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07-16-2010, 01:09 AM   #1
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K20D vs K-x : high ISO & processing

Hi,

Has anyone tried to process/denoise high ISO pictures (RAW) from a K20D, using some modern software like LR3, and then compare this result to K-x ?

In other word, I'd like to know if a K20D + PP can provide high ISO pictures about as good as a K-x does.

I can easily imagine that "out of the box" pictures from the K-x are better, but most of the threads I've read were about jpgs and "appeal". So I don't know ...

07-16-2010, 01:34 AM   #2
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Look around the forum. Lots of people have gotten great high-ISO results out of the K20D, albeit with a fair degree of PP, using LR and other tools. These results can often be compared to what can be done on a K-x.

But at a low level, as the sensor data on dxomark.com shows, the hardware guts of the K-x and K20D are simply different, which means the results they produce are going to be different. The K-x sensor design in particular gives it some capture-time advantages over the K-7 and K20D that are hard to duplicate using sophisticated out-of-camera post processing.
07-16-2010, 04:14 AM   #3
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Based on what I have seen there is about one stop difference between Kx RAW photos and those of the K20. There is a bigger gap if you are shooting jpegs. Obviously it depends on how big you are printing and how aggressive you want to be with noise reduction, but the Kx just starts with less noise and a little more dynamic range.
07-16-2010, 06:03 AM   #4
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Up to ISO 1600, I can get comparable images from the K-x and K20d using Noise Ninja with different profiles that compensate for the differences in noise. To my eyes, at ISO 3200, the K-x pulls ahead. However, to some extent, this is a subjective evaluation which depends on the subject and upon our individual sensitivity to noise and to the effects of noise reduction.

07-16-2010, 06:29 AM   #5
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QuoteOriginally posted by skb0 Quote
In other word, I'd like to know if a K20D + PP can provide high ISO pictures about as good as a K-x does.
The simple answer is no.

Like Rondec explained, the Kx holds a(rougly) one stop advantage in noise over the K2D. However the discrepancy I see with this is where one would assess how the K20D could clean-up in comparison to the Kx while the Kx itself could also be cleaned-up. So the performance differences are not not black and white either

For what it's worth, the K20D can deliver pretty good ISO6400 images, but that requires a good deal of work in terms of NR processing etc. While the Kx RAW files can achieve the same results with hardly no PP needed(in most cases). Not to mention that the Kx can deliver 12800ISO images with better base definition(see magenta cast) than the K20D does at ISO6400.

So all in all, the Kx has superior high ISO and DR performance over that of the K20D. However... the Kx is an entry level camera too! IOW. I rarely use it(my wife's) because it doesn't have the versatility of the K20D in terms of controls and shooting performance(buffer etc).

So my conclusion is, if you're not in need of a deeper buffer and the surface controls of a prosumer camera, then the Kx is definitely the better camera.

PS. the Kx sensitivities can easily exceed the camera's capacity to take pictures in low light(ie. lighting so low, that it can't achieve focus lock).
07-16-2010, 07:02 AM   #6
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QuoteOriginally posted by JohnBee Quote
PS. the Kx sensitivities can easily exceed the camera's capacity to take pictures in low light(ie. lighting so low, that it can't achieve focus lock).
Ha-ha! I'm one of those people who gets caught out by that limitation -
please see Posts #60, #101, #103, #105 (links) in Kx in Use.

One might ask why not use manual focus - that's very difficult too - the image in the viewfinder is so dark that I cannot focus with any certainty - this may well be the penta-mirror instead of a real penta-prism - but I don't think so, I still have very good film SLRs with quite stunningly bright penta-prisms and I still would have difficulties seeing clearly enough to focus on the plain ground glass parts - if I can focus with the split image finder - then the K-x probably could AF..... yes, it's that dark.

More often I have to find an area of higher contrast to focus on - see especially Post #105.
07-16-2010, 07:10 AM   #7
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QuoteOriginally posted by UnknownVT Quote
One might ask why not use manual focus - that's very difficult too - the image in the viewfinder is so dark that I cannot focus with any certainty - this may well be the penta-mirror instead of a real penta-prism - but I don't think so, I still have very good film SLRs with quite stunningly bright penta-prisms and I still would have difficulties seeing clearly enough to focus on the plain ground glass parts - if I can focus with the split image finder - then the K-x probably could AF..... yes, it's that dark.
Yea its an interesting conundrum for sure...
TBH, the K20D suffers from the same problem.

Recently, we went to visit an underground mine and flash were not allowed due to the effects it had on peoples eyes underground, so I decided to equip my Katzete K20D with a f/1.4 lens to cope with the task. Needless to say the camera had no problems maintaining 1/100 shutter at ISO6400, however... focusing was near impossible to achieve(even with the katzeye).

So all in all, I don't know if there is any solution other than waiting for better AF performance.
Having said that,l I still managed to snag a few keepers that day(6 out of 50 )
07-16-2010, 07:16 AM   #8
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Thanks JohnBee :-)

In fact, I'm mostly interrested in having a nice sensors, capable of delivering nice images with high ISO and a good viewfinder.

But I'm working a pretty simple way : Av about all the time (I'm a former CANON AV-1 user)
, no need for big buffer or high fps, and auto ISO (with the K-x, that should be wonderful).

I might miss the bigger and larger viewfinder, for manual focus purposes (macro and hard to focus situtations). But maybe the nice LiveView can help a bit ? I could live without it on my K200D, so I should survive !

Weather sealing is nice, but I've never distroyed a camera in wet weather or winter, and I don't plan to go sailing or trekking into desert.

07-16-2010, 08:36 AM   #9
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QuoteOriginally posted by JohnBee Quote
Katzete K20D with a f/1.4 lens to cope with the task. Needless to say the camera had no problems maintaining 1/100 shutter at ISO6400, however... focusing was near impossible to achieve(even with the katzeye).
Unfortunately when it's too dark -
it is simply too dark....

The K20D has a real penta-prism and is actually one of the better viewfinders out there - and I would imagine with Katzete this would be even better.

Here you've done just about everything one could to be able to see, and allow the AF to work.

Pentax AF may be slow at lower light levels but they can reach as low as most other competition - and reliably -
from Popular Photography-

the horizontal axis scale is misaligned the extreme right should be -3EV and the next to the left ought to be 0EV - so the K20D is capable of focusing as low as -1EV albeit a little slowly.

The K-x also manages to focus as low as -1EV and a bit quicker.

from PopPhoto.com



QuoteOriginally posted by skb0 Quote
In fact, I'm mostly interrested in having a nice sensors, capable of delivering nice images with high ISO and a good viewfinder.

I might miss the bigger and larger viewfinder, for manual focus purposes (macro and hard to focus situtations). But maybe the nice LiveView can help a bit ? I could live without it on my K200D, so I should survive !
Although it is only a penta-mirror viewfinder the K-x is pretty good, probably one of the best penta-mirrors out there. If you are reasonably happy with your K200D then the viewfinder on the K-x probably would not disappoint.

Beware of the "grass is greener" syndrome - like I said I have film SLRs with real penta-prism and stunningly bright viewfinders - but they would not do any better focusing on the plain ground glass parts than I could do on the K-x, and that includes the acu-matte screens on Minoltas. I also have Olympus OM-2 and 4 which are also reputed to have great finders.


I think it basically comes down to this if a dSLR cannot focus due to darkness one probably will find it very difficult trying to focus manually as the image in the viewfinder is not bright enough or more likely lack the necessary contrast to focus with any certainty.

As a kind of proof the K-7 has a real penta-prism so ought to be intrinsically brighter and the K-x AF is most probably based on the same AF as the K-7 -
so why is the K-7 AF limit both on spec and in test no better than the K-x with its darker penta-mirror - at the low light levels?
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