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07-14-2017, 09:58 AM   #1
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K-5 vs. K-7? Why the difference?

I noticed today that the K-7 only has 12-bit RAWs. I assumed that the K-5's superior low/light/noise performance was due to a newer sensor, but I'm wondering if the difference in bit depth was a factor? Or is it more a chicken or the egg thing, where the superior K-5 sensor performance made 14-bit RAWs worth the trouble of keeping the extra data? Or maybe the K-7 sensor wouldn't even provide 14 bits of data?

https://www.dxomark.com/Cameras/Compare/Side-by-side/Pentax-K5-versus-Pentax-K7___676_615

07-14-2017, 10:12 AM   #2
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K-7 had a Samsung sensor. The K-5 a Sony sensor. The K-5 came pretty soon after the K-7 because of the better Sony sensor. There was a Sony CMOS in the K-r and people noticed it was outperforming the K-7.
07-14-2017, 10:16 AM   #3
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The K-7 & K-5 both use the same Prime II image processor. So the improved capabilities of the K-5 are mostly Sensor/Software improvements.

But I wouldn't put much faith in DxO...The K20D outperforms the K-7 according to them...same sensor...

Also, Pentax seems to have squeezed as much out of the Sony sensor as possible. At least more than Nikon and Sony did...

https://www.dxomark.com/Cameras/Compare/Side-by-side/Sony-Alpha-580-versus-N...___685_680_676

Again, it's DxO...

Last edited by boriscleto; 07-14-2017 at 10:27 AM.
07-14-2017, 10:18 AM   #4
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QuoteOriginally posted by D1N0 Quote
There was a Sony CMOS in the K-r and people noticed it was outperforming the K-7.
The K-x had the same sensor. At the time there were a lot of people on this board demanding a "K-7 with the K-x sensor".

07-14-2017, 10:43 AM - 1 Like   #5
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QuoteOriginally posted by boriscleto Quote
The K-7 & K-5 both use the same Prime II image processor. So the improved capabilities of the K-5 are mostly Sensor/Software improvements.

But I wouldn't put much faith in DxO...The K20D outperforms the K-7 according to them...same sensor...
Not quite the same sensor... the K-7 sensor supported video, having a 4-channel readout. The K20D's was an older version with 2-channel readout. There could have been other changes in optimizing the sensor for video that affected the stills image quality just a little bit, especially on higher ISOs. That, I think, would not be uncommon.
07-14-2017, 11:12 AM   #6
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The problem during that generation (K-x and K-7) was that the K-x, meant to be a cheaper model, delivered better low light performance. The K-5 fixed that issue and established itself as the best performing DSLR until the 24 MP sensor came out.

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07-14-2017, 11:55 AM   #7
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QuoteOriginally posted by Adam Quote
The K-5 fixed that issue and established itself as the best performing DSLR until the 24 MP sensor came out.
And even now, some people swear it has an edge of some sort, even over the K-1 (pixel for pixel) in some respects.

07-14-2017, 12:01 PM   #8
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QuoteOriginally posted by pathdoc Quote
And even now, some people swear it has an edge of some sort, even over the K-1 (pixel for pixel) in some respects.
I still use my K5, while I also have the K3, because of its high ISO performance.
So it doesn't surprise me when you say that some people claim it has an edge over the K-1 "in some respects".
Of course, a K-1 would be ... Nice ! (to have).
07-14-2017, 01:28 PM - 1 Like   #9
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QuoteOriginally posted by pathdoc Quote
And even now, some people swear it has an edge of some sort, even over the K-1 (pixel for pixel) in some respects.
QuoteOriginally posted by jpzk Quote
I still use my K5, while I also have the K3, because of its high ISO performance.
I also have the K-5 as well as the K-3. At 1:1 reproduction, the K-5 does have a slight edge at higher (but not its highest) ISOs to my eye, but I tend to believe that may be due to in-camera "pre-processing" of the RAW images. With gentle processing in Lightroom, I can get at least equivalent (and often better) results out of the K-3 with no additional loss of detail. Furthermore - and this is the biggie - because of its considerably-higher resolution, resizing images to the same dimensions as those from the K-5 results in "finer" noise. Plus, the K-3 holds on to colour reproduction at higher ISOs better than the K-5 can manage. All of this is just my opinion, of course... YMMV

That said, the K-5 does have great high ISO performance, especially considering its age!

Last edited by BigMackCam; 07-14-2017 at 03:49 PM.
07-14-2017, 02:48 PM   #10
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The superior lower noise at higher ISO of the K-5 over the K-7 is also very evident in JPEG shots. That should answer your question about the K-5's 14 bit RAW, which is also good to have.

You can see this for yourself in using the "comparometer" of the Imaging Resource website. You can compare the same shot from any two cameras at the same ISO. These are JPEG images straight from the camera. At the top of each column, select "all cameras" to get the discontinued models included. Once you select your 2 cameras, scroll down to the example image given of various objects, including fabrics, bottles, etc. then scroll further to one of the higher ISO settings, say ISO 3200. After you bring that image up for both cameras, click on it again to get the blowup. Look between the objects for areas where shadowing is about the same for each camera to see the difference in noise. Also look for detail preservation in the objects, especially on the bottle labels.

I passed on the K-7 because I got a great deal on a K20D after the K-7 came out, and the difference in image quality was negligible according to test reviews I saw. If anything, noise was not quite as good from the K-7. The K-5 series was a whole different story. I now have the fine little K-S2 and more recently the delightful, excellent KP, but I still very much enjoy using my K-5 IIs as it suits certain circumstances. It is still great camera.

Last edited by mikesbike; 07-14-2017 at 03:00 PM.
07-14-2017, 03:07 PM   #11
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QuoteOriginally posted by mikesbike Quote
You can see this for yourself in using the "comparometer" of the Imaging Resource website. You can compare the same shot from any two cameras at the same ISO. These are JPEG images straight from the camera. At the top of each column, select "all cameras" to get the discontinued models included. Once you select your 2 cameras, scroll down to the example image given of various objects, including fabrics, bottles, etc. then scroll further to one of the higher ISO settings, say ISO 3200. After you bring that image up for both cameras, click on it again to get the blowup. Look between the objects for areas where shadowing is about the same for each camera to see the difference in noise. Also look for detail preservation in the objects, especially on the bottle labels.
You have to be very careful in drawing any conclusions from this online tool, IMHO. As you rightly mention, these "comparometer" tests use straight-out-of-camera JPEG files, and whilst that might be valuable for the casual user, it's of limited use in showing real sensor and imaging performance, as so much processing (good and bad) is carried out by the respective JPEG engines in the cameras.

Years ago, when I switched from a Nikon D40X to Pentax K-7, I remember being somewhat underwhelmed by the image quality I got from the Pentax. It was only years later (my K-7 long gone) that I realised the culprit was the JPEG processing engine, which - until recently - hasn't been a Pentax strong-point.

The best possible comparisons would use RAW files at a range of different ISOs and in a range of lighting conditions, plus the user would want to take those RAW files and play with them in their chosen RAW converter and post-processing tool.

All of that aside, for casual JPEG shooting, the "comparometer" has it's uses
07-14-2017, 03:33 PM   #12
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The difference is in dynamic range at higher ISOs, 1600 or more. The K-7 isn't that bad for noise, but at 1600 or more, images start to look more like graphic novels than reality. I don't think it's bit depth, just not enough sensitivity to start. You can get away with some shots that don't require that DR. The K-5 has a lot better dynamic range at 3200-6400. Then add its better metering, AF and other upgrades. The K-7 should be cheap and is great for a lot of things, but the K-5 deserves its higher used price.
07-14-2017, 05:21 PM   #13
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The reduced noise with the K-5 JPEGS over the K-7 JPEGS still prove it is not the K-5's 14 bit RAW that is responsible, which was the question. It has been determined by test reviews that the K-5 series' sensor has exceptionally low native base noise characteristics. Yes, JPEG in-camera processing can be substandard. And it is indeed this engine that is largely responsible for JPEG image sharpness and quality. The results from RAW files also are variable, depending on how much expertise those doing the post-processing have. The otherwise excellent for its time K10D did not have a very good JPEG engine. Nor does the present K-1. Many other Pentax DSLR models, however, do a very good job. The K-5 series is exceptionally good, including the ability to select extra-high quality (one extra star), which I've found to even more closely resemble a RAW file post-processed and saved as JPEG. My K-S2, I've found does a fine job, yet it does not have 14 bit RAW, just a very good JPEG engine and very good in-camera processing with very well-designed auto-noise reduction. My recently-acquired KP has been outstanding in every way.

Last edited by mikesbike; 07-14-2017 at 05:37 PM.
07-14-2017, 06:31 PM   #14
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QuoteOriginally posted by mikesbike Quote
The reduced noise with the K-5 JPEGS over the K-7 JPEGS still prove it is not the K-5's 14 bit RAW that is responsible, which was the question. It has been determined by test reviews that the K-5 series' sensor has exceptionally low native base noise characteristics. Yes, JPEG in-camera processing can be substandard. And it is indeed this engine that is largely responsible for JPEG image sharpness and quality. The results from RAW files also are variable, depending on how much expertise those doing the post-processing have. The otherwise excellent for its time K10D did not have a very good JPEG engine. Nor does the present K-1. Many other Pentax DSLR models, however, do a very good job. The K-5 series is exceptionally good, including the ability to select extra-high quality (one extra star), which I've found to even more closely resemble a RAW file post-processed and saved as JPEG. My K-S2, I've found does a fine job, yet it does not have 14 bit RAW, just a very good JPEG engine and very good in-camera processing with very well-designed auto-noise reduction. My recently-acquired KP has been outstanding in every way.
Actually Mike the reason why the K5 sensor performs well is not that it is particularly low in read noise. In fact the K3 has lower read noise as does the KP. The reason for the K5's fairly wide DR relative to the K3 is due to its saturation value. Its Quantum Efficiency is about the same. As to the K7 its read noise is quite high - almost 6 times higher than the K3 and K5 while at the same time having a significantly lower QE and about the same sensor saturation as the K3 (about 60% of the K5). The K5 can make use of a 14 bit ADC as its DR at base ISO (~13.8 stops) is above what a 12 bit convertor would convert comfortably as base ISO. The K7 at roughly 10.2 stops of DR at base ISO will fit well with a 12 bit ADC. Someone above mentioned that the K20D; it has lower read noise than the K7 but it has roughly the same sensor saturation and QE. That gives is a slight bit better DR. Not really much to matter though - its about a third of a stop better.
07-15-2017, 12:22 PM   #15
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QuoteOriginally posted by Fauxton Quote
Actually Mike the reason why the K5 sensor performs well is not that it is particularly low in read noise. In fact the K3 has lower read noise as does the KP. The reason for the K5's fairly wide DR relative to the K3 is due to its saturation value. Its Quantum Efficiency is about the same. As to the K7 its read noise is quite high - almost 6 times higher than the K3 and K5 while at the same time having a significantly lower QE and about the same sensor saturation as the K3 (about 60% of the K5). The K5 can make use of a 14 bit ADC as its DR at base ISO (~13.8 stops) is above what a 12 bit convertor would convert comfortably as base ISO. The K7 at roughly 10.2 stops of DR at base ISO will fit well with a 12 bit ADC. Someone above mentioned that the K20D; it has lower read noise than the K7 but it has roughly the same sensor saturation and QE. That gives is a slight bit better DR. Not really much to matter though - its about a third of a stop better.
Very interesting. How you are able to gain this technical information is mystifying, but your insights are impressive. Upon re-reading, what I notice is the evaluated differences between these models closely resembles my own judgments and impressions, either from tests I have read or from personal experiences. I have never used a K-7.

For years, it was a given that going to a design of higher MPs would include a greater noise factor, and the need for greater noise suppression with detail-smearing side-effects. Many people were sticking to their 6mp DSLRs. The K10D and K200D came along with advanced features, and at 10MP noise control was pretty good with good detail preservation. The K20D was a surprise in that noise control factors were still decent despite increasing resolution to over 14 MP. The K-5 was a shocker. It seemed achieving such outstanding noise control with good detail preservation in a DSLR of more than 15MP was miraculous! Now we have even better results in the K-70 and KP at 24MP! I have always thought if sensor technology can be advanced to create less noise to begin with, we would not require as much NR and get much cleaner results at higher ISO settings. I think we still have more room for improvement here, but what we now have is amazing. I still value my K-5 IIs greatly for its controls, fine IQ, excellent build and ergonomics, relatively low weight, and fine handling. Even though it has now been surpassed, it is capable of very high-quality images. Between it, my KP, and K-S2, it is more about what features I will need, how high the ISO I might need, and the practical aspects of portability, etc. So far, I have found the KP to be truly outstanding in many aspects.
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