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

[Fischer]

I’m not saying it isn’t a problem for some people with some lenses, only that I haven’t experienced the problem. There are, however, myriad things that can go wrong when photographing skittish arthropods in vivo and in situ.

You have now twice made references to your photo - which I have not commented on at all. I'm sure its a great macro shot and it looks good too.

 

[AJ]

The focus shift issue is surprising. You'd think this would have dropped out of their CAD modeling, or ray-tracing, or whatever they do. Or else out of testing of physical prototypes. I imagine this will be an easy fix with firmware. If so, why didn't they do this right off of the bat, rather than a later fix? Did they rush this lens to market? In any case this seems somewhat of an embarassment for the Canon brand. I imagine many 'togs will wait for the firmware update before plunking down their dollars/euros/pounds/dinars etc.

 

[Viggo]

Not really a reliable source. There are plenty of professional photographers to chose from rather than pushing online magazines and publishers.

TDP not reliable?

 

[InchMetric]

Canon would do well to implement a firmware fix on the focus shift issue as they have on another model.

But let's dispense with the drama. The technical reality check is that an object optimally focused wide open gets even sharper as the lens stops down, not defocusing one iota. WITH a "focus shift" problem.

The "shift" is for the reason that the ideal focus for the bundle of rays that includes those from the peripheries of the lens is slightly different than the bundle with only a central part of the lens. Microscopically so. (If they all focused to the exact same spot then stopping down wouldn't make an image sharper - perhaps that's nearly true for a $12,000 telephoto).

So, that subject test chart in focus wide open is even sharper when stopped down, but the "shift" is simply a misnomer for the fact that stopped down there is an even slightly better point of focus just forward or aft of the subject.

Those who take pictures of rulers laying on tables might document if they tried very hard, but I've never seen a real life example of an image visibly harmed by focus shift.

Let's not pretend that the engineering and optical design geniuses who develop these products are boneheads who don't have a clue about these things that impact 0.00% of actual owner images, and the internet commenters are the smarties who'd do a better job at designing lenses. Get the lenses to the customers who need them, then worry about the little fixes of hypothetical problems.

 

[neuroanatomist]

So, that subject test chart in focus wide open is even sharper when stopped down, but the "shift" is simply a misnomer for the fact that stopped down there is an even slightly better point of focus just forward or aft of the subject.

Those who take pictures of rulers laying on tables might document if they tried very hard, but I've never seen a real life example of an image visibly harmed by focus shift.

Plenty of 'real world' examples of the focus shift on the 50/1.2L. Having a blurry eye and 'an even slightly better point of focus' on the ear is not better at all. Here's one blog example.

 

[bbasiaga]

I am thinking that they will update it via FW.
The fact they did not get it on the initial deliveries of the product is about par for so many businesses today.

SHIP NOW! Fix later.

This is an artifact of 'Agile' buisness models. MINIMUM VIABLE PRODUCT - what is just enough to get to the customer? Whatever that is, ship it and update it later. This was born in the software industry. Anyone who plays PC games knows how buggy they are when they first come out. Same process.

This lens works, lets say, 90% of how you would expect it to. That's good enough. Get free testing from your customers and fix it later.

Brian

 

[bbasiaga]

Canon lens engineering has taken a HUGE step backwards the last few years.

f/11 primes, f/7.1 zooms, telescoping 70-200’s, and now we have a poorly engineered macro lenses. And don’t forget the 24-240, top contender for the worst lens Canon has ever produced.

RF mount has very little going for it that didn’t exist in the same or better form in EF.

Let’s hope they get some better engineers on staff in the future.

You mean an 800mm lens regular people can afford - made possible by the new system's ability to focus all the way down to F11, zooms with all the functionality of those that came before plus an extra 100mm of reach (100-500), the smallest package professional 70-200 lenses on the market, and 10x zoom range consumer lens for about $800 that does really well when compared with the built in lens correction capability in the new bodies?

RF is definitely going places.

Let's hope they don't hire people like you to work in their engineering department.

 

[yeahright]

Plenty of 'real world' examples of the focus shift on the 50/1.2L. Having a blurry eye and 'an even slightly better point of focus' on the ear is not better at all. Here's one blog example.

correct me if I'm wrong, but what is described in this blog post appears to be backfocusing instead of focus shift. In particular, it says 'The backfocusing happens only when using autofocus. Manual focus works OK.'

Focus shift would affect manual focus as well.

 

[yeahright]

correct me if I'm wrong, but what is described in this blog post appears to be backfocusing instead of focus shift. In particular, it says 'The backfocusing happens only when using autofocus. Manual focus works OK.'

Focus shift would affect manual focus as well.

and since I could not wrap my head around how a *lens* (instead of a body) could actually backfocus, I searched a little more and found the accepted answer to this question (https://photo.stackexchange.com/questions/73740/how-can-lens-cause-consistent-front-or-back-focus) which says that AF control algorithms are (or were?) typically open loop (which explains why lenses can back-, or frontfocus), when I really couldn't imagine that open loop control was used for the purpose of autofocus.

 

[neuroanatomist]

correct me if I'm wrong, but what is described in this blog post appears to be backfocusing instead of focus shift. In particular, it says 'The backfocusing happens only when using autofocus. Manual focus works OK.'

Focus shift would affect manual focus as well.

I missed that, but note that focus shift in the context of a lens focused wide open (which is how AF works) then stopped down for the exposure will always result in backfocus. Even in a perfectly AF microadjusted body/lens combo. The 50L has deliberately undercorrected spherical aberration (SA) to improve the bokeh, and that leads to focus shift.

Manual focus with the DoF Preview button pressed is one of the workarounds for the 50L's focus shift. Another is to just shoot the lens wide open, since it's the change in aperture that's causing the focus shift. Or shoot at a sufficiently narrow aperture that the shifted focus is still within the DoF. But f/2 isn't narrow enough on an f/1.2 lens with a fair bit of SA.

 

[yeahright]

I missed that, but note that focus shift in the context of a lens focused wide open (which is how AF works) then stopped down for the exposure will always result in backfocus. The 50L has deliberately undercorrected spherical aberration to improve the bokeh, and that leads to focus shift.

Manual focus with the DoF Preview button pressed is one of the workarounds for the 50L's focus shift.

but do we agree that @InchMetric is correct in saying that even in the presence of focus shift the point in 'perfect' focus wide open will not become blurrier due to focus shift but sharper, albeit not as sharp as a point further away (or nearer). Focus shift can only affect lenses that are quite soft wide open.

 

[InchMetric]

Plenty of 'real world' examples of the focus shift on the 50/1.2L. Having a blurry eye and 'an even slightly better point of focus' on the ear is not better at all. Here's one blog example.

That blog was written by someone with vision problems, judging by the giant type face.

I'm glad to know that the best example is an old design for a camera mount I don't have. And the article doesn't seem to be about focus shift when stopping down, and might be a totally different issue with a bad lens. Evidence of focus shift might include an image showing focus on a subject point at full aperture, then an image stopped down with something at a different distance focused better than the subject point.

 

[neuroanatomist]

That blog was written by someone with vision problems, judging by the giant type face.

I'm glad to know that the best example is an old design for a camera mount I don't have. And the article doesn't seem to be about focus shift when stopping down, and might be a totally different issue with a bad lens. Evidence of focus shift might include an image showing focus on a subject point at full aperture, then an image stopped down with something at a different distance focused better than the subject point.

That was the first example I ran across (and the typeface is rather small on my iPhone and Mac, although the blogger seems to have issues with those devices). I’ve seen others. Focus shift is independent of the design age of a lens. In practice, it’s probably not a huge issue with the 50L because the typical subject distance for that lens is great enough to obviate the issue.

The magnitude of focus shift is inversely proportional to subject distance, and the RF 100L is a macro lens. If you’re using it for portraits, you likely won’t be affected by the focus shift. If you’re stopped down to f/14 for macro, also little to no effect. But with macro subjects at middle apertures, I suspect it will be noticeable with subjects like insects, where sharp focus on the eyes (or nearest eye) is critical, and focus shift would put the focal plane behind the eye.

 

[pardus]

picked up the RF100 the other day, shooting in studio it is noticeably softer than my EF version. pulled out the Spyder Lenscal and is also back focusing as well. At f11 is about 1/2" off. I guess no micro adjustment on the R5. Taking it back to the store tonight or tomorrow. attached image show 400% zoom on product label. for $2000cdn, you would expect it to be at least as good as the EF version. R5 on camera stand, IS off (on makes no difference in sharpness I found), f11. left is EF and right is the RF.

 

[Chris.Chapterten]

There is a possibility that some of these RF 100 macro lenses are more affected than other copies when it comes to focus shift. My RF 35mm 1.8, for example, was quite bad with it, to the point that I returned it for a refund. My RF 85mm F2 Macro on the other hand is one of my best focusing lenses at any aputure (even though some reviews say it also has a bit of focus shift?).

Honestly, I wouldn’t consider this lens if the Focus shift is picked up by other reviewers… but if it seems like a one off, I would be a bit less concerned…. Let’s see if other people pick up on this issue..

 

[darth mollusk]

Just tested my copy using the same methods as TDP – no sign of focus shift at all...

 

[InchMetric]

That was the first example I ran across. I’ve seen others. Focus shift is independent of the design age of a lens. In practice, it’s probably not a huge issue with the 50L because the typical subject distance for that lens is great enough to obviate the issue.

The magnitude of focus shift is inversely proportional to subject distance, and the RF 100L is a macro lens. If you’re using it for portraits, you likely won’t be affected by the focus shift. If you’re stopped down to f/14 for macro, also little to no effect. But with macro subjects at middle apertures, I suspect it will be noticeable with subjects like insects, where sharp focus on the eyes (or nearest eye) is critical, and focus shift would put the focal plane behind the eye.

View attachment 199065

When your best example has no relation to the topic, I’m unimpressed.

 

[neuroanatomist]

When your best example has no relation to the topic, I’m unimpressed.

I said it was the first example I ran across, not ‘my best example’. Either read more carefully or avoid attributing statements to me that I didn’t make. The issue isn’t of sufficient importance to me to find a ‘best’ example.

Not many examples out there at all from a barely-released new lens. Neither my EF 100 L macro nor my MP-E 65 exhibit focus shift (nor does my EF-M 28mm macro), and because I have both of those, I have no intention of buying the RF 100 L macro to see it and/or demonstrate it personally.

I trust Bryan’s (TDP) reviews, and if he tested two copies and found focus shift, it’s there. If you’re interested in the lens and confident the focus shift will not affect your images, you should buy the lens. I am neither, so I’m not planning to buy it.

 

[Del Paso]

It's a pity...
My dream macro combo was the R3 with Eye-Control AF plus the RF 100 .
Exit RF 100, unless a convincing fix is offered by Canon. I still can't understand what went wrong, how can a brand new macro lens have focus-shift, didn't anybody notice before Brian ???

 

[InchMetric]

I said it was the first example I ran across, not ‘my best example’. Either read more carefully or avoid attributing statements to me that I didn’t make. The issue isn’t of sufficient importance to me to find a ‘best’ example.

My apologies. I'll still note that there are no good examples of any modern Canon lens with "focus shift" problems that weren't quickly resolved in formware, virtually undectable in normal shooting, or both. Nothing posted yet on this thread but the hyperbolic "concern".