Memory Card Speed

Simo70

I am thinking of getting an SDHC card to be used as a back card on my D300s. My primary memory card is a Sandisk CF 8GB Extreme III at 30mb/s. The questions is: if I get a 20mb/s SDHC card such as the Sandisk 16GB Ultra will it slow the transfer of photos while I am bursting?? I usually shoot compressed RAW files and the Idea of using two cards would be either, Raw files on CF card and Jpegs on SD, or Raw on primary CF card and backup on the SD.
Another option would be taking Raw+Jpeg Normal on the primary (CF) and backup on the secondary (SD), although I am not sure about the advantage of shooting both together.
Thank you for any help.:scratch

ziggy53

The card manufacturer speed ratings aren't really a very accurate measure of transfer speeds in a camera. Camera/card combinations are different from card to card and camera to camera. The best way to gauge actual transfer speeds is to measure them empirically, and I have only seen those tests at Rob Galbraith's site.

Unfortunately, I don't see that the Nikon D300S has been tested yet. The closest is the D300 which, of course, is only using CF cards.

http://www.robgalbraith.com/bins/camera_multi_page.asp?cid=6007-9254

I suggest that you try some cards and see for yourself. Buy cards singularly and, when you find a setup that works, duplicate that set.

If you are being held up and speeds are that important then do go with faster manufacturer rated cards. Generally the higher the capacity of the card, the slower the card within the same family and ratings. I also note some slowdown as cards fill up and when I'm shooting for fastest transfer I don't fill cards beyond 75 - 80 percent.

ziggy53

Relating to the dual-card strategy, using both cards for "redundant/duplicate" image files is probably best left for shooting of once-in-a-lifetime events and situations. JPG files are the best use of buffer and transfer speeds. RAW files give you the best opportunity for post-processing.

RAW + JPG is fairly wasteful of storage and slowest to write. I would reserve that for those occasions where the "customer" requires that method. Otherwise JPGs are fairly easily derived from RAW files so I never use the RAW + JPG storage myself.

SoCalAl

I shoot primarily with a D3 but I believe this would apply to the D300s also. If you have Active d-Light and/or viginette control on this will definitely slow down the transfer rate as the camera has to process the images before writing to the card. I know this is true for .jpg and have heard too many discussions in both directions for RAW to know if it affects them. The buffer will fill in 14~16 shots depending on the image @ 4 fps, .jpg. The camera will clear it in about 5~8 seconds and you can shoot again. Using Sandisk Extreme IV, 8gb, the transfer rate listed on the card 45mbps. Just my experience hope this info helps a bit, a lot of the speed depends upon your camera settings. Without Active d-Light and/or viginette control I basically can just hold down the shutter button and let her rip at 4 fps. Did that once for about 20 seconds, just to see what would happen, large fine .jpg.

Simo70

Ziggy-Thanks for the response. I will try your advise and see which set works best for me. The link was very helpful thanks. I usually don't burst much..well only with flying birds, but never had the speed issue. Yet I feel that having another slot on my camera that I am not using it is a waste and would like to catch the opportunity of using it. Bottom line it seems that SD cards are much slower than CF cards and I am afraid to slow down the system.
I also agree with you that Raw+Jpeg uses a lot of space and I mostly shoot on Raw but trying to minimize the post processing, therefore I feel I should just go with Jpeg, but sometimes I need post processing and the Raw file offers so much more opportunities to recover from mistakes. Maybe I should use the CF for the Raw files and the SD as Jpeg, use the jpeg and take the Raw file only if I need to post process. In general I don't see much difference between Jpeg and Raw files...please correct me if I am wrong.

Simo70

SoCalAl wrote: »

I shoot primarily with a D3 but I believe this would apply to the D300s also. If you have Active d-Light and/or viginette control on this will definitely slow down the transfer rate as the camera has to process the images before writing to the card. I know this is true for .jpg and have heard too many discussions in both directions for RAW to know if it affects them. The buffer will fill in 14~16 shots depending on the image @ 4 fps, .jpg. The camera will clear it in about 5~8 seconds and you can shoot again. Using Sandisk Extreme IV, 8gb, the transfer rate listed on the card 45mbps. Just my experience hope this info helps a bit, a lot of the speed depends upon your camera settings. Without Active d-Light and/or viginette control I basically can just hold down the shutter button and let her rip at 4 fps. Did that once for about 20 seconds, just to see what would happen, large fine .jpg.

Thanks Al. My camera settings are pretty standard: Usually I set the WB and I have 3 different picture control settings (Landscapes - Portraits - StudioFlash) Active D Light is set on AUTO. Other than this everything else is by default.
I can see though that shooting Jpeg, even with these settings, is much faster that shooting Raw or Raw+Jpeg, on the same memory card. I haven't tested yet if there are any benefits shooting Raw on the CF cards and Jpeg (Normal) or (Fine) on the SD card.

Overfocused

@Simo70

Aside the camera's own write speed ability, card speed is the main thing that slows down your burst transfer. Lets say Camera X can write 30MB/sec. Using a 20MB/sec card, you would run out of buffer space %50 faster than writing to a 30MB/sec card. Also, once you run out of buffer it would take %50 longer to flush it to the card at 20MB/sec. Although, if camera X can only write 25/MB sec or 20MB/sec, then the performance would be different or possibly not change at all. Whether a card will run at a satisfactory speed compared to its rating is another monster. Simply put though, yes, if you run out of buffer your burst speed will slow down with a slower card directly proportionate to the actual speed of the card.

@Ziggy

I also note some slowdown as cards fill up and when I'm shooting for fastest transfer I don't fill cards beyond 75 - 80 percent.

My technical brain is curious because this shouldn't actually happen with a clean solid state type media. From a standpoint of how flash technology works, the amount of the card filled up shouldn't matter. All write accessing and read seeking speed should be uniform no matter which sector the card is trying to access, whether reading or writing data, if it is a freshly wiped card. If it's been re-used a lot without a format, only deleting folders, the speed will degrade over time. Deleting allocates it as open but the data there hasn't actually been changed. This is why 'undelete' programs are possible. Also, if only SOME files are deleted, and some are left on, then it REALLY slows down because it's then made into a puzzle for the hardware to search through to find the next blank piece it can write in. I had a memory card stop recording video randomly because of this. The bandwidth of the card was just enough, but with the messy file table, it would choke sometimes. I regretted not formatting prior to that shoot. It's like scanning for somewhere to plug in, plugging in, then scanning for the next blank space, instead of easily stacking one on the other in an easy to build row. I have a ritual of formatting my card, letting it fill, then reformatting it. I've never noticed a speed drop as long as I format the card instead of deleting. Although, the cards get hot after heavy use, maybe this is why and I'm wasting my brains and time with all of this lol. Whatever, I enjoy this stuff anyway. Let me know what you think.

** forgot to mention, when I say format I do a FULL format. Quick format is the same thing as deleting. It labels the whole card and shows it as free space, yet its not actually erasing the data

SoCalAl

Hi Simo70. The burst mode was just to illustrate what some camera settings can to to write speed. Most folks generally don't shoot like that. You will have lots of great images and fun with your D300s! I have gotten a lot of great information, that has helped me immensely, from DGRIN. Just keep reading this forum & playing with your camera..... Most of all have FUN! DGRIN

Simo70

Great point overfocused, I haven't thought about it in this way. Now the million dollar question is "where do I find how fast my D300s transfers the files??" I wasn't able to find it in the owner manual.
I have my camera set up for 3fps and I can see that after few shoots it does slow down and the images keep displaying on the screen way after I stop shooting. It is a very good point. Thank you for the clear explanation.

ziggy53

Overfocused wrote: »

... @Ziggy

My technical brain is curious because this shouldn't actually happen with a clean solid state type media. From a standpoint of how flash technology works, the amount of the card filled up shouldn't matter. All write accessing and read seeking speed should be uniform no matter which sector the card is trying to access, whether reading or writing data, if it is a freshly wiped card. If it's been re-used a lot without a format, only deleting folders, the speed will degrade over time. Deleting allocates it as open but the data there hasn't actually been changed. This is why 'undelete' programs are possible. Also, if only SOME files are deleted, and some are left on, then it REALLY slows down because it's then made into a puzzle for the hardware to search through to find the next blank piece it can write in. I had a memory card stop recording video randomly because of this. The bandwidth of the card was just enough, but with the messy file table, it would choke sometimes. I regretted not formatting prior to that shoot. It's like scanning for somewhere to plug in, plugging in, then scanning for the next blank space, instead of easily stacking one on the other in an easy to build row. I have a ritual of formatting my card, letting it fill, then reformatting it. I've never noticed a speed drop as long as I format the card instead of deleting. Although, the cards get hot after heavy use, maybe this is why and I'm wasting my brains and time with all of this lol. Whatever, I enjoy this stuff anyway. Let me know what you think.

** forgot to mention, when I say format I do a FULL format. Quick format is the same thing as deleting. It labels the whole card and shows it as free space, yet its not actually erasing the data

It is my understanding that the most likely cause for the slowdown is a result of the complicated FAT type lookup structure that flash media uses.

Unlike a hard drive, most flash media uses a "write leveling" technology to spread the wear and tear of writes across the card. A "format" issued from either a camera or a computer does not reset the leveling table history, only the traditional FAT table that is shown to the operating system.

Unfortunately the combination of conventional FAT and the leveling table seem to add up and the entire addressing structure becomes rather convoluted as files are added. It is this complicated, convoluted lookup and distribution of file fragments that appears to cause the bulk of the slowdown as the card fills.

If a card is much, much more capable at write speeds than the host device is at delivering data, the bottleneck will be at the host device and you may not see any slowdown at all.

While I prefer the term "Write Leveling", the industry tends to call this process "Wear Leveling". Here are some links:

http://en.wikipedia.org/wiki/Wear_leveling

http://www.corsair.com/_faq/FAQ_flash_drive_wear_leveling.pdf

Overfocused

ziggy53 wrote: »

It is my understanding that the most likely cause for the slowdown is a result of the complicated FAT type lookup structure that flash media uses.

Unlike a hard drive, most flash media uses a "write leveling" technology to spread the wear and tear of writes across the card. A "format" issued from either a camera or a computer does not reset the leveling table history, only the traditional FAT table that is shown to the operating system.

Unfortunately the combination of conventional FAT and the leveling table seem to add up and the entire addressing structure becomes rather convoluted as files are added. It is this complicated, convoluted lookup and distribution of file fragments that appears to cause the bulk of the slowdown as the card fills.

If a card is much, much more capable at write speeds than the host device is at delivering data, the bottleneck will be at the host device and you may not see any slowdown at all.

While I prefer the term "Write Leveling", the industry tends to call this process "Wear Leveling". Here are some links:

http://en.wikipedia.org/wiki/Wear_leveling

http://www.corsair.com/_faq/FAQ_flash_drive_wear_leveling.pdf

Yeah I'm aware of all of that. Since not all SSD hard drives have this feature and sometimes I see it is advertised as a special feature, I automatically assumed CF cards weren't even there yet. That's probably backwards thinking, since CF cards came first, lol.

Still I use a 133x 16GB Transcend card, and have never noticed a performance decrease, even if it gets filled using a 5D MKII which can eat 600x cards.