Are larger capacity SDHC cards slower?

[Dave Humphries]

I have been using a 4GB Sandisk Ultra (C2) "15 MB/s" SDHC card in my Nikon P510 camera.

Its buffer holds 5 large fine jpgs, then it pauses for several second to write them to the card before I can shoot again - quite frustrating, as it takes say, 5 seconds - and in wildlife shooting, that's a long time.

Thinking it would be nice to put a faster card in, and larger, so I don't run out of space, I bought a 32GB Sandisk Ultra (C10) "30 MB/s" SDHC card.

The bad news is that this new card takes probably 2-3 time longer to clear the buffer, not less

So the question is; has anyone else found that larger cards (with more address space), take longer to write to?

Or have Amazon UK shipped me a fake?
Or did I misunderstand something in the spec.?

Thanks in advance,

[Andrew1]

Christopher posted this link a couple of weeks ago. It may help identify the card.

http://www.softpedia.com/get/System/.../H2testw.shtml

Also

http://www.youtube.com/watch?v=Hs54vdZejAk

http://www.fredmiranda.com/forum/topic/1121416

On-line reviews for this card seem to be very good.

[jprzybyla]

Hi Dave, I can only speak from my experience. I recently bought and use a SanDisk Extreme 45 mb/s 32 gb. In my D7000 I find that this card has increased the speed for clearing images from the buffer onto the card and also importing the images when downloading. Previous to that I was using a SanDisk Extreme Pro 45 mb/s 16 gb card, not sure why because the listed speed is the same but the newer card is much faster when I shoot birds in flight which fills the buffer in burst mode.

[Manfred M]

Dave - I had the same concerns when I upgraded to my first 32GB card from 8GB and subsequently 16GB cards. Frankly, the only time I notice any appreciable speed difference is when I download my data onto the computer, and it takes Bridge longer to scan the card. I assume that this is simply related to the fact that there is a lot more data. I use "cheap" Patriot cards on my D90, On the D800, I tend to shoot 32GB 400X CF as my primary memory, but did test my Class 10 Lexar Gold 64GB cards that I normally use in my video camera. Again, speed wise, they seem to be the same as the 32GB cards.

From a write from buffer standpoint, I've never noticed any difference except when I when to a faster card. In those cases, the buffer tends to clear more quickly. I tend not to be a burst shooter, so there is often more than enough time when I am shooting to clear the buffer.

[rpcrowe]

Before I purchased my 7D, I never really noticed which of my many CF cards that I was using. None seemed to be noticeably faster or slower than others. Even, my 4GB Lexar 300x UDMA CF cards did not appear to be any faster. This was probably due to the fact that my 40D camera could not take advantage of UDMA technology. However, when I used a UDMA compatible CF card reader, the UDMA cards transferred the files to my computer noticeably faster than non-UDMA cards...

When I began shooting with my 7D, I did notice a difference in write speed. My older smaller and slower cards had a definite and noticeable slowness about them. This was because the 7D's files are larger than those the 40D produces and also that the 7D can take advantage of the UDMA technology. Now, I shoot my 7D only with 400x Lexar Professional UDMA capable CF cards. I have three 4GB 300x cards which I most often use with my 40D and two 16GB 400x cards which I use with my 7D. My slower and smaller capacity cards are used for back up only.

I have never used a camera which takes SDHC cards and I have only gone into this lengthy explanation of my CF card capabilities to show that certain camera/card combinations may function more swiftly than others...

[Black Pearl]

I use Sandisk Extreme SDHC cards of many different capacity in the D300s and they all run super fast.
If yours came direct from Amazon it should be fine but if its from a re-seller it has a good chance of being a fake, personally I'd send it back and get another from a solid source.

[pnodrog]

Went to Sandisk web site to try and find out the write speed which in some memory products can be much slower then the read speed that they always give. To my disappointment they did not give a full specification the only info was Performance/speed: Up to 30MB/s read speed; write speed lower which is a totally useless specification. Class10 indicates it will have a write speed of least 10MB/sec which worst case would be about the same as your 4GB card. So it does seem you either have a faulty or counterfeit card.

[Clactonian]

Interesting opening post HERE which would seem to suggest some write speed limitations abound.

[Brocken]

In objective tests, the same card can be seen to perform at quite different speeds in different makes and types of camera, and the apparent read speeds of cards often reflect only the make/type of card reader used, rather than any properties of the card itself.

A detailed card-by-card performance analysis is given for many Nikon and Canon cameras, and a good number of card readers, here: http://www.robgalbraith.com/bins/mul...e.asp?cid=6007

[Inkanyezi]

I can only agree with Brocken, and add that the card speed might not be the most important factor involved.

The P510, being lower spec on some counts than most system cameras, should not be expected to write very fast. I have noticed with some compact cameras, also from Nikon, that they write faster to a small card than to a large one. Maybe it is only a matter of file system size and the specs of the camera hardware and its firmware, but for example my Coolpix 5200 writes substantially faster to a 2 GB SD card than to an 8 GB SDHC card, even though the former is class 4 and the latter class 10. When I put the same cards into the OM-D camera, the 8 GB SDHC is lightning fast by comparison, and the class 4 SD card grinds to a stop when trying to shoot video at high resolution.

So the camera itself might matter.

[Brocken]

So the camera itself might matter.

Indeed, the camera's communication with the card is at the bottom of maximum read and write speeds. For example, a SanDisk Extreme Pro 45 MB/s 8GB SDHC card can be written to in RAW at 29.9 MB/s in a Nikon D800, but at only 24.3 MB/s in a Nikon D7000.

Nor do you always get much more by paying more. Using a Canon EOS 5D Mk III, the very expensive SanDisk Extreme Pro 95MB/s 8GB can be written to at 19.4MB/s, while the much cheaper SanDisk Extreme Pro 45MB/s 8GB card is only slightly slower at 18.6 MB/s - not enough to notice in practice.

Speed variations between different makes and models are even more prevalent in card readers. The same SanDisk Extreme Pro SDHC 45 MB/s 8GB card can be read at 38.8MB/s in a Lexar USB 3.0 Dual-Slot card reader on a Windows 7 system*, and at only a disgracefully slow 4.6MB/s with an internal Addonics AEIDDSAU SATA card reader on the same system.

* Intel Core i5 3.2GHz, 8GB RAM, 1TB 7200RPM hard drive, Windows 7 Home Premium 64-Bit.

[pnodrog]

Christopher is correct.

Yes camera does matter. So does the card reader, computer interface, performance and software.



Rob Galbraith's tests show a Nikon D4 can write to a memory card at up to about 95MB/sec but the Nikon D7000 max was about 28MB/sec. So it is little point in fitting the D7000 with a memory card with a write speed of over 30MB/sec unless you have USB 3 interface that can take advantage of a faster transfer to your computer.



Transfer to your computer provided the cards read speed is over 20MB/sec is restricted on how the card is being read. Below 20MB/sec the cards read speed is usually the limiting factor.



USB 2 (480Mbits/sec – 60MB/sec) with most readers only having an effective transfer of about 20MB/sec.
USB 3 (5Gbits/sec – 625MB/sec) with the current card readers only effectively able to transfer at up to about 70 MB/sec. No doubt this will improve over the next few years.

[Dave Humphries]

Hi all,

Thank you for the replies, I quote from some below, but the thanks goes to everyone.

To clarify, I am only concerned about the time to clear the buffer while shooting; i.e. that which is going to be determined by the card - and camera as many pointed out.

Today I took the cameras to a bird of prey flying display, I had another 32GB Sandisk Ultra (C10) "30 MB/s" SDHC card in the D5000.

I didn't time anything, but this DID feel quicker; I could shoot small bursts of 2-4, then just keep going adding more in (while the earlier ones were beng written out
It also didn't fill up, as the 8GB would have

I have noticed with some compact cameras, also from Nikon, that they write faster to a small card than to a large one.

Urban, this is exactly what I was hoping someone might confirm, thank you. As you can see, it is now also my experience, a better camera (D5000), did give the intended performance boost I was looking for. The P510 should benefit from a faster than Class 2 card - just not a bigger one it seems!

If yours came direct from Amazon it should be fine but if its from a re-seller it has a good chance of being a fake, personally I'd send it back and get another from a solid source.

It did Robin, for precisely the reason you state, I avoided resellers and only shortlisted the ones fulfilled by Amazon UK themselves. I got caught with a fake battery not so long ago like that! Got my money back no problem, but it took a lot of time and effort to 'prove' it was fake.

I guess my next step is swap the two cards I have between cameras, just to confirm the one I pt in the P510 isn't faulty (doubtful), then keep these two 32GB'ers for the D5000 and consider buying a faster 4GB card for the P510.
I have a 4GB Class 6 normally kept in the Canon S100 I could try before I buy, but ideally a bit more space would be nice, so I may try an 8GB Class 10 (and cross my fingers).

Once again, thanks to all responders,

[ktuli]

I didn't time anything, but this DID feel quicker; I could shoot small bursts of 2-4, then just keep going adding more in (while the earlier ones were beng written out

Dave,

This was a suggestion I was going to make. I have read from multiple sources that it is better to use multiple short bursts than to push the extent of your camera's listed burst rate. For example, with my 7D, it can shoot up to 8 fps, with up to 23 RAW files in a single sustained burst (just under 3 seconds I guess) before the buffer will fill up.

But what I have read is that if you release the shutter every so often, the camera can do a better job of managing clearing the buffer than it can if the buffer becomes entirely full. So the theory is that in a 4 or 5 second burst, you will get more shots off if you press, hold, release, press, hold, release, etc rather than simply press, hold, hold, hold, buffer full, release, wait, press.

What happens (at least in the 7D's case, and I suspect in many cameras) is that if the buffer is not full, it allows you to continue shooting; however, once the buffer becomes full, it triggers a routine that says to clear the whole buffer. Most times, those routines are not written in such a way that allow you to continue shooting, so you have to wait for the whole buffer to clear before you can shoot again (which sounds like *exactly* what issue you're running into); whereas if you give it pauses in between, it just clears some of the buffer and lets you continue shooting.

Granted, the overall number of frames you gain is minimal (as is the missed frames from releasing the shutter), but the suggestion was being made because it keeps you from getting into that situation where you have to wait for the whole buffer to be written before you can take more shots.

Hope this helps!

- Bill

[Dave Humphries]

Hi Bill,

Yes, I do usually shoot in short bursts of between 2 and 4, but found that after a few bursts, I got to the point where I couldn't shoot anymore because I was filling the buffer quicker than it was being emptied, but that didn't seem to happen yesterday with the faster card in.

As a test, with each card (8GB C2 and 32GB C10), I could do a long burst (until it stops), then see how many seconds before I can shoot again (keep finger on button and EXIF data will give me the answer).

That sounds like a way to put another 100+ clicks on my almost 60k D5000 shutter

On the one hand, I am looking for an excuse to buy a D5100
but on the other; why worry, it feels better, so just take pictures

Cheers,

[Dave Humphries]

With the P510, there will be a crossover of the two (imaginary) graphs in my head; one where delay increases with larger capacity and another where delay reduces with faster card speed.

It would be nice for me if this where 8GB - going from 4GB to 32GB was a big slow down, despite the speed (kinda*) doubling - * I know the published speeds aren't really relevant as Paul eloquently put it but the address space was multiplied by 8x, not 2x.

The problem with the P510 is that once you lift your finger off the shutter button, it insists on clearing the whole buffer before you can shoot again (Grrr), so I was wanting to reduce that time with a faster card.

This behaviour also means if you think something is going to happen imminently (e.g. a bird launch from a perch), you might as well fill the buffer with 5 shots because taking one or two will mean not being able to start shooting again for several seconds anyway. Unlike the DSLR, you can't do the "several short bursts" technique

[Dave Humphries]

OK, I did some test bursts on the Nikon P510;

The first thing I discovered is you cannot rely on the EXIF data!

If I shoot a burst of images, the buffer fills with 5 Large, Fine jpgs.
At a shutter speed of 1/2000s, this is all over in about 1 second, but the EXIF data assigns them consecutive timestamps one second apart. This means I can only be guided by the first timestamp in a sequence to determine buffer clearance (i.e. card write) speed - and then not numerically (insufficient resolution), only for comparison.

The results, using the four cards available today, showing the number of seconds between the first image in each of two sets of five, shot as close together as possible*, are;

32GB C10 card; 14.5 seconds
8GB C2 card; 7 seconds
4GB C2 card; 7.5 seconds
4GB C6 card; 6 seconds

the .5 second figures arose as I averaged two pairs (e.g. 14 on one and 15 on another = 14.5)

* You cannot shoot one burst and shoot second without, sometime in the buffer emptying process, lifting off the shutter button and re-pressing, this was the most consistent way to test.

Now I am intrigued as to whether the Canon S100, which although I don't use it for bursts, is also affected by the "larger memory space, longer write time", issue. So I may test that in a similar manner, mainly to discover whether the 32GB C10 I now have 'spare' is better off in that camera than the 4GB C6 I was using.

As they say; watch this space ...

Cheers,

[pnodrog]

I find your results interesting. It takes 32bits to address up to 4GB. If the problem is related to your camera having a 16 or 32 bit processor and the timing change was a function of needing an extra address byte to write to the card I would have expected the timing jump to have been between the 4Gb and 8GB cards. Keep up the research but try and get hold of another 32GB card to make sure it is not just related to your 32GB card.

[Dave Humphries]

Thanks Paul,

I see the reasoning, but I don't know if the logic of PC 16/32 bit address busses applies to cameras, I suspect not (in the same way), since the camera's maximum is 128GB and surely the processor will have been designed with that address bus width in mind - but then again, it isn't behaving as one would wish

I started trying to compare the 32GB C10 and 8GB C2 in the S100 and immediately hit a snag; it works more like a DSLR and the buffer throughput is much higher, in continuous jpg only, you get a lot more images before it slows down, but even then it doesn't "sieze up" like the P510 does. So I tried jpg + RAW to give it more to chew on, just to get the timings into human measurable sizes, but still the buffer copes amazingly well. Sure, I get flashes of "Busy" on the LCD, but it appears to be capable of shooting at about 1 fps until the proverbial "cows come home".

The difference with the 8GB C2 card wasn't really discernable.
I suppose this means I am better off with the larger card in the S100, although, as it isn't my main camera, the liklehood of me filling up 4GB was remote, so 32GB is 8x overkill but it releases the 4GB C6 for use in the P510 for now.

I'll have to think on this and try a different approach, perhaps counting the number of exposures in say, 10 seconds (and time how long it takes to finish writing them to the card) will give some meaningful comparisons.

What I need is the Canon processing engine in the P510
Or the Nikon lens on the S100 - perhaps the SX40HS, although with a bit less focal length, would have been better choice for continuous shooting - I wonder how that compares?

It looks like I'll be buying some 4 and 8 GB C10 cards soon, as the main and spare for the P510 and hope that at least one of them improves on the 6 second figure above.

Cheers,

[pnodrog]

Keep up the good work Dave.

All microprocessor based systems have control, data and address buses either multiplexed or parallel. But who knows what is causing the inconsiderate behavour of your 32GB card.
Try disciplining it by giving it a good format every now and then.

Good luck