How do you "detune" a lens

[Matt W.]

I noticed the Rokinon's optical design is pretty close to a K35 or Minolta with a few elements added in.

What would happen if I just removed a few elements?

 

[Phil Holland]

Rokinons are far, far closer to Canon CN-e Primes. It was something pretty apparent when we did the last bit SALT test.

Detuning has grown in popularity as a term. I'd say now it covers a few potential modifications such as experimenting with air gaps, stripping coatings, replacing coatings, removing paint and flocking within the lens, etc. Sometimes this even involves swapping elements out for others or custom made stuff.

All of this can have an impact on lens flare, contrast, veiling glare, and image draw. Also take care that it's real easy to enhance image artifacts like chromatic aberration.

If you are starting to tinker on this front, I recommend starting with a very inexpensive prime and buying about a dozen of them.

 

[Matt W.]

That's probably true, I was looking at the 35mm f1.4 Rokinon in particular. But CN-E lenses I think evolved from K35 designs?

Anyone know how they "detuned" the Sumires? Those are even softer wide open than K35s by quite a lot imo. What is Panavision doing to detune lenses?

The wide open chromatic and spherical aberration of the 35mm K35 is something I'd actually like.

If I removed any given lens element would the lens no longer focus to infinity? Or would removing the right one simply decrease the optical performance? The optical diagram is quite similar to the 35mm f1.4 from Minolta, but with a few more elements.

I'd love to try this but will probably just end up with a 35mm f1.4 AIS or something.

 

[Phil Holland]

That's probably true, I was looking at the 35mm f1.4 Rokinon in particular. But CN-E lenses I think evolved from K35 designs?

Anyone know how they "detuned" the Sumires? Those are even softer wide open than K35s by quite a lot imo. What is Panavision doing to detune lenses?

The wide open chromatic and spherical aberration of the 35mm K35 is something I'd actually like.

If I removed any given lens element would the lens no longer focus to infinity? Or would removing the right one simply decrease the optical performance? The optical diagram is quite similar to the 35mm f1.4 from Minolta, but with a few more elements.

I'd love to try this but will probably just end up with a 35mm f1.4 AIS or something.

CN-E Primes are very literally Canon EF L-Series Primes rehoused with cinema gearing. Duclos Lenses initially created the modified PL Mount version of these, which was a big to do at the time.

Sumires are the same optics as CN-E primes with different coatings I believe on the front element only. Stopped down 1-2 stops the impact of that virtually vanishes.

Most recently Duclos Lenses and Northwest Camera Co. focused on a new CN-E set with a bit more of a K35 aim called the V35:
https://www.newsshooter.com/2021/11...clos-lenses-canon-cn-e-primes-k35-conversion/

Won't fully describe CN-E as a legacy set, but I do think you'll see exploration of some of the earlier full frame/VistaVision glass detuned or modified to get more creative looks.

I can't say publicly what all Panavision does to their lenses as it's a complicated answer often on a project by project basis. Been working with them on and off for 25 years and lots of different glass get tuned as needed per each film, which is why you likely see that in BTS or a new bleep. It's pretty much what I'm describing really though.

Removing an entire element from an optical design will not work. You won't only not be able to focus to infinity, but very likely not focus at all. You want to keep the optics, change their spacing, strip their coatings, examine other things within the lens that can have an impact on optical performance. For instance polishing the internals and removing paint can produce a lot of internal flare.

The way I got started with all of this was plastic tubes and dismantling cheap lenses, then tinkering from there. You can indeed come up with very interesting looks. My old Helios mods produced many unique variations, all of which could be used really. I've moved onto a different vintage set to tinker with and one more recent cinema one.

 

[Matt W.]

CN-E Primes are very literally Canon EF L-Series Primes rehoused with cinema gearing. Duclos Lenses initially created the modified PL Mount version of these, which was a big to do at the time.

Sumires are the same optics as CN-E primes with different coatings I believe on the front element only. Stopped down 1-2 stops the impact of that virtually vanishes.

Most recently Duclos Lenses and Northwest Camera Co. focused on a new CN-E set with a bit more of a K35 aim called the V35:
https://www.newsshooter.com/2021/11...clos-lenses-canon-cn-e-primes-k35-conversion/

Won't fully describe CN-E as a legacy set, but I do think you'll see exploration of some of the earlier full frame/VistaVision glass detuned or modified to get more creative looks.

I can't say publicly what all Panavision does to their lenses as it's a complicated answer often on a project by project basis. Been working with them on and off for 25 years and lots of different glass get tuned as needed per each film, which is why you likely see that in BTS or a new bleep. It's pretty much what I'm describing really though.

Removing an entire element from an optical design will not work. You won't only not be able to focus to infinity, but very likely not focus at all. You want to keep the optics, change their spacing, strip their coatings, examine other things within the lens that can have an impact on optical performance. For instance polishing the internals and removing paint can produce a lot of internal flare.

The way I got started with all of this was plastic tubes and dismantling cheap lenses, then tinkering from there. You can indeed come up with very interesting looks. My old Helios mods produced many unique variations, all of which could be used really. I've moved onto a different vintage set to tinker with and one more recent cinema one.

From what I've seen the Sumires are much softer than the K35s wide open, and probably sharper (nearly identical to CN-E, as you mention) stopped down.

I struggle to believe this can be attributed to coatings alone. I'd expect that would impact flare alone.

The CN-E lenses I suspect are just rehoused EF Ls with different apertures and maybe different coatings; given that the FD designs are essential the same as K35 designs, the 24mm CN-E for instance should look quite similar to a K35 unless it's using the MK 2 EF L:

https://www.mir.com.my/rb/photograp...lenses/EF24mmf14LUSM/EF_FD_optic_compared.gif

Coatings, of course, are likely a world apart.

I'm trying to find the right super speed 35mm for a K35 set. Nikkor? Early EF L rehoused? Minoltas seem pretty expensive. Rokinon?

That sounds super fun modifying cheap lenses. I love what Richard Gale has done and am envious of his patience and perseverance.

 

[Michael Lindsay]

I'm trying to find the right super speed 35mm for a K35 set. Nikkor? Early EF L rehoused? Minoltas seem pretty expensive. Rokinon?

Minolta 35 f1.4 is often rehoused to match in to 'K35 type' sets of S.S.C Canons FDs...

PS Japanese optical forms often worked together and made lenses for each other... Zeiss and Pentax also collaborated a bit... (Note I don't know where the K35 35mm comes from..)

 

[Matt W.]

Minolta 35 f1.4 is often rehoused to match in to 'K35 type' sets of S.S.C Canons FDs...

PS Japanese optical forms often worked together and made lenses for each other... Zeiss and Pentax also collaborated a bit... (Note I don't know where the K35 35mm comes from..)

The 35mm K35 is a 10 element in 9 group aspherical design:

https://www.pacificrimcamera.com/rl/00967/00967.pdf

Whereas the Minolta is 10 elements in 8 groups (also aspherical).

Since the 24mm EF L (and consequently 24mm CN-E) evolved from the FD/K35 design, I assume the 35mm EF L (11 elements in 9 groups, one aspherical) evolved from the K35 design.

 

[Matt W.]

Are there any lens diagrams for the 35mm K35? Granted it's t1.4 and not t1.6 like the 24mm K35, but it's >15mm longer than the 24mm K35.

Whereas the MK1 24mm FD L for EF mount (similar design to the k35 and FD L) is longer than the 35mm f1.4 EF L Mk1. The Minolta is shorter than either.

Curious what the 35mm K35's optical design looks like. Might be something really weird.

The 35mm Minolta matches the FDs well, but I'm not so sure it's at all similar to the K35.

 

[Karim D. Ghantous]

I am so surprised that nobody makes decent lenses made from plastic elements. Yeah, you can get plastic lenses from disposable 35mm cameras, but I'm talking about fully functional, multi-element lenses.

 

[Phil Holland]

I am so surprised that nobody makes decent lenses made from plastic elements. Yeah, you can get plastic lenses from disposable 35mm cameras, but I'm talking about fully functional, multi-element lenses.

They do. Just rarely for our industry due to the expense of creating larger elements. Which may sound funny considering the cost of optical grade plastic versus glass, but that is indeed the case.