RF35mm f/1.8 IS STM MACRO AF performance.

Hello Everyone,

I am using an RF 35mm f/1.8 IS STM MACRO on a Canon R. I am having AF and sharpness issues with this lens, particularly indoors when I am taking pictures of family. In particular, I find that:

(A) the AF struggles going from near to far objects and vice versa.

(B) About 5% of the time, the AF refuses to engage on the subject - it will go out of focus trying to focus. Touching the LCD to make it to focus also won't work. I will have to repeatedly press the AF-ON/Shutter button, about 5-10 times, to get it to reengage. This is true even when there is a high contrast subject in the scene / near bright light sources.

(C) Finally, at about 5ft distance, the lens is its sharpest at f/8.0, and does not behave like what is usually claimed about this lens (sharpest from f/2.8 onward). Is this a normal behavior for this lens at this distance?

I wonder if anyone has had any similar experiences? Or, could this lens be defective needing repair?

Thanks!

bharathmsk wrote:

Hello Everyone,

I am using an RF 35mm f/1.8 IS STM MACRO on a Canon R. I am having AF and sharpness issues with this lens, particularly indoors when I am taking pictures of family. In particular, I find that:

(A) the AF struggles going from near to far objects and vice versa.

(B) About 5% of the time, the AF refuses to engage on the subject - it will go out of focus trying to focus. Touching the LCD to make it to focus also won't work. I will have to repeatedly press the AF-ON/Shutter button, about 5-10 times, to get it to reengage. This is true even when there is a high contrast subject in the scene / near bright light sources.

(C) Finally, at about 5ft distance, the lens is its sharpest at f/8.0, and does not behave like what is usually claimed about this lens (sharpest from f/2.8 onward). Is this a normal behavior for this lens at this distance?

I wonder if anyone has had any similar experiences? Or, could this lens be defective needing repair?

Thanks!

Mine does not behave like that, and is very sharp at f2.8, though the STM focusing is not as fast or quiet as a USM lens.  Do other lenses work correctly on your R body?  If so, it seems likely your lens is faulty and needs repair.

Couple turns of the focus ring to close enough, then AF.

Thanks @drsnoopy and @justus7.

Here is how the resolution charts taken at about ~2ft distance look. Any thoughts? My interpretation is that the lens starts out a bit sharper at 1.8 than f/2.8, dips in sharpness by 2.8, then becomes significantly better at 8. If you think the resolution chart results are expected/not expected/falls in the gray area from this lens, I would greatly appreciate it if you could let me know.

Every time the lens focused, the AF motor did a couple of "tr, tr" sounding drives, and then focused on the target. @drsnoopy, to answer your question on making sure if other lenses are performing well with body, yes, they do (Definitely not as smooth and snappy as my RF24-105L). If you have any other suggestions on debugging the problem/ making sure that the lens is at fault before I contact manufacturer, I would greatly appreciate it!

RF 35mm f/1.8 IS STM MACRO

bharathmsk wrote:

Thanks @drsnoopy and @justus7.

Here is how the resolution charts taken at about ~2ft distance look. Any thoughts? My interpretation is that the lens starts out a bit sharper at 1.8 than f/2.8, dips in sharpness by 2.8, then becomes significantly better at 8. If you think the resolution chart results are expected/not expected/falls in the gray area from this lens, I would greatly appreciate it if you could let me know.

Every time the lens focused, the AF motor did a couple of "tr, tr" sounding drives, and then focused on the target. @drsnoopy, to answer your question on making sure if other lenses are performing well with body, yes, they do (Definitely not as smooth and snappy as my RF24-105L). If you have any other suggestions on debugging the problem/ making sure that the lens is at fault before I contact manufacturer, I would greatly appreciate it!

RF 35mm f/1.8 IS STM MACRO

To my eye, the middle panel (F2.8) looks a bit sharper than the left (F1.8), though they are all more than sharp enough.

Thanks @Alastair Norcross! That is good to know.

I too think that the f/2.8 appears sharper ( I used the wrong word in my previous post. f/2.8 has significantly better contrast but the ability to resolve may go to the f/1.8 - if we look through the Dpreview "Loupe". But f/8 is still significantly better than the f/2.8.

The reason I wanted to get the 35mm STM (when I have the 24-105L) is the wider apertures. But I am left wondering if the lens I have is good enough at those apertures. Hence the interest in knowing if these are performances that we expect from the lens, from other users. Thanks a lot!

bharathmsk wrote:

Hello Everyone,

I am using an RF 35mm f/1.8 IS STM MACRO on a Canon R. I am having AF and sharpness issues with this lens, particularly indoors when I am taking pictures of family. In particular, I find that:

(A) the AF struggles going from near to far objects and vice versa.

This is kind of normal for lenses with close focus ability. Outdated STM motor not helping here.

(B) About 5% of the time, the AF refuses to engage on the subject - it will go out of focus trying to focus. Touching the LCD to make it to focus also won't work. I will have to repeatedly press the AF-ON/Shutter button, about 5-10 times, to get it to reengage. This is true even when there is a high contrast subject in the scene / near bright light sources.

What is your AF setting at those situations usually?

(C) Finally, at about 5ft distance, the lens is its sharpest at f/8.0, and does not behave like what is usually claimed about this lens (sharpest from f/2.8 onward). Is this a normal behavior for this lens at this distance?

Do you like the photos?

Opticallimits.com show, that lens is sharpest at f4-f5.6 (as expected), but in general is pretty sharp through the aperture range, f22 is poor due to diffraction.

I wonder if anyone has had any similar experiences? Or, could this lens be defective needing repair?

Thanks!

Thanks all.

@Martin_99, following your link to opticallimits, I read through the review and I had some hope instilled in me. I repeated the resolution chart experiments (attached pictures, I have concatenated images, use Dpreview loupe).

To my dismay, the lens gets sharpest at f/11-f/16! And the resolution drop from f/1.8 -> f/2.8, f/4 and the recovery thereafter at around f/5.6 is also very clear. These results were highly reproducible.

So the lens is poorer than I had originally thought (I should have taken the time to sweep through the entire aperture range). At this point, I certainly feel like this lens is a lemon. And the poor optical performance could have lead to a poor AF performance like the opticallimits review indicate. I think I should contact the manufacturer. If you all have other insights to add, please, I would greatly appreciate them!

To answer your question @Martin_99 on the AF settings, when I photograph family, these are left at eye tracking & servo. For these resolution chart pictures, they were left at single point AF on the target.

RF 35mm f/1.8 IS STM MACRO

Thank you for your help and support!

bharathmsk wrote:

Thanks all.

@Martin_99, following your link to opticallimits, I read through the review and I had some hope instilled in me. I repeated the resolution chart experiments (attached pictures, I have concatenated images, use Dpreview loupe).

On what are we looking at actually? 100% magnified photos in center?

To my dismay, the lens gets sharpest at f/11-f/16! And the resolution drop from f/1.8 -> f/2.8, f/4 and the recovery thereafter at around f/5.6 is also very clear. These results were highly reproducible.

Hard to judge. If somebody tell me such result, my first thought is user testing error. What is your distance from target? Are you sure that camera is perpendicular to test chart?

So the lens is poorer than I had originally thought (I should have taken the time to sweep through the entire aperture range). At this point, I certainly feel like this lens is a lemon. And the poor optical performance could have lead to a poor AF performance like the opticallimits review indicate. I think I should contact the manufacturer. If you all have other insights to add, please, I would greatly appreciate them!

What I mostly do - testing decentering based on below link:

https://phillipreeve.net/blog/how-to-check-how-decentered-your-lens-is/

Conclusion is not allways easy though.

To answer your question @Martin_99 on the AF settings, when I photograph family, these are left at eye tracking & servo. For these resolution chart pictures, they were left at single point AF on the target.

RF 35mm f/1.8 IS STM MACRO

Thank you for your help and support!

bharathmsk wrote:

Thanks all.

@Martin_99, following your link to opticallimits, I read through the review and I had some hope instilled in me. I repeated the resolution chart experiments (attached pictures, I have concatenated images, use Dpreview loupe).

To my dismay, the lens gets sharpest at f/11-f/16! And the resolution drop from f/1.8 -> f/2.8, f/4 and the recovery thereafter at around f/5.6 is also very clear. These results were highly reproducible.

So the lens is poorer than I had originally thought (I should have taken the time to sweep through the entire aperture range). At this point, I certainly feel like this lens is a lemon. And the poor optical performance could have lead to a poor AF performance like the opticallimits review indicate. I think I should contact the manufacturer. If you all have other insights to add, please, I would greatly appreciate them!

To answer your question @Martin_99 on the AF settings, when I photograph family, these are left at eye tracking & servo. For these resolution chart pictures, they were left at single point AF on the target.

RF 35mm f/1.8 IS STM MACRO

Thank you for your help and support!

If you feel the lens is a lemon, and you are within the return period, just return it and try another copy.

Thanks @Martin_99. Please find the answers below.

1. You are looking at 100% magnified photos in the center.

2. I use the electronic levels to judge horizontal and vertical tilts of the camera. I also used a laser distance measurer from the target to check distances of the camera from the target. The images I had attached were taken at about 2 ft. All results were reproducible at ~4ft, ~8ft.

3. Thank you for the note on decentering. I have never done this before. I will check this.

Given 1 and 2, any thoughts on the results? Thank you!

Martin_99 wrote:

bharathmsk wrote:

Thanks all.

@Martin_99, following your link to opticallimits, I read through the review and I had some hope instilled in me. I repeated the resolution chart experiments (attached pictures, I have concatenated images, use Dpreview loupe).

On what are we looking at actually? 100% magnified photos in center?

To my dismay, the lens gets sharpest at f/11-f/16! And the resolution drop from f/1.8 -> f/2.8, f/4 and the recovery thereafter at around f/5.6 is also very clear. These results were highly reproducible.

Hard to judge. If somebody tell me such result, my first thought is user testing error. What is your distance from target? Are you sure that camera is perpendicular to test chart?

So the lens is poorer than I had originally thought (I should have taken the time to sweep through the entire aperture range). At this point, I certainly feel like this lens is a lemon. And the poor optical performance could have lead to a poor AF performance like the opticallimits review indicate. I think I should contact the manufacturer. If you all have other insights to add, please, I would greatly appreciate them!

What I mostly do - testing decentering based on below link:

https://phillipreeve.net/blog/how-to-check-how-decentered-your-lens-is/

Conclusion is not allways easy though.

To answer your question @Martin_99 on the AF settings, when I photograph family, these are left at eye tracking & servo. For these resolution chart pictures, they were left at single point AF on the target.

RF 35mm f/1.8 IS STM MACRO

Thank you for your help and support!

bharathmsk wrote:

Thanks @Martin_99. Please find the answers below.

1. You are looking at 100% magnified photos in the center.

2. I use the electronic levels to judge horizontal and vertical tilts of the camera. I also used a laser distance measurer from the target to check distances of the camera from the target. The images I had attached were taken at about 2 ft. All results were reproducible at ~4ft, ~8ft.

3. Thank you for the note on decentering. I have never done this before. I will check this.

Given 1 and 2, any thoughts on the results? Thank you!

Martin_99 wrote:

bharathmsk wrote:

Thanks all.

@Martin_99, following your link to opticallimits, I read through the review and I had some hope instilled in me. I repeated the resolution chart experiments (attached pictures, I have concatenated images, use Dpreview loupe).

On what are we looking at actually? 100% magnified photos in center?

To my dismay, the lens gets sharpest at f/11-f/16! And the resolution drop from f/1.8 -> f/2.8, f/4 and the recovery thereafter at around f/5.6 is also very clear. These results were highly reproducible.

Hard to judge. If somebody tell me such result, my first thought is user testing error. What is your distance from target? Are you sure that camera is perpendicular to test chart?

So the lens is poorer than I had originally thought (I should have taken the time to sweep through the entire aperture range). At this point, I certainly feel like this lens is a lemon. And the poor optical performance could have lead to a poor AF performance like the opticallimits review indicate. I think I should contact the manufacturer. If you all have other insights to add, please, I would greatly appreciate them!

What I mostly do - testing decentering based on below link:

https://phillipreeve.net/blog/how-to-check-how-decentered-your-lens-is/

Conclusion is not allways easy though.

To answer your question @Martin_99 on the AF settings, when I photograph family, these are left at eye tracking & servo. For these resolution chart pictures, they were left at single point AF on the target.

RF 35mm f/1.8 IS STM MACRO

Thank you for your help and support!

I would wait for your decentering test results.

Additional question - what ISO was set on this set of photos?

Nevertheless I believe that even you have subpar copy, you will most probably not see it on your images. But for your peace of mind, if it will be confirmed, return it.

As others suggest, you might have a bad copy. Mine is sharp wide open and never had any issues focusing, I use it every day to take close-up pictures of small jewelry with no issues at all.

Thank you all for your helpful comments.

I will do the decentering test for completeness, and send the lens back.

PS: @Martin_99, thank you. The ISO was set to 400 in all these.