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Author Topic: Why is auto exposure so useless?  (Read 87583 times)

Justinr

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Re: Why is auto exposure so useless?
« Reply #40 on: August 26, 2015, 07:35:11 am »


As I have already mentioned, I'm not looking for perfection, just a more consistent result overall.


Stick to the one camera/sensor and you will learn to get consistent results?

Just so long as I use manual, then yes, probably so.
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spidermike

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Re: Why is auto exposure so useless?
« Reply #41 on: August 26, 2015, 07:43:26 am »

I'm not looking for perfection, just a more consistent result overall.

Are you talking about consistency between cameras or between different situations?

Quote
Overall though printers tend to reduce the quality of image considerably so I need to make it as good as possible to begin with.
This sounds to me like it is your own personal desire to get things absolutely spot on according to what you see rather than a perfectly publishable image for people who were not there at the time. Nothing wrong with that but it means you are putting way more requirements on the internal meter than it was ever designed to do.

I am still not sure what the difference is between your approach using manual, and a situation where you set AE and think "I know from experience I need to overexpose this mage by 2 stops" and turning the compensation dial. For me, that suits my way of thinking better than 'ah, that needs f8 1/200 but add 2 stops which mean f8 1/50'.
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stamper

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Re: Why is auto exposure so useless?
« Reply #42 on: August 26, 2015, 07:51:23 am »

Are you talking about consistency between cameras or between different situations?
This sounds to me like it is your own personal desire to get things absolutely spot on according to what you see rather than a perfectly publishable image for people who were not there at the time. Nothing wrong with that but it means you are putting way more requirements on the internal meter than it was ever designed to do.

I am still not sure what the difference is between your approach using manual, and a situation where you set AE and think "I know from experience I need to overexpose this mage by 2 stops" and turning the compensation dial. For me, that suits my way of thinking better than 'ah, that needs f8 1/200 but add 2 stops which mean f8 1/50'.

Spot on. :)

MarkL

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Re: Why is auto exposure so useless?
« Reply #43 on: August 26, 2015, 08:00:47 am »

I have to confess I have got lazy for less critical work, my D800E has so much DR and there is no real penalty for pushing exposure in post that I worry less.

The histogram is great as long as (with a DSLR) you have time for a trial and error approach to exposing each time.
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Justinr

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Re: Why is auto exposure so useless?
« Reply #44 on: August 26, 2015, 08:15:58 am »

Are you talking about consistency between cameras or between different situations?
This sounds to me like it is your own personal desire to get things absolutely spot on according to what you see rather than a perfectly publishable image for people who were not there at the time. Nothing wrong with that but it means you are putting way more requirements on the internal meter than it was ever designed to do.

I am still not sure what the difference is between your approach using manual, and a situation where you set AE and think "I know from experience I need to overexpose this mage by 2 stops" and turning the compensation dial. For me, that suits my way of thinking better than 'ah, that needs f8 1/200 but add 2 stops which mean f8 1/50'.

I fear you may be hearing the wrong things in that case and as for demanding more from the meter that it was ever designed to provide then I suggest that little nugget of wisdom be more widely dispersed and it is good to see it aired in the open here for I am sure there are many who have somehow come to believe that AE is just that, if only because that is the inference from the various marketing ploys used by the vendors/manufacturers.  Honesty is wonderful stuff don't you think?



and a situation where you set AE


And therein lies the major problem, AE is not consistent so there is no point in setting any exposure compensation. Your way of thinking seems to miss this point.

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Justinr

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Re: Why is auto exposure so useless?
« Reply #45 on: August 26, 2015, 08:20:59 am »

I have to confess I have got lazy for less critical work, my D800E has so much DR and there is no real penalty for pushing exposure in post that I worry less.

The histogram is great as long as (with a DSLR) you have time for a trial and error approach to exposing each time.

Not necessarily each time, but certainly it will indicate when you are close to the required exposure under certain circumstances and you can then work from that point, using it to check whether you are recording the information you want. Shadow detail is often more important than a burnt out sky for instance.
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Petrus

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Re: Why is auto exposure so useless?
« Reply #46 on: August 26, 2015, 08:21:48 am »


And therein lies the major problem, AE is not consistent so there is no point in setting any exposure compensation. Your way of thinking seems to miss this point.


But AE is predictable enough that exposure compensation is a valuable tool. If exposure varies +-1 stop from the optimal one because AF is not perfect, and you know it will underexpose 1 or 2 stops on the average (light background, beach, snow), setting the compensation dial to +1 or +2 will bring the results back to normal. All there is to it.
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spidermike

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Re: Why is auto exposure so useless?
« Reply #47 on: August 26, 2015, 08:26:54 am »

I fear you may be hearing the wrong things in that case and as for demanding more from the meter that it was ever designed to provide then I suggest that little nugget of wisdom be more widely dispersed and it is good to see it aired in the open here for I am sure there are many who have somehow come to believe that AE is just that, if only because that is the inference from the various marketing ploys used by the vendors/manufacturers.  Honesty is wonderful stuff don't you think?


I still do not recognise these 'marketing ploys' you talk about. Where do the manufacturers overplay the internal metering capability?  Can you point me to a website or catalogue?


and a situation where you set AE


And therein lies the major problem, AE is not consistent so there is no point in setting any exposure compensation. Your way of thinking seems to miss this point.

Again, what do you mean by 'consistent'? If it gives the same reading under the same conditions it is consistent. If you change the conditions and it gives a different reading them maybe it is because the conditions have changed. Now, if your 'manual setting' is the same for both conditions and gives the same result, but the meter gives different readings then that is something to look at.
From your description in the OP it seems to me that you take a picture, look at the image and change settings manually. I use the meter as a start point and apply the compensation I think it needs, take a picture, look at the image and change settings with the compensation dial if I need to. Same difference but I have no expectations that the meter is perfect, just a starting point.


[/quote]
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Justinr

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Re: Why is auto exposure so useless?
« Reply #48 on: August 26, 2015, 08:31:07 am »

But AE is predictable enough that exposure compensation is a valuable tool. If exposure varies +-1 stop from the optimal one because AF is not perfect, and you know it will underexpose 1 or 2 stops on the average (light background, beach, snow), setting the compensation dial to +1 or +2 will bring the results back to normal. All there is to it.

That's just what I am saying, it is not predictable, if it was we wouldn't be having this conversation.
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Justinr

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Re: Why is auto exposure so useless?
« Reply #49 on: August 26, 2015, 08:32:30 am »

I still do not recognise these 'marketing ploys' you talk about. Where do the manufacturers overplay the internal metering capability?  Can you point me to a website or catalogue?

Again, what do you mean by 'consistent'? If it gives the same reading under the same conditions it is consistent. If you change the conditions and it gives a different reading them maybe it is because the conditions have changed. Now, if your 'manual setting' is the same for both conditions and gives the same result, but the meter gives different readings then that is something to look at.
From your description in the OP it seems to me that you take a picture, look at the image and change settings manually. I use the meter as a start point and apply the compensation I think it needs, take a picture, look at the image and change settings with the compensation dial if I need to. Same difference but I have no expectations that the meter is perfect, just a starting point.




Exactly the problem.

It is not predictable.
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Petrus

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Re: Why is auto exposure so useless?
« Reply #50 on: August 26, 2015, 08:35:34 am »

That's just what I am saying, it is not predictable, if it was we wouldn't be having this conversation.

If it was not predictable and reasonably consistent, we would not be having this conversation, as I would not be making a decent living photographing most everything with AE and would not be sitting at my office at the publishing company typing this.
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Justinr

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Re: Why is auto exposure so useless?
« Reply #51 on: August 26, 2015, 08:42:01 am »

If it was not predictable and reasonably consistent, we would not be having this conversation, as I would not be making a decent living photographing most everything with AE and would not be sitting at my office at the publishing company typing this.

Good to hear, but there are others who may well work under different circumstances and for whom AE is not reliable enough.
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hjulenissen

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Re: Why is auto exposure so useless?
« Reply #52 on: August 26, 2015, 08:42:17 am »

If an "ISOless" camera AE attempted to ETTR, it would be "consistent" (and also "optimal" in some significant ways). It would probably not look "pretty" as interpreted in current raw developers.

That could perhaps be improved by the camera (meter) tagging the ETTR-exposed raw file with a scalar suggesting to the raw developer how bright the file should be rendered. The user should (of course) be free to alter that value or to default to some other value.

I think it makes sense for the photographer to concentrate on recording those parts of the scene that she cares about accurately in the field, then decide on rendering brightness at a later stage (possibly leaving it to automatic tools).

-k
« Last Edit: August 26, 2015, 08:44:28 am by hjulenissen »
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spidermike

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Re: Why is auto exposure so useless?
« Reply #53 on: August 26, 2015, 09:15:16 am »

Exactly the problem.

It is not predictable.

Odd. If I set my camera on a tripod and set an aperture under Av program and change the aperture, or go to Tv or go to manual and tweak until the compensation meter reads zero they all give the same readings. For every camera I have had. Whether it is the exposure I want is a different matter.
If I swing the camera to give a different balance of (for example) land and sky the meter reading changes which is exactly what I would expect.

You seem very reluctant to explain what you mean by consistency
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Justinr

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Re: Why is auto exposure so useless?
« Reply #54 on: August 26, 2015, 09:29:25 am »

Odd. If I set my camera on a tripod and set an aperture under Av program and change the aperture, or go to Tv or go to manual and tweak until the compensation meter reads zero they all give the same readings. For every camera I have had. Whether it is the exposure I want is a different matter.
If I swing the camera to give a different balance of (for example) land and sky the meter reading changes which is exactly what I would expect.

You seem very reluctant to explain what you mean by consistency

I'm sure you do, but as I have explained several times in this thread that for much of what I do I don't have time to mess about with such niceties as tripods.

If you fail to understand what is meant by consistency in exposure then I do begin to wonder what benefit you may gain from being involved in this thread.

Now put the text book down and back away slowly.
« Last Edit: August 26, 2015, 09:31:18 am by Justinr »
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Justinr

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Re: Why is auto exposure so useless?
« Reply #55 on: August 26, 2015, 09:52:44 am »

Every auto exposure system I've ever used has been utterly consistent but it is dependent on the being behind the camera pointing it at a suitable value.

Alas, not every subject has a grey card attached to it.
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Slobodan Blagojevic

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Re: Why is auto exposure so useless?
« Reply #56 on: August 26, 2015, 10:10:22 am »

Alas, not every subject has a grey card attached to it.

Yes, but every camera has a gray matter attached behind it ;)

Justinr

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Re: Why is auto exposure so useless?
« Reply #57 on: August 26, 2015, 10:36:50 am »

Yes, but every camera has a gray matter attached behind it ;)


Apparently not it seems.  ;D It's probably best to recap at this point.

I was covering an event for a couple of magazines back in July where there were numerous tractors and forage harvesters strutting their stuff. Also present were two colleagues working for other publications. We got talking to each other and we all despaired of the fact that AE was pretty blo*dy useless in our line of work as it was likely to deliver less than optimal results, quite a bit less on frequent occasions. It was not always wrong but certainly not consistent enough to trust.

The work entailed taking pictures of machines as they worked the harvesters and so our positions in relation to them changed constantly, if only to avoid having our legs chewed off!

Personally I have been taking pictures professionally for over 12 years with a variety of cameras and formats and I know the other two as  competent photographers. Whatever tricks and settings I tried on the day the camera would deliver a variety of exposures, some of which were fine, some of which would be acceptable after adjustment but many were instantly deleted mainly because of gross under exposure.

If it were just me then perhaps we could settle on my stupidity but my experience was mirrored by two others who's work I respect, so it's either us poor lads in the field not having a clue or posters on here lacking in grey matter.

Take your pick!
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Justinr

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Re: Why is auto exposure so useless?
« Reply #58 on: August 26, 2015, 10:59:03 am »

Done.

Jolly good, and I trust that some other posters on here are not too offended.
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Colorado David

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Re: Why is auto exposure so useless?
« Reply #59 on: August 26, 2015, 11:27:32 am »

When I've been faced with similar circumstances, I've studied my subject to find a spot that nearly approximates 18% grey, spot metered it, and reframed for the shot.  Shoot only raw.  I have never submitted images to anyone that I have not processed to my satisfaction . . . except once many years ago.  I had a client approach me with a job for his website.  He had a limited budget and said his web design guy could process the images if only I could shoot them for what he could pay.  That was a learning experience I will never repeat.  I don't think there's a viable shortcut for processing.
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