[BruceBanner]

Um... anyone? Can someone answer my question above? (post #29)

[ShawnH]

Dunno if this helps also, but with the KP, Menu 1>ISO Auto Setting>ISO Sensitivity Options>put it to 'Tv'. Now you will notice that the Minimum Shutter Speed below changes from Fast, Normal and Slow to actually allowing you to specify a lowest acceptable shutter speed, so if for example 1/15 is as low as you ever want to go, it will give you that and no lower.

I really wish the K-1 got the same firmware as the KP, it just has a few more options as well as the Aperture Bracketing Shooting Mode.

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Anyway, I'm a bit late to the party, I'm just wanting to get my head around the OP's point. Am I to understand that say the following settings were used in a shot and were necessary to correctly expose the image;

Shot A
1/50
f5.6
ISO 3200

The user could not drop shutter speed further without running the risk of motion blur (either from the subject in the frame moving or user shaking the camera+lens)
f5.6 is the preferred aperture used, optimum sharpness and correct DoF for the required shot
ISO 3200 is given because of the available light the scene is given (ie it's no overly bright environment etc).

If the user took the shot at;

Shot B
1/50
f5.6
ISO 100

then the shot would be grossly underexposed, to chimp the back of the camera LCD screen would show a black screen. However, once the user is back at home in front of a computer, taking Shot B into a RAW editor like LR, increasing Exposure slider and thus bringing the shot 'back to life', once increasing the exposure enough to catch up somewhere close to the brightness that Shot A obtained with it's ISO 3200, would the image quality/noise be better, or worse? Would the detail in the shadows be better or worse? Clearly highlights would be better protected?
And so this is 'ISOless'? The idea that underexposed images are not a deal breaker, because just boost the exposure in post and you get something with a similar or even better IQ than what you would have had at the time of the shot with a higher ISO and more correct exposure?

If Shot B is the intention of the OP, but Av is not allowing holding at 1/50 well enough, does TAv then become a viable option? I just tested now with my K-1. I set my camera to use 1/50, f5.6 and it gave ISO 1250. If I then pressed the EV Comp button I could just lower the ISO and thus underexpose the image and get ISO 100 with still having 1/50 and f5.6.

Yes. Your image shot at Iso 100 when adjusted in post to look like the one shot at iso 1250 will have the same noise but with much better highlights and in my experience better color fidelity. You will also notice that you will often not raise the Iso as much the camera. Search ISO invariable in this forum and see image quality test results on dpreview for more info. BTW This technique is most useful for night photography. ATV is my favorite mode.

[photoptimist]

And so this is 'ISOless'? The idea that underexposed images are not a deal breaker, because just boost the exposure in post and you get something with a similar or even better IQ than what you would have had at the time of the shot with a higher ISO and more correct exposure?

Yes, this is what "ISO less" or "ISO invariant" means.

A RAW image taken at ISO 100 and boosted +4 EV in post will be almost undistinguishable from a RAW image taken at ISO 1600 of the identical scene using the identical aperture, shutter speed, lighting, etc.

The IQ for the two options is identical with two key differences:
* ISO 100 + 4 EV in post will preserve highlights (much lower chance of clipping/blown highlights)
* ISO 1600 will have slightly smoother gradients (lower chance of banding in continuous tones)

The ISO 1600 option has two workflow advantages:
* ISO 1600 lets you chimp the result after the shot
* ISO 1600 provides a usable JPEG for SOOC delivery


NOTE: a properly exposed ISO 100 image will have the highest IQ (unless there's clipping) but that might require too slow a shutter speed or too wide an aperture. Thus "ISO invariant" does not mean "use base ISO and whatever shutter and aperture you like." The more underexposed the image at base ISO, the lower the IQ. Thus, the photographer still must think about the exposure triangle and the trade-offs between image noise (due to high ISO or post-processing EV boost), motion blur due to too slow a shutter speed, or image softness/defocus due to too wide an aperture.

[normhead]

NOTE: a properly exposed ISO 100 image will have the highest IQ (unless there's clipping) but that might require too slow a shutter speed or too wide an aperture. Thus "ISO invariant" does not mean "use base ISO and whatever shutter and aperture you like." The more underexposed the image at base ISO, the lower the IQ. Thus, the photographer still must think about the exposure triangle and the trade-offs between image noise (due to high ISO or post-processing EV boost), motion blur due to too slow a shutter speed, or image softness/defocus due to too wide an aperture.

Or in other words, there's no free lunch.....

You want, the lowest ISO, at the slowest effective shutter (without incurring motion blur) with the appropriate aperture setting (often ƒ5.6 for APS-c or ƒ8 for FF.)

If you can't get to 100 ISO, ƒ8, 1/100s everything after that is likely a compromise. It's always your choice as to what you'll sacrifice in your image but whatever it is, it won't be ideal once you vary from optimum settings.

But there's a lot of leeway between "ideal" and "good enough." Almost any camera will produce great results with ideal settings, it's how much of the less than ideal is still useable that defines how good the camera is.

The fact that some prefer to shoot at 2.8 or 1.4 doesn't change that. There is a technically definable ideal setting for each camera at every f-stop. Most are impractical.

I'd love to be able to look at the charts and decide for what I want to do 100 ISO, ƒ11, and 1/2000s would be the best solution. But the practical problems with using such a setting on a regular basis are obvious to anyone with experience in the field.

Deciding where to put your compromises, a bit of noise weighed against a bit of motion blur, a wider depth of field weighed against better subject sharpness, that's why photography is an art, not a science. Even with sharpness, an ƒ11 which is well past the diffraction limit can look sharper than an ƒ4 image, because the whole subject is in focus. The science can't predict how pleasing the combination of variables will be based on what looks good to a human. Only on how it looks to a test chart.

It is our individual biases as to how to compromise that in most cases sets us apart from other photographers and gives us a unique style. It also means 20 photographers shooting the same scene will likely produce 20 different images. None of them are "wrong". But some may be found more pleasing by a large part of the population.

Even then, you may not be in agreement with what the majority of the population thinks looks good. Using a good camera, which for digital I would define as anything form 4/3 to 645, gives you more chance of producing images you like, as more deviation from the standard "everything in focus shot in broad daylight" is possible.

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Last edited by normhead; 03-25-2020 at 08:34 AM.

[ShawnH]

To chimp during night photography I have set up a User mode like this: TAV > Shutter 1/60 > F stop: wide open> ISO 100~3200> Bracketing +/- 2 stops 0 > Exposure Compensation -2 stops. This is a setup so that ISO is bracketed from 3200 through 100. The ISO 3200 is used for chimping and ISO 100 for actual processing. You can vary the shutter speed and F stop to suit the scene while considering how far under exposed you may be.

[BruceBanner]

Yes. Your image shot at Iso 100 when adjusted in post to look like the one shot at iso 1250 will have the same noise but with much better highlights and in my experience better color fidelity. You will also notice that you will often not raise the Iso as much the camera. Search ISO invariable in this forum and see image quality test results on dpreview for more info. BTW This technique is most useful for night photography. ATV is my favorite mode.

ATV? I don't have that mode on my K-1 or KP, is that what Av used to be called or something?

Yes, this is what "ISO less" or "ISO invariant" means.

A RAW image taken at ISO 100 and boosted +4 EV in post will be almost undistinguishable from a RAW image taken at ISO 1600 of the identical scene using the identical aperture, shutter speed, lighting, etc.

The IQ for the two options is identical with two key differences:
* ISO 100 + 4 EV in post will preserve highlights (much lower chance of clipping/blown highlights)
* ISO 1600 will have slightly smoother gradients (lower chance of banding in continuous tones)

The ISO 1600 option has two workflow advantages:
* ISO 1600 lets you chimp the result after the shot
* ISO 1600 provides a usable JPEG for SOOC delivery


NOTE: a properly exposed ISO 100 image will have the highest IQ (unless there's clipping) but that might require too slow a shutter speed or too wide an aperture. Thus "ISO invariant" does not mean "use base ISO and whatever shutter and aperture you like." The more underexposed the image at base ISO, the lower the IQ. Thus, the photographer still must think about the exposure triangle and the trade-offs between image noise (due to high ISO or post-processing EV boost), motion blur due to too slow a shutter speed, or image softness/defocus due to too wide an aperture.

K, cheers, got it.

[ShawnH]

ATV? I don't have that mode on my K-1 or KP, is that what Av used to be called or something?



K, cheers, got it.

Sorry, Mode: TAV

[BruceBanner]

Sorry, Mode: TAV

Ah hehe, no worries, I think I saw you write it twice and was thinking it was a real thing haah