Exposure Compensation vs ISO adjustment

[Manfred M]

This has been a good discussion. I tend to approach the subject slightly differently when I teach this aspect of photography. I look at it more from the standpoint of the trade-offs one makes and I generally start with the discussion of what correct exposure is.

Sanjib's question and Bill's response partially miss what the intent of the exposure is. If the intent is to shoot an image like the one Bill shows in #16, then I would have given a similar response and probably would have gotten into writing about adding a fill light from a flash as an option. He does allude to this by saying "The metering - the question is "what to expose for?" That dictated by what you want." If the intent was a silhouette, the metering / exposure would have been quite different.

Ultimately, I suggest that what metering is all about is getting quality data to create the image you are trying to create. The answer will be different for someone who is looking to get a strong straight-out-of-camera JPEG versus someone with good post-processing skills who is working with raw data.

When it comes to the Exposure Triangle I tend to start with what the trade-offs that need to be consider are:

1. Shutter Speed - controls motion; intentional and otherwise. If freezing motion is critical is critical, then there is one answer, if a softer look of water in a fountain or water fall is important, then there will be a different answer.

2. Aperture - controls depth of field and the optical quality of the image. I generally am concerned with depth of field but some people get into a real twist when they are not shooting using the "sweet spot" of their lens. Wide open and some of the optical deficiencies of the lens design come out and stop down too much and diffraction softening reduces image quality.

3. ISO - As others have pointed out the base ISO is going to give the highest image quality (maximum dynamic range, maximum colour depth and minimum digital noise). All of that really doesn't matter if the shutter speed is too slow and unintended subject or camera movement blur have a negative impact on the image or if the image is not sharp enough where required because the depth of field was too shallow.


My usual work flow is to decide if I am trying to control motion or depth of field. I will make those decisions and then go with as low an ISO setting as I can (I generally do not use auto-ISO), for a given shutter speed and aperture. Obviously the focal length I am shooting at is also a consideration when assessing the settings I am using. I also tend to use the same preset white balance for the entire shoot, rather than using auto-WB, even though I am shooting raw + JPEG.


I generally use evaluative metering and on occasion pop over to either spot metering or high-light weighted and will always look at my histograms on the first shot of a set to ensure I am getting good data.


I do use exposure compensation or switch to manual mode in tricky light situations were I know the recommended exposure will not give the quality data I need for PP work.

[cauger61]

I adjust my ISO using exposure compensation, if needed. I have recently been doing a lot of shooting using manual exposure (I select both shutter speed and f/stop) with auto ISO (the camera selects the ISO within the parameters that I have selected).

If I had chosen aperture priority, the camera would have selected the aperture and might have closed down beyond f/5.6 or opened up to f/4. Shutter speed priority would have put me in the chancy situation of slowing down the shutter speed to a point in which Duke would have been blurred.

Thnx for a nice demonstration of the two settings EC vs ISO. But, then one question comes to my mind. How, is it that in Aperture priority mode, camera would have chosen the f-value? it is you who are at liberty to chose the f-value in Av mode and also in shutter priority, you would have the every control to select a shutter speed fast enough to capture the moving creature. BTW, What shutter speed did you end up with this photograph, just for knowledge?

[cauger61]

Ah!! great, Manfred. I was just waiting for you to appear in the scenario to make things more juicy and vibrant. Getting immensely encouraged by all of yours participation and very knowledgable inputs. Thnx a lot.

[Manfred M]

Thnx for a nice demonstration of the two settings EC vs ISO. But, then one question comes to my mind. How, is it that in Aperture priority mode, camera would have chosen the f-value? it is you who are at liberty to chose the f-value in Av mode and also in shutter priority, you would have the every control to select a shutter speed fast enough to capture the moving creature. BTW, What shutter speed did you end up with this photograph, just for knowledge?

It depends on your camera.

In aperture priority / Av mode you select the camera calculate the appropriate shutter speed for a given ISO for a "proper exposure". In shutter priority / Tv mode you select the shutter speed and the camera selects the appropriate aperture for a given ISO setting to get you a "proper exposure".

Which image are you referring to? Focal length image shooting at and camera sensor size are also considerations I will make when determining shutter speed. If I have a stabilized lens that is good for 3 ev I will make a different choice than for when shooting without a stabilized lens. There are so many variables in place, I can't give you a definitive value. That's where practice and experience come in.

[xpatUSA]

<>. BTW, What shutter speed did [rpcrowe] end up with this photograph [of a dog], just for knowledge?

The EXIF says f/5.6 at 1/1000 sec. ISO was 4000. No EC because he shot in Manual Exposure Mode.

[William W]

Thnx a lot William for the great answer; though you have misspelled my name "Sinjab" instead of "Sanjib" (ha, ha)!!

Apologies. Absolutely unintended error.

WW

[rpcrowe]

The EXIF says f/5.6 at 1/1000 sec. ISO was 4000. No EC because he shot in Manual Exposure Mode.

I made a mistake... Since I have never needed to adjust my exposure using Manual Mode + Auto ISO, I was under the impression that EC would change the exposure + or -. I have tested it a moment ago and it does not.

I still enjoy using Manual Exposure + Auto ISO when I want a specific aperture and shutter speed combination especially in changeable lighting conditions. This is mostly for shooting fast action such as sports when stopping action and a narrow DOF is desirable. If the specific aperture combined with a specific shutter speed is not needed then Aperture Priority Auto or Shutter Speed Priority Auto exposure is fine...

However, using Programmed Auto Exposure, I can adjust my f/stop or aperture by simply rotating either the aperture dial or the shutter speed dial (if a camera is so equipped). The camera will select a total exposure considering the ISO I have chosen and the brightness of the subject. If I am at 1/100 second at f/16 and rotate the shutter speed to 1/200 second, the programmed auto will compensate by opening up the aperture to f/11. Conversely, if I am at 1/500 second at f/5.6 and close down my aperture to f/8, Programmed Auto will shift the shutter speed to 1/250 second.

If the image at any shutter speed or f/stop is too bright or too dark (either in the EVF or a mirrorless camera or when reviewed on the LCD with a DSLR) you can adjust the total exposure by using EC in any of the three auto modes: Aperture, Shutter Speed (which Canon lists as T) or Programmed. The total exposure will be locked in regardless of the shutter speed or aperture chosen until the EC is readjusted.

The shutter speed. f/stop. exposure compensation and ISO are easier to read in some cameras than others. Some viewfinders have larger and seemingly brighter numbers than other viewfinders.

[Manfred M]

I made a mistake... Since I have never needed to adjust my exposure using Manual Mode + Auto ISO, I was under the impression that EC would change the exposure + or -. I have tested it a moment ago and it does not.

That may be true for Canon cameras but not for Nikon. EC does change the ISO value when shooting in manual mode with auto-ISO set. I thought I had read somewhere that this feature exists in some of the newest Canon models as well.

[DanK]

It may be true of some of the newest Canons, but as far as I can tell, my 5D III lacks EC in manual mode.


Sent from my iPad using Tapatalk

[xpatUSA]

Originally Posted by rpcrowe I made a mistake... Since I have never needed to adjust my exposure using Manual Mode + Auto ISO, I was under the impression that EC would change the exposure + or -. I have tested it a moment ago and it does not.

That may be true for Canon cameras but not for Nikon. EC does change the ISO value when shooting in manual mode with auto-ISO set. I thought I had read somewhere that this feature exists in some of the newest Canon models as well.

Life is much simpler for my Sigma. Neither Auto-ISO nor EC are available in Manual.

In other words, WYSIWYG ... what you select is what you get ...

[pschlute]

I still enjoy using Manual Exposure + Auto ISO when I want a specific aperture and shutter speed combination especially in changeable lighting conditions. This is mostly for shooting fast action such as sports

On Pentax cameras they call this mode TAv and I use it in the same conditions as you. Usually capturing my hounds running in the garden. Unlike Tv or Av mode you are never going to find a shot is suffering from too much camera shake or subject blur, or indeed too narrow a DOF.

With the improvement in higher ISO/lower noise results this mode has come into it's own.

[rpcrowe]

Must be my age showing... My Sony cameras don't allow the use of EC when combined with manual exposure and auto-ISO...

However, my Canon 7D2 allowed EC in manual with Auto ISO... I guess that the Canon 6D2 being a later camera than the 7D2 or 80D also allows EC in manual with auto ISO. Obviously, my present Sony cameras (tried it on both the A6400 and A7iii) don't have that capability. I just assumed that the Sony cameras allowed that. Since I have never been in a situation with my Sony cameras when when auto ISO did not nail the exposure, I never needed EC with the A6400 or A7iii...

Glad that I found out by testing...

Here is some info from the Canon site:

"Yes, it is now possible to use Exposure Compensation in Manual mode with Auto ISO with some of Canon’s newer cameras:

EOS-1D X

EOS-1DX Mark II

EOS 5DS / EOS 5DS R

EOS 7D Mark II

EOS 80D

The easiest way is to assign a Custom Function to the “Set” button.

Brian Worley: Manual mode, auto ISO and exposure compensation"

Here is a Grant Atkinson YouTube video on setting up Auto ISO on the later Canon cameras...
https://www.youtube.com/watch?v=Xmud7-O8HNs

If I had the money or inclination to do an African Safari (I have neither) I would seriously consider doing so with Grant Atkinson...

[cauger61]

Apologies. Absolutely unintended error.

WW

Thnx U; thnx u — nothing serious. Just mentioned that jokingly!!

[DanK]

Richard,

Thanks for sending this information. I can't justify replacing my camera now, unfortunately, but down the road, I will welcome having this feature. I don't use auto ISO much, but in situations when I do, EC would be very helpful.

Dan

[rpcrowe]

Dan,

The first camera that I had with a viable Auto ISO was either the Canon 7D or the 7D2; I don't remember which. I played with Auto ISO but, never really used it seriously until I started shooting Sony cameras. I have never really made a head to head test but, I suspect that the Sony cameras that I have used (A6500, A6400 and A7iii) have better high ISO capabilities than my Canon cameras.

I have no hesitation shooting even the crop sensor Sony cameras such as my A6400 up around ISO 6,400 or even ISO 8,000... I never shot my Canon DSLR's at ISO levels that high. Perhaps they would have been O.K and perhaps not. Too late to second guess now, every bit of my Canon gear has found a new home...

[DanK]

The issue with auto ISO, IMHO, is ETTR as much as low-light capabilities. The more you boost ISO, the more degradation you will see if you underexpose. I posted a series of shots here a long time ago showing that even with a 7D (first generation), which is not known for good low-light performance, you can boost ISO a lot without too much degradation if you expose to the right.

That's why I want EC with auto ISO. For example, I was asked to photograph a play with only stage lighting, which was low and variable. I had to constrain shutter speed (people moving on stage) and aperture (for sufficient DOF). That meant that I had to use auto ISO if I wanted the camera to adjust for variations in lighting. The problem was that the camera "properly" exposed, putting the peak of the histogram around the middle. There was plenty of room for an additional stop or more, so if possible, I would have added positive EC, which would have produced noticeably cleaner images.

[Antonio Correia]

I do have learned a lot from this thread !
As much as a way to shoot Manual under certain conditions...
Thank you all. You opened my eye to the manual mode with auto ISO and EC.
All this combined to get the right histogram...
Kudos !

[rpcrowe]

The issue with auto ISO, IMHO, is ETTR as much as low-light capabilities. The more you boost ISO, the more degradation you will see if you underexpose. I posted a series of shots here a long time ago showing that even with a 7D (first generation), which is not known for good low-light performance, you can boost ISO a lot without too much degradation if you expose to the right.

That's why I want EC with auto ISO. For example, I was asked to photograph a play with only stage lighting, which was low and variable. I had to constrain shutter speed (people moving on stage) and aperture (for sufficient DOF). That meant that I had to use auto ISO if I wanted the camera to adjust for variations in lighting. The problem was that the camera "properly" exposed, putting the peak of the histogram around the middle. There was plenty of room for an additional stop or more, so if possible, I would have added positive EC, which would have produced noticeably cleaner images.

I have not shot stage plays with mostly spot lighting. The stages that I have shot have been lit with generally overall lighting...

However, I do wonder if I could not use EC with manual exposure, whether I might still be able to adjust the ISO up and down to get the image that I am looking for while I am still in manual.

With the Sony, I would still use manual exposure with auto ISO and choose a minimum shutter speed that would stop the performer's motion and select an f/stop which would give me the depth of field that I needed.

I have not used face priority in exposure determination but, I think that combined with spot metering, the Sony face priority would give me the best chance at a correct (workable) exposure... Being able to see the results of the exposure prior to pressing the shutter button would also be an aid in selecting exposure.

Sony: Spot metering point - focus point link. This can be used in auto ISO... Don't know how you do this on Nikon or Panasonic..

Linking the exposure to the focus point is available on some Sony cameras as well as on Panasonic and I think Nikon. I don't think that Canon has this capability, yet...