what is the diffraction limit of the Leica 25mm f / 1.4?

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Alexander555 New Member • Posts: 4
what is the diffraction limit of the Leica 25mm f / 1.4?

Hello!

Can you please tell me what is the diffraction limit of the Leica 25mm f / 1.4?

Thank you!

ANSWER:
This question has not been answered yet.
Tom Axford Veteran Member • Posts: 7,692
Re: what is the diffraction limit of the Leica 25mm f / 1.4?
2

Alexander555 wrote:

Hello!

Can you please tell me what is the diffraction limit of the Leica 25mm f / 1.4?

Thank you!

Here is a tutorial on diffraction, with a calculator to enable you to work it out for yourself.

Guy Parsons
Guy Parsons Forum Pro • Posts: 36,113
Re: what is the diffraction limit of the Leica 25mm f / 1.4?
4

Alexander555 wrote:

Hello!

Can you please tell me what is the diffraction limit of the Leica 25mm f / 1.4?

Thank you!

In practical terms there is no "limit", it's just that diffraction is there from wide open to smallest aperture but the effects are not usually noticeable in the M4/3 world until maybe f/8 or f/11 with very fussy people even complaining at f/5.6.

The lens itself is probably worst at wide open due to lens design and construction limitations and worst again at f/22 or f/16 whatever is the limit.

In between somewhere is the sweet spot which is a compromise between lens aberrations and diffraction, probably f/4 with a lens like that.

In the real world with the Oly 12-40/2.8 as my most used lens I stick to f/5.6 as the default walking around aperture as that represents the best compromise between image quality and required depth of field, that despite the lens probably being best at f/4 to wide open, depending on focal length.

In macro work usually the diffraction is ignored as depth of field matters most so macro users may happily use f/16 despite the purists being horrified by possible diffraction robbing detail.

Summary: worry less about diffraction and just go take pictures, probably keeping in the range wide open to maybe f/8 depending on desired depth of field and ambient light conditions. That's for M4/3, for FF is would be wide open to f/16.

By the way, it annoys people to repeat the question, only ask once and then wait a few days to see if sensible answers emerge.

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alcelc
alcelc Forum Pro • Posts: 14,914
Diffraction of M43

Had saw a few posting from you regarding the diffraction limit on various M43 lenses.

I suppose it is more of a system wide matter (so the sensor size been involved) as well as certain relatively variation among individual lens.

Generally, you will never go wrong, if diffraction (or indeed you have ore interest on where would the the end of the best ~ better sharpness range of the lens) which might start to soften your image be your primary concern, take f/8 be a general guideline. The further stopping down the softer would be the image.

https://www.dpreview.com/forums/post/64750188 and https://www.dpreview.com/forums/post/63900203

Except for a few exceptions, e.g. the 45-200 or 100-300 that at their longest end f/7.1~8 are their sweetest spot, most other lens should better keep using wider or max at f/8 for the sharpest result unless the very deep DoF can outweigh the sharpness concern of the lens for certain application.

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El Jeffe Contributing Member • Posts: 549
Re: what is the diffraction limit of the Leica 25mm f / 1.4?

Possessing a 4th grade math level I can not understand or answer your question, but generally, by what I read, f/5.6 seems to be the sweet spot for m4/3 prime lenses.

I am curious why you ask this question. Are you looking for a good landscape lens?

Consider m4/3 has an advantage over larger sensors for increased depth of field. So f/5.6 might for instance perform similar to f/11 on a full frame in that regard.

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rogerstpierre Veteran Member • Posts: 4,770
Re: what is the diffraction limit of the Leica 25mm f / 1.4?

You seem focused on diffraction (pun intended) asking the same question for various lenses, which have little relationship to each others. The thing is when diffraction matters depends on FL and sensor in a given context and desired DoF, so without context the answer is meaningless really. If I were to tell you diffraction is X on a 20Mpix Oly camera at f16 for a given lens then what are you going to conclude from that information?

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Great Bustard Forum Pro • Posts: 45,199
There is no diffraction limit for that lens or any other.
4

Alexander555 wrote:

Hello!

Can you please tell me what is the diffraction limit of the Leica 25mm f / 1.4?

Diffraction exists right from wide open and only gets more severe as you stop down. Lens aberrations exist right from wide open and lessen as you stop down. The aperture at which increasing diffraction softening overtakes lessening lens aberrations is often referred to as "the diffraction limited aperture". This is typically (but not always) 1-2 stops down from wide open in the center, and 2-3 stops down in the corners.

However, portions of the photo that are not within the DOF are not going to be sharp regardless, so, depending on the scene, apertures well past the diffraction limited aperture may result in an overall sharper photo.

Conversely, apertures wider than the diffraction limited aperture will be less noisy for a given exposure time, and the lower noisiness (along with the concomitant more shallow DOF) may be more important than the lower sharpness.

So, in the end, there is no diffraction limit. There is a diffraction limited aperture where the lens is at it's sharpest for the portions of the scene within the DOF, and that's f/4 for both the center and edges for the Leica 25 / 1.4:

Courtesy Lenstip

Thank you!

Hope this answers your question!

Gnine Senior Member • Posts: 2,672
Re: what is the diffraction limit of the Leica 25mm f / 1.4?
2

El Jeffe wrote:

Possessing a 4th grade math level I can not understand or answer your question, but generally, by what I read, f/5.6 seems to be the sweet spot for m4/3 prime lenses.

I am curious why you ask this question. Are you looking for a good landscape lens?

Consider m4/3 has an advantage over larger sensors for increased depth of field. So f/5.6 might for instance perform similar to f/11 on a full frame in that regard.

You don't even have to understand maths at all to work it out Take some shots starting at say f/5.6, stopping down a ful stop at a time & taking some more, until you're not happy with the sharpness. That's the acid test. What you personally are happy/not happy with. Who cares what a maths formula says. And I write that as someone who has a pretty decent grasp on the whole maths thing.

john isaacs Veteran Member • Posts: 5,022
Re: what is the diffraction limit of the Leica 25mm f / 1.4?

Alexander555 wrote:

Hello!

Can you please tell me what is the diffraction limit of the Leica 25mm f / 1.4?

Thank you!

f/5.6

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mostlyboringphotog Veteran Member • Posts: 9,651
Re: what is the diffraction limit of the Leica 25mm f / 1.4?

El Jeffe wrote:

Possessing a 4th grade math level I can not understand or answer your question, but generally, by what I read, f/5.6 seems to be the sweet spot for m4/3 prime lenses.

I am curious why you ask this question. Are you looking for a good landscape lens?

Consider m4/3 has an advantage over larger sensors for increased depth of field. So f/5.6 might for instance perform similar to f/11 on a full frame in that regard.

DOF effect due to the aperture is the same regardless of the sensor size.

f/2 on 4/3rd or FF will have the exactly the same CoC size on the sensor.

However, for the same FOV, 4/3rd sensor uses 1/2 the FL of FF sensor, this has the effect of reducing the size of CoC by 1/4, which increases the DOF by 4x.

Since the 4/3rd image is enlarged by 2x (relative to FF - ignoring the aspect ratio), the DOF increase is now only 2x, which can be equalized by increasing the f/stop by 2 stops for the 4/3rd sensor.

Obviously, the above has nothing to do with diffraction.

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Great Bustard Forum Pro • Posts: 45,199
Actually...

mostlyboringphotog wrote:

El Jeffe wrote:

Possessing a 4th grade math level I can not understand or answer your question, but generally, by what I read, f/5.6 seems to be the sweet spot for m4/3 prime lenses.

I am curious why you ask this question. Are you looking for a good landscape lens?

Consider m4/3 has an advantage over larger sensors for increased depth of field. So f/5.6 might for instance perform similar to f/11 on a full frame in that regard.

DOF effect due to the aperture is the same regardless of the sensor size.

No, 'cause DOF depends on more than just the aperture.

f/2 on 4/3rd or FF will have the exactly the same CoC size on the sensor.

CoC is an arbitrary value -- it's not a physical thing, like focal length or aperture.

However, for the same FOV, 4/3rd sensor uses 1/2 the FL of FF sensor, this has the effect of reducing the size of CoC by 1/4, which increases the DOF by 4x.

For photos displayed at the same size and viewed in the same manner, the CoC scales with the linear dimensions of the sensor, and thus the DOF as well (so 1/2, not 1/4; 2, not 4).

Since the 4/3rd image is enlarged by 2x (relative to FF - ignoring the aspect ratio), the DOF increase is now only 2x, which can be equalized by increasing the f/stop by 2 stops for the 4/3rd sensor.

It's much simpler to understand that for the:

  • same perspective
  • same framing
  • same aperture diameter (aperture diameter = focal length / f-number)
  • same display size
  • same viewing conditions

the DOF will be the same for all systems. With all those things being equal, you'd think there was a term for it.

Obviously, the above has nothing to do with diffraction.

Actually, it has everything to do with diffraction because the same principles hold. For the same f-number, the Airy Disk (the spread of a point source) will have the same diameter, but span a smaller portion of a larger sensor than a smaller sensor, thus resulting in less diffraction softening in the final photo.

On the other hand, for the same DOF (twice the f-number on FF than on mFT), the Airy Disk spans the same proportion of the sensor, and thus the effect of diffraction softening is the same for all systems at the same DOF.

El Jeffe Contributing Member • Posts: 549
Re: what is the diffraction limit of the Leica 25mm f / 1.4?

mostlyboringphotog wrote:

El Jeffe wrote:

Possessing a 4th grade math level I can not understand or answer your question, but generally, by what I read, f/5.6 seems to be the sweet spot for m4/3 prime lenses.

I am curious why you ask this question. Are you looking for a good landscape lens?

Consider m4/3 has an advantage over larger sensors for increased depth of field. So f/5.6 might for instance perform similar to f/11 on a full frame in that regard.

DOF effect due to the aperture is the same regardless of the sensor size.

f/2 on 4/3rd or FF will have the exactly the same CoC size on the sensor.

However, for the same FOV, 4/3rd sensor uses 1/2 the FL of FF sensor, this has the effect of reducing the size of CoC by 1/4, which increases the DOF by 4x.

Since the 4/3rd image is enlarged by 2x (relative to FF - ignoring the aspect ratio), the DOF increase is now only 2x, which can be equalized by increasing the f/stop by 2 stops for the 4/3rd sensor.

Obviously, the above has nothing to do with

The increased depth of field suggests we can be confident our micro 4/3 landscape exposed at f/5.6 will provide acceptable results.

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TorsteinH
TorsteinH Senior Member • Posts: 1,329
NOT AGAIN, STOP THIS TROLL!!
1

Troll

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Torstein

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mostlyboringphotog Veteran Member • Posts: 9,651
Re: Actually...

Great Bustard wrote:

mostlyboringphotog wrote:

El Jeffe wrote:

Possessing a 4th grade math level I can not understand or answer your question, but generally, by what I read, f/5.6 seems to be the sweet spot for m4/3 prime lenses.

I am curious why you ask this question. Are you looking for a good landscape lens?

Consider m4/3 has an advantage over larger sensors for increased depth of field. So f/5.6 might for instance perform similar to f/11 on a full frame in that regard.

DOF effect due to the aperture is the same regardless of the sensor size.

No, 'cause DOF depends on more than just the aperture.

No? Are you saying lens aperture affect DOF differently depending on the sensor size?

Yes, there are other factors that affect the DOF and each factor factor affect the DOF the same regardless of the sensor size and the sensor size itself affects the DOF.

f/2 on 4/3rd or FF will have the exactly the same CoC size on the sensor.

CoC is an arbitrary value -- it's not a physical thing, like focal length or aperture.

It's not arbitrary at all - 0.030 mm or smaller is considered within DOF limit for the FF sensor. CoC size of 0.015mm is required for 4/3rd sensor because it is enlarged by 2x relative to FF image.

However, for the same FOV, 4/3rd sensor uses 1/2 the FL of FF sensor, this has the effect of reducing the size of CoC by 1/4, which increases the DOF by 4x.

For photos displayed at the same size and viewed in the same manner, the CoC scales with the linear dimensions of the sensor, and thus the DOF as well (so 1/2, not 1/4; 2, not 4).

CoC diameter is affected 4x for the 2x FL change. CoC diameter is affected 2x for 2x aperture change. Sensor size does not affect the CoC diameter. However, the viewed CoC is enlarged by the crop factor.

Since the 4/3rd image is enlarged by 2x (relative to FF - ignoring the aspect ratio), the DOF increase is now only 2x, which can be equalized by increasing the f/stop by 2 stops for the 4/3rd sensor.

It's much simpler to understand that for the:

  • same perspective
  • same framing
  • same aperture diameter (aperture diameter = focal length / f-number) - bold added
  • same display size
  • same viewing conditions

the DOF will be the same for all systems. With all those things being equal, you'd think there was a term for it.

Ya, so? if you keep the SS and f/stop the same, the exposure will be same for all the systems, also.

Yes - it called math. DOF is proportional to the aperture diameter and proportional to the sensor area, which, together, compensates for the inverse square of FL.

  • same aperture diameter (aperture diameter = focal length / f-number)

The above needs clarification as many folks believe the above means the DOF is same if the aperture diameter is the same. It works when the sensor size is also scaled. On the same sensor, change of 2x FL requires 4x change in f/stop to keep the same DOF.

Try it with DOF calculator.

Obviously, the above has nothing to do with diffraction.

Actually, it has everything to do with diffraction because the same principles hold.

No. Diffraction is a wave interference phenomena and is present even with the perfectly focused point light source. DOF blurs because the lens focuses only at the focal plane. They are unrelated optical property.

You know that, of course, but you have tendency to equate the physical properties if both have same mathematical relationship

The below perfectly illustrates what I mean by your tendency to equate.

For the same f-number, the Airy Disk (the spread of a point source) will have the same diameter, but span a smaller portion of a larger sensor than a smaller sensor, thus resulting in less diffraction softening in the final photo.

On the other hand, for the same DOF (twice the f-number on FF than on mFT), the Airy Disk spans the same proportion of the sensor, and thus the effect of diffraction softening is the same for all systems at the same DOF.

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