OpticalLimits Reviews the Canon RF 35mm f/1.8 IS Macro STM

Travel_Photographer

Travel, Landscape, Architecture
Aug 30, 2019
94
126
You just may have solved 80% or my irritation, which may well
Make me happily keep this lens. I’m happy to buy the 24-70 F2.8 and or the 50 1.2. But this might make both unnecessary given my love for my compact 70 f2.8 (that happens also to zoom to 200).
I hope that's the case! (That a good part of the irritation with the lens is resolved).

Please let me know if / when you have a chance to check that setting and give the camera a test, if you haven't already. I'd love to hear if it helped.
 
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Optics Patent

Former Nikon (Changes to R5 upon delivery)
Nov 6, 2019
310
248
Disabling the Continuous AF in camera menu page 7 makes things much better. I'll spend some time shooting this way to verify. I might just keep this lens. I need it.
 
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Travel_Photographer

Travel, Landscape, Architecture
Aug 30, 2019
94
126
Disabling the Continuous AF in camera menu page 7 makes things much better. I'll spend some time shooting this way to verify. I might just keep this lens. I need it.
Excellent, and thanks for the update. I think you'll find it significantly better. I'm so glad you casually mentioned the part about it making the noise when you set it on a table... as soon as I heard that I figured you had Continuous AF on. Keep in mind too that it was doing that with all your lenses. You just may have never noticed because the focus on your 70-200 or any other lenses you have is much faster. It would have been constantly hunting and focusing with every single lens, all the time. I imagine it totally drains your battery as well.
 
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canonnews

EOS 7D MK II
Dec 27, 2017
594
890
Canada
www.canonnews.com
Since when did a 1:2 become a true macro lens. My understanding is that macro lenses are 1:1 on a full frame sensor or greater. I've seen 5:1 but never 1:2 considered macro. Sounds like a marketing ploy using cheaper materials than the L line
since around the birth of EOS.. the 50mm F2.5 Compact Macro is .5x but could go to 1:1 with the lifesize converter.
 
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flip314

EOS RP
Sep 26, 2018
270
385
Since when did a 1:2 become a true macro lens. My understanding is that macro lenses are 1:1 on a full frame sensor or greater. I've seen 5:1 but never 1:2 considered macro. Sounds like a marketing ploy using cheaper materials than the L line
The "official" definition of macro is that the image on the sensor is life-sized (1:1). I've never heard qualifications about the sensor size though.

It's always seemed arbitrary to me though, whether you really need 1:1 depends entirely on what you're photographing. A small close focusing distance is always useful whether you're doing "macro" work or not
 
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brad-man

Semi-Reactive Member
Jun 6, 2012
1,547
370
S Florida
Since when did a 1:2 become a true macro lens. My understanding is that macro lenses are 1:1 on a full frame sensor or greater. I've seen 5:1 but never 1:2 considered macro. Sounds like a marketing ploy using cheaper materials than the L line
You do understand that it's not an L lens, right?
 

Optics Patent

Former Nikon (Changes to R5 upon delivery)
Nov 6, 2019
310
248
Since when did a 1:2 become a true macro lens. My understanding is that macro lenses are 1:1 on a full frame sensor or greater. I've seen 5:1 but never 1:2 considered macro. Sounds like a marketing ploy using cheaper materials than the L line
since when is a 35mm lens a “macro”? What genius thinks they can light a subject two inches from the lens?

If they are accurately describing the specs then the huffing is unjustified
 

Profit007

EOS T7i
Nov 2, 2014
59
40
The huge deal here is FOCUS SHIFT, rendering this lens total garbage.

For those who don't know, your AF selects accurate focus @ f1.8, then as you take the photo the lens stops down to your selected aputure (say f2.8) and the focus point changes due to the aputure change... It's not till you get enough DoF (ie f4.0) to cover the shift that everything is 'all right' again.

The only way to avoid it is to use live view, so your aputure doesn't change after focus.
 

SecureGSM

2 x 5D IV
Feb 26, 2017
1,938
864
The huge deal here is FOCUS SHIFT, rendering this lens total garbage.

For those who don't know, your AF selects accurate focus @ f1.8, then as you take the photo the lens stops down to your selected aputure (say f2.8) and the focus point changes due to the aputure change... It's not till you get enough DoF (ie f4.0) to cover the shift that everything is 'all right' again.

The only way to avoid it is to use live view, so your aputure doesn't change after focus.
In live view mode camera still focusing at the widest available aperture. This is my understanding happy to be corrected.
 

uri.raz

EOS RP
Jan 5, 2016
213
134
Since when did a 1:2 become a true macro lens. My understanding is that macro lenses are 1:1 on a full frame sensor or greater. I've seen 5:1 but never 1:2 considered macro. Sounds like a marketing ploy using cheaper materials than the L line
Canon calls the new TS-E lenses (50mm, 90mm, 135mm) macro though their max magnification is 1:2. IIRC, I've read that back in the film days, lenses with max magnification of 1:4 were also called macro, though I can't find the source at the moment.
 

koenkooi

EOS 6D MK II
Feb 25, 2015
879
661
since when is a 35mm lens a “macro”? What genius thinks they can light a subject two inches from the lens?

If they are accurately describing the specs then the huffing is unjustified
The Canon MTxx flashes can, as well as their 35mm lens with builtin lighting: https://www.the-digital-picture.com/Reviews/Canon-EF-S-35mm-f-2.8-Macro-IS-STM-Lens.aspx

Or use a hot-shoe cord and put your flash on a flexible arm or something. The Canon MP-E and Laowa lenses have a working distance of less than 2 inches at maximum magnification.
 

Optics Patent

Former Nikon (Changes to R5 upon delivery)
Nov 6, 2019
310
248
A small close focusing distance is always useful whether you're doing "macro" work or not
Potentially useful but in this case at a cost of 3/4 of the focusing range being less than a foot so it can spend most of its effort where the subject isn’t. Which is why some lenses have focus range limit switches. Usually (such as with telephotos having limit switches) closer is better. For AF macros without a switch when macro shooting is not the goal, there’s a potential downside.

As far as the concern that reducing the aperture to remove some peripheral rays can defocus the central rays as has been recently explained with appreciated clarity, I’ll have to test that at normal focal distances.
 

Optics Patent

Former Nikon (Changes to R5 upon delivery)
Nov 6, 2019
310
248
The huge deal here is FOCUS SHIFT, rendering this lens total garbage.

For those who don't know, your AF selects accurate focus @ f1.8, then as you take the photo the lens stops down to your selected aputure (say f2.8) and the focus point changes due to the aputure change... It's not till you get enough DoF (ie f4.0) to cover the shift that everything is 'all right' again.

The only way to avoid it is to use live view, so your aputure doesn't change after focus.
Very clear explanation. I sought to replicate this with a flat subject at 30" from the lens. f1.8, 2, 2.8, 4, 5.6, 8. All indistinguishable at full magnification of the finder. Is this something rarely encountered like the RF70-200 near close focus error? I'd like to understand this better before I dismiss the concern as irrelevant to my usage (like the to-be-fixed RF70-200 focus error).

With a foreshortened ruler I thought I might have seen some shift, but had a hard time replicating (if it isn't repeatable, it isn't science).

I'd be happy to see a link to anyone who has published tests I can replicate.
 
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jjesp

EOS M50
Dec 30, 2016
25
10
I really hope Canon will make some smaller prime alternatives in the 28mm to 50mm range. Especially since they have cameras like the RP. Would be so nice to have for travel and street photography.
 

Travel_Photographer

Travel, Landscape, Architecture
Aug 30, 2019
94
126
Very clear explanation. I sought to replicate this with a flat subject at 30" from the lens. f1.8, 2, 2.8, 4, 5.6, 8. All indistinguishable at full magnification of the finder. Is this something rarely encountered like the RF70-200 near close focus error? I'd like to understand this better before I dismiss the concern as irrelevant to my usage (like the to-be-fixed RF70-200 focus error).

With a foreshortened ruler I thought I might have seen some shift, but had a hard time replicating (if it isn't repeatable, it isn't science).

I'd be happy to see a link to anyone who has published tests I can replicate.
It's a non-existent problem. The lens focuses flawlessly in both autofocus and manual modes. Some reviewers just like to come up with something to discuss. It's a natural optical phenomenon with wide aperture lenses that generally causes no-real world effects, as you have seen in your own tests. Feel free to enjoy your lens worry-free about AF issues. If it actually had this problem, it wouldn't be rated so highly almost universally. Perhaps most importantly, the ultimate test of a lens's performance is how well it works for you. If it works great for you and gives you the results you want, that's all that matters.
 
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Optics Patent

Former Nikon (Changes to R5 upon delivery)
Nov 6, 2019
310
248
It's a non-existent problem. The lens focuses flawlessly in both autofocus and manual modes. Some reviewers just like to come up with something to discuss. It's a natural optical phenomenon with wide aperture lenses that generally causes no-real world effects, as you have seen in your own tests. Feel free to enjoy your lens worry-free about AF issues. If it actually had this problem, it wouldn't be rated so highly almost universally. Perhaps most importantly, the ultimate test of a lens's performance is how well it works for you. If it works great for you and gives you the results you want, that's all that matters.
I’ve just shot a real world test of sunlit toddler with eye focus and all apertures are eyelash sharp. If it can do that I don’t care much about some bloggers lab results.
That said, this optics industry technology expert is interested in the principles by which removing outer rays can shift a sharp central focus point. I have an open mind.
 
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Travel_Photographer

Travel, Landscape, Architecture
Aug 30, 2019
94
126
If it can do that I don’t care much about some bloggers lab results.
Exactly. It's some bloggers lab results.

As for the physics of it, see the diagram below. In the top example, with the aperture wide open (which it would be during autofocus) the light rays enter from a variety of more extreme angles, creating a focus plane that is not a single point, but rather a bit of a blurry blob. The AF would focus in the middle of this blurry blob (the middle vertical green line).

In the second example with the aperture stopped down slightly, the "extreme angle" rays entering the lens are eliminated by the smaller aperture opening, producing a more accurate point of focus, in this case, shifted slightly leftward (the vertical red line).

These are all tiny amounts (if at all) measured in some lab, as you correctly state. Aspherical elements in the lens can eliminate or drastically reduce it.

Your real-world tests with this lens are the same as mine -- excellent autofocus at all apertures and distances.

Focus.jpg
 

Optics Patent

Former Nikon (Changes to R5 upon delivery)
Nov 6, 2019
310
248
Excellent, thanks. This fits with my reading that the actual point of focus gets sharper at smaller apertures and NEVER gets worse by stopping down. It is a “one hand clapping” philosophical matter of whether at a reduced aperture there is a focus setting that provides slightly sharper focus?

My lens is sharp wide open and get sharper at every reduced aperture until diffraction intervenes. I’m a little sorry I wasted time on this. But glad to have learned a bit more. Clients come to me and are glad I’ve already been familiarized with their issues like these.

a
 
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David - Sydney

EOS 80D
Dec 7, 2014
117
64
www.flickr.com
Note that on RF lenses the focus ring is complete controlled by software, there are a few options in the camera to tweak it, one of which is the direction. Maybe it has a section for sensitivity as well?
DPReview TV did an item a few weeks back about software controlled focus limiting, a thing I would very much like to have.
But I want it for the reverse: lock it down from MFD to 1 meter so it stays in macro mode. It's very annoying when you try to focus on an insect and it grabs the background instead.
I too would like a menu option to limit focus range. My 100mm f/2.8 macro has the switch which is great when I am shooting above water but not accessible when in an underwater housing :)
Mostly I would shoot close up/macro subjects under water with the lens but occasionally further distant subjects if the vis is okay. Only option now is to keep the full range available and put my hand in front to bring the focus close and start the focusing close up. The focus hunting can be quite annoying though.