AUTO ISO

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LouiedS2000

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Need some advise on auto iso, on a bright sunny day i cannot adjust for proper exposure. All my images are over exposed, on a dark situation I can adjust for proper exposure by using command dials. Auto iso on manual mode. Please advise. Z9- V. 5.0
Thank you
Louie D
 
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Use exposure compensation. When the background is brighter you most often would brighten (positive exposure compensation). When the background is darker, you would usually darken (negative exposure compensation.) If you have blinkies/overexposure warning you can take some test shots to find what level of compensation gets you the brightest image without the blinkies flashing. Or look at the histogram and get as close to the right wall as you can without climbing up the wall even a little.

Rule of thumb: background brighter - brighten, background darker - darken. The reason this seems backwards is that when the meter sees mostly very dark it wants to pull it up too much to the middle, so you compensate by moving it back darker. When the meter sees mostly bright it wants to pull it down to the middle, so you compensate by brightening/adding exposure.
 
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LouiedS2000 said:
Need some advise on auto iso, on a bright sunny day i cannot adjust for proper exposure. All my images are over exposed, on a dark situation I can adjust for proper exposure by using command dials. Auto iso on manual mode. Please advise
Thank you
Louie D
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When running in any automated exposure mode such as Aperture Priority, Shutter Priority or even Manual with Auto ISO (it's still an automated exposure mode) it pays to have a good grasp on how the camera meters and how and when to use positive or negative exposure compensation.

These are good starting points to get a handle on using exposure compensation and how metering actually works:

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Exposure Compensation Made Easy! - Backcountry Gallery

Exposure compensation – I don’t think there’s another exposure control that causes more confusion. In fact, I think most people are in for a surprise or two when they watch this one! In this video, we’ll explore every aspect of exposure compensation and knock confusion to the curb. We’ll discuss...
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Spot Metering Crash Course - Backcountry Gallery

Wanna get the most out of your spot meter? Did you know that most people think they’re using it correctly but they really aren’t? YIKES – could that be you??? In this video, we’ll go over what spot metering is, where the camera spot meters in the viewfinder, how the spot meter thinks, where it […]
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Manual Mode With Auto ISO - Backcountry Gallery

Did you know your Nikon camera has a “hidden” exposure mode? Sure, we’re all familiar with Program, Aperture Priority, Shutter Priority, and Manual – but there’s one that’s left off of the list – and that’s Manual Mode with Auto ISO. Basically, this setup allows you to adjust your F/stop and...
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The key thing is the camera doesn't know what kind of scene you're shooting and works on the assumption that everything is mid toned. When a scene isn't actually mid toned an automated exposure mode will over or under expose unless you use exposure compensation to tell the camera how much brighter or darker your scene should be.
 
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If exposure comp isn't working you're probably bottoming out. If you're using a fast lens with a modest shutter speed on a bright day, you need a low ISO - 64 might not be low enough. If you're at ISO 64 there's really no where else for the camera to go - you are in control of the shutter speed and F/stop and the only tool the camera has is ISO. If it can't go any lower, it'll overexpose. Also, since exposure comp comes from ISO in that scenario, the same applies - you can request negative compensation but the camera can't give it to you if you're already as low as you can go. A clue that you're bottomed out is if the affected photos are at ISO 64.

At this point though this is just a guess - some samples and EXIF data would make it easy to pin down :)
 
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LouiedS2000 said:
I have tried that, not working either
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The only reason I can think of that this would happen is if your shutter speed/aperture (your "real" exposure) are set such that the camera can't lower the ISO enough to avoid overexposing.

For instance, if on a bright sunny day you're shooting wide open at 1/400 then the ISO may be at 64 and have nowhere lower to go to avoid overexposing and so lowering the exposure compensation value wouldn't make a difference.

So the practical answer is that if you're getting overexposed images and you're at an ISO greater than 64, lower the exposure compensation until you're not overexposing any more. On the other hand, if you're overexposed and already at ISO 64 then you need to increase shutter speed or narrow aperture.
 
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I shoot with a Z9 and agree with what Steve Perry has posted. To better help you, let us know if you are in Aperture Priority Auto ISO or Manual Auto ISO. (I use both on my Z9). In the Photo Shooting Menu, make sure that you select your base ISO to ISO 64 so your camera has access to the lowest possible ISO to limit the risk of over exposing. In the Z9 Reference guide see pages 145 + on ISO sensitivity control.
 
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Not to highjack here, but a related question I've been meaning to ask which seems to fit in here so as not to make a whole thread: is there a point in adjusting exposure compensation upwards in manual with auto ISO? E.g., if I have an animal which is too dark and I put in a compensation of for instance +1.3 but without increasing the aperture or lowering the shutter speed to let in more actual light, is there any difference between this and just brightening in editing?
 
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SCoombs said:
Not to highjack here, but a related question I've been meaning to ask which seems to fit in here so as not to make a whole thread: is there a point in adjusting exposure compensation upwards in manual with auto ISO? E.g., if I have an animal which is too dark and I put in a compensation of for instance +1.3 but without increasing the aperture or lowering the shutter speed to let in more actual light, is there any difference between this and just brightening in editing?
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Depends on the specific sensor and ISO in use. IOW, if you're well into an ISO range in which the camera/sensor is ISO invariant then no there's no difference in terms of the resulting image of making the adjustment in the field or in post. But if your ISO happens to span an area of dual gain shift in the ISO DR curve then there can be a difference between making the adjustment in the field and making the adjustment in post. Basically if you're operating in a region where the camera/sensor is not ISO invariant then an adjustment in post isn't the same as an adjustment in the field and many cameras have these regions which are where the shape of the DR curve changes abruptly.

There can also be advantages to nailing the exposure in the field in terms of AF system performance as there's some evidence that things like underexposure can lead to AF acquisition and tracking issues in some cases.

But yeah, in a lot if not most situations a small exposure differences can be handled in post as long as the camera is operating in an ISO invariant region. It's one of the things I really like about shooting Manual with Auto ISO. Small changes in ISO for the most part are the same in camera or in post (most of the time) but similar changes in shutter speed or aperture if shooting in a different automatic exposure mode can't really be adjusted in post or at least not as easily.
 
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DRwyoming said:
Depends on the specific sensor and ISO in use. IOW, if you're well into an ISO range in which the camera/sensor is ISO invariant then no there's no difference in terms of the resulting image of making the adjustment in the field or in post. But if your ISO happens to span an area of dual gain shift in the ISO DR curve then there can be a difference between making the adjustment in the field and making the adjustment in post. Basically if you're operating in a region where the camera/sensor is not ISO invariant then an adjustment in post isn't the same as an adjustment in the field and many cameras have these regions which are where the shape of the DR curve changes abruptly.

There can also be advantages to nailing the exposure in the field in terms of AF system performance as there's some evidence that things like underexposure can lead to AF acquisition and tracking issues in some cases.

But yeah, in a lot if not most situations a small exposure differences can be handled in post as long as the camera is operating in an ISO invariant region. It's one of the things I really like about shooting Manual with Auto ISO. Small changes in ISO for the most part are the same in camera or in post (most of the time) but similar changes in shutter speed or aperture if shooting in a different automatic exposure mode can't really be adjusted in post or at least not as easily.
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That's what I find. I do exposure compensation in the camera to try and get it reasonably close, but I'm tweaking exposure in post processing all the time if I'm shooting in varying light. My main worry is not to blow the highlights (egrets, I'm looking at you ...) so I tend to underexpose in camera a bit more than I probably should. But ... it looks fine in post after adjusting.

But obviously, if my shutter speed + aperture doesn't let enough light in, I'm going to have a noisy image. Or when I bring up the shadows, they show extreme noise.
 
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joe43 said:
I shoot with a Z9 and agree with what Steve Perry has posted. To better help you, let us know if you are in Aperture Priority Auto ISO or Manual Auto ISO. (I use both on my Z9). In the Photo Shooting Menu, make sure that you select your base ISO to ISO 64 so your camera has access to the lowest possible ISO to limit the risk of over exposing. In the Z9 Reference guide see pages 145 + on ISO sensitivity control.
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My settings are. ISO Sensitivity 64, Sensitivity ON, Max 12800, Minimum 1000, Manual Mode
 
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DRwyoming said:
Depends on the specific sensor and ISO in use. IOW, if you're well into an ISO range in which the camera/sensor is ISO invariant then no there's no difference in terms of the resulting image of making the adjustment in the field or in post. But if your ISO happens to span an area of dual gain shift in the ISO DR curve then there can be a difference between making the adjustment in the field and making the adjustment in post. Basically if you're operating in a region where the camera/sensor is not ISO invariant then an adjustment in post isn't the same as an adjustment in the field and many cameras have these regions which are where the shape of the DR curve changes abruptly.

There can also be advantages to nailing the exposure in the field in terms of AF system performance as there's some evidence that things like underexposure can lead to AF acquisition and tracking issues in some cases.

But yeah, in a lot if not most situations a small exposure differences can be handled in post as long as the camera is operating in an ISO invariant region. It's one of the things I really like about shooting Manual with Auto ISO. Small changes in ISO for the most part are the same in camera or in post (most of the time) but similar changes in shutter speed or aperture if shooting in a different automatic exposure mode can't really be adjusted in post or at least not as easily.
Click to expand...
Well for instance this question first occurred recently when photographing some red winged black birds with my Z8. I was shooting at my widest aperture and the lowest shutter I thought I could reasonably use as I was trying to catch them flying around.

On the computer, I found they were all underexposed on the birds' bodies (the background was fine) to the point that in many cases there was really no meaningful detail to bring back even with LR's effective denoising. Now I understand the limitations here. At a certain point, if I'm not going to bring more actual light with a wider aperture or longer exposure some subjects will just be underexposed to the point there's nothing to work with. It got me wondering, though, if increasing ISO in the field would have made any difference in such a case or if it really was just at that hard limit where I needed to compromise on the shutter speed to get anything.
 
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I think Steve pointed out what's happening, at least that was my first thought. You're bottoming out. The camera can only go so low on ISO. Most it's ISO100 or ISO64. You mentioned Z9 and I think that is ISO64 for the bottom.

On bright sunny days, you're going to have to expose for the highlights and then hope you can boost the shadows. In other words, smaller aperture (larger number) or faster shutter speed or both,

Hope this helps.
Jeff
 
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Another tool in your disposal are ND filters, both the variable and not variable varieties. In video work, where base ISO is 640 and you can't use a fast shutter due to deviation from 180 shutter angle, ND is widely used. There are some very high quality ones that won't introduced a chroma shift of other imperfections. My go-to are Nisi for variable and Lee's for 100 format.
 
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