Is using Aperture priority bad?

[John Woodworth]

Thanks for your succinct summary. I avoided mention of Luminance, as this thread is not discussing using flash, or other light sources, to change the luminance

I was also trying to avoid going deeper into the subject of "Sensor Innards". After all, the topics of Exposure, and ISO Invariance etc fuel a cottage industry of articles and forum debates (!)

Personally, I dod believe to understand the basic concepts of how a sensor works. This nerdy video does a fair job

One has to be critical of the www material. Photography Life, for example, has a large section of articles on Concepts and 'How To...' by different authors, but at least one is still hung up on the exposure-triangle idea, which can lead to misleading ideas: e.g. that increasing ISO increases luminance

ISO Invariance Explained

In this article, we will explore ISO invariance in detail and how you can use it to your advantage in your photography

photographylife.com

Learning to Shoot in Manual Mode

photographylife.com

Everything You Need to Know About Aperture Priority Mode

Aperture priority mode is a great way to control the look of your photos. In this article, we look into this mode in detail and explain how it works.

photographylife.com

Thank you for the references.

If I'm walking in the woods with an expert birder, and we both have normal hearing. How does he hear the song of a certain bird in the distance but I don't? By one definition he is more sensitive to birdsong than I am, yet we both have equal results on a hearing test.

Same idea with ISO. Light hitting a photosite/pixel dislodges electrons. The number dislodged doesn't depend on ISO, so in that sense ISO doesn't affect how sensitive the pixel is. But the camera system as a whole turns those electrons into a single raw number. That number gets bigger with higher iso settings. So in that sense, like my birder friend, we could say the ISO affects the sensitivity of the camera system to light. We certainly can force a pixel to blow out irretrievably with too high ISO. So in that sense one can be forgiven for including ISO at least in the photographic triangle if not the exposure triangle.

ASA in film days was a measure of film sensitivity. Using films with different ASA’s allowed matching shutter speed and/or aperture to the practical/creative requirements of the shot. The trade off was between motion blur, depth of focus and grain. The word ‘exposure’ loosely meant a particular set of the independent variables shutter speed and aperture. But, ASA, which represented sensitivity to light, was also an independent variable chosen by the operator.

For modern digital cameras that are ISO invariant, sensitivity is NOT an independent variable. It is fixed and the operator can’t change it. ASA is not conceptually the same as ISO. The former is a measure of sensor (film) sensitivity, whereas the latter is ultimately related to signal-to-noise (SNR).

Why is this? After all, for typical daylight, handheld shooting, the amount of electronic/thermal noise is insignificant (an engineering marvel). So, the noise must be part of the light detection process. It is.

Light consists of quantized waves, which sometimes behave as waves and sometimes as particles. Which behavior is manifest depends on the “scale” of the problem being analyzed. In the case we are considering here, light behaves as particles.

So an appropriate analogy is that someone in the scene being photographed is throwing particles at a pixel in your camera. Sometimes it’s a hit…Sometimes a miss. Mathematically, if on the average N photons would hit your pixel, there will be a random deviation of Sqrt(N) from N. This inherent randomness at low levels of light dominates the noise in the images from modern cameras.

The important takeaway is that the SNR scales as N/(Sqrt N) = Sqrt(N), so as the number of photons of decreases, so does the SNR also decrease. Thus, less light produces noisier images. Since ISO scales so that it directly reflects the deterioration of SNR with decreasing amounts of light at the sensor, increasing ISO is a fundamental measure of image noise.

This is an fundamental limitation imposed by physics. The wave/particle nature ultimately limits the size of camera pixels due to counting statistics (and also diffraction), and hence limits the number of pixels that can be reasonably fit within a 35mm sensor for normal use. That modern cameras are pushing hard against Mother Nature in this way is truly astonishing.

I prefer to think of ISO as a measure of noise…commonly represented as dynamic range on the charts.

And this is why Steve councils in an eBook to put high-ISO images into the can with good shutter speed, and then start lowering shutter speed (and ISO) and taking bursts, hoping to capture a sharp, less noisy image with higher SNR.

 

[ARClark]

That depends on the camera so worth checking. I know Canon always spot meters from the center and only do considers the focus point in evaluative (matrix) metering. Does Nikon have a setting where you can choose?

Agree. In this case I was responding to someone who shoots with the Z9 and Z8, and my experience was with the Z9. But yes, other Nikon camera models and models from other brands will vary.

 

[fcotterill]

Thank you for the references.


ASA in film days was a measure of film sensitivity. Using films with different ASA’s allowed matching shutter speed and/or aperture to the practical/creative requirements of the shot. The trade off was between motion blur, depth of focus and grain. The word ‘exposure’ loosely meant a particular set of the independent variables shutter speed and aperture. But, ASA, which represented sensitivity to light, was also an independent variable chosen by the operator.

For modern digital cameras that are ISO invariant, sensitivity is NOT an independent variable. It is fixed and the operator can’t change it. ASA is not conceptually the same as ISO. The former is a measure of sensor (film) sensitivity, whereas the latter is ultimately related to signal-to-noise (SNR).

Why is this? After all, for typical daylight, handheld shooting, the amount of electronic/thermal noise is insignificant (an engineering marvel). So, the noise must be part of the light detection process. It is.

Light consists of quantized waves, which sometimes behave as waves and sometimes as particles. Which behavior is manifest depends on the “scale” of the problem being analyzed. In the case we are considering here, light behaves as particles.

So an appropriate analogy is that someone in the scene being photographed is throwing particles at a pixel in your camera. Sometimes it’s a hit…Sometimes a miss. Mathematically, if on the average N photons would hit your pixel, there will be a random deviation of Sqrt(N) from N. This inherent randomness at low levels of light dominates the noise in the images from modern cameras.

The important takeaway is that the SNR scales as N/(Sqrt N) = Sqrt(N), so as the number of photons of decreases, so does the SNR also decrease. Thus, less light produces noisier images. Since ISO scales so that it directly reflects the deterioration of SNR with decreasing amounts of light at the sensor, increasing ISO is a fundamental measure of image noise.

This is an fundamental limitation imposed by physics. The wave/particle nature ultimately limits the size of camera pixels due to counting statistics (and also diffraction), and hence limits the number of pixels that can be reasonably fit within a 35mm sensor for normal use. That modern cameras are pushing hard against Mother Nature in this way is truly astonishing.

I prefer to think of ISO as a measure of noise…commonly represented as dynamic range on the charts.

And this is why Steve councils in an eBook to put high-ISO images into the can with good shutter speed, and then start lowering shutter speed (and ISO) and taking bursts, hoping to capture a sharp, less noisy image with higher SNR.

Excellent explanation. Thanks

Another interesting complication with thinking of ISO as a '3rd Variable' is ISO only kicks in after the light has hit the sensor.

And yet another complication is many modern sensors have dual gain amplification, which partitions Dynamic Range and the noise levels (depending on different ranges of ISO settings).

Dependent on the specific dual gain sensor, two respective optimum settings influence noise and how one can best exposes scenes to minimize blowing out highlights and maximize dynamic range.

For example, the Z9 is basically ISO-invariant up to ISO 400, then the gain shifts to reset ISO invariance from ISO 500 upwards to 12800. Conversely, noise increases with gain in the D6 sensor until ISO 2500, where after the sensor is ISO Invariant.

 

[John Woodworth]

Excellent explanation. Thanks

The other complication with thinking of ISO as a '3rd Variable' is that many modern sensors have dual gain amplification, which partitions Dynamic Range and the noise levels (depending on different ranges of ISO settings).

Dependent on the specific dual gain sensor, two respective optimum settings influence noise and how one can best exposes scenes to minimize blowing out highlights and maximize dynamic range.

For example, the Z9 is basically ISO-invariant up to ISO 400, then the gain shifts to reset ISO invariance from ISO 500 upwards to 12800. Conversely, noise increases with gain in the D6 sensor until ISO 2500, where after the sensor is ISO Invariant.

Right on!

And one always needs to keep an eye on the camera settings and watch for lighting and metering changes.

To the original point, I often use Aperture Priority for non-action, particularly outdoors because it responds automatically to changing cloud cover (for instance). However, I constantly ride the Exposure Compensation setting to adjust for local changes in the scene and lighting.

For non-action my priority is mainly depth-of-focus, which is determined by aperture, and I can set ISO below 500 so as not to worry (much) about dynamic range (noise) and also have an in-camera-determined shutter speed auto-set between a minimum speed preventing motion blur and the top speed of the camera.

For action, it would probably be Manual with Auto-ISO, probably riding the Shutter Speed as necessary to keep noise in check.

In low/difficult light, I tend to go full manual and take test shots if possible. I shoot musical groups, so for the group I might want good depth-of-focus and I will be juggling Aperture and Shutter at the highest ISO I dare (usually 6400). If I want a close-in portrait of a soloist wearing a bright white, 10-gallon cowboy hat list with lights from above that produce a huge dynamic range between the hat and the shadowed face, I will bag some sharpies at ISO 6400 with aperture wide open, and then slowly reduce ISO and Shutter Speed and fire off bursts, hoping to get a blur free image at ISO 1600 or 800. That way, I have a chance of pulling out the shadowed face in post processing.

Any way you set up your camera, you must be constantly ready to adjust or correct a setting for optimum overall exposure.

In controlled lighting and scene, like indoor portraits, full manual.

 

[John Woodworth]

Adding one more thought, some form of AutoExposure can be indispensable. If I am shooting a stage scene that is not changing that much, I can go to Aperture Priority (or some other autoexposure mode). Then, if there is a sudden reaction in the crowd which has quite different lighting, I can swing around and capture it with reasonable certainty that the camera will get the exposure close enough.

 

[eaj101]

Like John, I use 'auto-something' as my default when I may see something suddenly and need to react quickly. (the immediate thing that came to mind is whales). So aperture priority where DOF is a concern, shutter priority when as specific faster-than shutter speed is needed, etc. Once I've gotten a shot I then will probably switch to manual. But I'm often wandering/hiking with no specific shot in mind and want to be ready.

Or I could be fooling myself...

 

[John Woodworth]

No. I think you are right on.

 

[bleirer]

Thank you for the references.


ASA in film days was a measure of film sensitivity. Using films with different ASA’s allowed matching shutter speed and/or aperture to the practical/creative requirements of the shot. The trade off was between motion blur, depth of focus and grain. The word ‘exposure’ loosely meant a particular set of the independent variables shutter speed and aperture. But, ASA, which represented sensitivity to light, was also an independent variable chosen by the operator.

For modern digital cameras that are ISO invariant, sensitivity is NOT an independent variable. It is fixed and the operator can’t change it. ASA is not conceptually the same as ISO. The former is a measure of sensor (film) sensitivity, whereas the latter is ultimately related to signal-to-noise (SNR).

Why is this? After all, for typical daylight, handheld shooting, the amount of electronic/thermal noise is insignificant (an engineering marvel). So, the noise must be part of the light detection process. It is.

Light consists of quantized waves, which sometimes behave as waves and sometimes as particles. Which behavior is manifest depends on the “scale” of the problem being analyzed. In the case we are considering here, light behaves as particles.

So an appropriate analogy is that someone in the scene being photographed is throwing particles at a pixel in your camera. Sometimes it’s a hit…Sometimes a miss. Mathematically, if on the average N photons would hit your pixel, there will be a random deviation of Sqrt(N) from N. This inherent randomness at low levels of light dominates the noise in the images from modern cameras.

The important takeaway is that the SNR scales as N/(Sqrt N) = Sqrt(N), so as the number of photons of decreases, so does the SNR also decrease. Thus, less light produces noisier images. Since ISO scales so that it directly reflects the deterioration of SNR with decreasing amounts of light at the sensor, increasing ISO is a fundamental measure of image noise.

This is an fundamental limitation imposed by physics. The wave/particle nature ultimately limits the size of camera pixels due to counting statistics (and also diffraction), and hence limits the number of pixels that can be reasonably fit within a 35mm sensor for normal use. That modern cameras are pushing hard against Mother Nature in this way is truly astonishing.

I prefer to think of ISO as a measure of noise…commonly represented as dynamic range on the charts.

And this is why Steve councils in an eBook to put high-ISO images into the can with good shutter speed, and then start lowering shutter speed (and ISO) and taking bursts, hoping to capture a sharp, less noisy image with higher SNR.

I think what I said is still true, though.

 

[John Woodworth]

I think what I said is still true, though.

Not everything you said is true. Probably same for me, too.

I have spent some time trying to discover how Nikon in particular does its secret sauce but have run into a blind alley. Links have disappear and I naively failed to copy the relevant articles while I had a chance.

If you want to engage in a friendly way, both of us seeking to understand, I am happy to.

 

[eaj101]

Not everything you said is true. Probably same for me, too.

I have spent some time trying to discover how Nikon in particular does its secret sauce but have run into a blind alley. Links have disappear and I naively failed to copy the relevant articles while I had a chance.

If you want to engage in a friendly way, both of us seeking to understand, I am happy to.

You might sift through Thom Hogan's website for info on how Nikon figures out exposure. I recall a number of articles on the subject over the years, but I don't know how many of them are still there. (Exposure and color rendition are two of Nikon's strong points, in may opinion).

 

[grossidm]

I used to shoot everything exclusively in manual - because I was a bad-ass. Then, when I got over myself, I learned that there is a place for most camera modes. Today much of what I shoot is in aperture priority, I use the ISO to control my shutter speed along with exposure compensation to fine-tune what the camera gets wrong. Do whatever gets you the most keepers I'd say. Nobody has ever said to me "wow, great shot, were you in manual?"

 

[fcotterill]

This lecture series takes some stamina and concentration but it's well worth the time spent

I started here, reading this derived essay

The Best Explanation of Dual (Native) ISO We've Seen Yet

The Dual ISO sensor is on the rise, and every major camera manufacturer has made one (or will very soon). What is it, though, and what does it mean?

www.premiumbeat.com

Then the lectures....

 

[fcotterill]

Last but not Least

 

[Feiertag]

I have never used auto ISO, so maybe I don't understand how it works. I thought if you are in manual (regardless of ISO mode) the camera will give a fixed exposure which may or may not be correct; it is whatever aperture and shutter speed you choose. Does auto ISO somehow override this? (Forgive my ignorance, I honestly do not know).

Someone posted the answer to your question. I just want to add that you have absolutely nothing to lose by giving auto ISO a whirl. You will get it as to why most people use this mode.

BTW, when I first got into taking bird shots (11 years ago), the worst piece of advice given to me was to use Aperture Priority. Many blurred birds in flight as a result. Shutter speed is more important to me than "f" stops.

 

[photosport]

I want to thank everyone for their insight and inspiration on this topic. After 40 years with another manufacturer, I switched to Nikon 4 years ago. The exposure systems Nikon has blows my mind in the best of ways. I have learned so much this last year from threads like this one. I believe camera settings are truly situational based on a variety of factors. The most limiting factor is my own ability. I thought I was well versed in photography having shot 35mm and medium format. Boy was I wrong!

Picked up a D500 last year and it spun my head around at first. I will go FF sometime in the future. Please don’t stop contributing to threads like this one!

 

[Anjin San]

I used to do everything in Aperture preferred but switched to M + auto ISO and don’t look back. Still have a U mode and bank for landscapes and waterfalls though that’s set up for bracketing…A preferred and fixed ISO which gets adjusted as needed and shutter floats for the bracket…same aperture and ISO shots blend better in post.

 

[Ken Miracle]

The problem with spot metering mode is always being able to place the spot on your subject. AND I am always confused if "the spot" is the spot under the focus point OR a central spot. I assume it is the spot being used for AF -- see extracts below.

I note that photographers of HUMANS receive the benefit of Matrix Metering with Face Detection -- and Nikon makes this clear that the faces have to be HUMAN -- Dear Nikon how about applying this to ANY Subject recognised by Subject Detection AF.

Wouldn't that be a great feature -- well it may already work that way -- but on has to dig for it -- and if the subject is small or unevenly lit 4mm may be unhelpful /need EC correction.

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With shutter half press AF spot metering or center weighted has always been the where I placed the focus point and activated AF in the days with my D500, D4S, D850 and D600. Now with the Z9 and using things like 3D AF Area mode + AF-ON I am not sure whether it meters from the first focus point 3D starts at and then changes as it goes or what exactly.

Since the OP is using a D500 things are different with it than with my Z9. I never used face detection with my DSLR's since I wanted to control where my focus point was so if I wanted to focus and meter off the critter next to a person not the person I could do so. So I never really experienced face recognition impact on metering etc..

Just curious which Nikon manual you show above?

 

[Ken Miracle]

Nikon metering is different than Canon etc..

One of the best references on exposure and metering is @Steve book Secrets to Exposure and Metering for Nikon.

Secrets To Exposure And Metering For Nikon – Backcountry Gallery Web Store

 

[NorthernFocus]

One question I have for the aperture or shutter priority shooters. Is the display blinking 12:00 on your microwave

 

[grossidm]

Someone posted the answer to your question. I just want to add that you have absolutely nothing to lose by giving auto ISO a whirl. You will get it as to why most people use this mode.

BTW, when I first got into taking bird shots (11 years ago), the worst piece of advice given to me was to use Aperture Priority. Many blurred birds in flight as a result. Shutter speed is more important to me than "f" stops.

I thouroughly disagree regarding using aperture priority. Which further enforces that people should use whatever it is that works for them.

 

[Ken Miracle]

I thouroughly disagree regarding using aperture priority. Which further enforces that people should use whatever it is that works for them.

Whatever works for us also changes with changes in gear and for some subject etc..

Aperture Priority (AP) was almost my only program mode used back in the days with D300s I used AP for almost everything including birds in flight. I just had to keep ISO easy to move up quickly to keep shutter speeds high enough but my priority was to choose my depth of field.

Then along came my D4s and Auto ISO actually worked. From there on for efficiency I have shot in Manual with Auto ISO and get to choose my depth of field and shutter speed and the ISO has to be what the ISO has to be unless I am willing compromise on shutter speed or depth of field.

One caveat that I would alert anyone to: since birds and I are mobile and moving between light and shade moment to moment I recommend having exposure compensation easy to apply quickly if needed.

 

[Robert S]

I prefer this one

But this one is my favorite

 

[ccirelli]

I mean, hey if it works for you and you're happy - no it's not bad at all. Personally I prioritize shutter and aperture and the first I sacrifice for light is ISO (via Auto-ISO usually). Once I went to Manual + Auto-ISO, I never looked back.

It really depends on your needs / goals / use case, but again generally speaking, if you're happy with the results - that's all that matters

 

[Roy]

Is using Aperture priority considered an amateur setting vs manual setting? IU found that my whites are less blown out on my Egrets and Pelicans when I used to use aperture priority but in order to learn to be a “professional” wildlife photographer some day I switched to Manual with auto ISO. But I am struggling with blowouts even with using up to -1.0 exposure adjustment. But I am tempted to return to aperture priority except for the fear I will be viewed as a noobie beginner.

As a Pro photog since 1978 - there are no rules.
Most of my I cameras are in Aperture Priority or Manual but I'm only a Product shooter.
Choose the mode of most importance - Aperture for DOF, Shutter for movement etc.
Letting the ISO control exposure is convenient but other than noise the dynamic range can suffer.
Wildlife and Sport shooters often use shutter priority to reduce movement blur.
Just go with whatever works for you ...

 

[arbitrage]

After reading this thread I've been challenging myself to do more M+AutoISO shooting this past weekend.
It has its place but I've blown my exposure more times than I typically do in full M.

The way I see it...if I shoot M+Auto ISO then I'm working my EC dial all the time. If I shoot full M then I'm working my ISO dial all the time. No real difference there.
However, in full M, in a given flight sequence, when the bird flies over different coloured backgrounds or becomes bigger in the frame (blocking out more of the background) full M always has the correct exposure and brightness dialled in....M+Auto ISO can literally require EC adjustment during the flight sequence to not ruin an exposure. I can't be adjusting a variable while shooting an Osprey diving down from sky over dark trees, over light grass and ultimately over light water all within a second or two.

That is where I can't understand how many people tell me they always shoot M+Auto ISO....because I understand when M+Auto ISO can be a more effective option (ie when the light is quickly changing on the subject) but even then if I've locked in my exposure for the subject while in the brightest light that will hit it then even if it underexposes as the subject comes into shadow, I can make use of the ISO-less nature of the modern sensors and lift the brightness in post....this gets me just as good of a shot as if I'd changed ISO on the fly and still avoids the pitfalls of Auto ISO screwing up and overexposing because the EC is wrong. With these ISO-less sensors all we really need to do is shoot at or above the dual gain value and not blow highlights. Full M can accomplish this with little effort and won't result in a ruined exposure (brightness) that can't be recovered.

All I can say is if you are shooting a MILC with WYSIWYG, I'd give full M a try...it is less to juggle and it is simple to never ruin a shot due to the camera making a decision.