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10-03-2016, 08:53 AM   #1
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Buffer performance

Just took a couple series shots and was not impressed by the frame rate and buffer size of the K1. Frame rate is OK, but the buffer cleared really slowly. I am saving raw images on two SD cards (one for backup). Cards are rated 95 MB/s and 80MB/s. Would faster cards really help clearing the buffer faster? Is saving to a single card faster? Saving in JPEG may also be faster? Tell me about your experience.
Deleting images sometimes takes rather long - maybe one of my cards is defective.

Btw... are there any tests out there for comparison. dpreview used to tell you how many images you could take before the buffer was filled.

10-03-2016, 09:03 AM   #2

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There is a logic to the K-1 - and part of that is that you're never (with current technology) gong to get fast frame rate with a 36Mp sensor (the Nikon D810 can only do 5.5 fps FF RAW) - I suspect that they took this as a starting point and didn't over-invest in AF-tacking and buffer size because from the word 'go' the sensor size determined the characteristics of the camera.
10-03-2016, 10:17 AM   #3
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I am not simply complaining about frame rate, but about the time it takes to clear the in camera buffer after it was filled. How fast can the K1 write to my SD cards? Would faster cards help clear the buffer faster. With only one SD card - my frame rate with full buffer feels like 1 fps and the buffer clears fairly fast. With two cards the frame rate with full buffer goes down to something like 0.3 fps - this implies that the time it takes to clear the buffer is limited by the data transfer in the camera and/or the write speed of my SD cards.

Manual claims 4.4 fps and 17 images to fill the buffer in raw, JPEGs are processed on the sensor and have reduced file size, so Pentax claims up to 70 frames before the buffer is full

You cannot define different card saving setting for different user settings - this would be a nice feature for a firmware update, saving to one card only for something you call Sports User.

It is also noteworthy that raw images have different files sizes. It means that Pentax applies some compression otherwise every frame should be exactly the same size - assuming I am not running any auto correction function that is slowing something down, but I think I disabled them all.

oops, now I see this thread:
10-03-2016, 11:23 AM   #4

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The buffer is of the K1 is pretty large... but 36Mpixels RAWs heavy to swallow.
For example, if you select jpeg 22Mp, you get similar or more buffer depth than Canon/Nikon competition.
Of course, you want it all, 36Mpixel RAW AND the depth of a 5DIII/D750/D500 , which would require Pentax to fit a 1Dx or D5 electronics into a K1 at the price of the K1, which is impossible.

10-03-2016, 11:39 AM   #5
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Saving files to both cards doubles the total write time. Those cards are just about the fastest that the K-1 can take advantage of, so they're not likely to be the problem, either.

If you have distortion correction enabled for your JPEGs, this considerably increases write time, so be sure to turn it off.

We've published buffer size tests here:

Pentax K-1 Review - Introduction | Reviews

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10-03-2016, 11:45 AM   #6
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First: Logically if you ask the camera to write to one card only, it will empty the buffer faster than if tasked to write to two cards. Whether it writes simultaneously or sequentially, to fill data in two cards will take longer than just one.

Second: I believe you are referring to the max read speeds of your cards. The important claimed performance in your case is the write speed, and you can ignore the max write speed; what matters is finding the fastest minimum write speed. This is often expressed as UHS-I vs. UHS-II class cards.

So if I compare these two 128GB memory cards:
SanDisk SDXC 128GB card with 95MB Max read, 90MB Max write, and 30MB Min write rated, UHS-I
SanDisk 128GB Extreme PRO UHS-I SDXC Memory Card SDSDXP-128G-A46

Delkin SDXC128GB card with 285MB Max read, 100MB minimum write, UHS-II
Delkin Devices 128GB UHS-II SDXC Memory Card (U3) DDSD19001H B&H

Problem: The K-1 does not support UHS-II cards. So the best you can do are considered Class 10/U3 (faster sustained write speeds vs. Class 10/U1), UHS-I, SDXC cards.
If RAW is essential, shoot to only one card and back it up later. If two cards are essential, shoot in the highest quality jpeg option.
10-03-2016, 12:10 PM   #7
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What about the delete speed? I have noticed that the K-1 is very slow to delete pictures; is it doing something different than the K-3 when it deletes? Sometimes (usually?) deleting one picture takes way longer than it should.
10-03-2016, 12:24 PM   #8

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Let's be clear, the K1 isn't designed for actions photography, and priced accordingly. For enthusiasts, top of the range apsc DSLR suit this purpose, and there are the D5 and 1Dx for professionals, but the price is also higher.

10-03-2016, 12:34 PM   #9

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QuoteOriginally posted by zapp Quote
Btw... are there any tests out there for comparison
Imaging Resource run such tests for every camera they review:

Pentax K-1 Review - Performance
10-07-2016, 06:08 AM - 1 Like   #10
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QuoteOriginally posted by biz-engineer Quote
Let's be clear, the K1 isn't designed for actions photography, and priced accordingly. For enthusiasts, top of the range apsc DSLR suit this purpose, and there are the D5 and 1Dx for professionals, but the price is also higher.
Nobody here is asking for increased performance. I am just interested how to make best use of K1 features.

Delete times for individual images can take several seconds - while blocking the camera. Thatīs not a feature.
10-07-2016, 07:01 AM   #11

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Just to be somewhat pedantic - sorry! - you're not talking about "buffer performance" but card transfer speed. Which is not exactly up to date in the K-1.
From what I saw, the K-1 can use UHS-I SDR50 speeds and that's it; in other words, it can't use the full 90MB/sec write speed of the Sandisk Extreme Pro. An UHS-I card offering over 40MB/sec would do.
Using an UHS-II card shouldn't give any performance penalty compared to the fastest UHS-I cards, but no benefit either; it would still work at UHS-I SDR50 speeds.

What can we do? Three things, basically:
- use a fast UHS-I card, but not necessarily the fastest. I preferred the Sandisk Extreme Pro because they're (supposedly) reliable, future proof and were reasonable priced.
- manage your bursts. You don't really need to fill the buffer with one contiguous sequence, do you? Shoot smaller bursts, and your buffer won't fill so easily.
- delete images when you have time to do it - and when all the data was written to the card. Get cards of a large enough capacity so you can afford to wait for a proper moment.
Which is a bit of stating the obvious, sorry again!
10-07-2016, 08:52 AM   #12
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I have found that if you try to delete an image while the camera is still writing , it can take quite awhile to complete the task. Since preview is available before the image has completed writing, I find it faster to delete an image if you wait for the writing to stop first. That little orange LED is your friend in this regard, If you just call up an image later and delete it, I see no difference between models.

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