Help me understand Nikkor Phase Fresnel elements (PF)

[Midway]

I have never owned or researched a Nikon PF lens. The rumored 600 PF lens has me interested in what that means now and for future lens development. The little research I have done seems to indicate PF allows smaller and lighter elements while maintaining quality. Since PF has only been around for a few years, how will Nikon develop this moving forward?

The top tier Z 400 f2.8 TC and 600 f4 TC lenses do not have PF elements nor does the 400 f4.5. That tells me that if the higher end lenses don’t use PF, while a great way to maintain quality with lighter lenses, PF is still not the best glass Nikon offers.

I am looking for a lighter lens for longer hikes and my current 600 f4 TC and 180-400 TC are large and heavy. I’m leaning towards a 400 f4.5 for a casual hiking lens but curious what the new 600 PF will offer since I rarely find 600 too long but also find myself in trees and low light while hiking.

Since PF is so new, it will be interesting to see how Nikon will advance this relatively new technology and if it will make its way into the exotics.

 

[StevieJSmall]

I'll let the more technically inclined folks weigh in. Some are even former Optical engineers.

From a simpleton's point of view (that would be me as it pertains to optics), given Nikon has come out with the 300PF and 500 PF for the F Mount and the 800 PF for the Z Mount, the 600 PF "formula" for success isn't complicated. The 500 PF and 800 PF are very highly regarded and the advantages gained in terms of size, weight and price for the performance you get offset the compromises you make in image quality in not using a 400 f/2.8 or 600 f/4.

Key word is compromise here in that the PF's won't be able to get to the same performance level as the high prices exotics because those are designed to get you the ultimate image quality across a broad spectrum...but especially when the loss of light becomes more impactful. A f/2.8 or f/4 is always going to win out over a f/6.3 in dealing with lower light...but the PF lenses offer more versatility in weight, hand holdability, and again, price for performance.

Can the average person tell the difference between a f/4 exotic or the 6.3 PF? Most likely not...and I'd argue even those who are more discerning would have trouble in "normal" conditions.

Bottom line: PF's are the "poor photographer's" exotics and would never expect them to make their way into the cream of the crop...and they don't need to because they're unto a class all themselves and deservedly so.

 

[MrFotoFool]

I am not a technician, but here is my layman's understanding of Nikon PF, which I think(?) is the same as Canon DO (Diffractive Optics, which as far as I know they have only used in some SLR lenses and not in any of their mirrorless lenses)? One of the lens elements (or is it more than one) has concentric circles etched into it which bends the light, allowing for a smaller than usual design on a telephoto lens.

I owned the Nikon F mount 500 PF for a couple years and based on my own experience I only noticed one issue with PF design over traditional design. In distant shots (focusing on a coyote far away) the ground immediately behind the subject (next to it) had what is described as nervous bokeh. It was not smooth, but just looked odd (hard to describe in words but very apparent to me). On closeup shots, such as a bird on a perch with a soft background, it is a non-issue.

 

[fcotterill]

Phase-fresnel optical elements have been around for many years, and concept was invented in the early 19th century. They are used in very bright lanterns, as for lighthouses to concentrate light rays etc.

Phase Fresnel Lenses and the Long History of Optics

I file a lot of stories, and very occasionally one doesn't work out. The below explanation of phase Fresnel lenses is one of them. I couldn't hit the right tone for its original destination, and shopped it around, but it wasn't quite a fit anywhere. Enjoy this look into lighthouses, lenses, and the

glog.glennf.com

The technical challenges for a photography application is to achieve very high precision in the concentric rings at a microscale and build the machines to mass produce PF elements of basically faultless quality - within tight specifications.

Nikon's solution as to how it makes Phase Fresnel elements is classified. But it appears to involve precision molds using a proprietary polymer shaped from two types of optical resin. I'd also speculate Nikon's expertise in ultralithography (semiconductor etching etc) positions them to apply this technology in precision optics... Pure guess here, however.

There's these articles and interview at the launch of the 300 f4E PF with useful diagrams (Google translates...)

Phase Fresnel: From Wildlife Photography to Portraiture

Nikon Ambassador Moose Peterson tests out the AF-S NIKKOR 300mm f/4E PF ED VR lens.

www.nikonusa.com

Nikon Nikkor AF-S 300 mm f/4E PF ED VR review - Introduction - LensTip.com

Best digital cameras and lens reviews. If you are looking for the information about digital cameras and lenses you are in a right place. We have many professional tests of digital photography equipment.

www.lenstip.com

小型化と高性能化を両立 ニコン「AF-S NIKKOR 300mm f/4E PF ED VR」 位相フレネルレンズの仕組みとは?

ニコンが1月に発売した「AF-S NIKKOR 300mm f/4E PF ED VR」は、従来から大幅に小型化を図ったと同時に画質も向上させた35mmフルサイズ用の超望遠レンズ。実に14年ぶりとなったリニューアルでは、ニッコールレンズで初めてとなる「位相フレネルレンズ」を採用した。

dc.watch.impress.co.jp

And see this older thread

More Nikon PF Lenses?

I think the PF technology is incredible! However, none of the existing lenses using it are exactly what I want from it. So I thought it would be interesting to talk about other possibilities for the technology. For me, I wish they were slightly heavier. Not cause I want more weight but because I...

bcgforums.com

 

[Steve W]

Apart from some electronics, almost nothing is new anymore, just more refined. Fresnel lenses have been around since the late 1700’s, The first supercharger was in the late 1800’s, turbo charging in early 1900’s, electronic fuel injection in the late 50’s, telescopes, cameras, power tools, nothing new, just vastly improved.

 

[Wes Peterson]

Normal lenses are refractive, PF lenses are diffractive. Those 2 type of lenses used together cancel out each others chromatic aberrations quite effectively. That in turn reduces the overall number of large elements needed to correct the CA. That seems to be the reason why the PF lenses can get away with being smaller than their refractive only counterparts.

 

[EricBowles]

Nikon's released three lenses with PF elements to date - the 300mm f/4 PF, the 500mm f/5.6 PF, and the Z 800mm f/6.3 PF. The upcoming 600mm PF is the latest version.

The big advantage of PF lenses is they are smaller and lighter than typical non-PF alternatives. To date, every PF lens has been very sharp so there are no issues with sharpness. The one issue that concerns me is the bokeh with specular highlights in the background. The bokeh is textured rather than smooth. This is not something you run into frequently, but can be a problem because it is a unique artifact associated with PF elements. The more recent 800mm PF has very little sign of problem bokeh - so I suspect is is not going to be a factor with the 600mm PF.

Nikon originally designed the Z 400mm f/4.5 with a PF lens element, but revised the design to not use a PF element. I suspect they were not happy with the bokeh - and the 400mm f/4.5 has wonderful smooth bokeh.

In my mind the advantages of PF lenses far outweigh the disadvantages, but this was a factor in my decision to choose the 400mm f/4.5 over the 500mm f/5.6. I do have the 800mm PF and consider the bokeh pretty good, but I may just not have run into the right circumstances to surface a problem.

Here is what it looks like on a 500mm f/5.6 PF. The bokeh has an amoeba-like pattern. It's a little worse on the 300mm PF.

You can only see EXIF info for this image if you are logged in.

 

[MrFotoFool]

...Nikon originally designed the Z 400mm f/4.5 with a PF lens element, but revised the design to not use a PF element...

I was not aware of this. I wonder if the PF version would have been f4?

 

[EricBowles]

I was not aware of this. I wonder if the PF version would have been f4?

It's pretty compact already. I think they had originally planned f/4.5. In addition to the bokeh issue, PF lenses are harder to produce and reportedly take a lot longer to manufacture. During the time China was shut down with lingering Covid issues, I'm not sure Nikon was willing to accept uncertainty in the supply chain. There are pros and cons with PF lens elements.

 

[Midway]

Phase-fresnel optical elements have been around for many years, and concept was invented in the early 19th century. They are used in very bright lanterns, as for lighthouses to concentrate light rays etc.

Phase Fresnel Lenses and the Long History of Optics

I file a lot of stories, and very occasionally one doesn't work out. The below explanation of phase Fresnel lenses is one of them. I couldn't hit the right tone for its original destination, and shopped it around, but it wasn't quite a fit anywhere. Enjoy this look into lighthouses, lenses, and the

glog.glennf.com

The technical challenges for a photography application is to achieve very high precision in the concentric rings at a microscale and build the machines to mass produce PF elements of basically faultless quality - within tight specifications.

Nikon's solution as to how it makes Phase Fresnel elements is classified. But it appears to involve precision molds using a proprietary polymer shaped from two types of optical resin. I'd also speculate Nikon's expertise in ultralithography (semiconductor etching etc) positions them to apply this technology in precision optics... Pure guess here, however.

There's these articles and interview at the launch of the 300 f4E PF with useful diagrams (Google translates...)

Phase Fresnel: From Wildlife Photography to Portraiture

Nikon Ambassador Moose Peterson tests out the AF-S NIKKOR 300mm f/4E PF ED VR lens.

www.nikonusa.com

Nikon Nikkor AF-S 300 mm f/4E PF ED VR review - Introduction - LensTip.com

Best digital cameras and lens reviews. If you are looking for the information about digital cameras and lenses you are in a right place. We have many professional tests of digital photography equipment.

www.lenstip.com

小型化と高性能化を両立 ニコン「AF-S NIKKOR 300mm f/4E PF ED VR」 位相フレネルレンズの仕組みとは?

ニコンが1月に発売した「AF-S NIKKOR 300mm f/4E PF ED VR」は、従来から大幅に小型化を図ったと同時に画質も向上させた35mmフルサイズ用の超望遠レンズ。実に14年ぶりとなったリニューアルでは、ニッコールレンズで初めてとなる「位相フレネルレンズ」を採用した。

dc.watch.impress.co.jp

And see this older thread

More Nikon PF Lenses?

I think the PF technology is incredible! However, none of the existing lenses using it are exactly what I want from it. So I thought it would be interesting to talk about other possibilities for the technology. For me, I wish they were slightly heavier. Not cause I want more weight but because I...

bcgforums.com

While I didn't know how long PF technology has been available, I could have been more specific in that Nikon first offered it in their lenses a few years ago. The 300 was 8 years ago I learned.

This is a lot of great information. Thank you.

 

[Midway]

Thanks all for the input. I decided to buy the Z 400mm f/4.5 VR S Lens. I was tempted to wait for details on the rumored Z 600 PF but already owning the 600 f4 TC, I didn’t want to duplicate focal lengths. I also own a Z TC 1.4 that gets me close to what the new rumored lens focal range and aperture offers while having a faster 400mm option the 600 doesn’t have. I looked at the 800 6.3 but it is twice the weight of the 400 f4.5.

With size and weight a main concern for longer hikes and casual use, I still wanted a top-quality lens. I considered the 100-400 and 180-600 zooms that I think I would also be happy with, but the 400 f4.5 seemed the best fit for my type of shooting. I still have the 180-400 TC as a great zoom though like the 600 f4 TC it is a heavy lens for longer hikes.

Thanks again.

 

[JoelKlein]

@EricBowles
What’s the source of the 400/4.5 original PF plan? It’s not that I don’t believe you, I don’t recall Nikon telling us their plans, I’m curious.

 

[DRwyoming]

I was not aware of this. I wonder if the PF version would have been f4?

PF lenses don't allow a larger aperture in the same lens diameter. Sure the PF elements are lighter and thinner but the overall diameter for f/4 vs f/4.5 remains the same whether conventional elements or PF elements are used. I guess it's possible that Nikon might have considered a 400mm f/4 in PF to keep the weight similar but it would have been a larger diameter lens with a larger diameter front element and larger diameter body so really a very different lens than what the 400mm f/4.5 that they released.

 

[JoelKlein]

PF lenses don't allow a larger aperture in the same lens diameter. Sure the PF elements are lighter and thinner but the overall diameter for f/4 vs f/4.5 remains the same whether conventional elements or PF elements are used. I guess it's possible that Nikon might have considered a 400mm f/4 in PF to keep the weight similar but it would have been a larger diameter lens with a larger diameter front element and larger diameter body so really a very different lens than what the 400mm f/4.5 that they released.

Nikon is taking advantage of the better ISO technology and noise reduction, they are setting new standards with those f/6.3 lenses.
Next camera mount will be even bigger, better sensors, and the new lens lineup would be f/8…

 

[Larry S.]

Nikon's released three lenses with PF elements to date - the 300mm f/4 PF, the 500mm f/5.6 PF, and the Z 800mm f/6.3 PF. The upcoming 600mm PF is the latest version.

The big advantage of PF lenses is they are smaller and lighter than typical non-PF alternatives. To date, every PF lens has been very sharp so there are no issues with sharpness. The one issue that concerns me is the bokeh with specular highlights in the background. The bokeh is textured rather than smooth. This is not something you run into frequently, but can be a problem because it is a unique artifact associated with PF elements. The more recent 800mm PF has very little sign of problem bokeh - so I suspect is is not going to be a factor with the 600mm PF.

Nikon originally designed the Z 400mm f/4.5 with a PF lens element, but revised the design to not use a PF element. I suspect they were not happy with the bokeh - and the 400mm f/4.5 has wonderful smooth bokeh.

In my mind the advantages of PF lenses far outweigh the disadvantages, but this was a factor in my decision to choose the 400mm f/4.5 over the 500mm f/5.6. I do have the 800mm PF and consider the bokeh pretty good, but I may just not have run into the right circumstances to surface a problem.

Here is what it looks like on a 500mm f/5.6 PF. The bokeh has an amoeba-like pattern. It's a little worse on the 300mm PF.
View attachment 71418

You can only see EXIF info for this image if you are logged in.

Exactly as Eric described… this cardinal was shot a couple weeks ago w/Z9 & 500mm pf wide open at f/5.6. The bokeh behind the bird is roundish or not at all…..

 

[fcotterill]

While I didn't know how long PF technology has been available, I could have been more specific in that Nikon first offered it in their lenses a few years ago. The 300 was 8 years ago I learned.

This is a lot of great information. Thank you.

Interesting technology There's a 1001 Nights article cited in the thread (also linked above). To quote:

It also has been mentioned by a Nikon engineer they had planned PF camera lenses earlier: “….Mr. Fujie was active in many fields, not only with photographic lenses, but also with viewfinder optics and device optics. He also took the initiative in the development of PF lenses, though none of these lenses were ever released.” https://imaging.nikon.com/history/story/0057/index.htm

Nikon has used phase-fresnel elements in some of its microscopes and one of the Coolpix lenses. The great leap forward for Nikon seems to have been developing the technology to mass produice much larger PF elements. So as of today, Nikon now has a total of 4 PF primes in its Greater Ecosystem. There is also a more recent patent for zoom PF telephotos, but many patents do not materialize.

In summary: "Conventionally, it has been known that providing a diffraction surface in an optical system has an achromatic effect (for example, see Patent Document 1). Particularly in telephoto lenses, a greater achromatic effect can be achieved by placing the diffractive surface as close to the front of the lens group (on the object side) as possible, which allows the overall length and weight of the optical system to be reduced. However, on the other hand, if strong light enters the diffraction surface from outside the imaging screen, the diffracted light may become flare and reduce the contrast of the entire screen. For this reason, it is desired that the diffraction surface be placed at an appropriate position where it can sufficiently exhibit the achromatic effect while reducing the reduction in contrast due to flare."

 

[EricBowles]

@EricBowles
What’s the source of the 400/4.5 original PF plan? It’s not that I don’t believe you, I don’t recall Nikon telling us their plans, I’m curious.

It was in one of the announcement videos - an interview with Nikon engineers I believe.

 

[JoelKlein]

It was in one of the announcement videos - an interview with Nikon engineers I believe.

Thank you. I like those interviews

 

[Len Shepherd]

At the basic level a "Diffractive Element" has concentric rings on the surface.
A "Diffractive element" enable a lens to be made physically shorter and lighter with fewer lens elements than a conventional lens.

In the current Grays of Westminster Nikon Owner Magazine (number 80) there are comments by their technical specialist Simon Stafford who is very close to Nikon and IMO very likely to be right.

1/ A number of manufacturers have different approaches to making Diffractive Elements

2/ "Phase Fresnel" is specific Nikon technology.

3/ With Nikon "Phase Fresnel" the concentric rings across the lens element surface of a Nikon Diffractive Element have a slightly variable curvature instead of a single curvature of a conventional Diffractive Element.

4/ There is a caution strong off centre back lighting can can produce flare - that I describe as a former owner of the 300 PF as "interesting".

The Nikon specification for the 500 PF says "--- by adopting newly developed lens materials, flare effect due to the characteristics of the PF lens ("lens element" might be a better description) is optimally controlled ---"

The Nikon specification for the 800 PF says "With the combination of optimal shape and location of the PF lens element and proven Nano Crystal Coat, clearer images with reduced ghost can be achieved".

I can confirm as a several years owner of the 500 F mount PF and owner of the 800mm S PF lens that so far I have not encountered the "interesting flare" I occasionally encountered with the 300 PF.

Summing up it seems Nikon Phase Fresnel Diffractive Elements are different to other manufacturers DE lens elements.

If you wish you can subscribe to Nikon Owner (with access to all back copies) via Grays of Westminster.

 

[Bob Hullinger]

I have never owned or researched a Nikon PF lens. The rumored 600 PF lens has me interested in what that means now and for future lens development. The little research I have done seems to indicate PF allows smaller and lighter elements while maintaining quality. Since PF has only been around for a few years, how will Nikon develop this moving forward?

The top tier Z 400 f2.8 TC and 600 f4 TC lenses do not have PF elements nor does the 400 f4.5. That tells me that if the higher end lenses don’t use PF, while a great way to maintain quality with lighter lenses, PF is still not the best glass Nikon offers.

I am looking for a lighter lens for longer hikes and my current 600 f4 TC and 180-400 TC are large and heavy. I’m leaning towards a 400 f4.5 for a casual hiking lens but curious what the new 600 PF will offer since I rarely find 600 too long but also find myself in trees and low light while hiking.

Since PF is so new, it will be interesting to see how Nikon will advance this relatively new technology and if it will make its way into the exotics.

Fresnel is about the past and the future because it's solid science.

I was a lighthouse keeper a long time ago and Fresnel lenses are standard equipment even back when lights burned oil to create the light they emitted. Fresnel lens are efficient light gathering tools that have existed for hundreds of years. The one on our light was really bright and it was installed in 1877, of course without the electricity. Originally it revolved on a bed of mercury to display it's light characteristic to the mariner.

Legacy of Light: World’s largest lens shines Aloha light

From the Makapu’u Light on Oahu’s southeastern most point, the world’s largest lighthouse lens reflects a beam that can be seen from 19 nautical miles away.

www.dvidshub.net

Fresnel lens - Wikipedia

en.wikipedia.org

From what I have read, some people swear by Nikons Fresnels and others don't like them at all. I'm betting the one you are looking at is absolutely amazing.

 

[Bob Hullinger]

I'll let the more technically inclined folks weigh in. Some are even former Optical engineers.

From a simpleton's point of view (that would be me as it pertains to optics), given Nikon has come out with the 300PF and 500 PF for the F Mount and the 800 PF for the Z Mount, the 600 PF "formula" for success isn't complicated. The 500 PF and 800 PF are very highly regarded and the advantages gained in terms of size, weight and price for the performance you get offset the compromises you make in image quality in not using a 400 f/2.8 or 600 f/4.

Key word is compromise here in that the PF's won't be able to get to the same performance level as the high prices exotics because those are designed to get you the ultimate image quality across a broad spectrum...but especially when the loss of light becomes more impactful. A f/2.8 or f/4 is always going to win out over a f/6.3 in dealing with lower light...but the PF lenses offer more versatility in weight, hand holdability, and again, price for performance.

Can the average person tell the difference between a f/4 exotic or the 6.3 PF? Most likely not...and I'd argue even those who are more discerning would have trouble in "normal" conditions.

Bottom line: PF's are the "poor photographer's" exotics and would never expect them to make their way into the cream of the crop...and they don't need to because they're unto a class all themselves and deservedly so.

All good comments but I think you might be wrong about the "cream of the crop" given the history and future of Fresnels. I don't think the Fresnel discussed in this article is too shabby of a lens and will definitely be the cream of the crop in space exploration when it is launch. It wouldn't shock me to learn that Nikon has made fresnel lenses in their industrial department that are taking pictures of the earth and space right now.

A new, thin-lensed telescope design could far surpass James Webb – goodbye mirrors, hello diffractive lenses

Space telescopes are limited in size due to the difficulties and cost of getting into orbit. By revamping an old optical technology, researchers are working on a lightweight and thin telescope design.

theconversation.com

 

[fcotterill]

All good comments but I think you might be wrong about the "cream of the crop" given the history and future of Fresnels. I don't think the Fresnel discussed in this article is too shabby of a lens and will definitely be the cream of the crop in space exploration when it is launch. It wouldn't shock me to learn that Nikon has made fresnel lenses in their industrial department that are taking pictures of the earth and space right now.

A new, thin-lensed telescope design could far surpass James Webb – goodbye mirrors, hello diffractive lenses

Space telescopes are limited in size due to the difficulties and cost of getting into orbit. By revamping an old optical technology, researchers are working on a lightweight and thin telescope design.

theconversation.com

Very interesting article. Thank you.
I've often speculated whether Nikon has leveraged its expertise in ultralithography to modify an etching method for its Phase Fresnel elements, or at least the key process in their manufacture.