lens optimized for smallest aperture

[rbrigham]

Hi All

Are there any lens types that are optimised for high stop/deep focus not specifically macro
as in a lens that performs better at f64 than if dose at f11 for example
I know that normal lenses will suffer with diffraction at high stops and normally perform best a couple of stops down from wide open

thanks

robin

 

[RobC]

look up the "Rayleigh Limit"

this a physical law which can't be got around with lens design. It is a limit of obtainable resolution at any aperture in line pairs.

F45 35
F32 50
F22 70
F16 100
F11 140
F8 200
F5.6 280
F4 400
F2.8 560

smaller aperture gives greater DOF but at a lower resolution. There's nothing can be done to alter that.

 

[ic-racer]

Yes, but they use different forms of electromagnetic radiation with shorter wavelength.

 

[Old-N-Feeble]

A tiny 'black hole' might work but good luck finding the image.

 

[Gerald C Koch]

Yes, they are called process lenses and are optimized to work at smaller apertures. They are intended to make color separation negatives but can be used for general photography. They are NOT cheap.

 

[Dan Fromm]

Diffraction depends on relative aperture in process lenses exactly as it does in all other lenses. The law's the law.

Rodenstock recommends that Apo Ronars up to 600 mm be used at f/22, the longer ones, including the semi-mythical 1800/16, want f/32.

These days short process lenses aren't very expensive. Longer that 600 mm are somewhat dearer.

Robin, please tell us what you're trying to accomplish. What format are you planning to shoot, how deep is your subject (and what's the film-to-subject distance?) and how large do you intend to print?

 

[jjphoto]

look up the "Rayleigh Limit"

this a physical law which can't be got around with lens design. It is a limit of obtainable resolution at any aperture in line pairs.


smaller aperture gives greater DOF but at a lower resolution. There's nothing can be done to alter that.

So 'Group f/64' could be called 'Group 25 l/mm' ?

 

[RobC]

So 'Group f/64' could be called 'Group 25 l/mm' ?

Correct. But if you're only contact printing or enalarging 8x10 negs by a linear factor of 4 then then its still pretty darn good.

 

[dynachrome]

I have used medium format enlarging lenses on a bellows for macro work on 35mm film. A 150/5.6 at f/11 will probably show less diffraction than a 150/2.8 or f/4 at f/11.

 

[Dan Fromm]

I have used medium format enlarging lenses on a bellows for macro work on 35mm film. A 150/5.6 at f/11 will probably show less diffraction than a 150/2.8 or f/4 at f/11.

Please explain. Could you have meant residual aberrations?

 

[Nodda Duma]

Folks here have correctly stated there's no real way around diffraction limit. What smaller maximum apertures get you is manufacturing/assembly simplicity and lower cost. So typically I design optics at the smallest aperture I can get away with and still meet the requirements.

During design, any optimization for stop settings other than wide open is related to requirements such as minimizing focus shift as the lens is stopped down, or to meet MTF requirements specified for smaller stop settings. Stuff like that.

 

[Mustafa Umut Sarac]

Ideal aperture for 35mm design is between 5.6 to 8. If you go less aberrations increares , if you go more diffraction error increases. But either way , spherical aberration is more stable at leica and zeiss.
I read a long review at Leica magazine and will post to articles in pdf form , dated from 1955 , I dont know what been developed afterwards but not even a single better lens except two above corporations.

 

[alanrockwood]

Are you working with flat objects, such as documents and photos, or three dimensional objects? It makes a difference. If you are working on three dimensional objects then you need to use a small aperture, and diffraction limits the resolution, but you get greater depth of field. If you are working at larger aperture then it works the other way around, except that if the aperture gets to big then it is limited not by diffraction but by lens aberrations.

 

[Dan Fromm]

Oh, dear. Zombie threads are coming to eat our brains.

 

[Sirius Glass]

Folks here have correctly stated there's no real way around diffraction limit. What smaller maximum apertures get you is manufacturing/assembly simplicity and lower cost. So typically I design optics at the smallest aperture I can get away with and still meet the requirements.

During design, any optimization for stop settings other than wide open is related to requirements such as minimizing focus shift as the lens is stopped down, or to meet MTF requirements specified for smaller stop settings. Stuff like that.

That is exactly the reason that we need to repeal the Rayleigh Criterion! Death to Lord Rayleigh!

 

[Maris]

The wavelength of the imaging radiation has an effect at a given f stop. Deep blue optical images are about twice as sharp as deep red ones. Curiously, the sharpest lenses known can work at f100 but they are the electron lenses in a transmission electron microscope. The f100 is to suppress hard-to-correct aberrations. And the extremely short de Broglie wavelength of the imaging electrons means that the inevitable diffraction is still not severe enough to prevent atomic scale resolution.

 

[Dan Fromm]

Maris, have you been transformed into a zombie? I ask because although all you've said is true it seems a little, um, irrelevant to photography as generally practiced.

 

[RobC]

Yes, they are called process lenses and are optimized to work at smaller apertures. They are intended to make color separation negatives but can be used for general photography. They are NOT cheap.

They usually have low magnification ratios too. Maybe only 1:2 or 2:1 before they go out of optimum performance. But they are still diffraction limited just like any other lens. Where I think they score highly is that they are designed to be truly flat field and they'll get the resolution out of the source futher out to the edges than a normal enlarging lens will. But not if you use it outside its optimum performance envelope.

 

[Dan Fromm]

They usually have low magnification ratios too. Maybe only 1:2 or 2:1 before they go out of optimum performance. But they are still diffraction limited just like any other lens. Where I think they score highly is that they are designed to be truly flat field and they'll get the resolution out of the source futher out to the edges than a normal enlarging lens will. But not if you use it outside its optimum performance envelope.

Process lenses not particularly useful outside of 1:2 to 2:1? Are you sure?

I ask because user reports on dialyte type process lenses, e.g., Apo Artars, symmetrical type Apo-Nikkors, Apo-Ronars, Repro Clarons, shot at distance are uniformly very positive. Perhaps a zombie idea has eaten your brain.

 

[Maris]

Maris, have you been transformed into a zombie? I ask because although all you've said is true it seems a little, um, irrelevant to photography as generally practiced.

Yes, there might be a bit of zombie there. It comes from working with electron microscopes, exposing and developing EM plates,worrying about resolution and contrast, etc. Transmission electron microscopes are basically cameras and working with them becomes familiar and normal...which it isn't as you pertinently point out.

 

[alanrockwood]

Hey guys, how about if people quit calling each other zombies and return to a serious discussion of the topic of the thread?

 

[Dan Fromm]

Hey guys, how about if people quit calling each other zombies and return to a serious discussion of the topic of the thread?

Alan, note when this discussion was started and when it seemed to have petered out. You dug it up. Are you a zombie master?

Thread drift and frivolous posts are common on APUG. On the second point, see post # 15 above. Posters here should expect both.

 

[Sirius Glass]

How do you kill a zombie?

kill -9 <<process-id>>​

 

[RobC]

Process lenses not particularly useful outside of 1:2 to 2:1? Are you sure?

I ask because user reports on dialyte type process lenses, e.g., Apo Artars, symmetrical type Apo-Nikkors, Apo-Ronars, Repro Clarons, shot at distance are uniformly very positive. Perhaps a zombie idea has eaten your brain.

I'm not saying all are limited to that magnification range but my belief is that most are or possibly upto 1:4. I think maybe your understanding of what a process lens is for and mine may be different.

For starters, any lens shot at distance for landscape won't matter a jot if its not flat field. So please go back to the people telling you these process lenses are good for distance work and get them to confirm that at distance they can get flat field resolution as high as they can at the lenses design envelope.
Just using a lens outside its design enevelope and saying its perfectly good is fairly meaningless if you are not comparing to what it was designed for.

 

[Dan Fromm]

Rob, ancient (1960s) Rodenstock propaganda recommended using Apo Ronars at all distances, claimed that they were superior to contemporary telephoto lenses.

Nikon propaganda says this about dialyte type Apo-Nikkors:

The lenses are also suitable for work, where no distortion is permissible at a reproduction ratio close to full size. On the other hand, since the lenses give an excellent image, for a wide picture angle at infinite distance as well as in enlarging work, they can also be utilized for a large size camera or on an enlarger.

Please adjust your beliefs.