[Serkevan]

If two cameras shoot the same settings at 64 ISO and 100 ISO then the ISO or the two cameras are functionally the same. This is kind of like amps that go to 11.

Yeah... I'm not even sure ISO is standardized for the, well, exact ISO standard that is supposed to guide this (and I'm not paying over a hundred bucks just so I can *read* the standard ).

Ah the FA*200 macro... the lens every drools over but no one can afford. If anyone ever feels motivated to send me a birthday present.

I'd be perfectly happy to receive a donation as well . At this point if Pentax ever re-does that lens with a good AF motor and WR, keeping it anywhere under 3000€ (yes, I know it's cheaper than what most used copies go for, but that's because the supply is almost nonexistent) I'm pretty certain they'd fly off the shelf.

[BigMackCam]

Yeah... I'm not even sure ISO is standardized for the, well, exact ISO standard that is supposed to guide this (and I'm not paying over a hundred bucks just so I can *read* the standard )

I'd be a tad miffed if ISO 100 on my cameras didn't conform at least fairly closely to the ISO standard. Of late, I've been using a handheld light meter on occasion (actually, a smartphone app that's remarkably well calibrated with my phone), and the exposure of my K-3 seems pretty much spot-on... though I guess I wouldn't know if it was maybe +/- 1/3rd stop out.

[Serkevan]

I'd be a tad miffed if ISO 100 on my cameras didn't conform at least fairly closely to the ISO standard. Of late, I've been using a handheld light meter on occasion (actually, a smartphone app that's remarkably well calibrated with my phone), and the exposure of my K-3 seems pretty much spot-on... though I guess I wouldn't know if it was maybe +/- 1/3rd stop out.

Yeah I don't suggest there's a huge disparity, but ISO 100 to ISO 80 isn't *that* much of a jump... Honestly I'd be more suspect of different lenses not giving precisely the same exposure at a given f-stop (which is why cine lenses work on T-stops).

[UncleVanya]

Yeah I don't suggest there's a huge disparity, but ISO 100 to ISO 80 isn't *that* much of a jump... Honestly I'd be more suspect of different lenses not giving precisely the same exposure at a given f-stop (which is why cine lenses work on T-stops).

If you check the DXOMARK iso tests they have a standard and show how closely cameras adhere to it. The Nikons are almost 43% off. 70 vs 100 is at the low end. But as you go higher it continues to overstate “sensitivity” compared to actual output. Sony is likewise on the models I checked. Pentax is one of the few that seems to be close to the standard.

[normhead]

If you check the DXOMARK iso tests they have a standard and show how closely cameras adhere to it. The Nikons are almost 43% off. 70 vs 100 is at the low end. But as you go higher it continues to overstate “sensitivity” compared to actual output. Sony is likewise on the models I checked. Pentax is one of the few that seems to be close to the standard.

I wonder if that explains why I usually under-expose my photos by -0.7 EV?

[UncleVanya]

I wonder if that explains why I usually under-expose my photos by -0.7 EV?

You too! Lol.

[Serkevan]

I wonder if that explains why I usually under-expose my photos by -0.7 EV?

I resemble that remark, -0.7EV unless the scene is very flat... and -1.3-1.7 EV in strong backlight

[BigMackCam]

If you check the DXOMARK iso tests they have a standard and show how closely cameras adhere to it. The Nikons are almost 43% off. 70 vs 100 is at the low end. But as you go higher it continues to overstate “sensitivity” compared to actual output. Sony is likewise on the models I checked. Pentax is one of the few that seems to be close to the standard.

Sony... wow The SLT-A99 (on which my Hasselblad HV is very closely based) is way off the standard...

You're right, though - all the Pentax models I checked are remarkably close to standard. Go Pentax!

I didn't learn until today that ISO 100, 200, 400 etc. doesn't really mean ISO 100, 200, 400 on digital cameras.

Since a lot of pro photographers (and a fair few amateurs) use handheld light meters, does this mean they need to mentally adjust readings for their particular camera(s)?

[Ian Stuart Forsyth]

Can you clarify where this is shown? I'm confused since the Pentax K-1 essentially (both models) has nearly perfect ISO accuracy. The Nikon overstates ISO. I struggle to understand how an ISO 46 (Z7ii set to 64) shot would have the same exposure as an ISO 95 (K-1ii set to 100) shot. As for highlight protection - shooting at ISO 70 and exposing for ISO 100 will give more headroom as it underexposes a bit.

The iso standard relates to the out going image lightness and not how the camera uses the sensor, and if you look a the the standard it specifically states that it is not related to the raw file. If you look at how Nikon uses it sensors and how much headroom is contain within the raw file.
Depending on how Pentax uses the sensor you have to remember that sensors have no iso setting, setting the iso tell the camera how and for some cameras program how the sensor is to be used. The iso setting for the Z7II at iso 64 is the iso setting for iso 64 as this relates to how the final image lightness will appear within a color space and not how the sensor is operated, Now if you are using DXO measured iso this has nothing to do with iso and the iso standard that governs what the iso standard governs, The measurement at DXI is of how much headroom is contained within the raw file so if we look at iso 64 it can accept an exposure that is equal to iso 46. And to state this again the measured iso at DXO has nothing to do with the iso standard.

As for just shooting at iso 70 and using iso 100 giving you more headroom it really depends on how the manufacture utilizes the sensor and it depends on how much headroom they have decided for. The only camera from pentax that i know of that using an iso lower than 100 was the K5 series cameras that gave the user a lower iso setting while retaining the same headroom that was not simply an expanded iso range.

A person can also gauge how much high light headroom raw file contains by looking at the baseline exposure tag found within the raw file that tells the converter where to place the 0 point so a positive the camera has more headroom and a negative less headroom
https://photographylife.com/where-are-my-mid-tones-baseline-exposure-compens...0make%2Fmodel.

For most pentax cameras we usually see around BLE of -0.5 where as Nikon usually around +0.35

Now if well look at images taken under controlled lighting the Z7 is using the same exposure at iso 64 as pentax at iso 100
Nikon Z7 Review - Thumbnails

Pentax K-1 II Review - Thumbnails

Now if we look at the headroom



Many times when lowering the iso setting all that is happening is you are calibrating the meter for a lower iso and changing the BLE in the raw tag telling the raw converter how to process the image


going from iso 64 down to iso 31 did not change how much light you can store and did not change , there would be no different is shooting the iso 64 shot at with as large exposure as iso 31 ( or ETTR )and adjusting the lightness of the final image in the converters as this is what the tag in the raw data is telling the converter to do anyways.
Also setting the camera to iso 31 and shooting it with an exposure = to iso 64 change how much headroom the camera has
But with how Nikon has decided to use the sensor they are able to increase the size of the exposure to collect more light


---------- Post added 09-01-2021 at 01:50 PM ----------

I wouldn't think they are that different if you shoot RAW. Looking at Photons to Photos graph of DR

You have to be careful as to how you are interpret PTP graphs as they are based on the iso setting and not how the sensor is being saturated (EETR) and as shown for the same exposure you have very similar PDR but if you use nikon as (ETTR) there is a difference to the PDR

---------- Post added 09-01-2021 at 01:56 PM ----------

Exactly, two cameras with virtually the same DR have virtually the same headroom.

Headroom has nothing to do with the DR, the headroom is determined by manufacture as to how they want to use the storage within the raw file

If two cameras shoot the same settings at 64 ISO and 100 ISO then the ISO or the two cameras are functionally the same.

Far from it. take the Z7 at iso 64 has the same DR but with over 1.3 stops of headroom over the K1 so no.

---------- Post added 09-01-2021 at 01:58 PM ----------

If you check the DXOMARK iso tests they have a standard and show how closely cameras adhere to it.

That has nothing to do with the standard, all they are showing is how much headroom in the raw file is there

The iso standard determines how light or dark the image will be within a color space for a given exposure
For pentax this is usually around 1/3 stop over but for Nikon its around 1/3stop under, and again this has nothing to do with raw and the DXO measured iso as this is for normalizing the cameras performance based on the saturation of the sensor.
We can have 2 different camera manufactures that use the same sensor with very different head rooms as to why raw converters need to use very different baseline exposure values to correctly process the image.
But both cameras will render the image very closely to the iso standard, which is why the raw converter needs the BLE value when editing a raw file

[UncleVanya]

Sony... wow The SLT-A99 (on which my Hasselblad HV is very closely based) is way off the standard...

You're right, though - all the Pentax models I checked are remarkably close to standard. Go Pentax!

I didn't learn until today that ISO 100, 200, 400 etc. doesn't really mean ISO 100, 200, 400 on digital cameras.

Since a lot of pro photographers (and a fair few amateurs) use handheld light meters, does this mean they need to mentally adjust readings for their particular camera(s)?

I wish I knew. But when shooting in raw the ability to adjust is pretty strong.

[sundown]

shooting raw with the z-bsi sensor and the smc lenses is really nice - I don't know if it is sensor/pixels count-microslenses+smc combination and white balance/exposure metering or outright colour profiling in your raw processor but sometimes looking at the back of the screen of the nikon and you just see a very pleasing warm glowing image.
these are post processed but only highlights/shadows curves, maybe finetuning the white balance and overall master colour balance in C1.

43


77

[Rondec]

The iso standard relates to the out going image lightness and not how the camera uses the sensor, and if you look a the the standard it specifically states that it is not related to the raw file. If you look at how Nikon uses it sensors and how much headroom is contain within the raw file.
Depending on how Pentax uses the sensor you have to remember that sensors have no iso setting, setting the iso tell the camera how and for some cameras program how the sensor is to be used. The iso setting for the Z7II at iso 64 is the iso setting for iso 64 as this relates to how the final image lightness will appear within a color space and not how the sensor is operated, Now if you are using DXO measured iso this has nothing to do with iso and the iso standard that governs what the iso standard governs, The measurement at DXI is of how much headroom is contained within the raw file so if we look at iso 64 it can accept an exposure that is equal to iso 46. And to state this again the measured iso at DXO has nothing to do with the iso standard.

As for just shooting at iso 70 and using iso 100 giving you more headroom it really depends on how the manufacture utilizes the sensor and it depends on how much headroom they have decided for. The only camera from pentax that i know of that using an iso lower than 100 was the K5 series cameras that gave the user a lower iso setting while retaining the same headroom that was not simply an expanded iso range.

A person can also gauge how much high light headroom raw file contains by looking at the baseline exposure tag found within the raw file that tells the converter where to place the 0 point so a positive the camera has more headroom and a negative less headroom
https://photographylife.com/where-are-my-mid-tones-baseline-exposure-compens...0make%2Fmodel.

For most pentax cameras we usually see around BLE of -0.5 where as Nikon usually around +0.35

Now if well look at images taken under controlled lighting the Z7 is using the same exposure at iso 64 as pentax at iso 100
Nikon Z7 Review - Thumbnails

Pentax K-1 II Review - Thumbnails

Now if we look at the headroom



Many times when lowering the iso setting all that is happening is you are calibrating the meter for a lower iso and changing the BLE in the raw tag telling the raw converter how to process the image


going from iso 64 down to iso 31 did not change how much light you can store and did not change , there would be no different is shooting the iso 64 shot at with as large exposure as iso 31 ( or ETTR )and adjusting the lightness of the final image in the converters as this is what the tag in the raw data is telling the converter to do anyways.
Also setting the camera to iso 31 and shooting it with an exposure = to iso 64 change how much headroom the camera has
But with how Nikon has decided to use the sensor they are able to increase the size of the exposure to collect more light


---------- Post added 09-01-2021 at 01:50 PM ----------



You have to be careful as to how you are interpret PTP graphs as they are based on the iso setting and not how the sensor is being saturated (EETR) and as shown for the same exposure you have very similar PDR but if you use nikon as (ETTR) there is a difference to the PDR

---------- Post added 09-01-2021 at 01:56 PM ----------



Headroom has nothing to do with the DR, the headroom is determined by manufacture as to how they want to use the storage within the raw file



Far from it. take the Z7 at iso 64 has the same DR but with over 1.3 stops of headroom over the K1 so no.

---------- Post added 09-01-2021 at 01:58 PM ----------



That has nothing to do with the standard, all they are showing is how much headroom in the raw file is there

The iso standard determines how light or dark the image will be within a color space for a given exposure
For pentax this is usually around 1/3 stop over but for Nikon its around 1/3stop under, and again this has nothing to do with raw and the DXO measured iso as this is for normalizing the cameras performance based on the saturation of the sensor.
We can have 2 different camera manufactures that use the same sensor with very different head rooms as to why raw converters need to use very different baseline exposure values to correctly process the image.
But both cameras will render the image very closely to the iso standard, which is why the raw converter needs the BLE value when editing a raw file

I guess I really don't understand. When I am taking landscape photos with my K-1, I shoot at iso 100 (and probably pixel shift) and pick the brightest exposure that doesn't clip the highlights. The dynamic range then is the difference between the brightest parts of the image and the darkest parts of the image that still contains detail.

My understanding with the Z7 is that it has a little bit more range than the K-1 at its lowest iso setting, but that this range is negatively impacted by banding and striping from the PDAF array on the sensor so that sites like DXO Mark may actually overstate it by a bit. I have no idea what headroom is though and I suppose it just doesn't affect me with my style of shooting.

[Ian Stuart Forsyth]

It depends on what is meant by DR, there is the DR that the sensor can record and the DR of the very scene you are trying to photograph. With different manufactures many have different amounts of headroom within the raw, so if I place my meter over the very brightest part of my scene the metering systems tells me that it is +3 over middle grey but how it is stored within the raw file from the standpoint of sensor saturation it can be very underexposed for the optimum use of the sensor.

Simply not clipping the highlights is not that easy



This is what the headroom looks like when using the cameras metering system. I adding above the raw histogram the jpeg histogram of the very same image and aligned it with the raw with where the camera metered for white 9.5.
So if If I used the cameras meter and placed my point over the white and metered for that white I am leaving headroom within the raw file that can be used.


here is the image using the cameras histogram while using the baseline exposure compensation tell the raw convert how to process the image


Here is what the raw file looks using no BLE and also no color channel offset ( uniwb shown more accurately as the sensor captured the File)


Here is the measurements of the known target, looking at the 9.5 target the camera metering system metered the scene rather accurately L-91 captured. The same with the 5 natural target captured as L-48. and looking at the histogram distributed more or less accurately. L is the luminosity valve




Now it altogether different when we remove the BLE and use uniwb. The White 9.5 target is now sitting at L-67, so you have room to increase your exposure to aid in lowering the noise in your image into areas that are not going to be displayed. within the jpeg image. This is more important to many and not the DR which is the noise floor of the camera.


Here is what it would look like if we used an exposure more accurately for a raw file. We shift the distribution of you scene into the area where the sensor is able to gather more light. The very basic way of thinking about it is you are aligning the DR of the scene with what your camera's DR is able to capture and also shifting all of your tones into the areas of your sensor can capture them with less noise.

I also added this to show how Nikon uses the sensors and the raw container

This is an image of the same target with the Nikon using iso 64 with much more headroom

[biz-engineer]

Geee, perhaps there is something interesting to get from those curves, raw container etc.., I'm don't understand all this. I look at DXO curves between Z7 and K1, the difference between the curves is what? 0.1 ev? The Z7 lower ISO, I think I can get it by dialing +0.3 exposure compensation on the K1. My base ISO images on the K1 are stunning, my problem isn't that I don't have ISO64, it's more like I don't have enough situation where I can use ISO100 handheld. A lot of available light situations, I haven't used ISO100 and I wouldn't have used ISO64 either. Performance of SR really helps here, and IMO SR on the K1 now lags behind Nikon and Canon. I've seen SR tests done with MILCs camera (Sony, Nikon, Canon , Pana), some cameras stabilize 6 stops, 7 stops, no way I get 6 stops of SR on my K1. Practically, the K1 SR gives me approx. 2 to 3 stops depending on the lens, and maybe best case 4 stops with a wide lens.

[BarryE]

This discussion has drifted a little away from photography reality, I feel. Either bracket and mask/blend in post or use -0.7 EV. On the K-1 this covers most DR situations.

A few blown highlights are acceptable in most photographs and if, for example, in a sunny woodland, they're impossible to avoid - the viewer will not be bothered anyway (unless they're a picky photo type ;-) ). Blocks of burnt out detail is obviously not OK, so re-compose the shot.