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10-07-2019, 05:16 PM   #1
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Should Pentax bring “extended ISO” back to the new APSC or future FF flagship body? –

I was reading about extended ISO. K5 has extended ISO 80, some Nikon’s body offer ISO 64 … and the question pop up in my head.

Should Pentax bring “extended ISO” back to the new APSC or future FF flagship body?
Will it benefit you?

10-07-2019, 05:30 PM   #2
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More ISO range is always nice although a fraction of a stop of extension would hardly make that much difference.

The question that I've never seen addressed is the IQ effects of the mode? Why make it a special setting unless it has a downside? I'm wild-ass guessing that that the mode might be prone to some fixed pattern noise in the brightest pixels if not all the pixels have a full well capacity that allows that extended ISO. That is, some pixels might saturate at less than 100% of the value range.

That said, it could be especially useful for extended highlight protection -- the camera might set exposure for ISO 100, run the sensor at ISO 50 and provide more protection for the small parts of the image that would other wise blow out.
10-07-2019, 05:48 PM   #3
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QuoteOriginally posted by tokyoscape Quote
I was reading about extended ISO. K5 has extended ISO 80, some Nikon’s body offer ISO 64 … and the question pop up in my head.

Should Pentax bring “extended ISO” back to the new APSC or future FF flagship body?
Will it benefit you?
IMO, no. All ISO settings should either be baseline, or excluded from the camera entirely. Gating ISOs behind a setting merely confuses users.

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10-07-2019, 06:08 PM - 1 Like   #4
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I agree with Adam. Only child lock should need special menus. A filter that recognizes subject matter and prevents nude selfies.😁

10-07-2019, 06:43 PM   #5
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I'm personally fine with having ISO as just pure settings. You go from base X to highest X with no [ISO HI 1/2] or [ISO LOW 1/2] at the extrema. That being said, I would like to see ISO 64 or 50 built in but I don't know what benefits that may bring other than slightly longer exposure times because I don't know the science behind digital ISO. But I think that it would be nice to have available.
10-07-2019, 06:49 PM   #6
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I had only owned cameras with base ISO 100 until I bought my K-5 which had extended ISO down to 80.
I thought it was a 'fun' feature and didn't mind using it. But I had a hard time seeing any difference in my shooting or images because of extended ISO.
10-07-2019, 06:55 PM - 1 Like   #7
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Semantics, but the K-5 had AFAIK a base iso of 80, otherwise if "extended iso" the DR would not be greater at iso 80, than its true base iso.

I guess I was wrong and it is termed extended iso! However, seems odd that it improved versus what I have seen for other sensors.

Last edited by dms; 10-07-2019 at 07:13 PM.
10-07-2019, 07:52 PM   #8
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QuoteOriginally posted by dms Quote
Semantics, but the K-5 had AFAIK a base iso of 80, otherwise if "extended iso" the DR would not be greater at iso 80, than its true base iso.

I guess I was wrong and it is termed extended iso! However, seems odd that it improved versus what I have seen for other sensors.
I haven't seen a good explanation on why it's 'extended'. I recall a few test charts that showed an increased performance over iso100 (however slight), and the consensus seems to be that it's the base iso as you say.

I use iso80 all the time on my k5iis, I can't say I can see much of a difference from iso 100, but I've certainly never run into any funky issues. I'd prefer to have it as an option in my next camera (or even lower if it was problem free), but a minimum iso of 100 wouldn't cause me any major headaches.

10-07-2019, 09:39 PM   #9
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Xtended low iso is like over exposing. One could overexpose 1 stop and enable high light protection auto so that iso would be like iso50 unless the dynamic range requires a 1 stop underexposure.

IMo I'd much prefer an automatic ETTR exposure mode on Dslr, based on information from the AE sensor and writing down in exif how much over exposure or how much underexposure was achieved.

---------- Post added 08-10-19 at 06:48 ----------

Basically, AE exposes for 18% grey, and a gamma curve is applied to the raw data. Which means for 0 eV of exposure compensation the average light level is centered at 1/4th of the sensor digital scale, 2 stops below clipping, which is enough underexposure to protect high lights for most images but too conservative for low DR images.
10-07-2019, 09:51 PM - 1 Like   #10
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Rather than an extended ISO range, I would prefer extending the range of native ISO. Having ISO 64 for a Sunny day is useful for me.
10-07-2019, 09:53 PM   #11
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For almost all images that don't contain sky and with indirect light, the sensor can run comfortably with mid scale exposure (+1 exp comp) which provides a noticeable increase in IQ but requires contrast correction because of the gamma curve already applied to raw data.

---------- Post added 08-10-19 at 07:01 ----------

QuoteOriginally posted by parinya-ekparinya Quote
Rather than an extended ISO range, I would prefer extending the range of native ISO. Having ISO 64 for a Sunny day is useful for me.
Native iso64 means that you only get the best image quality when there is a lot of light and less image quality in all other cases. A better a sensor is a sensor with higher native iso such as iso200 base iso, faster shutter speed with same DR and same SNR is better for shooting hand held is more situations. So what does matter is DR, SNR and best possible exposure.

---------- Post added 08-10-19 at 07:10 ----------

A sensor with 14bits DR at base iso64 is not as good as a sensor having 14bits of DR at iso100 or 14bits DR at iso200. Newer BSI sensors have higher base iso, and the actual exposure times are faster than indicated by cameras so that the camera user think he's got low iso values...indicated iso 64 values are fake.
10-07-2019, 10:30 PM   #12
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QuoteOriginally posted by dms Quote
but the K-5 had AFAIK a base iso of 80
as far a I can remember this was the case
10-07-2019, 10:39 PM   #13
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QuoteOriginally posted by photoptimist Quote
More ISO range is always nice although a fraction of a stop of extension would hardly make that much difference.
1 stop overexposure at ISO100 on K1 does make a small difference (images slightly smoother, looks like an 645z at Iso100 0ev exp. comp.). Extended ISO, e.g ISO 50 at base ISO is an exposure time x2 of the sensor followed by /2 scaling of data, good for shooting JPEG. Now, I'd wonder why someone would want best image quality out of an extended ISO setting, slower shutter speed and OOC JPEG, clipped high light in JPEG can't be recovered in post. Maybe the benefit of extended ISO (such as Nikon) is to separate exposure compensation concerns from ISO concerns?
10-08-2019, 12:18 AM   #14
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ISO50 native can be achieved with a ISO100 native camera with a 1 stop ND filter.

---------- Post added 08-10-19 at 09:19 ----------

Would Ricoh better off be making and release f1.8 primes for it's full frame system?
10-08-2019, 12:22 AM   #15
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QuoteOriginally posted by biz-engineer Quote
Would Ricoh better off be making and release f1.8 primes for it's full frame system?
Yes that would be good, but they might want to get the f1.4's in place first.
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