Review: Canon RF 100mm f/2.8L IS USM Macro

koenkooi

EOS 5D Mark IV
CR Pro
Feb 25, 2015
1,806
1,726
The lens definitely keeps making the same whirring sound when I go into menus. No discernible change (at least to my ears) when going in and out of menus.

It does stop making the sound when the camera goes to sleep, or when I switch it off.
If I recall correctly, there's a 30s or 60s time-out when using the menus. A better test is using the IS switch in the lens, that should disable both IS and IBIS.
 

PaulStoffregen

I'm New Here
Jul 21, 2021
11
4
Ok, here's the images from my attempt at a controlled focus shift test.

a1.jpg


a2.jpg


a3.jpg


a4.jpg


a5.jpg


a6.jpg


a7.jpg


Again, here's the subject. These 3 tiny parts are about 0.5mm tall, and each is on card stock holding it about 1mm different height.

fc1.jpg


Here is how I manually focused before taking these 7 shots.

fc2.jpg


fc3.jpg


The focus of the F16 & F22 pictures definitely isn't as good as the others, but I'm having a hard time guessing if the focus shifted or the whole images just isn't as sharp?

Any opinions? Is this focus shift?
 

PaulStoffregen

I'm New Here
Jul 21, 2021
11
4
A better test is using the IS switch in the lens, that should disable both IS and IBIS.

The whirring sound from the lens does change slightly when switch the stabilizer switch from ON to OFF. It's still going in the OFF position, but a slightly higher pitch. Difficult to describe the sound with words. Not sure if I have the right sort of gear to get a good recording of the sound.
 

Charlie_B

EOS M50
Oct 23, 2020
33
38
Ok, here's the images from my attempt at a controlled focus shift test.

View attachment 199105

View attachment 199106

View attachment 199107

View attachment 199108

View attachment 199109

View attachment 199110

View attachment 199111

Again, here's the subject. These 3 tiny parts are about 0.5mm tall, and each is on card stock holding it about 1mm different height.

View attachment 199112

Here is how I manually focused before taking these 7 shots.

View attachment 199113

View attachment 199114

The focus of the F16 & F22 pictures definitely isn't as good as the others, but I'm having a hard time guessing if the focus shifted or the whole images just isn't as sharp?

Any opinions? Is this focus shift?
Definitely rear focusing I'm afraid. The object on the left ( furthest away) is more in focus than the one on the right
 
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PaulStoffregen

I'm New Here
Jul 21, 2021
11
4
Not sure if it matters, but I had the SA ring in the middle position for all 7 shots. The lock switch was off.

IS was on. The focus range was set to 0.26m-0.5m, though I kept the camera in manual focus mode the whole time and focused just once before taking the 7 pictures.
 

Charlie_B

EOS M50
Oct 23, 2020
33
38
Not sure if it matters, but I had the SA ring in the middle position for all 7 shots. The lock switch was off.

IS was on. The focus range was set to 0.26m-0.5m, though I kept the camera in manual focus mode the whole time and focused just once before taking the 7 pictures.
Its definitely rear focusing, with DSLR we could Micro focus adjust for each lens, most of my Canon lenses including primes were rear or front focusing , 5 to 10 adjustment fixed the issue on my lenses/cameras. No option but lens firmware update to fix this on R5/R6, you can see the rear focusing on your first image at f2.8
1627043552635.png
 
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PaulStoffregen

I'm New Here
Jul 21, 2021
11
4
At least on my R6, it automatically appears when I turn the focus ring with the lens AF/MF switch is in manual focus mode.
 

jd7

EOS R
CR Pro
Feb 3, 2013
914
275
I didn't realise "focus shift " was the same as back/front focusing , back focusing in this case. My RF 70-200mm f2.8 had the same issue but was quickly fixed in lens firmware update, I would sincerely hope Canon will provide a fix ASAP, it wasn't a major issue on the 70-200 but it certainly will be an issue on a Macro lens
Focus shift is different from front or back focusing, although the result is essentially the same.

With front or back focusing, the camera thinks it has focused correctly, but it's actually focused a little in front or behind where it should.

Focus shift is where the camera does focus correctly initially, but the focus point moves when the lens stops down to take the shot. So, you wouldn't see any issue if you took the shot with maximum aperture for the lens. You also don't expect to see it if you shoot quite stopped down, or if the subject is quite a distance away, as the focus point will move but the depth of field in the shot will be large enough to hide it. So, you are most like to see if you stop down a little (say one or perhaps two stops from maximum aperture) and take a photo of a subject which is reasonably close (so the shot has a shallow depth of field).

That's my understanding anyway. The result is an out of focus shot either way, and in that sense either way you get a shot which is front or back focused.
 
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Charlie_B

EOS M50
Oct 23, 2020
33
38
Focus shift is different from front or back focusing, although the result is essentially the same.

With front or back focusing, the camera thinks it has focused correctly, but it's actually focused a little in front or behind where it should.

Focus shift is where the camera does focus correctly initially, but the focus point moves when the lens stops down to take the shot. So, you wouldn't see any issue if you took the shot with maximum aperture for the lens. You also don't expect to see it if you shoot quite stopped down, or if the subject is quite a distance away, as the focus point will move but the depth of field in the shot will be large enough to hide it. So, you are most like to see if you stop down a little (say one or perhaps two stops from maximum aperture) and take a photo of a subject which is reasonably close (so the shot has a shallow depth of field).

That's my understanding anyway. The result is an out of focus shot either way, so in that sense either way you get a shot which is front or back focused.
Thanks for the explanation, the plot thickens ! I'm sure Canon will sort it out with firmware
 

Bundu

EOS 90D
Nov 24, 2014
100
42
South Africa
Its definitely rear focusing, with DSLR we could Micro focus adjust for each lens, most of my Canon lenses including primes were rear or front focusing , 5 to 10 adjustment fixed the issue on my lenses/cameras. No option but lens firmware update to fix this on R5/R6, you can see the rear focusing on your first image at f2.8
When focused on an object, is there not always more in focus to the rear than to the front?
 

koenkooi

EOS 5D Mark IV
CR Pro
Feb 25, 2015
1,806
1,726
When focused on an object, is there not always more in focus to the rear than to the front?
Yes, the rule of thumb is that DoF is 1/3 in front of the focus point and 2/3 behind the focus point. But I'm not sure of that holds true for macro distances as well.
 
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FrenchFry

Wildlife enthusiast!
Jun 14, 2020
442
553
Not sure if it matters, but I had the SA ring in the middle position for all 7 shots. The lock switch was off.

IS was on. The focus range was set to 0.26m-0.5m, though I kept the camera in manual focus mode the whole time and focused just once before taking the 7 pictures.
Hi,
Thank you very much for performing these tests.
Two things that might be affecting your results would be the lack of a sturdy tripod and not re-focusing in between each shot.
If you are touching the camera dials to change the aperture and then pressing the shutter, you could inadvertently be moving the camera imperceptibly, which would affect your results.
One way to reduce any shutter shock effects would be to take the photos with the 2 second timer or a remote, so you know there is no movement or vibration caused by pressing the shutter. This would not, however, guarantee that the camera is not moving ever so slightly when you adjust the aperture.
For this reason, I think you might want to consider re-focusing in between each shot.
Thanks again for setting up the test!
 

David_D

EOS M6 Mark II
Apr 19, 2021
52
52
If you are touching the camera dials to change the aperture and then pressing the shutter, you could inadvertently be moving the camera imperceptibly, which would affect your results.
Not sure if it can do this, but could the Canon phone app be used to change settings and trigger remotely, to avoid touching it at all? (Never had a camera it would work with, so never tried it.)
 

PaulStoffregen

I'm New Here
Jul 21, 2021
11
4
Now having several hours to think about this and second guess myself, I'm wondering if I may have made any errors in the methodology of my little test? In particular, I'm wondering if the magic arm holding the R6 and heavy lens may have slipped ever so slightly during the test. In hindsight, after the F22 shot, I probably should have gone back to F2.8 and made an 8th shot, to verify the camera didn't actually move throughout the entire test. Probably should have also gone back into zoom mode on the screen and taken another photo of the screen too.
 

FrenchFry

Wildlife enthusiast!
Jun 14, 2020
442
553
Now having several hours to think about this and second guess myself, I'm wondering if I may have made any errors in the methodology of my little test? In particular, I'm wondering if the magic arm holding the R6 and heavy lens may have slipped ever so slightly during the test. In hindsight, after the F22 shot, I probably should have gone back to F2.8 and made an 8th shot, to verify the camera didn't actually move throughout the entire test. Probably should have also gone back into zoom mode on the screen and taken another photo of the screen too.
Tests like this are a lot of work!
Would you be able to rest the camera on a table or something so you can eliminate "arm sag" as a variable?