Beginner EOS 250D - Auto ISO and Exposure

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HantsPete

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Pedro
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As a relative beginner I've been using my trusty 2000D for a few years. But I liked the idea of a Flip LCD screen plus other features that the 250D has, so I decided to buy one.

Although I'm generally happy with the picture quality of the 250D, I've noticed a key difference compared to the 2000D, namely Auto ISO.
I'm finding that the 250D tends to use much higher Auto ISO settings than my 2000D when taking an identical picture. More noticeable in close-up / low light conditions.
There may also be a difference in the evaluative metering between the 2000D and 250D - again only noticeable indoors.

For example, if I take a picture of a focus test chart at a distance of 2m in Av mode, the 250D tends to look washed out.

With general outdoor photography the 250D nails the exposure perfectly.

The 250D uses a more advanced processor than the 2000D. I am tending to think that the processor is designed to bump up the iso in the semi manual modes (Av and Tv).

Just wondering if anyone has experienced different Auto ISO or exposure quirks with their different cameras. Thanks for any comments or advice.
 
No two cameras will have the same algorithm (mathematical formula) to balance the exposure. Because the engineers will tweak the settings to take advantage of the sensor (or hide its shortcomings)

It’s one of those areas that I never really think about - I’ve said it before but getting hung up on the minutiae of exposure will get on the way of creating good pictures (cos the picture is the reason you picked up a camera).
Just to add - keep at it; and share some of your shots.

A question that I’d like you to acknowledge as I struggle to see how this works:
Why buy the latest entry level camera when for the same money you could have bought something much better but older?
 
Two more things:

Yoy should be able to set the range of allowable ISO that AutoISO can chose similar to this

images.jpeg

There's a similar option on many/most/all Canon bodies to set the type of picture (Landscape, Portrait,Wildlife,...) they dial in different parameters for saturation, contrast etc. in the resulting JPG - you may have a personal preference (I know I do - almost everything is taken in Landscape)
 
Check if highlight tone priority is turned on in one of the cameras, that can make iamges look different and affect exposure slightly.
 
Auto ISO, over the years, has sometimes undergone improvements in newer models as they are released (Auto ISO first 2007 in Canon). The 250D is a relative latecomer to dSLR history, introduced in 2019, so its technology has had benefit of some dozen years of refinement. In comparing Auto ISO results between cameras, one needs to ensure that camera settings in the menu are set up as similar as possible before jumping to any conclusion in the observations.

My longtime complaint about Auto ISO was that it would choose a combination of ISO+shutterspeed+fstop that I myself would not choose, because the ISO value chosen by the camera was much higher that I would be inclined to choose -- even while ensuring that the shutter speed avoided motion blur or shakey-photographer caused blur. Higher ISO means more circuit noise amplification and reduction in the Dynamic Range capability of the camera.

For example of Auto ISO 'illogic', I posted this in response to a posted photo shot with Auto ISO:
"But the camera selection of 1/1250 • f/5.6 • ISO 32000 is why I never use Auto ISO...I would have selected 1/320 and ISO 8000, for less noise in the picture (not that I even see noise in what you posted) and slower shutter probably would have reduced the issue with banding/flicker.... Even now, auto ISO selects stupid values when a different ISO value might make more sense,"​
​
In 2017, mnother member posted three photos taken under the constant light of the interior of a gymnasium...Auto ISO chose to use three different values of ISO for the shots...6400, 12800, 25600. Why did it use the more noise-prone 25600 when 6400 had worked under the same light. Due to these and other foibles I continue to not even try to use Auto ISO.
 
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You can set a range for the AutoISO - varies where exactly in the menus it is but it will be there - so if you want it to be 100-1600 ISO as the range, you can.
 
The earliest cameras I had w auto ISO were terrible to the point I never used it and would never recommend it. Then I got the 6d, which along with the R6 appear to do just about what I would - sticking close to my chosen minimum shutter speed.
 
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