5 megabytes/second.

OldSmoke wrote on 8/6/2014, 4:39 PM

So you are actually using one of those x400 and x600 Delkin cards with your AX100? I am asking because I couldn't get a basic Class10 card working for 4K recording, only the one in the photo worked.

John_Cline wrote on 8/6/2014, 4:51 PM

Yes, I played with an AX100 and used a Delkin card. As you found out, not all Class 10 cards are created equal. Maybe the cheap cards can burst up to 10 MB/s, but sustaining 7.5 MB/s over a long period of time is the trick.

OldSmoke wrote on 8/6/2014, 5:26 PM

Well, I had two of these http://www.bhphotovideo.com/c/product/992491-REG/sandisk_sdsdxs2_032g_x46_extreme_sdhc_uhs_1_80mb_s.html and I couldn't record 4K on it unless I would format the disk on my PC first using exFat32. When formatted in the AX100 I got a warning that it wasn't suitable for 4K recording and I really could only do HD XAVC.

John_Cline wrote on 8/6/2014, 10:56 PM

I did use the Delkin 633x Elite card during my short test with the AX100, its specs are comparable to the Sandisk Extreme Pro card. They both have the same read speed, but where Sandisk says "up to 90MB/s write", Delkin says "over 45 MB/s write." They both have lifetime warranties, but the Delkin 64GB card is $85 at Amazon and the Sandisk Extreme Pro is $110. I also use the Delkin cards in my GoPro Hero3+ Black camera to record in the ProTune mode, which is 45-50 Mb/s. This model of GoPro camera is incredibly picky about which cards can be used to record at the highest bit rate. GoPro specs only three manufacturers; Sandisk, Lexar and Delkin.

OldSmoke wrote on 8/7/2014, 7:31 AM

I must give the Delkin a try. The interesting part was that after formatting the 32GB Sandisk Extreme card on my PC rather then in the camera I could actually use it for 4K recording. By right it should work from the start as it states 60MB/s write in their specs. I Just didn't want to take the risk and I use the 32GB now for my NEX-3 and that works flawless.

Dexcon wrote on 8/8/2014, 5:56 AM

Thank you very much OldSmoke and John for the advice.

You've convinced me to go for the higher speed SDXC cards, more than likely the SanDisk 64GB Extreme Pro.

Thanks again.

Cheers

Conrad

John_Cline wrote on 8/8/2014, 6:27 AM

Once again, the AX100 does not record at 60 megabytes/second (60 MB/s), it records at 60 megabits/second (60 Mb/s). Small "b", which is 7.5 megabytes/second.

Dexcon wrote on 8/8/2014, 7:09 AM

"... the AX100 does not record at 60 megabytes/second (60 MB/s), it records at 60 megabits/second (60 Mb/s). Small "b", which is 7.5 megabytes/second ..."

Yes, I understand this, and this calculation formed part of my original post. But now I am a bit confused. I thought that the recommendations in the replies was to go for a higher speed read rate SDXC card because the write speed would be much more likely to sustain a write speed of 7.5MB/s or more (i.e. a Sandisk 95MB/s Extreme Pro is much more preferable over a Sandisk 30 MB/s Ultra).

Perhaps I have misunderstood.

OldSmoke wrote on 8/8/2014, 7:50 AM

John

Yes I know the difference very well too but that doesn't explain my case with the 32GB cards. However, after a bit more research, I think I know what happened. The 32GB cards I used at first where only SDHC which are using as standard FAT32 and SDXC uses the exFAT format. The AX100 would see the SDHC and format it accordingly as FAT32 but that doesn't work for 4K recording. Surprisingly, Win7 didn't care and formatted it as exFAT and then it worked but I am not sure if that is a safe operation. To sum it up, the AX100 needs a SDXC card speed class 10 or U1... did I get that right?

John_Cline wrote on 8/8/2014, 3:53 PM

The AX100, the GoPro Hero3+ Black and many other cameras require SD cards with the Ultra High Speed (UHS) bus. The newer families of SD cards improve card speed by increasing the bus rate (the frequency of the clock signal that strobes information into and out of the card). Whatever the bus rate, the card can signal to the host that it is "busy" until a read or a write operation is complete. Compliance with a higher speed rating is a guarantee that the card limits its use of the "busy" indication, how often the camera gets a "busy signal" can mean the difference between successfully streaming high bit rate video or having it choke on it. Sandisk ULTRA cards are not UHS.

Not all UHS cards are created equal, cards designated with the "UHS-1" logo and claiming to be "Class 10" can operate at speeds of 12.5 MByte/s (SDR12), 25 MByte/s (SDR25), 50 MByte/s (SDR50 and DDR50), and 104 MByte/s (SDR104). Cards with the UHS-II logo can operate at 156 MByte/s (FD156) or 312 MByte/s (HD312).