TC Match - Discussion

[JoelKlein]

We all know the built in TC’s are carefully matched to the lens.

I would like to learn more about this.

Is there a way to match an external TC to my 600PF?

 

[MrFotoFool]

We all know the build in TC’s are carefully matched to the lens.

We do?

 

[JoelKlein]

Lenses with built in TC’s or older F 800/5.6 had a matched TC

 

[Doug Herr]

We all know the build in TC’s are carefully matched to the lens.

I would like to learn more about this.

Is there a way to match an external TC to my 600PF?

It's possible, it has to be designed for that one lens and its use with other lenses will likely result in sub-optimal performance.

 

[MrFotoFool]

I misunderstood your initial post. I think you meant to type built-in TC's, not build in TC's. My apologies.

In that case the answer is no. Any stock Z TC (either 1.4x or 2x) should match your lens. Unless you mean is it theoretically possible for Nikon to design a TC that is tailored specifically for the 600PF. In that case the answer is theoretically yes but they would not bother because the current TC's work with that lens and others as well resulting in higher sales and profits than designing a TC that only works with one lens.

 

[Lance B]

Most of Nikon's tele and tele zoom lenses have been designed to be used with TC's. In the actual development process of a tele lens or tele zoom, they designers will design the lens so as to be able to use the TC's with little degradation as possible. In a way, adding a TC into the optical path of a tele prime is not that much different to them designing a tele zoom with a few extra elements or for that matter a zoom. The result should be as good if not better than a zoom in the same focal range as there are no moving parts to consider, just a prime and a TC with no zooming parts to consider. A zoom is obviously more complicated to design well as there are more aberrations to control like CA and distortion in a movable system and a TC will add to those issues if not done correctly or if the zoom is poor in that area to start with. This is why the pro spec zooms or tele prime for that matter work so well with a TC compared to a lesser zoom or prime. Some tele primes have few elements and thus a few extra elements in a TC will mean ending up with probably fewer elements than a zoom for the same given range and thus will have less degradation than a zoom.

The issue pre ML was that the AF system was more the culprit when poor results were obtained rather than the actual design of the lens/TC system. Now we have ML and focusing is off the sensor, the AF woes of the DSLR days are gone and the results are as the designers intended. There were also AF light restrictions for cross type AF sensors in that f8 max aperture was as far as you could go and even then the AF was still hit and miss. The results I have obtained on my Z cameras with both F mount primes with F mount TC's as well as Z mount lenses and TC's have borne out the notion that in reality a TC should do little to degrade IQ in most scenarios.

As for an external TC for your 600 PF, just use the Z 1.4x TC as it will be 99% as good as a dedicated inbuilt TC like that of the Z 400 f2.8 + TC or the Z 600 f4 + TC, bearing in mind the fact that the latter lenses are high priced pro spec teles with faster apertures and thus let more light in and will have a lower ISO for a given scenario. I can assure you that my 400 f2.8E FL VR + 1.4x TCIII would stack up very well against the new Z 400 f2.8 + TC (inbuilt) when you consider that my 400 f2.8 E FL VR is not a Z lens nor has the newer lens type elements and newer computer design advantages. The Z lens would have possible better CA and edge to edge sharpness benefits, but that has much to do with the wider lens mount rather than a lens/TC matching issue.

 

[Steve W]

We all know the built in TC’s are carefully matched to the lens.

I would like to learn more about this.

Is there a way to match an external TC to my 600PF?

The short answer is no.
There is no way to calibrate the TC to the lens. About all you can do is fine tune your a/f settings when the TC is mounted.

The “ carefully matched” in built TC’s you speak of will simply be checking the alignment and ensuring that the lens / TC combo performs within the manufacturer’s specifications. The unit you receive should be within tolerance. They will not be shuffling through piles of TC’s to find one that is as good as it can be. They are doing volume manufacturing not making “ one off’s”.

 

[Len Shepherd]

Short answer - I do not own enough equipment to test for myself

The .25x converter for the 800 mm F mount lens I consider a one off.
As far as I know it cannot be bought other than with this 800mm lens.
Nikon indicate it is designed specifically for this one lens, and each converter is matched to each individual lens. How this is done seems not explained.

The external F mount 1.4 converters work with a range of about 12 lenses; some of which like the 400 f4 sold in good numbers and some like the 600 F4 primarily because of price have low volume sales.
Looking at the Z system, few would doubt that the Z 1.4x converters is likely to be used most on the 180-600 because of the lens price point.
What I can say is that, possibly because of the wider lens throat, I find higher optical quality comes with Z mount converters than F mount converters.

The only lens I own with an internal converter is the 180-400.
I cannot detect any optical difference between using the internal converter and an external 1.4x III.
Some others report a little disappointment with this internal converter.
Either way I find it is extremely convenient to use.

While marginal optical improvements might be possible with a 1.4 x specifically designed for a 600, sales might at best be a few hundred units, likely making it economic to design, manufacture and market.
If it happened for those owning several Z mount 1.4x compatible lenses different converters would be needed for each lens.
I consider it fair to say it will never happen for F mount lenses because product development seems to have definitely ended for F mount products.

 

[bleirer]

I shoot Canon but I think it's the same idea. Only some lenses take an extender, but those that do are built to be compatible with the Canon 1.4 or 2.0. The other lenses won't even mount the extenders.

 

[MrFotoFool]

For the record I use a Z 2x teleconverter on my Z 70-200 f2.8 and the results are outstanding. With SLR I would not use a 2x (I tried) because it was too soft so I stuck with 1.4x, but on Z mount the 2x is really sharp. I am sure the 1.4x is even better and with your 600PF I doubt you would see much of any difference with or without it (other than the one stop slower aperture).

 

[fcotterill]

The critical differences and factors determining image quality with a Teleconverter are known only to an elite cadre of Nikon experts, who designed these optics. This includes the specific optical glass made at their Hikari factory.

This 1001 Nights essay lauds the engineer for his overcoming the challenges to improve the quality of the redesigned F AFS Nikkor primes with Teleconverters in the mid 1990s and thereafter

NIKKOR - The Thousand and One Nights No.67 | NIKKOR - The Thousand and One Nights | Nikon Consumer

The TC125-800 is indeed a one off in Nikon's long history of optical innovation. I use my 800 f5.6E FL mostly as a 1000 f7.1 (examples). It is an excellent combination. Latterly, the integral TCs in the 3 newer telephotos have probably superseded this design, and each is fine tuned with its lens.

There are variations in quality in the f mount TC's, notably TC2 III (if you find a good copy, treasure it!). The production quality of the new Z mount versions seems to be more consistent, probably thanks to robotics and improved QC.

Nikon lists compatible lenses, but doesn't say much more about optimal pairings. However, some of the best pairings are shared here in BCG threads.

 

[arbitrage]

I really don't think the built-in TCs are matched to the lens. I've never seen any evidence of that. Maybe the bespoke external 1.25x for the 800E was but even then I saw many reports of a random off the shelf 1.4TCIII being better than the supposedly "matched" 1.25xTC.
I know when I owned the Canon 200-400TC the external 1.4TCIII was slightly better than the built-in. Of course Canon could be different than Nikon so maybe Nikon is matching them better.
As someone already mentioned, all I see Nikon doing during final testing of a given lens is testing it meets specification tolerances with the built-in TC switched in or out.

As far as matching an external TC to the 600PF, I guess you could purchase one and send it to NPS to have them calibrate? Not sure if they would even do that. Back in DSLR days this was sometimes done but often involved the camera as well. Or people micro-adjusted themselves with the TC on.
I don't think I'd worry much about it. Sounds like people are getting great results with any random Z1.4TC they already own and stick on their new 600PF.

 

[fcotterill]

I've read, and also been told by an ambassador who toured the factory in Japan that a skilled technician does the final assembly and checks alignments and quality etc by hand. This includes the 180-400 f4E TC14. The same factor possibly explains the low numbers and delays with shipping the 400 f2.8S and 600 f4S with their integral TCs.

"Which Nikon telephoto(s)?" for Wildlife Genres: Updated

The internal lever shifts the TC elements LR on the 180-400 f4E TC14, and presumably the same in the 400 f2.8S. Note the internal TC in the latter is larger and more complex than any of Nikon's external F mount TC14's, although its large anterior element is reminiscent of the ext ZTC14. If each...

bcgforums.com

Visite d’usine : sur la ligne d’assemblage du NIKKOR Z 24-70mm f/2.8 S à Nikon Tochigi au Japon

Nous avons visité l'usine Nikon, dans la préfecture de Tochigi, à moins de 200km au nord du Japon. C’est dans cette région montagneuse, qui regroupe plusieurs domaines skiables, que Nikon fabrique notamment ses optiques NIKKOR haut de gamme comme le dernier NIKKOR Z 24-70mm f/2.8 S.

phototrend.fr

Thom Hogan also mentioned these factors entailed in the high quality production and cost of telephoto exotics - notably hand assembly:
".... the really large fluorite elements also have a supply limitation. Top end glass in general has a year-long gestation from pour to final polish, and not all pours net the huge sections of glass needed for the big elements as easily as they do for smaller ones. Someone once told me that element size was almost an exponential constriction in supply. Add in (2) hand assembly and alignment to insure highest quality, and you have a very non-modern, tough-to-scale manufacturing problem on your hands."

Further to above, Nikon's new lens coatings are also a factor in improved optical performance of the Z lenses. Who knows how the New Z TC's differ from the F models in coatings and also their optical glass(es) used in their elements. Apart from schematics of Super-ED, ED, FL, SR elements etc, the marketing copy about Nikkor optics details nothing much more about the propriety optical glasses used in the company's exotic lenses. However, a recent technical report describes how the 58 f0.95S uses many different types of glass.

Nikon enjoys these advantages to fine tune its optical designs from its own glass [Hikari] factory. Building with such rarer types of glass elements will also be a major factor in the selling price of a lens. While a large fluorite element in a telephoto pushes up the price, Nikon could also be using other special propriety glass in these optics.

View attachment 72095

 

[EricKlees]

I thought i read somewhere that the Z 400f2.8TC and the 600f4TC built-in TC's were designed to be part of the Internet lens elements and mage then optically better then an external TC. That was one of the reasons of the shower production rates.

 

[JoelKlein]

When a TC is matched, it’s matching what to what?

 

[DRwyoming]

When a TC is matched, it’s matching what to what?

It's really just checking the optical alignment of the lens plus TC combo to make sure everything is still in spec.

That might mean trying a different TC group assembly for a better total optical performance or it might mean some amount of main lens alignment to make sure it still performs to spec with the 'matched' TC engaged. In the case of something like the F mount 800mm f/5.6 that shipped with a matched TC it might just mean testing several candidate TCs and shipping the one that gave the best, in spec performance of the lens plus TC combo.

Basically everything that comes off an assembly line in mass production has production tolerances and slight variations in performance. If you're unlucky enough to get a lens with its own manufacturing tolerances paired with a TC with its own tolerances and those tolerances don't play well together the net result might be out of spec or sub-optimal.

A matched TC whether internal or something like the matched TC shipped with the 800mm f/5.6 means that either the lens or TC is selected and the lens itself may potentially be adjusted so both the bare lens and lens with TC added are within a defined spec and ideally work particularly well together. That's as opposed to a situation where the lens may be on one side of the acceptable tolerance range, the TC on the other side of the range, both in spec individually but perhaps not working well together.

 

[Lance B]

When a TC is matched, it’s matching what to what?

Are you referring to the Z 400 f2.8 + TC and Z 600 f4 + TC or the standard F mount and Z mount tele lenses matched to the F mount and Z mount TC's respectively?

In the Z mount 400 f2.8 + TC and 600 f4 + TC, they are matched during the design stage to be as optically perfect as they can be designed within the constraints of size, weight and cost etc.

With regards to say a Z mount tele lens matched to a Z mount TC, the TC and tele lens are designed together as though they are a single unit so that they will work together - in essence "matched" to get the best with the combo within the constraints of size, weight and cost.

 

[JoelKlein]

It's really just checking the optical alignment of the lens plus TC combo to make sure everything is still in spec.

That might mean trying a different TC group assembly for a better total optical performance or it might mean some amount of main lens alignment to make sure it still performs to spec with the 'matched' TC engaged. In the case of something like the F mount 800mm f/5.6 that shipped with a matched TC it might just mean testing several candidate TCs and shipping the one that gave the best, in spec performance of the lens plus TC combo.

Basically everything that comes off an assembly line in mass production has production tolerances and slight variations in performance. If you're unlucky enough to get a lens with its own manufacturing tolerances paired with a TC with its own tolerances and those tolerances don't play well together the net result might be out of spec or sub-optimal.

A matched TC whether internal or something like the matched TC shipped with the 800mm f/5.6 means that either the lens or TC is selected and the lens itself may potentially be adjusted so both the bare lens and lens with TC added are within a defined spec and ideally work particularly well together. That's as opposed to a situation where the lens may be on one side of the acceptable tolerance range, the TC on the other side of the range, both in spec individually but perhaps not working well together.

Nailed it.
Back to my question,
In the Z world,
A TC (1.4) on one end of the tolerance range, a lens on the other end, would not play nice together.
Vs.
Both, TC and lens are as close as possible to perfection.

How do we measure that? We can’t.
Its a guessing game? Probably.
With the F TC’s it was for sure a guessing game. I cycled 3 TC’s for the 500pf.

So I don’t have the budget for a 400/600TC lens, but at least I would like the idea of matching a TC for the 70-200, or 600pf. Is Nikon the only ones capable of performing these calculations? Or it’s something someone with knowledge and skill and the right tools that can do this as well?

I’m curious.

 

[fcotterill]

Nailed it.
Back to my question,
In the Z world,
A TC (1.4) on one end of the tolerance range, a lens on the other end, would not play nice together.
Vs.
Both, TC and lens are as close as possible to perfection.

How do we measure that? We can’t.
Its a guessing game? Probably.
With the F TC’s it was for sure a guessing game. I cycled 3 TC’s for the 500pf.

So I don’t have the budget for a 400/600TC lens, but at least I would like the idea of matching a TC for the 70-200, or 600pf. Is Nikon the only ones capable of performing these calculations? Or it’s something someone with knowledge and skill and the right tools that can do this as well?

I’m curious.

Probably the only practicable way is to buy several copies of the ZTC14 and test them on your lens.

Perhaps it will reveal slight variation but only with a strictly rigorous methodology and ideally using a MTF software on a test bed.

A setup like LensRentals is ideally qualified to do this. They test multiple copies of lenses in their inventory.

 

[fcotterill]

The Z7 built in Nikon's Sendai factory relied on robots for 75% of the assembly processes. This was the situation in September 2018. And note the author was astounded at the increased reliance on robots from what he'd seen used previously for the D3 circa 2007.

Nikon's reliance on automated robotics can only have grown since ~6 years ago; especially as their corporate restructuring has created an entire Robotics Division, leveraging on recent acquisitions of pioneering companies (eg Roberts).

Of particular relevance to the quality of today's Teleconverters is the section in this Z7 article describing how Nikon was already assembling the EVF of the Z7 entirely with dedicated robotic plant. This method guarantees much higher, consistent precision compared to human assembly, even by experts.

Robotics is likely to be a major factor that undergirds the improved quality of the Z Optics... A system similar to the "EVF Robot" is ideally suited to dedicate for the precision alignment of the elements in a TC.

Nikon Sendai factory tour: A rare chance to see Z7 production up close and personal

I recently had a chance to tour Nikon’s Sendai camera factory, as part of the festivities surrounding the launch of their new Z-series full-frame mirrorless line. While we couldn’t take any photos during the tour, it…

www.imaging-resource.com

 

[Len Shepherd]

Not discussed yet is that in lens TC's have relative small lens element diameters compared to largest element diameter in the detached TC 14-E III.

The reason seems to be that a built in TC has to be moved into and out of the optical axis to work, ideally without a huge hump on the side of the lens to accommodate a converter with larger lens element diameters.

With my 180-400 F there is more image corner shading wide open using the built in TC than the TC-1.4 E III.

It should be possible to correct or reduce any in lens TC corner shading electronically with the 400 f2.8 and 600 f4 S lenses each with their own built in TC.
Maybe one day I will have the money to own one or both to find out for myself.

 

[DRwyoming]

How do we measure that? We can’t.

It can certainly be measured but few of us would invest in the necessary optical testing equipment to make those measurements. We can do things like sharpness testing against testing targets to see if one combo of TC and lens works better than another combo from sharpness and contrast alone but an actual optical testing bench capable of measuring: MTF, collimation, astigmatism, distortion, field curvature, etc. especially for super telephoto lenses would cost much more than the lenses themselves. That and the knowledge and skill to not only use the testing equipment well but then to make any necessary lens element adjustments is beyond most of our skills.

The Imatest system is one of the most affordable lens testing systems but it's still crazy expensive and pushed to its limits when testing super telephoto lenses but it's one way to quantify lens testing.

I’m curious.

If you're curious about lens measurements, Google 'MTF test benches' or 'Imatest, lens testing equipment' or 'Lens test benches' or the like. There's an entire industry of lens testing equipment, methods, standards and the like that apply to testing lens plus TC combos just like it applies to testing individual lens elements or complex lens designs but it's not simple and not cheap.

A good lens repair shop should have equipment to measure and align lenses for things like: collimation, optical axis alignment and other first order characteristics but measuring every known aspect of lens and lens plus TC performance takes a lot of gear and a lot of skill to do well.

 

[Nimi]

It can certainly be measured but few of us would invest in the necessary optical testing equipment to make those measurements. We can do things like sharpness testing against testing targets to see if one combo of TC and lens works better than another combo from sharpness and contrast alone but an actual optical testing bench capable of measuring: MTF, collimation, astigmatism, distortion, field curvature, etc. especially for super telephoto lenses would cost much more than the lenses themselves. That and the knowledge and skill to not only use the testing equipment well but then to make any necessary lens element adjustments is beyond most of our skills.

The Imatest system is one of the most affordable lens testing systems but it's still crazy expensive and pushed to its limits when testing super telephoto lenses but it's one way to quantify lens testing.


If you're curious about lens measurements, Google 'MTF test benches' or 'Imatest, lens testing equipment' or 'Lens test benches' or the like. There's an entire industry of lens testing equipment, methods, standards and the like that apply to testing lens plus TC combos just like it applies to testing individual lens elements or complex lens designs but it's not simple and not cheap.

A good lens repair shop should have equipment to measure and align lenses for things like: collimation, optical axis alignment and other first order characteristics but measuring every known aspect of lens and lens plus TC performance takes a lot of gear and a lot of skill to do well.

To add. One of the issues of external TCs, especially with bigger lenses is alignment due to a slumping front, leading to "keystone" effect. The addition of two mounting surfaces, neither perfectly flat makes axis alignment nearly impossible. So it's no longer just center to edge difference, its also top to bottom. That's one of the reasons internal TCs are so far superior. With that said, the widening opening and the lightening of the lenses themselves help.

 

[Calson]

I used the TC-14 with the 500mm PF with some success. The 700mm at f8 was far from ideal in terms of the autofocus performance of the D850 camera, even in bright light conditions. I chose the 800mmm PF instead of a 600mm focal length lens as most of the time I used a 1.4x TC with my 600mm f/4 lenses.

The TC-14 III version is very sharp and the equal of the Z 1.4x TC for use with a lens. The II version was noticeably soft.