Canon 70D AF Microadjustments not static...why?

I have a 50mm f/1.8 IS STM lens with my 70D with a +10 AF Microadjustment (Adjust by Lens) configured for my camera.

I took several shots and when reviewing the EXIF on my images, all taken with the 50mm, some images show the adjustment of 10 and some images do not.

I have also noticed on my 55-250mm STM lens, that has an Adjust by Lens W:-2 T:+3 bouncing around from -2, nothing to 3, even on some images where focal length did not change!

My shots are in One Shot AF mode, no burst.

I was using a Yongnuo 560 II flash as well in case that matters.

I would just think, especially with a Prime Lens that the AF Micro adjustment would be consistently the same value on every shot!

Why does AF Microadjustment change, especially on a prime lens?

Unless it's an error in the recording of the value, I don't know. For the same focal length I agree that it should be the same value.
For zooms, if you have -2 at one end and +3 at the other, it's expected to interpolate between the two. So you should start with -2 at one end, and then gradually go to +3 as you zoom towards the other end.

I agree about zooms, especially when changing zoom, but when focal length remains constant or when using primes, I would think it would be static.

Hoping others see this and chime in.

Interesting find here...thanks to Google...

https://www.photo.net …sing-af-on-button.509568/

In manual mode:
Apparently, when using BBF, if I continuously hold the the BBF (using AF-ON), the AF Microadjustment is stored and shown in EXIF.
If I focus using BBF and release to recompose (or not even recompose, just releasing BBF) the AF Microadjustment is NOT stored and NOT shown in EXIF.

If I put the camera in full auto mode (green A+) , it is never stored.


From the read from the link above, it seems that person felt that while AF Microadjustment was NOT being recorded, it was still working. It seems that Canon will only write out the AF Microadjustment to EXIF if the focus button continues to be pressed when shutter is released or when not using BBF. All only in Manual mode.

interesting!

OK. That makes sense, in a way. If auto focus isn't active, there's no microadjustment active either.
It's like it doesn't store the AF point used if AF isn't active when the picture is taken.

Yes, to the camera it's like you used manual focus. This is also true of the show focus point on image playback. If you were pushing the focus button when you click the shutter it shows, if not it does not.

apersson850 wrote in post #18377328
OK. That makes sense, in a way. If auto focus isn't active, there's no microadjustment active either.
It's like it doesn't store the AF point used if AF isn't active when the picture is taken.

But I think from the findings of others is that the AF Microadjustment did take affect, its just NOT stored to EXIF when AF-ON has been released (as done when recomposing after focusing). I could be wrong from what I have read or misread, but I think it still works, just not recorded to EXIF.

No, I agree about that. I presume the microadjustment was used when focusing was done, but that's no longer active when the picture is taken. Hence the value isn't recorded. It's the same with the AF points. One or more was used to focus the image, but since it's not active when the picture is taken, it's not recorded in the image.