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11-04-2010, 04:11 AM   #46
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QuoteOriginally posted by ogl Quote
:ugh: I think that IQ shows us the final photo, not DXO's numbers
I linked to some photos, K-x vs K-r. Do you see an IQ advantage for the K-r? I sure don't, in fact the K-x looks a tiny bit better in spots.

11-04-2010, 04:32 AM   #47
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QuoteOriginally posted by audiobomber Quote
The statement that is attributed to Ned Bunnel says better IQ:

The sensor in the K-r is new. Yes, its 12MP like K-xs, but it is a new design and photographers will see an improvement in IQ because of this.
Speaking to Pentax at PhotoPlus Expo in New York | Enticing the Light

I don't see the justification for saying "better IQ" from the published DXO results or the comparison posted here https://www.pentaxforums.com/forums/pentax-dslr-discussion/120126-k-r-vs-k-x-...so-flower.html.
What else is he going to say? We put a worse sensor in? People often see what they want to in images. Often people claim to see differences in image quality between full frame and cropped cameras at web resolution -- even at lower isos. We are easy to fool, but on the other hand the question is does the camera take good photos and the answer is probably yes, just not a whole lot different from those taken by the kx.
11-04-2010, 06:06 AM   #48
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Hi all, great discussion. I do look at DxO numbers, but all the reviews I can get my "eyes on" as well.

As for K-x vs. K-r, some say sensor is essentially the same or exactly the same, others say different. I'd like to make one observation that is solely based on the PhotographyBlog review: If we trust that the reviewer took the sample images for both cams under the same conditions, then the sensor in the K-r does appear to be different: the RAW shots of the K-r seem to be cooler than those of the K-x. See Pentax K-x Review - Image Quality | PhotographyBLOG versus Pentax K-r Review - Image Quality | PhotographyBLOG , and note the RAW shots in the Noise section.

When I was originally deciding which brand to buy for my first DSLR, I did notice that Pentax DSLRs tended to produce warmer toned photos, or what I'd at first glance call yellowish, though that can of course be adjusted with white balance and post-processing. I liked what I saw as the finer-detailed output of the Pentax, and didn't mind the warmer tones, and I have been happy with my K10D ever since I gave Pentax the nod. However, it appears from the PhotographyBlog's samples that the warmness difference may no longer be true, with the K-r. Do others see this? Is this a good or bad thing? Should I have started a different thread to discuss this?
11-04-2010, 06:58 AM   #49
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QuoteOriginally posted by Rondec Quote
I really think they measure what they measure. The reality is that crop cameras, even good ones start losing dynamic range around iso 900 and full frame cameras around 1800. The numbers being thrown around sound like bigger differences than they are. These are quarter stop differences or less that are talked about -- not really visible in real shooting.
by this, are we expecting the k-5 to be no better DxO marks as well?

11-04-2010, 07:49 AM   #50
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QuoteOriginally posted by Pentaxor Quote
by this, are we expecting the k-5 to be no better DxO marks as well?
I don't expect miracles. The idea that the K5 will suddenly do a jump from the D90 range of iso 900 to full frame level of iso 1800 is silly. People are focusing on the presence or lack of noise at high iso, which is not what Dxo is looking at, but rather the dynamic range at a given iso level.

I think that I could easily shoot iso 6400 on the K5 and be very pleased with it, but I don't forsee Dxo measuring huge differences between it and past crop frame cameras. This is where I think the number is a little meaningless. They set the bar high enough that it doesn't really convey whether or not you can print a photo at a decent size or not, even if dynamic range is not great.
11-04-2010, 08:15 AM   #51
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QuoteOriginally posted by Rondec Quote
I don't expect miracles. The idea that the K5 will suddenly do a jump from the D90 range of iso 900 to full frame level of iso 1800 is silly. People are focusing on the presence or lack of noise at high iso, which is not what Dxo is looking at, but rather the dynamic range at a given iso level.
The K5 seems to have insane DR at base ISO from what I've seen so far. If Gordon B Good has guessed right and the DxO DR score is around 13, the K-5 will be among the top 5 cameras in the DxO "landscape" ranking.

Dxo is measuring a combination of different scores. From DxOMark - Use Case Scores :
Low-Light ISO is then the highest ISO setting for the camera such that the SNR reaches this 30dB value while keeping a good dynamic range of 9 EVs and a color depth of 18bits.

I think the minimum value we can expect here is 1/3 stop above the Sony A55, i.e. above ISO 1000.

For the overall score, my guess is also slightly more than 1/3 stop above the Sony A55.

So I guess a score of 78-80, which only FF and MF cameras have achieved so far.
11-04-2010, 08:34 AM - 1 Like   #52
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I don't really think it is that important to have huge dynamic range at high iso. I find that when I am shooting a high iso scene, it tends to have a fairly restricted dynamic range anyway. This is why I find that I can comfortably shoot at significantly higher iso than the Dxo score. Would I shoot landscapes at iso 1600? Probably not, but many other scenes require much less DR.
11-04-2010, 08:44 AM   #53
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QuoteOriginally posted by gazonk Quote
For the overall score, my guess is also slightly more than 1/3 stop above the Sony A55.
This is interesting. We should run a tipping contest to see who comes closest to predicting the K-5's DXOMark scores, esp the overall number and the high-ISO score.

My conservative tip is that the overall score will be very much in the K-x/D90 ballpark, maybe about 74, boosted by the great DR. And for the low-light ISO - I would guess [hope] 940 - ie a little bit less than the 12MP D90's 977 but better than the 14MP D3100's 919.

When the D7000 gets DXOMark'd, that will give a very good idea of how the K-5 would place, I think.

11-04-2010, 11:37 AM   #54
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QuoteOriginally posted by audiobomber Quote
I linked to some photos, K-x vs K-r. Do you see an IQ advantage for the K-r? I sure don't, in fact the K-x looks a tiny bit better in spots.
I don't see real comparision. I think you didn't see too.
11-04-2010, 04:08 PM   #55
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QuoteOriginally posted by ogl Quote
I don't see real comparision. I think you didn't see too.
You seem to want to believe that the K-r sensor is better than the K-x sensor. I think you're in for a let-down.
11-04-2010, 05:09 PM   #56
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QuoteOriginally posted by gazonk Quote
The K5 seems to have insane DR at base ISO from what I've seen so far. If Gordon B Good has guessed right and the DxO DR score is around 13, the K-5 will be among the top 5 cameras in the DxO "landscape" ranking.
13 was my guess I made in my Photokina preview report, maybe +/- 0.5. Gordon's guess was 14...

I had a private communication with him about it and I can see how he derives that figure. Still, there are too many assumptions for me to endorse his guess which therefore remains what it was after Photokina. I'll know if I run my own lab test which is very close to DxO DR. I don't participate in guessing overall scores which aren't very meaningful figures anyway.

The low light ISO score is based on an SNR of 30dB and yields about 1000 for best APSC (assuming K-5 and D7000 break this barrier) and crop^2*1000 or 2300 for best FF.

Nowadays and with entropy-based NR, an SNR of 30 dB is mid light ISO and DxO doesn't have a true low light score. The DR at ISO 1600 would be as close a low light score as possible.
11-04-2010, 05:25 PM   #57
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QuoteOriginally posted by falconeye Quote
Nowadays and with entropy-based NR, an SNR of 30 dB is mid light ISO and DxO doesn't have a true low light score. The DR at ISO 1600 would be as close a low light score as possible.
I'm sure you get this alot, but... I wondered if you could explain(in layman) terms why ISO1600 is the magic number when it comes to DR measurement etc...

Also, is 1600 relative to noise measurements as well?

ie. should we of conducted our software ISO push tests from an ISO1600 base?

I'm really not sure why our samples are not showing the NR threshold with the K-5... and trying to figure out why theory isn't meeting practicality.
11-04-2010, 06:18 PM   #58
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I just took a look at their K200D sensor stats for the first time, and they peg the 'sports' ISO at 561. From experience, I always have the auto-ISO ranging from 100-500 which tells me that DxO and I agree on what acceptable quality is - so to me it seems a very useful benchmark!

I'm happy that the K-r will let me get the same quality shots at around ISO800, and absolutely astonished by the figures for the high-end Nikons!
11-04-2010, 06:52 PM   #59
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QuoteOriginally posted by JohnBee Quote
why ISO1600 is the magic number when it comes to DR measurement etc...
There's nothing special with 1600. It's just my fetish. 1600 seems to be the figure where noise starts to be visible enough to seriously care about (at least for APSC). So, 1600 marks the "high iso" regime for me. But's that's entirely arbitrary. Except that it also sits in the exact middle between 100 and 25,600.

For the K-5, Gordon B Good additionally believes to have evidence that iso levels higher than 1600 are produced digitally from analog data read out at ISO 1600. That needs further verification though.

QuoteOriginally posted by JohnBee Quote
I'm really not sure why our samples are not showing the NR threshold with the K-5... and trying to figure out why theory isn't meeting practicality.
I'm awaiting your samples before I can comment. If hunting for signs of NR, comparing ISO1600 at -3EV, and ISO 12,800, for an identical subject, would be ideal.

I assume it will be hard to see signs of NR with the naked eye. A lab test is more easily able to show the difference. E.g., for the K-r, the effect of NR is only +1.8 dB extra SNR (about half a stop) above ISO 1600. Very difficult to discern by pure visual inspection.

QuoteOriginally posted by timh Quote
'sports' ISO at 561. From experience, I always have the auto-ISO ranging from 100-500 which tells me that DxO and I agree on what acceptable quality is
Yes, DxO's sports score (aka low light ISO score) is a good default for the upper AUTO ISO limit. Which means that one doesn't need to care about bad image quality.

However, real sports photography would actually go into the "unsafe" area and accept a certain level of grain to make fast pace action shots feasible. As shown by the K-5 samples (assuming it will have a sports score of about 1000), the K-5 has no problems of producing glossy magazine action shots at, e.g., ISO 6400 (with some post processing).
11-05-2010, 12:51 AM   #60
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QuoteOriginally posted by falconeye Quote
However, real sports photography would actually go into the "unsafe" area and accept a certain level of grain to make fast pace action shots feasible. As shown by the K-5 samples (assuming it will have a sports score of about 1000), the K-5 has no problems of producing glossy magazine action shots at, e.g., ISO 6400 (with some post processing).
I agree, I think the 522 "sports" score for the K10D is very conservative. If the exposure is right, ISO 800 shots from my K10D certainly look very good printed large, but of course I prefer to stay at 400 or below to keep some headroom in the shadows.
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