topic Re: Auto setting in EOS DSLR & Mirrorless Cameras

EOS 90D Auto vs Manual Exposure

Ramsden — Tue, 22 Apr 2025 13:16:33 GMT

Hi Folks

I've been quiet for a while - working with my EOS 90D as a keen learner. A month ago I was in London at St Pancras Railway Station, indulging in one of my favourite topics. At the time, I was perseveering with M and Raw - then this other photographer approached me for a chat. Cut a long story short, he takes up to 600 photos on his days out and just clicks away, then edits back home. He said I shouldnt be fiddling around with M on days like this - its ok for the studio.

He gave me his card and he has a professional website!

I like trying to work out compositions with M - and feel Auto is a cop out - but I could see his point as we spent an hour together and he was everywhere, clicking away while I worked out settings. ( I'm still learning, and its fun)

Ramsden

Re: Auto setting

stevet1 — Sun, 20 Apr 2025 12:43:37 GMT

Ramsden,

Yeah, but of those 600 photos, how many does he actually keep?

Plus, he has to take the time to go through all those 600 to decide which ones he want to keep.

You said that taking the time to work out the setting was fun. That's all that really matters, right?

Perhaps you could meet in the middle and try a semi-auto mode like Aperture Priority or Shutter Priority for a while, where you only pick one setting, and the camera takes care of the rest.

Steve Thomas

Re: Auto setting

Waddizzle — Sun, 20 Apr 2025 13:09:03 GMT

Welcome to the Community. If you have any specific questions unrelated to this topic, then start a new thread to ask about new and different topics.

I would hazard a guess that your acquaintance was shooting in M mode with ISO Auto enabled. I don’t follow the comment about shooting in a studio. He could have been alluding to using lighting equipment like strobes.

Many shooters have found a comfort zone shooting in M mode with ISO Auto enabled. I am one of them. But I also tend to keep -1/3 Ev of exposure compensation dialed in. I use Evaluative Metering most often and then compensathtion seems to protect the highlights from ever getting blown out.

Many purists don’t like the idea of setting ISO to Auto when you are M mode. They argue that you are not really in Manual mode unless you set ISO yourself, and they would be correct. You’re allowing the camera to set the ISO for you.

But ISO isn’t exactly an exposure setting. Exposure is set by shutter speed and aperture. Film cameras did not have an ISO setting. You could only control shutter speed and aperture. You changed the sensitivity of the camera to light by changing the film in the camera.

ISO is just an electronic substitute for the different slim speeds that you could buy when people were shooting with film. Light meters do not have an ISO setting. They are designed to report exposure settings when used with 100 ASA film, which is the sensitivity that the digital setting of ISO 100 tries to simulate.

The Exposure Triangle has three legs; shutter speed, aperture setting, and a film speed. For digital cameras the triangle is shutter, aperture, and ISO. The camera is able to control all legs of the exposure triangle at once, any two legs, or any single leg.

Any single leg, excerpt for ISO on older digital cameras. You could enable ISO Auto in M mode, but the older cameras did not allow you set AEC. Today, most digital cameras allow you to turn over control of ISO to the camera, and the camera is able to adjust AEC by varying the ISO.

If you set the camera to Tv mode and manually dial in ISO 100. The camera will control Av automatically, and use AV for AEC. Similarly, when you the camera to Av mode and manually dial in ISO 100. The camera will control Tv and use Tv for AEC. Tv mode allows you to define a fixed shutter speed. Av mode allows you to define a fixed aperture setting.

I like to think of shooting in M mode with ISO Auto as Ev mode. I am defining a constant exposure, which I can adjust up or down by setting an Automatic Exposuree Compensation, AEC, value. The M setting on the mode dial allows for two very different shooting modes, but some users don’t see it that way.

Canon introduced Fv mode, which seems to address this issue. You can set any leg of the Exposure Triangle to a constant setting or an Automatic setting determined by the camera. I am not a fan of this mode, as useful as it is. The muscle memory in my fingers is too accustomed to M mode and using the [Set] button to dial in AEC.

Have fun with your camera!

Re: Auto setting

justadude — Sun, 20 Apr 2025 14:17:16 GMT

Did he say "why" you should not be fiddling around with manual mode? Personally I would never tell another photographer anything like this unless they asked... and then I would only suggest it.

There are no "wrong" modes, even if you use full auto everything. Personally, I use manual roughly half of the time, which goes back to the 1970's and 80's when every camera I owned was full manual. But it's only under certain conditions. If I am wandering around taking random photo like in the scenario you described, depending on the mood I was shooting for I might want manual, but if it was a bunch of quick snaps here and there I'll use Aperture priority mode, ISO 100. I find this nice not to have to think if I'm walking downtown through an alleyway and shoot an old door where the light is strong, then turn around and shoot a shadowy building. The reason I use this mode? I spend more time concentrating on my composition than playing with camera settings, and end up with better subject matter in the end... and I know the depth of field is set to what I want for the looks I'm after.

If I'm shooting a hired sports event, then it's Shutter priority, ISO 100. Why? Because again, I spend time concentrating on the composition and the athletes... and I know the shutter is set fast enough to freeze action.

If I'm shooting landscape work, or nighttime work, or things like the Northern Lights, then it's full manual mode, always. Same if I'm shooting infrared photography simply because unlike visible light, infrared light is so difficult to read.

600 shots during a photowalk? I can see that for event photography, (and often way more), but for walking around... my opinion is this guy needs to practice composition and try to get things in a single shot instead of rapid fire then pick the best of each composition. I know a lot of other pros, (yes, a lot of us with web sites) and can't think of any that shoot like this. Get it right in camera is the best mentality.

Re: Auto setting

Ramsden — Sun, 20 Apr 2025 14:19:17 GMT

Hi Steve

Yes, he did say a lot get binned. You’re just confirming my thoughts. Thanks - I’ll stick to my learning process - it’s good for the brain!

Ramsden

Re: Auto setting

Ramsden — Sun, 20 Apr 2025 14:21:48 GMT

Thanks for your detailed reply. It’s really useful because some days I feel swamped with what this camera is capable of, but I have to admit to often leaving ISO on Auto

Ramsden

Re: Auto setting

Ramsden — Sun, 20 Apr 2025 14:32:31 GMT

Hi Gary

That’s really good advice. I am quite pragmatic at heart and your range of options makes sense. I totally agree about the composition, but need to keep reminding myself. I’ve got a holiday in the Scottish Highlands coming up soon and this will be a great opportunity in changing weather and fantastic scenery in the mountains and the seascape. Lots of things to practice on.

Thanks

Ramsden

Re: Auto setting

zakslm — Sun, 20 Apr 2025 19:15:03 GMT

I agree with Waddizzle.

I also use the 90D, shoot in M and use Auto ISO the majority of the time. There are situations where I switch to AV, TV or P depending on what I think would be best and of course. There are also times when I set a fixed ISO. I'm still learning (and have been since the '70's) and trial and error is a big part of that learning.

I also subscribe to the theory that the "camera is smarter than I am" and sometimes have to force myself to trust letting the camera set one or more of setting of the exposure triangle for me.

Re: Auto setting

Waddizzle — Sun, 20 Apr 2025 20:27:05 GMT

“ I also subscribe to the theory that the "camera is smarter than I am" and sometimes have to force myself to trust letting the camera set one or more of setting of the exposure triangle for me. “

Allow the camera to control only one leg, or no legs, of the Exposure Triangel.

I do not advise allowing the camera to control more than one leg of the exposure triangle. While the camera is pretty good at coming with a balanced exposure, sometimes it may not be what you need for a given shot. It may reduce Tv too low, or it could adjust Av and ISO too high.

I shoot most of my handheld shots Manual with ISO Auto. I can tweak the ISO +/- up to three stops. I normally use Evaluative Metering Mode. In Evaluative, the camera will bias the exposure to the location of your active and locked AF point.

This can cause undesireable, wide swings in the exposure under some shooting conditions, such as indoors with constant lighting. If I lock focus on a player with a dark jersey, the camera raises the exposure. If I lock focus on a player with a white jersey then the camera drops the exposure. So, I will set the ISO manually.

If I allow the camera to adjust more than one leg, instead, then I can get undesireable results in more ways than one. K.i.S.S. I try not to let the camera do too much for me. It usually does not know what I am thinking.

Re: Auto setting

jrhoffman75 — Sun, 20 Apr 2025 20:27:34 GMT

There are times for special settings (Av when you want a particular f/stop for depth of field, Tv when you want a particular shutter speed to stop action, M when you want to combine them both) but Canon has perfecting its shooting algorithms since about 1983 when the Program AE was released. For an awful lot of shooting (and I would label the Scottish Highlands in that category) P mode will be fine. I was there in 2023. Landscapes and castles; fantastic subjects.

Re: EOS 90D Auto vs Manual Exposure

ebiggs1 — Wed, 23 Apr 2025 15:26:46 GMT

"There are no "wrong" modes, even if you use full auto everything. "

This is a fact, jack, or Gary in this case. I am not against anyone using M mode but there is a reason it is last on the dial. It's a last resort when nothing else will work. Av and Tv can do virtually everything you need and sometimes the camera is smarter than you think.

Re: EOS 90D Auto vs Manual Exposure

ebiggs1 — Wed, 23 Apr 2025 15:33:01 GMT

"Yeah, but of those 600 photos, how many does he actually keep? Plus, he has to take the time to go through all those 600 to decide which ones he want to keep."

I maybe don't take 600 photos every time I go out but I do take a lot sometimes many hundred(s). Lightroom and/or Bridge make short work of sorting and yes a most go to the "bin". But digital is a totally different mind set so why not take many or hundreds? I am going to the Lawrence Wetlands this weekend if it doesn't rain so I expect I will have "hundreds" perhaps many hundreds to go through Monday.

I doubt any will be M mode.

Re: Auto setting

normadel — Thu, 24 Apr 2025 03:54:35 GMT

You say

"But ISO isn’t exactly an exposure setting. Exposure is set by shutter speed and aperture. Film cameras did not have an ISO setting. You could only control shutter speed and aperture. You changed the sensitivity of the camera to light by changing the film in the camera.

What are you talking about? Of course film cameras have ISO settings (unless they get the ISO speed from the film cannister DX codes), and of course light meters do. How else could they determine proper exposure settings? I don't believe you actually said this.

Re: EOS 90D Auto vs Manual Exposure

Ramsden — Thu, 24 Apr 2025 08:10:00 GMT

Thanks for all your fascinating replies to my question ( which I thought was quite simple). I think you’ve reinforced my realisation that the EOS90D has a lot to offer, and I’ll not be as wedded to M in the future. But I’m a control freak, so need to feel that I can work that magical exposure triangle. I’ve been re-reading Bryan Peterson’s book Understanding Composition - which I really like - and go back to one of his key points ‘get it done in the camera’ - which strikes a chord with me. Also his point about using our eyes and brains to see the arrangement appeals to me. I should add that I learnt photography with my late father and still have is old kit including an exposure meter!

Re: Auto setting

Waddizzle — Thu, 24 Apr 2025 11:37:39 GMT

“ What are you talking about? Of course film cameras have ISO settings (unless they get the ISO speed from the film cannister DX codes), and of course light meters do. How else could they determine proper exposure settings? I don't believe you actually said this. “

Believe it. A light meter will only provide Tv and Av values. Some film cameras used ASA values to compensate the metering system. But the exposure settings on film only allowed you to control Tv and Av.

This analog meter is capable of recalculating the values using the exposure triangle by turning a dial called ISO.

This more advanced digital only provides Tv and Av values at ISO 100. It’s left up to the user to determine Tv and Av values at other ISO values.

Re: Auto setting

normadel — Thu, 24 Apr 2025 15:48:48 GMT

You are contradicting yourself. The first light meter you show DOES HAVE an ISO setting dial. You said it yourself. How do you think it's giving Tv/Av results for varying light levels?

A light meter or camera that gives Tv/Av for different available light levels must have an ISO setting. If, as you say, a meter can ONLY give exposure values based on ISO 100, leaving it up to you to figure values for different ISO, makes no sense.

Re: EOS 90D Auto vs Manual Exposure

LeeP — Thu, 24 Apr 2025 20:22:43 GMT

AMEN and well said.

The mantra of "I must shoot in M" is such a photographic cliche. I learned this eons ago via a Pentax ME (aperture-preferred auto only) and was "limited" to +/- 2 stops of exposure compensation. The metering was so precise that manual was not needed. I shoot a lot of manual with my Nikon F, FM, Pentax MX, and K1000 but not once ever since hopping to Canon in 1998.

Re: Auto setting

LeeP — Thu, 24 Apr 2025 21:00:27 GMT

1,000% agree

I tend to find that the older the person more more they trot out the "exposure triangle" and "M is mandatory" mantras and chant them.

I'm 64 and when I got my degree in photography, exposure triangle and the need for manual were necessary tools, or so I thought.

The first camera to soften my stance was a Pentax ME (aperture-preferred auto with +/-2 stops of correction) that I bought for its tiny size as a go-everywhere camera. The metering accuracy was incredible to the point that I stopped carrying a manual body all the time.

I jumped from manual-focus cameras to Canon via an Elan IIe and 7e and I was astounded by the accuracy of P. I now shoot with an R100 and R8 when I'm in the Canon "world" and I am amazed by how capable both are when I let them do everything.
I do a lot of work in P and only do Av or Tv on occasion, but almost never M because it just isn't needed.

Re: Auto setting

Ramsden — Fri, 25 Apr 2025 07:35:35 GMT

Hi Lee

Thanks for your comments. You are the second person to mention P - which I'm almost embarrased to admit - I have rarely used. I'm an old guy and fell for the M Raw mantra 18 months ago. I also have to admit making some terrible photos in this setting. This post has really opened my eyes and made me reassess my journey with my EOS 90D.

My task today is to take my camera for a walk in P.

Any tips for using P most welcome - like should I stay in Raw?

Thanks

Ramsden

Re: Auto setting

Waddizzle — Fri, 25 Apr 2025 10:45:45 GMT

“ If, as you say, a meter can ONLY give exposure values based on ISO 100, leaving it up to you to figure values for different ISO, makes no sense. “

I guess the light meter example makes no sense, either then. It only provides Tv and Av values based on ISO 100. It’s left up to the user to recalculate exposure (Av and Tv) for other film sensitivities.

Beliveve it. ISO isn’t really part of exposure. Your camera allows for mechanical control of just Tv and Av. These two parameters are all that control exposure.

The analog meter is capable of recalculating Av and Tv for you. But the only exposure information the light meters provide is Av and Tv.