neuroanatomist said:

The supertele lenses all used to have a meniscus lens in front (essentially a flat piece of glass to protect the first refractive element, a permanent clear front filter). Dropping those from the design was a significant part of the weight saving for both Canon and Nikon lenses.

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DocInfoSci said:

With DLO the situation improves by leaps and bounds! It was DLO that kept the lens in my bag

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justaCanonuser said:

Due to a lack of time, I asked Perplexity (what I prefer since several years now over ChatGPT) why Nikon's Z system still offers AFMA and Canon's not, and explained in my prompt our specific AF problems with our Z8 & Z 600mm f/6.3 PF combo (with and w/o 1.4x TC). Perplexity's answer might be interesting for some nerds (like me) here:

Nikon Z cameras still offer AF fine-tuning because mirrorless autofocus is not automatically immune to optical tolerances. The camera can focus on the sensor plane very accurately, but a given camera/lens/teleconverter combination can still show small mechanical or optical offsets, especially when a teleconverter is added and the effective aperture gets smaller.[1][2]

Why the adjustment exists

The main reason is that focus accuracy is not just a software problem; it is also affected by lens design, manufacturing tolerances, adapter/teleconverter alignment, and how the camera interprets phase-detect data. Even in mirrorless, the system can be “close but not perfect” for a specific lens combination, so Nikon keeps fine-tune as a correction layer for edge cases and for users who need maximum precision.[3][2][1]

With long lenses, wide apertures, and teleconverters, the depth of field becomes very thin, so even a tiny offset looks like obvious backfocus or frontfocus. That is why a birding setup can seem fine in general use but still miss consistently on small distant subjects.[4][3]

Nikon vs Canon approach

Canon’s RF mirrorless system is generally more self-correcting in practice because Canon has leaned heavily on on-sensor phase detection and lens communication designed as a tightly integrated mirrorless platform. Nikon’s Z system also uses on-sensor phase detection, but Nikon still exposes AF fine-tune because it allows compensating for residual per-lens/per-body/per-converter variation rather than assuming every combination is perfect out of the box.[5][1]

The key difference is not simply “Canon has dual pixel, Nikon does not.” It is more about how each manufacturer implements lens-body calibration, predictive AF behavior, and tolerance management across the whole optical chain. Canon’s system tends to hide more of that from the user; Nikon gives the user a manual correction tool when the combination is off.[2][1]

Your specific setup

A Z8 plus Z 600mm f/6.3 PF plus TC 1.4x should normally focus well, so a “massive backfocus” points to an out-of-spec combination, a teleconverter/lens alignment issue, a body/lens calibration mismatch, or a focus-shift behavior that becomes visible only at the longer effective focal length and smaller maximum aperture. The fact that the issue appears both with and without the TC suggests the base lens/body calibration is already off, and the TC may be exaggerating it rather than causing it alone.[6][7][4]

Practical interpretation

So the short answer is: Nikon keeps micro-adjustment because mirrorless AF is not mathematically perfect for every optical combination, and Nikon chooses to let users compensate for residual system error. Canon’s RF system often feels more automatic because Canon’s implementation relies more on integrated on-sensor focusing and hides calibration differences better, but it is not because mirrorless AF fundamentally cannot need calibration.[1][5][2]

A useful rule of thumb is that if one Nikon Z lens or lens-plus-TC combo needs a large correction, that is usually a sign to test the lens, TC, and body separately, because the camera is compensating for a real mismatch rather than a normal tuning quirk.[8][6]

My personal conclusion: looks like we'd have to send this combo to Nikon's service because of too big production tolerances - typical Nikon's lousy quality, I have to say after many years of using Canon and Nikon gear side by side

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Nemorino said:

The German names are more different: Common - Sandregenpfeifer and Little - Flußregenpfeifer.


Thank you, Alan! The R5m2 and the RF 200-800 is a good combo to catch them. And I had good luck as they have been close enough.
Some more!
R5m2 + Rf 200-800 + 1.4 TC
View attachment 228916View attachment 228917View attachment 228918View attachment 228919

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ISv said:

In Germany you have two species of Ringed Plovers: the rare Common Ringed and the more often Little Ringed.

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AlanF said:

Well done! Those Little Ringed Plovers move very fast.

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justaCanonuser said:

...but my wife and I witnessed the murder of a mole (trigger warning: if you are too sensitive to the more brutal facts of life, don't scroll down).

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john1970 said:

A lightweight RF 500 mm f4 would be great as well and a nice surprise.

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neuroanatomist said:

I had one for a while. Bought it used and sold it a couple of years later for the same price that I had paid, essentially a free long-term rental.

I liked that it was the same size as my EF 24-105/4L IS. I was not a fan of the very busy bokeh, evident in the foreground here.

“Ribbit”
View attachment 228688
EOS 7D, EF 70-300mm f/4.5-5.6 DO IS USM @ 300mm, 1/500, f/6.3, ISO 640

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AlanF said:

The Canon EF 600mm f/4 DO IS BR USM was first announced as a working prototype in September 2015 during the Canon Expo in New York. 11 years later still not here. That is genuine vaporware, announced and never marketed.

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AlanF said:

I used Reiken Focal for may years to AFMA DSLRs. They still produce their software for mirrorless, which is basically a waste of time for Canon as it just gives some limited information, but it does work with Nikon AFMA, and they explain why and the improvements. https://www.reikanfocal.com/why-nikon-mirrorless.html

It was very good indeed for DSLRs and I found it invaluable and the quickest and most accurate AFMA tool.

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Bob Howland said:

Often, the best way to end the conversation is to let the other party have the last word.

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Del Paso said:

Friends!
When will we understand that it doesn't make sense to keep arguing with sect members, political fanatics, trolls or Sony fanboyz?
They never listen, convinced to be the beholders of Truth.
Let them keep their cute little tinfoil hats on and enjoy spreading their drivel !
If they have time to waste, let's not waste our time answering them.

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Nemorino said:

Somewhere I read Ringed Plover.

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John D P said:

Since, the current 400 & 600 primes are EF lenses adapted to the RF mount; their due for a refresh. Before the world cup would make sense, but that doesn't mean they will do it.

As for a switchable teleconverter; I would prefer a completely separate unit. That way it can be used on other lenses and when it's needed. A built in teleconverter adds weight, length, and cost to the lens. I only need 1.4, not a fan of a 2.0 teleconverters ( my personal opinion). They have a working switchable teleconverter from the EF 200-400mm, that has shown reliability for years. Why haven't they adapted this into a separate teleconverter; there is no doubt in my mind it would sell. I would buy it. SEE DISCUSSION BELOW. I've learned you can't make a generic separate switchable teleconverter.

In my opinion, since the introduction of the RF mount Canon has put the long glass needs on the back burner. During this time, Sony & Nikon have developed better options and it's time for Canon to step up. The classic example is the gap between the 100-500mm and 400/600mm primes in the "L" series lenses. If you want upgrade to 600mm or faster glass from your 100-500, your ONLY option is a $13 to 14k prime. Then there is the mythical 300-600mm that has been teased for years. This would be a great wildlife lens, if their smart enough to make it a variable aperture of f4 to 5.6. For those of us that shoot in low light and want better bokeh; a fixed f5.6 aperture is unacceptable at the 300 to 400mm range for the anticipated price of at least 7K.

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mimbu said:

Which is why Canon has blocked all 3rd party native glass from FF RF, and probably will do so in perpetuity.

Sigma's newer mirrorless native 150-600 is better optically than the EF glass while being less expensive, smaller, and lighter. Tamron's 150-500 is also excellent, and has extremely fast magnetic linear drive focus motors. (Sigma's 150-600 predates their magnetic linear AF, I expect their v2 will have that update.)

With no native RF competition, Canon can charge whatever they want for the 100-300/2.8 and 300-600/5.6. And they do/will.

Edit: For reference and comparison, the Sigma 150-600/5-6.3 DG DN OS Sports is US$875+tax here in Japan at the current exchange rate of USDJPY=159.

View attachment 228504


The Tamron 150-500/5-6.7 Di III VC VXD is US$737+tax:

View attachment 228505

These are the types of options that RF users miss out on because Canon does not believe in competition.

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Del Paso said:

And I paid just a little more for the RF100-500 and it is definitely better than The Sigma 150-600...

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AlanF said:

Yeah, people think that a TC should have minimal copy variation because they are relatively simple and have no moving parts. But, I've tested a few in the past and found variation. My RF 2xTC seems good. I was worried about my RF 1.4x but it's the same as two others I've tried.

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Ian K said:

It is yet to arrive, however I do agree, I couldn’t say no at that price. That said you do see grey imports on eBay for less, so I suspect they’re still making money.

Wex are as pukka a company as B&H in New York. They’re likely the largest camera retailer in the uk. They always have the stall right next to Canon every year. This year they had two stalls at the show. One next to Canon and another next to Nikon and Sony.

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Chig said:

Yes from what I've seen in reviews, Jan Wegener (who's highly regarded in the bird photography world and one of my favourite You Tubers) has tested it and said it's very good with 2x https://youtu.be/DYBNX16zIhw?si=yTqtOfKQ3DbILnkC

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justaCanonuser said:

Due to a lack of time, I asked Perplexity (what I prefer since several years now over ChatGPT) why Nikon's Z system still offers AFMA and Canon's not, and explained in my prompt our specific AF problems with our Z8 & Z 600mm f/6.3 PF combo (with and w/o 1.4x TC). Perplexity's answer might be interesting for some nerds (like me) here:

Nikon Z cameras still offer AF fine-tuning because mirrorless autofocus is not automatically immune to optical tolerances. The camera can focus on the sensor plane very accurately, but a given camera/lens/teleconverter combination can still show small mechanical or optical offsets, especially when a teleconverter is added and the effective aperture gets smaller.[1][2]

Why the adjustment exists

The main reason is that focus accuracy is not just a software problem; it is also affected by lens design, manufacturing tolerances, adapter/teleconverter alignment, and how the camera interprets phase-detect data. Even in mirrorless, the system can be “close but not perfect” for a specific lens combination, so Nikon keeps fine-tune as a correction layer for edge cases and for users who need maximum precision.[3][2][1]

With long lenses, wide apertures, and teleconverters, the depth of field becomes very thin, so even a tiny offset looks like obvious backfocus or frontfocus. That is why a birding setup can seem fine in general use but still miss consistently on small distant subjects.[4][3]

Nikon vs Canon approach

Canon’s RF mirrorless system is generally more self-correcting in practice because Canon has leaned heavily on on-sensor phase detection and lens communication designed as a tightly integrated mirrorless platform. Nikon’s Z system also uses on-sensor phase detection, but Nikon still exposes AF fine-tune because it allows compensating for residual per-lens/per-body/per-converter variation rather than assuming every combination is perfect out of the box.[5][1]

The key difference is not simply “Canon has dual pixel, Nikon does not.” It is more about how each manufacturer implements lens-body calibration, predictive AF behavior, and tolerance management across the whole optical chain. Canon’s system tends to hide more of that from the user; Nikon gives the user a manual correction tool when the combination is off.[2][1]

Your specific setup

A Z8 plus Z 600mm f/6.3 PF plus TC 1.4x should normally focus well, so a “massive backfocus” points to an out-of-spec combination, a teleconverter/lens alignment issue, a body/lens calibration mismatch, or a focus-shift behavior that becomes visible only at the longer effective focal length and smaller maximum aperture. The fact that the issue appears both with and without the TC suggests the base lens/body calibration is already off, and the TC may be exaggerating it rather than causing it alone.[6][7][4]

Practical interpretation

So the short answer is: Nikon keeps micro-adjustment because mirrorless AF is not mathematically perfect for every optical combination, and Nikon chooses to let users compensate for residual system error. Canon’s RF system often feels more automatic because Canon’s implementation relies more on integrated on-sensor focusing and hides calibration differences better, but it is not because mirrorless AF fundamentally cannot need calibration.[1][5][2]

A useful rule of thumb is that if one Nikon Z lens or lens-plus-TC combo needs a large correction, that is usually a sign to test the lens, TC, and body separately, because the camera is compensating for a real mismatch rather than a normal tuning quirk.[8][6]

My personal conclusion: looks like we'd have to send this combo to Nikon's service because of too big production tolerances - typical Nikon's lousy quality, I have to say after many years of using Canon and Nikon gear side by side

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