EOS Rebel T8i image differences in Av vs. Manual

[stevet1]

I'll state right up front that I am puzzled.

I have noticed this before, but I don't understand why there is a difference.

If I take a shot in Aperture Priority Mode, and take the exact same picture in Manual Mode with the exact same settings, the Av shot looks more washed out or lighter, and the Manual shot looks fuller.

Here's an example. I drew a dark diagonal line at the bottom of the Manual exposure to differentiate between the two. Look at the brown field in the upper right quadrant.

The settings are irrelevant, but they were both shot at 1/100, f/7.1 and ISO at 100. They were taken through a window. so you have to take that into account, but both were. I've noticed the difference before, even outside in the open air.

Why is there a difference?

It makes me want to stick with Manual.

Steve Thomas

[stevet1]

Peter,

Thanks. I'll have to look at the Exif data to see if what comes out of my camera is what I put in. There might be some slight variations. I'll have to take a couple of SOOC jpgs and look at the results.

Steve Thomas

[wq9nsc]

I always shoot in manual with auto ISO but I wonder whether the auto mode always uses 1/2 or 1/3 stop increments regardless of where you have your preference set for manual choice.  This could cause a slight difference if it is adjusting one of its automatic parameters in a finer or coarser step than you are choosing.  The EXIF data should show the exact parameters used at capture for aperture, shutter speed, and ISO.

Rodger

[stevet1]

Roger,

Thanks. I'm definitely going to examine to see if what comes out is the same as what I put in.

I think I'll also toy a little bit with a 1/3 stop of negative exposure compensation on my Av shots.

Steve Thomas

[wq9nsc]

Steve,

I look forward to your solution of this interesting mystery!  🙂

Rodger

[stevet1]

Here's another example:

img 1509 is on the left. Taken in Av at 1/20th. img 1510 is on the right. Taken in Manual. Also at 1/20th. I drew a circle on the Manual shot. Exif data reports 1/20th in both shots. Look at the tree on the left side, and the color of the jeep.

The Manual shot just looks a little fuller to me. The file size is 4/10th of a Mb larger than the Av shot.. Hmmm.

Steve Thomas

File Name IMG_1509.JPG File Size 3.0MB Camera Model Canon EOS Rebel T8i Firmware Firmware Version 1.0.0 Shooting Date/Time 11/28/2024 9:43:33 AM Owner's Name Shooting Mode Aperture-Priority AE Tv(Shutter Speed) 1/20 Av(Aperture Value) 7.1 Metering Mode Spot Metering Exposure Compensation 0 ISO Speed 100 Auto ISO Speed OFF Lens EF-S18-135mm f/3.5-5.6 IS USM Focal Length 19.0mm Image Size 5776x3836 Crop/aspect ratio 3:2 Image Quality Fine Flash Off FE lock OFF White Balance Mode Color Temperature (5300K) AF Mode AI Servo AF AF area select mode Manual selection Picture Style Standard Sharpness:Strength 4 Sharpness:Fineness 2 Sharpness:Threshold 4 Contrast 0 Saturation 0 Color tone 0 Color Space sRGB Long exposure noise reduction Auto High ISO speed noise reduction Standard Highlight tone priority Disable Auto Lighting Optimizer Disable Peripheral illumination correction Enable Chromatic aberration correction Enable Distortion correction Disable Diffraction correction Enable Digital Lens Optimizer Enable(Correction data not available) Dust Delete Data No Drive Mode Single shooting Live View Shooting OFF Camera Body No. 082031000350 Comment

File Name IMG_1510.JPG File Size 3.4MB Camera Model Canon EOS Rebel T8i Firmware Firmware Version 1.0.0 Shooting Date/Time 11/28/2024 9:44:24 AM Owner's Name Shooting Mode Manual Exposure Tv(Shutter Speed) 1/20 Av(Aperture Value) 7.1 Metering Mode Spot Metering Exposure Compensation 0 ISO Speed 100 Auto ISO Speed OFF Lens EF-S18-135mm f/3.5-5.6 IS USM Focal Length 19.0mm Image Size 5842x3743 Crop/aspect ratio 3:2 Image Quality Fine Flash Off FE lock OFF White Balance Mode Color Temperature (5300K) AF Mode AI Servo AF AF area select mode Manual selection Picture Style Standard Sharpness:Strength 4 Sharpness:Fineness 2 Sharpness:Threshold 4 Contrast 0 Saturation 0 Color tone 0 Color Space sRGB Long exposure noise reduction Auto High ISO speed noise reduction Standard Highlight tone priority Disable Auto Lighting Optimizer Disable Peripheral illumination correction Enable Chromatic aberration correction Enable Distortion correction Disable Diffraction correction Enable Digital Lens Optimizer Enable(Correction data not available) Dust Delete Data No Drive Mode Single shooting Live View Shooting OFF Camera Body No. 082031000350 Comment

[jrhoffman75]

Somewhere in the process image aspect ratio is being modified. 

 

[stevet1]

John,

I cropped both freehand to remove an offending window sill on the left. I may have cropped the Manual shot a little more than the Av.

Steve

[jrhoffman75]

---

@stevet1 wrote:

I'll state right up front that I am puzzled.

I have noticed this before, but I don't understand why there is a difference.

If I take a shot in Aperture Priority Mode, and take the exact same picture in Manual Mode with the exact same settings, the Av shot looks more washed out or lighter, and the Manual shot looks fuller.

Here's an example. I drew a dark diagonal line at the bottom of the Manual exposure to differentiate between the two. Look at the brown field in the upper right quadrant.

The settings are irrelevant, but they were both shot at 1/100, f/7.1 and ISO at 100. They were taken through a window. so you have to take that into account, but both were. I've noticed the difference before, even outside in the open air.

Why is there a difference?

It makes me want to stick with Manual.

Steve Thomas

---

Putting on my engineer hat, here is a possible explanation:

1. Nature doesn't work in increments of light; it is continuous.

2. all devices have acceptable levels of accuracy. 

3. Deleted.

4. The camera calculates exposure with the aperture wide open and "does the math" to select the appropriate settings.

5. The camera allows and reports settings in set increments, generally 1/3 stops. 

6. In Av mode you are setting aperture and ISO. The camera needs to determine the appropriate shutter speed using the internal computer. Then it reports the closest programed value within the accuracy of the algorithm. 

7. When you set Manual mode you are telling the camera to use set values of shutter speed, aperture and ISO. So when the internal computer analyzes the scene and tells you the exposure is correct by centering the needle on the meter there is an allowable tolerance. Since the hash marks are 1/3 stops the allowable tolerance would be maybe +/- 1/4 stop.

8. Perhaps that is why the images look slightly different.

In DPP I cropped the image you posted to create a left and right side image.

In Lightroom I increased the exposure of the right side image by .07 stops.

This is adjusted right compared to left.

This is right before/after exposure adjustment.

[p4pictures]

Hi John,

The anti flicker control on a DSLR works differently to a modern mirrorless camera. On the DSLR, the camera frame rate is adjusted in continuous shooting so that if flicker is detected the frames should be in-sync with the same part of the cycle of the lights to ensure consistent brightness and colour. Anti flicker is targeted to cope with lights powered from AC, so 50Hz 60Hz frequency.

Some of the newer mirrorless cameras have an additional High Speed Anti Flicker capability. This is designed to deal with the faster frequency that is sometimes used for LED lighting. With this function activated the camera fractionally adjusts the shutter speed. The EOS Rebel T8i does not have this capability.