Slow SD cards for K20D or perhaps...

Started Nov 18, 2012 | Discussions thread
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Slow SD cards for K20D or perhaps...
Nov 18, 2012

For those who own a K20D or perhaps any dSLR that uses SD cards.

I started using the K20D with a SanDisk Ultra II 4GB and 8GB Class 4 cards I used in my Samsung GX20 (same as K10D). Those cards were quick and I can fill a 4GB card in no time. I shoot in RAW, really RAW+JPEG many times. The higher end SanDisk Extreme cards were more than I wanted to pay for (like over $70). Moreover the Ultra II cards provided me with about 16 RAW shots and were pretty quick. I bought another SanDisk 8GB ultra II SDHC card to use with the K20D as it had larger files and would fill a 4GB card fairly quick sometimes. In the pic below the two black cards with no tags are the SanDisk Ultra II cards now over  about 4 years old. I had to take the tags off them so they would fit in the GX10 SD card holder. Some may remember a time when the new 4GB SDHC cards would fit really tight in the card slot. One solution was to remove the tag, as you see below. The K20D did not have that problem.

At an air show I was shooting hundreds of shots in continuous mode. When I filled one of my 8GB cards I ask my friend to quickly get my other 8GB card. In his rush he somehow pulled out the write protect tab. I just tossed it and went for my 4GB SanDisk Ultra II card. That SanDisk 8GB card I lost that day in August 2009, began a long, hard, some what money wasting, three year quest to get a card just equal in speed to the one I lost.

However I won’t burden you with too much of a long read. Oh who am I kidding! Yep it’s a typical jamesm007 post. But it could very valuable to some people. To the point. I discovered Class ratings are meaningless (almost)! I took back many SD cards over the years because none of them would allow the K20D to flush its buffer to the SD card as fast as my old SanDisk Ultra II 8GB or 4GB class 4 cards. They would flush the buffer in around 20 seconds. All of the cards I would buy took over 40 seconds, some almost 60 seconds to flush the buffer. The class rating and written specs said they should be much better compared to my old class 4 cards, they were twice as slow. I remember buying the fastest card at a value price, a Panasonic at Ritz camera (years ago) for like $70 and it was slower! This made me think SanDisk had the best cards for a short time. Remember I had the 8GB and 4GB SanDisk Ultra II cards anyways, so I was in no hurry, or in great need. So I did not buy the very best SanDisks at over $100. I just tried one when I thought for sure it had to be faster. Technology always gets faster, cheaper. But the SD cards kept getting slower.

Understand when I first went looking for a replacement my top price was much higher than now.  But it did not bring better results, but same old slow times of over 40/sec. I got tired of being burned and losing money if they would not return the card.

I just bought a SanDisk 8GB last week (package in pic below), its junk, taking over 40 seconds to flush its buffer. Same old story and disappointment. I then realized testing all my cards with my new SSD test programs it was poor write times, very poor write times making class 10 cards slowwwww. I searched (this week) for a card (without needing a UHS-I interface and stating it had fast write times in normal class 10 mode. My search found a Samsung 8GB class10 card. It had a  rated speed of 24MB/s read, 21MB/s write. This is now the fastest card I have ever had in my K20D.

The Samsung will do 17 RAW files and flush them at 18 seconds and at $12.00! Previews also come up almost instantly if shooting under ISO 800 now, nice, really nice! It use to take a second or two. Now its close to instant! What a card. Check outSamsungsSDcard line if you have a need. Pick the highest write speed.

Oh another discovery, believe this or not. Because I knew the K20D can reverse to older firmware, and keep copies of all firmware, and knew the last firmware upgrade was for better SD card compatibility (ver 1.4), I decided to go back to firmware ver 1.3 and test it. Firmware 1.3 is faster! So if you want, time your card, then go back to firmware ver 1.3 and time, then decide what’s best for you. With the new Samsung card version 1.4 is only 1.5/sec slower, so I am unsure which I will use right now; because there ‘may’, ‘might’, be more than just that in the update.

All of the tests below are timed by me with CrystalDisk (its for my SSD drive but works for SD cards) and a stop watch. All done yesterday, with the cards I just kept and did not return. I have many SD card timing tools, including my most trusted, a pc stop watch.

I have for sure noted its all in the write time for maximum camera performance. If  your shooting a series of BIF you want your high speed to be able to write to the SD card with no bottle necks from the card. That is, a card fast enough to handle the output of the camera flushing its buffer without slowing it down. For some reason latter SD cards got faster in read but had worse write times. I don’t get how a class 10 SD card can be slower than an class 4 card (over four years old) sometimes in both read and write. I was tricked. I really believed in SanDisk and thought of them as the best in all budget categories. Right now I think Samsung makes some of the best per dollar.

I found a memory card review site today.  I looked at cards tested in the Nikon D7000 because its files are about the same size as the K20D and it used SD cards versus CF (which are good!). Note that you have to buy very expensive relative to the very old (over 4 years) SanDisk ultra II to get the same read and write times. Do note it perfectly shows what I Just wrote. I wished I found it years ago (I think I did but the top cards were more than I was willing to pay for). Todays SDHC cards are slower than they were four years ago. You have to buy a $100 SanDisk to equal a $12 Samsung in a none video dSLR using SDHC cards.

Samsung 8GB  Class 10 (just bought in pic below)

Sequential Read :    19.713 MB/s

Sequential Write :    18.522 MB/s (fast write)

For whatever reason this card measures close to the old SanDisk ultra II 4GB but its stopwatch write times in the K20D are about 5 seconds faster. It also allows 17 shots instead of 16.

2GB ClassSanDisk Ultra II  4 (over 5 years old)

Sequential Read :     8.419 MB/s

Sequential Write :     9.843 MB/s (slow write, newer SDHC cards became faster)

SanDisk Ultra II 4GB  Class 4 (over four years old)

Sequential Read :    18.269 MB/s

Sequential Write :    17.300 MB/s (fast write)

SanDisk Ultra II 8GB  Class 4 (over four years old)

Sequential Read :    19.392 MB/s

Sequential Write :    13.499 MB/s (good write)

ADATA 8GB  Class 10 (new still sold)

Sequential Read :    18.592 MB/s

Sequential Write :    10.481 MB/s (slow write)

Kingston8GB  Class 10 (new still sold)

Having problems with this card. Sometimes it won’t format. Sometimes it will. This is my BYOPC computer at home, that has the latest everything (except USB 3). The card took 58/sec to flush the buffer of the K20D. This is about normal for this card.

SanDisk 8GB  Class 6, 30MB/s 200X speed rated full HD (brand new package in pic below)

Sequential Read :    18.695 MB/s

Sequential Write :     8.517 MB/s (slow write)

Kodak High Speed 8GB  100x class 8 (two years old)

Sequential Read :    17.988 MB/s

Sequential Write :     9.001 MB/s (slow write)

 jamesm007's gear list:jamesm007's gear list
Pentax K20D Pentax K-5 Sigma 10-20mm F4-5.6 EX DC HSM Pentax smc DA 55-300mm F4.0-5.8 ED Sigma 17-70mm F2.8-4 DC Macro OS HSM +9 more
Nikon D7000 Pentax K10D Pentax K20D Samsung GX-10
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