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10-28-2009, 09:06 PM   #16
ogl
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I think that K-7 even with NR in LR is not worse than K-x at ISO1600 and has better resolution and more details.
Тесты K-x и K-7 - огл - Участники - Фотогалерея iXBT

10-28-2009, 09:20 PM   #17
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QuoteOriginally posted by Daemos Quote

Well unfortunately I've tested the K7 vs KX twice now, both using different KXs.

I am AWAITING someone else who would actually do the same thing. I invite you to do it.
Having shot few hundred random test shots around, i really do not agree with unevenness part. A part of image is soft and some parts are sharp really do not make sense.

I have camera for one week and my first shots were done with very limited knowledge of handling.
This weekend i am going to take it out and shoot something, then we will see how it performs. So far very happy with it no complains of lack of sharpness on my part. I am getting what i expected from cam. Absolutely no complains, for 600$ its a steal.
10-28-2009, 09:25 PM   #18
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QuoteOriginally posted by zxaar Quote
Having shot few hundred random test shots around, i really do not agree with unevenness part. A part of image is soft and some parts are sharp really do not make sense.

I have camera for one week and my first shots were done with very limited knowledge of handling.
This weekend i am going to take it out and shoot something, then we will see how it performs. So far very happy with it no complains of lack of sharpness on my part. I am getting what i expected from cam. Absolutely no complains, for 600$ its a steal.
I have offered to re-test, so if there is anything you want to add, I'll take any suggestions to try and get as much as I can.
10-28-2009, 09:32 PM   #19
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QuoteOriginally posted by Daemos Quote
I have offered to re-test, so if there is anything you want to add, I'll take any suggestions to try and get as much as I can.
my only suggestion would be keep the sharpness to lowest setting and then apply sharpness in a controlled way afterwards. Many times different subjects may require different type of sharpening. This makes lot of difference visually.


Trying to get best out of k100d, i learned that more i rely on camera more likely i get into bad results. More i did myself better results were.

10-29-2009, 05:57 AM   #20
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Is it possible to discuss my findings rather than the faults of tests discussed in other threads?

E.g., my posting contains two razor sharp images, from K-7 and K-x respectively. I would be eager to see second and third opionions about my findings. Esp. my conclusion about the AA filter.

My measurement methodolgy is similiar enough to DxO's to compare figures. But systematic errors may be high enough to have 3dB systematic differences which is almots as much as the difference between APS-C and FF.

The only camera I could use to calibrate my curves vs. DxO is the K-m. But I am too busy to do it now. It is a lot of work every time ...

Then, I see that DxO's full SNR curves are very smooth. So, I guess I need a better test target (expensive, DxO makes theirs of glass) and a series of tests to average over (time consuming). So, as long as nobody pays me (magazines?), I will not match the accuracy of DxO figures.
10-29-2009, 07:22 AM   #21
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Thanks for the data.

You could do nicer graph graphics though, these are pretty hard to read. Especially the labels... Diamond vs Triangle that just look like very similar small dots on the screen. Also the grey background makes for poor contrast and the resolution of the graphs is piss weak... and it could use a better grid to allow quantification of the results.

The coloured graph is worse, you have to look back and forth between the key and the graph to try and figure out what is what. Its nearly useless.

I'd hate so see all your hard work go to waste because you didn't present it in a readable way.
10-29-2009, 08:33 AM   #22
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QuoteOriginally posted by WerTicus Quote
the resolution of the graphs is piss weak...
[...]
I'd hate so see all your hard work go to waste because you didn't present it in a readable way.
Thanks for the comment.

I am almost sure you only looked at the graphs attached to my original post. They are meant to be teasers only.

Please everybody, go to my blog article and click onto the graphs. Then, in the SmugMug gallery, click onto "O" for original size. The full SNR charts for both cameras is busy. So, the combined chart contains links to the charts for each camera only.

If looked at as intended, all charts should look clean and present no problem to read. The curves are colored in an easy to remember way, e.g., ISO 100 is green and ISO 1600 is black. You are right for the additional grid. But I wanted to preserve the DxO style as much as possible. If you care, my graphs have fine grain inner ticks. So, if you save the charts and open in PS, you can very well identify the exact data, using PS's movable ruler feature.


I hope indeed I didn't waste my time just because people are too lazy to have a proper look.
10-29-2009, 09:27 AM   #23
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QuoteOriginally posted by falconeye Quote
I hope indeed I didn't waste my time just because people are too lazy to have a proper look.
Not at all, some of us really enjoyed it

10-29-2009, 09:37 AM   #24
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great, detailed, and thorough tests. I personally have avoided commenting because I don't completely understand all of it yet! especially how ISO100 doesn't have ~1 stop less of DR than ISO200.

Is that because it just selects a shutter half the speed of ISO200 and bumps it up and applies NR to get the DR? I'm not sure how ISO100 works in RAW, really.

Last edited by Eruditass; 10-29-2009 at 09:43 AM.
10-29-2009, 10:29 AM   #25
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QuoteOriginally posted by Eruditass Quote
great, detailed, and thorough tests. I personally have avoided commenting because I don't completely understand all of it yet! especially how ISO100 doesn't have ~1 stop less of DR than ISO200.
Theoretically, going from ISO200 to ISO100 should increase DR by +0.5stops (not decrease by -1stop). ISO100 captures twice as many photons which results in 0.707x the noise.

Because the K-x hasn't native ISO100, it should make no difference though. And indeed, the difference for gray is almost null.

But digging into my data, I see that in a log-log plot, the SNR curves at ISO 100 and ISO 200 between 1% and 100% are both linear and meet each other at the 100% end. But slopes are different and at the 1% end, the ISO100 curve is 3 dB apart like for a native ISO 100 sensor.

The ISO 100 curve is flatter than pure photon shot noise would allow.

Currently, I don't know how they did it


To verify that I have no stupid measurement errors, I today had a lokk again and appended to my K-x sensor article wrt to the "ISO 100 bump".
10-29-2009, 10:36 AM   #26
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Still learning from and digesting your blog, but this has got to have somebody at Pentax smiling: "Currently, I don't know how they did it "

Thanks for sharing your passion -
10-29-2009, 10:57 AM   #27
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QuoteOriginally posted by falconeye Quote
Theoretically, going from ISO200 to ISO100 should increase DR by +0.5stops (not decrease by -1stop). ISO100 captures twice as many photons which results in 0.707x the noise.
not if the sensor's native ISO is 200, right? Instead, it should either chop off 1 stop of highlight range or underexpose by 1 stop and bump up the rest of the picture, also losing 1 stop, this time at the bottom?
10-29-2009, 11:55 AM   #28
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These numbers looks good. I think the DR numbers for K20 were much lower than that...
10-29-2009, 12:19 PM   #29
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QuoteOriginally posted by Eruditass Quote
not if the sensor's native ISO is 200, right? Instead, it should either chop off 1 stop of highlight range or underexpose by 1 stop and bump up the rest of the picture, also losing 1 stop, this time at the bottom?
Ah, I see what you mean:
If a ISO200 camera would allow you to set it to ISO100, then you would loose 1 stop clipped in the highlights without gaining the extra 0.5 stops in the shadows.

But this isn't what the K-x' ISO100 extended setting does: it seemingly does almost no clipping (it clips at above sRGB 91% or linear color 80% (ISO 200)). If it would just do clipping, it would clip at above 50% linear color.

This clipping should be visible as a slight right-shift of the ISO100 SNR curve.

On the other hand, the K-x does seem to gain the extra +0.5EV DR in the shadows at ISO 100.
10-29-2009, 12:21 PM   #30
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QuoteOriginally posted by ogl Quote
I think that K-7 even with NR in LR is not worse than K-x at ISO1600 and has better resolution and more details.
Тесты K-x и K-7 - огл - Участники - Фотогалерея iXBT
Interesting.

In those samples, I do think the K-7 has more noise even with the NR from LR (It looks good, especially when view like a normal photo and not pixel peeped, just more noise in comparison to the K-x), BUT try and read the numbers on the lens for both photos. Why is the K-x photo so hard to read? Is it more of the same noise vs. detail loss, blah, blah, blah - pick your poison?? Dunno....

I resized the K-7 photo to the same size as the K-x, and then I did a 600x600 crop at the lens to both photos.

K-x 100% crop from the iso 1600 photo:


K-7, resized to match K-x, then 100% cropped from the 1600 iso photo:
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