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12-16-2010, 02:00 PM   #1
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K-5 VS K-7 (iso100-iso51200)

I got my K-5 yesterday, and I thought I'd test it against the k-7 for iso performance in very poor light (check the exif).

EVERYONE BY NOW KNOWS THE k-5 IS BETTER AT HIGH ISO, BUT I WANTED TO SEE HOW THEY COMPARE AT ISO BELOW 3200.

DO NOT COMPARE SHARPNESS BETWEEN CAMERAS, ONLY HOW SHARPNESS HOLDS ON AS ISO IS INCREASED - This is because, sharpness is greatly influenced on accuracy of focus, and having done several tests, I know it can never be gotten exactly right inspite of everything I try. But, as the focus was kept the same between iso's the decrease in sharpness as iso is increased is not due to focus issues.

Methodology.

- 2 sec timer
- Tungsten WB
- Manual Focus using LV magnification
- First I did the K-5 in Av mode and found it needed +1 EV to get the exposure right and then the K-7 was done in M-mode with the same exposure parameter (same iso, aperture and shutter as that of K-5) - As the aperture, iso and shutter are the same between images, the +EV has no bearing.
- DNG RAW files were opened in LR3 and then just woith default setting saved.
- The full image is a crop with the long edge being 1000 pixels.
- The crops are 100% crops




THE TOP IMAGE IS k-5

iso 100



iso100





iso200



iso200





iso400



iso400





iso800



iso800





iso1600



iso1600





iso3200



iso3200





iso6400



iso6400




iso12800




iso25600




iso51200




12-16-2010, 02:20 PM   #2
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K-5 ISO12800 still looks good at the size presented here. Be interesting to see what the full shot (not a crop) looks like in a 8"x10" printout.

Dan.

Last edited by dosdan; 12-16-2010 at 02:26 PM.
12-16-2010, 02:34 PM   #3
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QuoteOriginally posted by dosdan Quote
K-5 ISO12800 still looks good at the size presented here. Be interesting to see what the full shot (not a crop) looks like in a 8"x10" printout.

Dan.
Dan, this image was taken in very poor light (iso 12800, f5.6, 1/15), and in better light thge general iso perfromance should be better.

If you have Mozilla Firfox, clicking the image below should take you to the full res. image. (well when firefeox shrinks the full res. image to fit the page, it looks a lot noisier than the image downsized to 1000 pixels on the long edge ???)




Last edited by pcarfan; 12-16-2010 at 02:40 PM.
12-16-2010, 02:42 PM   #4
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Very interesting. Thank you for the comparison.

Until and including ISO800, there seems to be little difference, but the K-7 noise at ISO1600 and above is visible.

I assume that you switched off High-ISO NR in both cameras... Correct? (The High-ISO NR [Strong] does make a hell of improvement in the K-7.]


12-16-2010, 02:44 PM   #5
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QuoteOriginally posted by hcc Quote
I assume that you switched off High-ISO NR in both cameras... Correct? (The High-ISO NR [Strong] does make a hell of improvement in the K-7.]
I used the RAW file, so it shouldn't matter.
12-16-2010, 06:49 PM   #6
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Thanks for the info.

And thank you again for this enlightening comparison....
12-16-2010, 07:57 PM   #7
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QuoteOriginally posted by pcarfan Quote
f you have Mozilla Firfox, clicking the image below should take you to the full res. image. (well when firefeox shrinks the full res. image to fit the page, it looks a lot noisier than the image downsized to 1000 pixels on the long edge ???)
Yeah, I'm using FF on a 1680x1050 monitor so I was viewing it full size (1000x662px).

I know that the K-5 sensor is applying NR above ISO1600. It looks effective here without losing too much detail. An ISO12800 shot framed so that most of the sensor's pixels were involved in capturing this scene would be interesting when printed at 8"x10". It looks like it would be usable.

Dan.
12-17-2010, 01:49 AM   #8
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nice. Color rendering of wrapper looks significantly different between k-5 & k-7

12-17-2010, 02:09 AM   #9
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QuoteOriginally posted by yusuf Quote
nice. Color rendering of wrapper looks significantly different between k-5 & k-7
I found that the K-7 lost colour accuracy very quickly at ISO3200 and above.
The K-5 seems to have that under control all the way to Very high ISOs.
12-17-2010, 02:14 AM   #10
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the K7 seems to show more detail to my eye, where as the K5 looks soft in the low ISO range..
12-17-2010, 05:34 AM   #11
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QuoteOriginally posted by Tommot1965 Quote
the K7 seems to show more detail to my eye, where as the K5 looks soft in the low ISO range..
This is a focus issue...I can tell you with 1/10th of a mm movement of the focus ring the focus can change. Even at max. mag and LV the focus can never be spot on. In fact the first K-7 images were too soft and I had to redo the test.

SHARPNESS DIFFERENCE BETWEEN CAMERAS IS DUE TO FOCUS ERRORS

I will take multiple shots at iso100 and pick the best and post later.

I like my K-7 very much and frankly I am not entirely sold on jutifying having spent $1.5k on the K-5, yet....yes, it is better at very high iso (iso 6400 and 12800 are useable now) and I defintely like the fact the AF button also engages the SR (I always use the AF button to focus and disengage the shutter) and every time I had to wait for the SR, but now it seems like it's always there.

I am still testing the metering to see whether it is as vonsistant as rthe K-7, as a few shots were iffy and it seems to change between lenses (like this test needed +1EV)...the few built-in flash shots I took in Av mode and P=TTL are just fine, possibly a tad bit more exposed than the K-7 but not blown out.
I have to compare iso 1600 and iso 3200 in good daylight to see how much better it is.

I ahven't made up my mind on any AF improvements. The DR is better, but I need to test it more to finds it useability for me.
12-17-2010, 05:54 AM   #12
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What was the shutter speed used Sanjeevan?
As with the K20D, the long exposure noise may have started to creep into the K-7's low ISO shots at 100%, even if ever so slightly.
12-17-2010, 05:56 AM   #13
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QuoteOriginally posted by Ash Quote
What was the shutter speed used Sanjeevan?
As with the K20D, the long exposure noise may have started to creep into the K-7's low ISO shots at 100%, even if ever so slightly.
Ash, you are absolutelhy right, as I was testing it I was thinking the same, but i wanted to do the test in poor light and din't want to change that.

EXIF is intact and the iso 100 shot needed a shutter of 8 seconds.
12-17-2010, 06:00 AM   #14
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That may indeed determine much of the difference between IQ, particularly in the low ISO registers.
There may be less in it with shutter speeds of milliseconds, but your test is appreciated.
Thanks for sharing.
12-17-2010, 08:38 AM   #15
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QuoteOriginally posted by Ash Quote
That may indeed determine much of the difference between IQ, particularly in the low ISO registers.
There may be less in it with shutter speeds of milliseconds, but your test is appreciated.
Thanks for sharing.
Thanks.... Higher shutter speed woul mean good light, which would defeat the purpose of using high iso. Both cameras got the same settings, and irrelevant of how they each handle long exposure, this tells me what each is capably.
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