Best Memory Cards For The Pentax K-1

Best Memory Cards For The Pentax K-1

The Pentax K-1 has had a lot of discussion about how memory cards are performing in camera. Some people have trouble getting the dual memory card function working correctly and others have some serious performance issues.

To get to the bottom of these issues, I tested both memory card slots in the Pentax K-1 and found out some very interesting facts that you may not be aware of.


Camera Specs

Sensor: Full Frame 36.4MP  /  Processor: PRIME IV Image Processor

Memory Card Type: SD UHS-I / SD UHS-I

Video: [1920 x 1080]: 29.97 fps / 23.976

Est. Size Of Buffer: 500MB

Continues Shooting Speed: 4.5fps

Shots To Fill Buffer:  17 RAW

Time To Clear Buffer: 23.5 seconds


Pentax K-1 – Amazon / Adorama


Best Memory Cards For The Pentax K-1

The Pentax K-1 baffles me. The design of how the camera interfaces with memory cards just makes zero sense and I think this is what’s causing people problems.

I’ve noticed a few issues when testing cards in this camera that I want to go over.

First, memory card slot 1 actually uses UHS-II hardware, however, the firmware does not support UHS-II. As a matter of fact, the cameras bus speeds don’t really even fully take advantage of UHS-I cards as the camera bottlenecks at speeds of around 30MB/s. Kind of sounds like it’s using the same old junk Sony cameras are using.

Second, because Slot 1 uses different hardware than Slot 2, you’ll run into a lot of issues when swapping cards between different slots. For example, if I formatted a card in Slot 2, it often will not work in Slot 1 and vise versa. Some cards like the Kingston didn’t work at all in Slot 1, but then worked fine in Slot 2.

So when you’re using the dual memory card slots in the Pentax K-1, you need to make sure that each card is formatted while in the Slot you intend to use it in. Also, don’t swap slot unless you plan on reformatting. I think this is what’s giving a lot of people problems.


 Pentax K-1 Memory Card Speed Chart

Speeds are rather disappointing for such an awesome camera. I’m not a Pentax guy but I really liked the K-1 for the time I had it, my only gripe is that it does the same thing the Sony A7rII does. It’s crazy slow at writing to memory cards. I guess it’s fine for landscape and some studio work where you’re not bursting all the time.

SD Memory CardsUSB 3.0 ReadUSB 3.0 WritePentax K-1 WriteSee Price
Delkin 100MB 64GB273.3 MB/s97.3 MB/s29.61 MB/sAmazon
Toshiba 64GB238.5 MB/s199.7 MB/s29.57 MB/sAmazon
Lexar 2000x 64GB280.9 MB/s181.4 MB/s29.51 MB/sAmazon / Adorama
Sandisk Extreme Pro 300MB 64GB263.2 MB/s233.4 MB/S29.45 MB/sAmazon / Adorama
Delkin 250MB 64GB245.1 MB/s164.6 MB/s29.16 MB/sAmazon
Transcend 64GB268.9 MB/s174.3 MB/s29.07 MB/sAmazon
Sony 64GB253.2 MB/s91.62 MB/s28.94 MB/sAmazon
Sandisk Extreme Pro 280MB 64GB257.3 MB/s109.9 MB/s28.69 MB/sAmazon / Adorama
Lexar 1000x 64GB145.0 MB/s60.7 MB/s28.62 MB/sAmazon / Adorama
Samsung Pro+ 64GB U397.5 MB/s87.3 MB/s29.89 MB/sAmazon / Adorama
Samsung Pro 64GB U397.7 MB/s78.6 MB/s29.86 MB/sAmazon / Adorama
Sandisk Extreme Pro 64GB U398.6 MB/s90.8 MB/s29.83 MB/sAmazon / Adorama
Sandisk Extreme Plus 64GB U399.0 MB/s64.4 MB/s29.61 MB/sAmazon / Adorama
Sandisk Extreme 64GB U372.43 MB/s54.1 MB/s29.53 MB/sAmazon / Adorama
Samsung Pro 64GB U196.3 MB/s82.2 MB/s29.27 MB/sAmazon / Adorama
Transcend 64GB U396.7 MB/s68.4 MB/s29.06 MB/sAmazon / Adorama
Lexar 633x 64GB U393.3 MB/s67.3 MB/s28.98 MB/sAmazon / Adorama
Sony 64GB U3 (Old Model)96.5 MB/s84.5 MB/s28.85 MB/sAmazon
Lexar 600x 64GB U195.4 MB/s64.8 MB/s28.83 MB/sAmazon / Adorama
PNY 64GB U396.5 MB/s66.1 MB/s28.70 MB/sAmazon / Adorama
Sony 64GB U3 (New Model)96.7 MB/s56.2 MB/s28.14 MB/sAmazon
PNY 64GB U196.5 MB/s66.5 MB/s24.32 MB/sAmazon
Samsung 64GB SDXC EVO U147.7 MB/s27.3 MB/s20.54 MB/sAmazon / Adorama
Kingston 64GB U398.1 MB/s90.4 MB/snot workingAmazon / Adorama

Based on the speed test, it doesn’t really seem to matter which card you use. However, I would stick with the trusted brands like Sandisk, Samsung, Transcend, Lexar, as they seemed to have the least issues. Especially Sandisk.



Fastest Memory Cards For the Pentax K-1 | The Results


Best UHS-II Memory Card

While the Pentax K-1 doesn’t take advantage of UHS-II, it does produce some enormous files, and if want quick transfer speeds from you camera to your computer, UHS-II can save you some time if you have a UHS-II compatible card reader.

My top three favorite UHS-II brands are Sandisk, Lexar and Delkin.

Sandisk Extreme Pro 300MB 64GBAmazon / Adorama

Delkin 250MB 64GB – Amazon / Amazon


Best UHS-I Memory Cards

Since UHS-I cards all perform the same in the Pentax K1 you can feel comfortable buying your favorite brand. However, since this camera is finicky, I would still stick with the top trusted brands. Sandisk, Samsung, Lexar or even Sony.

Sandisk Extreme Pro U3 64GB – Amazon / Adorama

Sandisk Extreme Plus 64GB U3 – Amazon / Adorama

Samsung Pro+ 64GB U3Amazon / Adorama

Transcend 64GB U3 – Amazon / Adorama


Where To Buy Memory Cards

When buying memory cards online you’ll need to be careful you don’t get stuck with counterfeit cards. Avoid Ebay completely and if you’re buying from Amazon, make sure you buy from a trusted store.

Adorama and B&Hphoto are fantastic and will always take care of you with your camera gear.



Best Cards For Video In The Pentax K-1

The Pentax K1 doesn’t have any restrictions on memory card when it comes to shooting video. Even at 1080p the camera shoots at a low enough bitrate so that any of the new memory cards, except maybe the Samsung EVO will work fine. The PNY U1 card was also giving me some issues with performance.



Frequently Ask Questions

I’ve been doing these memory card speed tests for several years now and I get a lot of the same questions asked, so I’ll do my best to answer those here.


Do I need a UHS-II Memory Card? – You do not need a UHS-II memory card and they actually will give you no benefit over UHS-I memory card when used in camera. The only difference a UHS-II memory card will make in the Pentax K-1 is it will allow you to transfer your data to your computer quick, if you have a fast UHS-II memory card reader.


What’s the difference between U1 and U3 SD Memory cards? – The main difference has to do with minimum write speeds. U1 cards are guaranteed to write at a minimum speed of 10MB/s, and U3 SD memory card can write at a minimum speed of 30MB/s. Now of course there are many things that go on inside the camera that might not guarantee this, but it’s usually not the cards fault. You’ll also start seeing V30, V60 and V90 written on cards. This has to do with the minimum write speeds V30 – 30MB/s, V60 – 60MB/s, V90 – 90MB/s.


What’s the difference between SDHC and SDXC with SD memory cards? – This has to do with the formatting of the card. SDHC cards are Fat32, and SDXC cards are exFat. Now pretty much SDHC means any card 32GB and smaller, and SDXC means 64GB and larger.


My memory card is creating corrupt shots what do I do? – Unfortunately in this situation you likely have a bad card. There isn’t a lot you can do about this other than to replace your card.


My memory card doesn’t work what do I do? – It’s likely you could have a bad memory card, but also make sure you always format your card in camera. This tends to reduce issues with cards not working or not performing correctly.



Best Memory Card For The Pentax K-1 | Conclusions

The main take away when using the dual memory card slots in the Pentax K-1 is to make sure you format each card in the slot you intend to use it in and don’t swap slots after formatting. That seems to solve most of the problems I was having.

If you have a card that isn’t working in one slot, try it in the other and if that’s the only slot it works well in, then let that card be designated to that slot.

Also, if Pentax ever updates their firmware to support the UHS-II hardware that’s found in Slot 1, I’ll retest to see if it makes any difference.


  • Gerard Dirks
    March 13, 2019, 6:52 am  Reply

    Last month we bought a couple of Kingston SDXC Canvas React UHS-I U3 256 GB & SDXC Canvas React UHS-I U3 32 GB Card. They work absolute fine in both the K-1 & K-3. The Problem is when I but them the 256 Gb Card in die Mac, I am able to copy the pictures but it will be destroyed. As soon a I put the Card in the Camera it is unreadable. When I put it again in the Mac. The DCIM is empty.

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