Aperture and Diffraction: min aperture limited!


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unseen

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#1
I was always under the impression that diffraction due to aperture too smal was a lens problem. Guess not.
It's a body problem.
well guys, go to the link below to have a read. Might be useful.
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

Well try read through the technical details, it's really quite useful.

A rough translation into layman's speak:
Smallest picture before diffraction spoils the picture-
D2X - F8
350D/20D - F10
D70 - F13
1DMkII/5D/1Ds - F16
1D - F22

Some diffraction is often ok if you are willing to sacrifice some sharpness at the focal plane, in exchange for a little better sharpness at the extremities of the depth of field. Alternatively, very small apertures may be required to achieve a long exposure where needed, such as to create motion blur in flowing water for waterfall photography.
Just thought that you guys would wanna know.
I know for sure this will change some bits of my way of photography..
 

denniskee

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#2
thanks unseen, will read it tonight.

questions,

1) since the FF digital can go to min aperture of f16, does it apply to film camera?:think: :dunno:
2) does lens performance affect the min aperture before diffraction sets in?:think: :dunno:
 

lsisaxon

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#3
denniskee said:
thanks unseen, will read it tonight.

questions,

1) since the FF digital can go to min aperture of f16, does it apply to film camera?:think: :dunno:
2) does lens performance affect the min aperture before diffraction sets in?:think: :dunno:
It doesn't care whether it's full frame or not. It depends on the pixel size. Diffraction limits affects everything. Which is why once the optical limits are hit, there is no point increasing the sensor resolution by reducing pixel size anymore.
 

IvT

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#4
Interesting read! Thanks.
 

Watcher

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#5
denniskee said:
thanks unseen, will read it tonight.

questions,

1) since the FF digital can go to min aperture of f16, does it apply to film camera?:think: :dunno:
2) does lens performance affect the min aperture before diffraction sets in?:think: :dunno:
1) Yes
2) Possible.

This is not a new issue.
 

unseen

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#6
hmmmmm well i suppose dSLR is limited by the pixel size, then film is limited by silver halide crystal sizes.. I'm not really familiar with film, and tech gadgets somehow "communicate" better with me.

I'm calculating the follow assuming that 35mm film using every single silver halide crystal as a single pixel..
After a quick search, seems like normal film grain size is about 0.2 - 5 µm. (!! WAH !! see why below) hmmmmmm means... aperture 4 max??
*scratch head*

Out of topic, but...
Film "pixel" area (roughly) = 0.2x0.2 or 5x5 = 0.04 to 25 µm2
5d = 12.8megapixels, pixel area size of 67.1µm2
means roughly, film has 3 to 1000+ more resolution than the 5D!!
film is about 35+++ megapixels!!
 

yanyewkay

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Sep 22, 2004
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#8
this was the basis of the 4/3 system that they claim to focus light perdendicular to the sensor plane so you don't get diffraction problems.

Diffraction shouldn't affect film because firstly the light falling on the negative is not directional sensitive as in the case of pixels in sensors. ALso they do not employ the bayer pattern have 3 different sites for each colour representation

also there was the assumption that the microlenses on the pixels are perfect and itself do not contribute to the diffraction which we all know it does and will.

it's a good read. I've been finding it hard to convince ppl that digital and film are 2 different mediums but just cannot prove this fact about diffraction :thumbsup:
 

lsisaxon

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Nov 29, 2004
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#10
unseen said:
hmmmmm well i suppose dSLR is limited by the pixel size, then film is limited by silver halide crystal sizes.. I'm not really familiar with film, and tech gadgets somehow "communicate" better with me.

I'm calculating the follow assuming that 35mm film using every single silver halide crystal as a single pixel..
After a quick search, seems like normal film grain size is about 0.2 - 5 µm. (!! WAH !! see why below) hmmmmmm means... aperture 4 max??
*scratch head*

Out of topic, but...
Film "pixel" area (roughly) = 0.2x0.2 or 5x5 = 0.04 to 25 µm2
5d = 12.8megapixels, pixel area size of 67.1µm2
means roughly, film has 3 to 1000+ more resolution than the 5D!!
film is about 35+++ megapixels!!
These are good reads.
http://www.imx.nl/photosite/technical/Filmbasics/filmbasics.html
http://www.luminous-landscape.com/essays/clumps.shtml
 

oeyvind

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#11
yanyewkay said:
this was the basis of the 4/3 system that they claim to focus light perdendicular to the sensor plane so you don't get diffraction problems.

Diffraction shouldn't affect film because firstly the light falling on the negative is not directional sensitive as in the case of pixels in sensors. ALso they do not employ the bayer pattern have 3 different sites for each colour representation

also there was the assumption that the microlenses on the pixels are perfect and itself do not contribute to the diffraction which we all know it does and will.

it's a good read. I've been finding it hard to convince ppl that digital and film are 2 different mediums but just cannot prove this fact about diffraction :thumbsup:
hmmm, rewriting law of physics?
 

Wai

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#12
unseen said:
Smallest picture before diffraction spoils the picture-
D2X - F8
350D/20D - F10
D70 - F13
1DMkII/5D/1Ds - F16
1D - F22
When i shoot products, sometimes i want to have everything in focus

i do notice that on 1DMKII, above F16 and i will see less details

but now then i realised that some camera up to F8 and diffaction will "kick-in" liao :eek:
 

Jan 23, 2005
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#13
yanyewkay said:
this was the basis of the 4/3 system that they claim to focus light perdendicular to the sensor plane so you don't get diffraction problems.
This has nothing to with diffraction.
 

yanyewkay

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Sep 22, 2004
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#14
oeyvind said:
hmmm, rewriting law of physics?
no.. diffraction is still there just that they minimised it (so they claimed) until it strikes the sensor plane head on.

ref: http://www.four-thirds.org/en/pdf/FourThirdsSystem.pdf
pg 4 fig 11

LittleWolf said:
This has nothing to with diffraction.
:think: is that so? sorry then I must have misunderstood the whole tech-concept thingy. Sorry to have misled everyone. Will the excuse "I'm a tech-newbie" be accepted?
 

Jan 23, 2005
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#15
yanyewkay said:
:think: is that so? sorry then I must have misunderstood the whole tech-concept thingy. Sorry to have misled everyone. Will the excuse "I'm a tech-newbie" be accepted?
To err is human... I don't think you owe anyone an excuse.
 

unseen

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#16
OOooo... this is educational.. Thanks a mil for the links!!
though the 1st one is kinda too long to be absorbed all at a go.. will take a 2nd wack at it later on to continue from where I left off.

I must say i'm quite impressed by the development of film photography, but must say I'm grateful to be living in the digital age. :)

Sigh.. now I know why my long exposure shot of some bridge at F22 turned out SO soft.. and sheesh.. guess they included the F32 for fun.

Hmmmm well given the diffraction problem, I really wonder how they plan to increase resolutiion on the APC sensor. as well as for the full frame.
 

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