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

[PaulStoffregen]

Yeah, might be able to the test without the arm, if I were to glue those pieces of cardboard and parts together, and mount that and the camera to the table somehow. Or find a different subject? But I wanted to use a subject that is 3 identical objects at known different distance from the lens.

Or maybe this is just the excuse I need to finally experiment with tethered shooting. This test really wants to be done without any physical touching of the camera!

If retry this, I'll use thinner material so they're not a full millimeter apart from each other. Maybe over the weekend...

 

[EOS 4 Life]

I don't know how you could "fix it in firmware"

The entire lens is controlled by software

 

[EOS 4 Life]

That's right, but in manual mode, there will be no "firmware focus correction".

What makes you think that?
There is firmware involved in every aspect of focusing.

 

[jd7]

When focused on an object, is there not always more in focus to the rear than to the front?

Not unless your lens has rear focusing issue

Depth of field is distributed equally in front and behind the plane of focus only in some situations.

As I understand it, longer focal lengths, higher subject magnification, shorter focus distance (which of course is related to higher subject magnification) and smaller apertures are factors which tend towards depth of field being distributed equally in front and behind the plane of focus.

For example, for typical landscape photography scenarios with a wide angle lens, in broad terms depth of field is distributed about 1/3 in front of the plane of focus and two thirds behind the plane of focus. That is the reason behind the common recommendation that landscape photographers should focus "one third of the way into the scene". In contrast, if you are using a longer focal length and magnifying the subject quite a lot (eg a common wildlife photography situation), depth of field is likely to be distributed about equally in front and behind the plane of focus.

Here are couple of references:

Understanding Depth of Field in Photography

www.cambridgeincolour.com

Depth of Field in Depth! - Bob Atkins Photography

 

[Del Paso]

What makes you think that?
There is firmware involved in every aspect of focusing.

Because a firmware correction has its limits, we aren't speaking of IBM's Deep Blue here...

 

[neuroanatomist]

Because a firmware correction has its limits, we aren't speaking of IBM's Deep Blue here...

It’s a really, really simple correction. If the aperture is x, adjust focus distance by y. No abacus or slide rule required, much less supercomputing.

Keep in mind that RF lenses don’t really manually focus – they are ‘focus-by-wire’ where all the focus ring does is signal the AF motor via actuators.

 

[Dj 7th]

I got my RF 100mm 2 days ago, my initial quick test does not show a focus shift but I may not have enough experience to deduce accurately. However I want to share a few of my real world tests for the stuff that I will be using the lens for to see how well it performed.

My first test was to focus stack a relatively small subject and this is the result. I will post my second test in a latter post.

 

[Dj 7th]

I got my RF 100mm 2 days ago, my initial quick test does not show a focus shift but I may not have enough experience to deduce accurately. However I want to share a few of my real world tests for the stuff that I will be using the lens for to see how well it performed

My second test was to shoot a flower in a normal windy morning handheld to see the difference the SA ring would make to my pictures. I shot these at f/2.8 I used Auto-focus for these pictures. I also took the same pictures with manual focusing and the pretty much looked the same.

Picture 1 with SA at 0
Picture 2 with SA at -1
Picture 3with SA at -2
Picture 4 with SA at 0
Picture 5 with SA at +1
Picture 6 with SA at +2

1 is halfway, 2 is full all the way

THIS IS NOT A SCIENTIFIC TEST, THIS IS JUST FOR THOSE WHO WOULD LIKE TO SEE THE EFFECTS OF SA ON NORMAL DAY TO DAY PICTURES.

 

[Bdbtoys]

Thanks @Dj 7th , pretty much matches what we seen already.

Unfortunately, I don't really see any benefit of using SA on close-up subjects. I'll still have to see distance subject before I give me final assessment.

Also, I plan on getting this lens at some point (seeing how I could use the macro)... be it using SA or not.

 

[Jethro]

I got my RF 100mm 2 days ago, my initial quick test does not show a focus shift but I may not have enough experience to deduce accurately. However I want to share a few of my real world tests for the stuff that I will be using the lens for to see how well it performed

My second test was to shoot a flower in a normal windy morning handheld to see the difference the SA ring would make to my pictures. I shot these at f/2.8 I used Auto-focus for these pictures. I also took the same pictures with manual focusing and the pretty much looked the same.

Picture 1 with SA at 0
Picture 2 with SA at -1
Picture 3with SA at -1
Picture 4 with SA at 0
Picture 5 with SA at +1
Picture 6 with SA at +2

1 is halfway, 2 is full all the way

THIS IS NOT A SCIENTIFIC TEST, THIS IS JUST FOR THOSE WHO WOULD LIKE TO SEE THE EFFECTS OF SA ON NORMAL DAY TO DAY PICTURES.

Thanks very much for doing these. Can I ask: were you refocusing (to the main subject) AFTER setting the SA?

 

[Dj 7th]

Thanks very much for doing these. Can I ask: were you refocusing (to the main subject) AFTER setting the SA?

Yes I did. Each time I set the SA, I refocused to the general lower yellow area of the flower. I was also on AutoFocus so I re-acquire focus before I take the picture. I also have a set where I used manual focus, so after I adjust the SA, I refocused using the R5's manual focus guide. The results are pretty much the same but I can post if you want to see them.

 

[Jethro]

Yes I did. Each time I set the SA, I refocused to the general lower yellow area of the flower. I was also on AutoFocus so I re-acquire focus before I take the picture. I also have a set where I used manual focus, so after I adjust the SA, I refocused using the R5's manual focus guide. The results are pretty much the same but I can post if you want to see them.

No, no, that's fine. I asked because I recall there was some discussion earlier about the need to re-acquire focus after applying the SA - and it does seem to be necessary.

 

[jeanluc]

So, is Canon aware of this issue?

 

[Charlie_B]

Got my RF 100 today , focus looks perfect . two images , one at f2.8 and f8 on R5 , no front or rear focusing . Both from about 10 inches, electronic shutter 10 sec delay on tripod, didn't see any focus shift as I changed apertures from 2.8 to f11 and back down again

 

[lexptr]

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?

It is Ok. They should be worse due to diffraction, which kicks in from f/10.6 on R6.
What is strange, is that the back subject appears sharper than the front in all shots. I don't think it is focus shift, because it appears on the f2.8 shot as well. Either manual focusing wasn't perfect or there is something else. May be the heights of cardboard steps aren't equal? But there is another theory, which bothers me. I'm not sure how SA control works but I know it blurs either background or foreground if you move it in one direction or another from neutral position. You say it was in the middle (neutral) but may be it was just slightly off and it affects the result that much in macro? Or could it be a calibration issue and on your lens the neutral SA control position is not in the middle?

 

[HenryL]

It is Ok. They should be worse due to diffraction, which kicks in from f/10.6 on R6.
What is strange, is that the back subject appears sharper than the front in all shots. I don't think it is focus shift, because it appears on the f2.8 shot as well. Either manual focusing wasn't perfect or there is something else. May be the heights of cardboard steps aren't equal? But there is another theory, which bothers me. I'm not sure how SA control works but I know it blurs either background or foreground if you move it in one direction or another from neutral position. You say it was in the middle (neutral) but may be it was just slightly off and it affects the result that much in macro? Or could it be a calibration issue and on your lens the neutral SA control position is not in the middle?

I believe that would be normal, DOF range typically extends further behind the plane of focus than in front. I would be concerned if the back subject was as sharp or sharper than the center one...but this demonstration looks ok to me.

 

[stevelee]

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?

The f/22 shot looks like it has some softening from diffraction, and the f/16 looks like it is creeping in. If it will stop down to f/32, I bet it will soften even more.

 

[jeanluc]

I just tried my lens out; if there is any focus shift it is very, very hard to see even at 300%.

 

[Charlie_B]

I just tried my lens out; if there is any focus shift it is very, very hard to see even at 300%.

It probably doesn't exist, my lens is perfect, possibly user error by inexperienced Macro photographers

 

[macrunning]

It probably doesn't exist, my lens is perfect, possibly user error by inexperienced Macro photographers

Nice shots Charlie_B! What aperture were you using? I don't ever seem to get that much in focus. Maybe I just need to push the aperture further.