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02-06-2011, 01:33 PM   #1
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ISO 100 and 12800 on Pentax KX?

How to reach ISO 100 and 12800 on Pentax K-X. I heard it was possible but I am unable to reach it. Anyone can help?

02-06-2011, 01:38 PM   #2
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set expanded sensitivity to ON in the custom menu (p91 of english manual, don't know the french page number)

It's on the first page of the 'C' menu #3
02-06-2011, 01:40 PM   #3
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QuoteOriginally posted by drugal Quote
set expanded sensitivity to ON in the custom menu (p91 of english manual, don't know the french page number)
Thanks! Is there other "hidden" things like this that improves my camera?
02-06-2011, 01:50 PM   #4
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Highlight correction also has to be off for ISO below 200 to be available.

02-06-2011, 01:57 PM   #5
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I already know this! Thanks though! Is highlight correction really effective?
02-06-2011, 02:12 PM   #6
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QuoteOriginally posted by HaWaIi50 Quote
I already know this! Thanks though! Is highlight correction really effective?
I would much rather have ISO 100. The noise difference between ISO 100 and 200 is noticeable and I don't think what you get with highlight correction is worth it.
02-06-2011, 03:01 PM   #7
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QuoteOriginally posted by KxBlaze Quote
The noise difference between ISO 100 and 200 is noticeable
Really?

ISO100 is really ISO200 "expanded" -
which means ISO100 is not a true sensitivity -
but mathematically derived from ISO200.

It may be a function of my eye sight -
but I find it very, very hard to tell the difference in noise levels between ISO200 and ISO100 -
take for example:
source: Pentax K-x Review: 15. Photographic tests (Noise): Digital Photography Review

please remember that these are 100% crops -
in real life - although there may be absolute measurable differences -
they probably are extremely unlikely to be seen.

There are very good reasons for retaining ISO100 like for very bright conditions -
but Highlight correction goes some way to protect highlight clipping -
it is also applied to all other sensitivities
- but it seems to me noise levels doesn't seem to be one of them.

Last edited by UnknownVT; 02-06-2011 at 03:08 PM.
02-07-2011, 03:58 PM   #8
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QuoteOriginally posted by UnknownVT Quote
Really?

ISO100 is really ISO200 "expanded" -
which means ISO100 is not a true sensitivity -
but mathematically derived from ISO200.

It may be a function of my eye sight -
but I find it very, very hard to tell the difference in noise levels between ISO200 and ISO100 -
take for example:
source: Pentax K-x Review: 15. Photographic tests (Noise): Digital Photography Review

please remember that these are 100% crops -
in real life - although there may be absolute measurable differences -
they probably are extremely unlikely to be seen.

There are very good reasons for retaining ISO100 like for very bright conditions -
but Highlight correction goes some way to protect highlight clipping -
it is also applied to all other sensitivities
- but it seems to me noise levels doesn't seem to be one of them.
Those itty bitty examples don't show the difference.

And there's a big one.

02-07-2011, 07:06 PM   #9
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QuoteOriginally posted by Ira Quote
Those itty bitty examples don't show the difference.
And there's a big one.
Those sample crops were 100% from dpReview - that's pixel peeping level.

Perhaps I am just looking at the wrong things -
be grateful if you could please point out the noise level differences from these 100% crops from the full sized K-x test samples Imaging-Resource.com.
Multi Target

hopefully I left in enough gray surround to show noise levels.

Still Life

This is the crop I use for looking at shadow noise

Indoor Portrait, No Flash




Thanks,
02-07-2011, 09:06 PM   #10
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The difference is visible when you're actually working with the files in post. There is far more usable information in the shadows of ISO 100 files; in other words, the noise "floor" is much lower.

Looking at standardized test shots done straight from the camera (with maybe a RAW converter in between) to your screen will not show the difference. Such are the limitations of test sites like IR and DPR.
02-07-2011, 09:55 PM   #11
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QuoteOriginally posted by er1kksen Quote
The difference is visible when you're actually working with the files in post. There is far more usable information in the shadows of ISO 100 files; in other words, the noise "floor" is much lower.

Looking at standardized test shots done straight from the camera (with maybe a RAW converter in between) to your screen will not show the difference. Such are the limitations of test sites like IR and DPR.
Thank you for the explanation.

So for an end result -
printing or posting a visible photo -
one is unlikely to see a difference?
but one can see differences at the post processing stage -
I have to take then it's only visible in the RAW files
and not in any JPGs?
02-08-2011, 12:15 AM   #12
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QuoteOriginally posted by UnknownVT Quote
Really?
This question was asked a while back and another member posted 100% crops of ISO 100 and 200 of a blue sky. He did not say which photo was 100 and which was 200 but instead asked if we could tell and everyone that responded could tell that the 100 has noticeably less noise than the 200. Now to some this is not a big deal because most people do not zoom to 100% in normal use but to others it's a big deal. Try searching for that thread, it surprised me that I could actually see a difference.
02-08-2011, 01:43 AM   #13
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QuoteOriginally posted by KxBlaze Quote
This question was asked a while back and another member posted 100% crops of ISO 100 and 200 of a blue sky. He did not say which photo was 100 and which was 200 but instead asked if we could tell and everyone that responded could tell that the 100 has noticeably less noise than the 200. Now to some this is not a big deal because most people do not zoom to 100% in normal use but to others it's a big deal. Try searching for that thread, it surprised me that I could actually see a difference.
OK now I'm confused -
unfortunately I could not find that thread using various search term variations.

I could understand er1kksen saying one may see this in post processing (RAW?)
but will not see the difference when converted to JPGs - and since we all look at JPGs -
that's the reason I could not see much difference from all those 100% crops of test images from dpReview and Imaging-Resource.

However what you are saying is that someone demonstrated this with what had to be JPGs with a plain blue sky.

Now there are plenty of examples of plain blue areas in the DPR and IR test images, and I could not see much difference in the noise - again I am quite willing to say I may not be looking at the right places - but I also have been studying K-x images for quite a while, and so far none of the 100% crop or full sized images show much difference to me.

Here are 100% crops of all the Blue Patches from the Imaging-Resource.com full sized Multi Target

There probably are measurable differences - but I am not seeing that much difference visually even with these 100% crops from the full-sized test images.
02-08-2011, 03:29 AM   #14
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QuoteOriginally posted by UnknownVT Quote
OK now I'm confused -
unfortunately I could not find that thread using various search term variations.

I could understand er1kksen saying one may see this in post processing (RAW?)
but will not see the difference when converted to JPGs - and since we all look at JPGs -
that's the reason I could not see much difference from all those 100% crops of test images from dpReview and Imaging-Resource.

However what you are saying is that someone demonstrated this with what had to be JPGs with a plain blue sky.

Now there are plenty of examples of plain blue areas in the DPR and IR test images, and I could not see much difference in the noise - again I am quite willing to say I may not be looking at the right places - but I also have been studying K-x images for quite a while, and so far none of the 100% crop or full sized images show much difference to me.

Here are 100% crops of all the Blue Patches from the Imaging-Resource.com full sized Multi Target

There probably are measurable differences - but I am not seeing that much difference visually even with these 100% crops from the full-sized test images.

When it's a single block of colour like that, it might be useful to express the difference mathematically using something like standard deviation on the different colour channels.
02-08-2011, 09:24 AM   #15
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QuoteOriginally posted by UnknownVT Quote
Thank you for the explanation.

So for an end result -
printing or posting a visible photo -
one is unlikely to see a difference?
but one can see differences at the post processing stage -
I have to take then it's only visible in the RAW files
and not in any JPGs?
Well, if you pull any of the shadows up in the RAW conversion process, for example, you most certainly will see the difference in the resulting jpegs, as well as prints if you're printing large. The noise doesn't disappear when converting to jpeg.

With jpegs straight from the camera (from any ISO), you don't have all that much available shadow detail anyways, so you're not really going to see the difference there.
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