topic Re: How do you approach the exposure triangle? in EOS DSLR & Mirrorless Cameras

How do you approach the exposure triangle?

Ramsden — Sat, 18 Oct 2025 12:32:18 GMT

Apologies for posting something that has probably done to death. But...

With my EOS90D I try to use M most of the time and am still learning. So my question is more to draw on your vast experience.

When I start to compose a shot, I tend to set go to depth of field first, partly because it sets the scene. Typical scenario: Railway viaduct with a train crossing. 70-300 lens on a tripod. I would probably take tbe soft option of f/11 or f/16 depending on how close I can get.

In this scenario I would probably go to shutter speed next - then ISO (not using Auto)

So my question is asking if you have procedures and processes when using the exposure triangle, that might be classed as best practice. What do you intuitively turn to first?

Thanks

Ramsden

Re: Exposure Triangle

Anonymous — Sat, 18 Oct 2025 09:00:44 GMT

Depends on what the subject is, for some shutterspeed is most important, others the aperture. I do use M with auto-ISO(with exp. comp. if necessary). With modern sensors and NR software ISO is no longer that important.

So procedure is first determine what is important for the subject, set Av and Tv accordingly and see how ISO turns out.

Re: Exposure Triangle

Ramsden — Sat, 18 Oct 2025 12:30:39 GMT

Thanks.

What I'm trying to learn and get better at, is doing all the three functions in M ie manualy. So when I use Av for example, the camera is taking 1 of the 3 decisions for me. If I use Av and ISO auto, the camera is doing 2 of the 3.

I'm just trying to get more control and flexibility, instead of relying on my camera's computer.

Cheers

Ramsden

Re: How do you approach the exposure triangle?

jrhoffman75 — Sat, 18 Oct 2025 12:43:02 GMT

@Ramsden wrote:

Apologies for posting something that has probably done to death. But...

With my EOS90D I try to use M most of the time and am still learning. So my question is more to draw on your vast experience.

When I start to compose a shot, I tend to set go to depth of field first, partly because it sets the scene. Typical scenario: Railway viaduct with a train crossing. 70-300 lens on a tripod. I would probably take tbe soft option of f/11 or f/16 depending on how close I can get.

In this scenario I would probably go to shutter speed next - then ISO (not using Auto)

So my question is asking if you have procedures and processes when using the exposure triangle, that might be classed as best practice. What do you intuitively turn to first?

Thanks

Ramsden

If you want to select a specific aperture and shutter speed then there are only two things you can vary to get a correct exposure - the amount of light and the camera ISO.

If you can't change the time of day, add flash or supplemental lighting then adjusting ISO is your only option.There is no best practice or special procedure.

Re: How do you approach the exposure triangle?

johnrmoyer — Sat, 18 Oct 2025 12:46:33 GMT

I like to make use of the software built into the camera. These are my preferences and may not match yours, but I hope some of it might be helpful anyway.

When depth of field is important, I use AV.

When freezing motion is important, I use Tv.

On my camera, I can use Fv and set the ISO to a fixed value while leaving either Tv or Av to auto, but I do not remember whether your camera has this mode. You might be able to get close to this if you are able to limit the range of values for ISO when using Tv or Av mode or M mode with auto ISO. I only use M mode when I cannot get the auto modes to do what I want.

Other considerations:

Small aperture diffraction blur depends upon F number and distance between photo sites on the sensor chip. For your camera, I expect there would be noticeable small aperture diffraction blur at F/11 and much at F/16. A Richardson/Lucy deconvolution can remove small aperture diffraction blur if some assumptions are met. Canon DPP software does this in "digital lens optimizer" and Rawtherapee free software does this in "capture sharpening". The radius should be set according to F number and spacing of photo sites on the sensor chip. A larger radius will be needed for F/16 than for F/11 and it is likely there is no small aperture diffraction blur for your camera at F/5.6.

Photons arrive at the sensor chip in a Poisson distribution. If there are enough photons, the count will match the expected color and brightness. For high ISO, there are fewer photons to count and a higher probability that one will look at the pixel brightness and color and call it noise. Some noise may give the illusion of a sharper image and be pleasing, but too much noise will result in loss of detail. For a high resolution crop sensor such as yours, the noise will appear at a lower ISO than when using a low resolution full frame camera with the same chip technology because the lower resolution or larger sensor will have larger photo sites on the sensor chip that can collect more photons in the same time improving the probability of getting the color or brightness that is expected.

Noise reduction algorithms usually trade detail for lack of noise. Gimp 3 free software has some very good noise reduction algorithms. After noise reduction, downscaling followed by unsharp mask can often restore the look of sharpness.

Re: How do you approach the exposure triangle?

Cyrilbrd — Sat, 18 Oct 2025 13:16:20 GMT

Hi,

Not a professional here, but I think some other readers might find your question relatable.
Here is a link (I am not affiliated with the site or author in any way) that briefly explains the three main concepts: how deep or shallow you want your depth of field to be, how much light you want to capture, and how sharp or blurred you want your picture to appear.

I trained during an era when film was everywhere, computers filled entire rooms and ran on magnetic tapes. Photography has evolved tremendously since then—both in capture and in post-processing—but thankfully, aperture, exposure, and shutter speed remain at the core.

My suggestion would be to try taking the same shot with different settings, then compare the results and decide which appeals to you most. Experimenting and saving images on an SD card is far quicker (and cheaper) than it was with multiple 35mm rolls of 24 exposures, where ISO was fixed.

At the end of the day, there’s no wrong way to capture light.

Re: How do you approach the exposure triangle?

Ramsden — Sat, 18 Oct 2025 14:59:31 GMT

Thanks Cyril

Great advice and I will start experimenting and taking notes. I looked at the link, and i think its one of the best I've read. The concept of a zero triangle/exposure is really helpful, and as I suspected there's no 'right or wrong way'.

The learning continues.

Thanks

Ramsden

Re: How do you approach the exposure triangle?

LeeP — Sat, 18 Oct 2025 15:09:12 GMT

I've taught photography A LOT over the years and exposure triangle is off the table for most of the time in the instruction process. I focus on composition vastly more than exposure triangle because if the composition isn't right, a perfect exposure won't save it. If the composition is right and the exposure is a little off, no one really cares. Exposure triangle is largely a film-era thing (I can see the pitchforks now), but with modern digital cameras, the exposure tends to be quite good and then Lightroom and Photoshop can do fixes.

To be blunt, I ignore ISO nearly 100% of the time. If I'm doing action, I go shutter preferred. If I want depth of field or bokeh I skew toward aperture, but rarely do I waste my time on manual.

In the film days, cameras had a much narrower window of opportunity and you were stuck with ISO for the most part, but even then basic exposure was sufficiently good that manual was only needed for the most tricky of lighting issues.

Re: How do you approach the exposure triangle?

Ramsden — Sat, 18 Oct 2025 15:20:03 GMT

Hi John,

Thanks for your detailed response and links to the apps etc. At the risk of sounding like a stick in the mud - as a 78yr old, I aim to keep my brain working, and the Ex Triangle is a great exercise for me!

When I'm out and about, say, in a railway situation, with alot going on I have switched to auto! My camera doesn't have the Fv mode, at least, I haven't seen it in 2yrs. I'll check out the apps.

Thanks

Ramsden

Re: How do you approach the exposure triangle?

Ramsden — Sat, 18 Oct 2025 15:27:03 GMT

Thanks John

I'll just keep practicing and 'learning" by trial and error. But I hope that if I'm more systematic and take notes I can build my own 'if ...then' scenarios with triangle formulae.

Ramsden

Re: How do you approach the exposure triangle?

Ramsden — Sat, 18 Oct 2025 15:34:54 GMT

Hi Lee

Thanks for your response. I grew up on film and my dad was semi- pro (hobbyist) and we used to develop our films in the basement, so I guess its in my DNA!

I've still got his camera with a seperate exposure meter.

Re: How do you approach the exposure triangle?

LeeP — Sat, 18 Oct 2025 15:58:09 GMT

Great response. It was exceptionally detailed and well written.

The following is an opinion tangent and in no way intended as a contradiction, but maybe a more as a counterpoint,

I think many times photographers fixate on the fear of too much noise "...but too much noise will result in loss of detail..." thinking that a tack-sharp, crystal-clear image is the only goal.

I have two friends that toil for hours in Photoshop to create completely perfect pictures that are completely perfect but completely boring because they are completely flavorless.

I want flavor.

I love noise/grain.

I am a huge fan of IoNiZeR and I love their use of noise for creative effect.

Even in the film era, I was more interested in pushing the limits of what a film could do for the creative effect than to have "picture perfect" pictures, which bore me (yes my opinion). I actively courted grain (AKA noise).

And nowadays with AI sharpening and fixing everything to "picture-perfect perfection", I find myself angered by the relentless pursuit of perfection as if that is what is expected.

The relentless pursuit of perfection can be boring (at least to me) because it removes room for creativity, individuality, and motivation to look at a photograph a second time.

Re: How do you approach the exposure triangle?

Ramsden — Sat, 18 Oct 2025 16:14:29 GMT

Hi Lee

I think we are on the "same page".

I have neither time or inclination to tart up my photographs. I used to teach 'quality management' a few yrs back. 'Get it right first time' was a well worn mantra at that time. Thats why I want to understand this basic process, and put it into practice.

Ramsden

Re: How do you approach the exposure triangle?

LeeP — Sat, 18 Oct 2025 19:11:00 GMT

Fair enough. I do a lot of street photography so imperfection is part of the creativity. I also live for bizarre films and outdated films because I want that challenge.

My mirrorless Canons are astoundingly good on program for nailing the exposure without excessive noise, so I only deviate when something's up and then exposure compensation is ridiculously easy and intuitive on them.

I'm currently also shooting with a Pentax MEF that has the ISO dial locked at 25, so I'm shooting ISO 100 film with the exposure compensation at 1/4X. I also have film in a K2 that is locked at ISO 400, but I can get 100-1600 by using the exposure compensation.

When I was in my degree program I had a Pentax ME and the professor said it wouldn't work because there was no way to set the aperture and shutter speed independently. I asked him to give me a combo. He did. I then set the aperture and used exposure compensation to get the desired shutter speed. He was partly annoyed, amused, and amazed because he hadn't thought past that mindset that manual was everything. Later he said that it was obvious my exposures were the way they were because I was using my version of manual. To which I replied that I was in automatic 100% of the time. I got an A in that course but showed up to the next one with a K1000. LOL

Re: How do you approach the exposure triangle?

Ramsden — Sat, 18 Oct 2025 20:29:37 GMT

Great story Lee.

Like the A!

Peeing off your Prof clearly paid off.

But i really like your overall strategy/philosophy , though I haven't got your ammount of equipment.

However, given the bad weather forecast here in the UK I may be drawn into some experimenting!

Cheers

Ramsden

Picture of my Dad in the Rainforest around 1942.

Not bad photo in the middle of a war, and i bet he used his exposure meter. Think he coloured this when he got home.