Optimum Sharpness/Optimum Aperture


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smallaperture

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I started Use Small Aperture and it was close before I could come back to say something. What a heated debate!

Some gurus said that optimum sharpness is obtain when you stop down by 2 stops or so, as a general rule of thumb.

When you shoot close-ups like flowers, you want optimum sharpness in every part of the flower, so that the optimum aperture could be somewhere at F16 iIMHO.

If you do not print larger than 8R or A4 size, Optimum aperture is preferred to optimum sharpness. Just my 2 cents worth.

and I heard someone saying extra small aperture of F64 - another guru was saying that at smaller aperture than F22, there is a beast called diffraction to attack your pix.
 

sweat100

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#2
I think for diffraction to occur the opening of the iris (aperture) must be in the same order as the wavelength of visible light. I think that is highly not possible cos it is in nanometers! so i think there is nothing much to worry abt diffraction.
I hope i am correct. correct me if i am wrong. :embrass:
 

smallaperture

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Actually diffraction occurs at every aperture! Only difference is that it is less significant up to F22. At what point it become significant is subjective, and it comes along gradually.

For most purposes, at the 35mm format, F22 is good enough to get the DOF we want. For med to large format, it is an entirely different ballgame.
 

erwinx

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no one doubts the need for smallaperture for closeup/ macrophotography, given the distance to subject. For my own photographs on 35mm film, I have never used f/22 (unless i wanted a slow shutter speed). The drop in image quality at f/22 is noticeable on the lenses i've used. With appropriate composition, f/16 is more than enough for my landscapes (I use f/11 quite often unless there is a compelling near-foreground i need to include)

Which is why i'm interested in seeing your photographs demonstrating why f/22 is necessary. Look forward to seeing your pictures.
 

Ian

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#6
smallaperture said:
Some gurus said that optimum sharpness is obtain when you stop down by 2 stops or so, as a general rule of thumb.
In purely optical terms a lens is at it's sharpest in terms of resolution when wide open, HOWEVER maximum resolution doesn't mean having a great image quality as there are other factors such as evenness of illumination in the corners to be considered. Diffraction and the aperture at which serious image degradation occurs varies with the design of the optical train.

smallaperture said:
When you shoot close-ups like flowers, you want optimum sharpness in every part of the flower, so that the optimum aperture could be somewhere at F16 iIMHO.
You are confusing optimium sharpness with optimum zone of focus. As you increase the maginifcation of a lens (ie use a macro lens, extension tubes etc) the Zone of focus for a given aperture and focal length decreases. In other words the distance between the forward and rear points of focus is reduced. Thus to increase the zone of focus you have to decrease the aperture makedely, often to around f16 or more if using bellows or other medium to high high magnification methods as the DOF as it's referred to here in CS often measured in millimeters or less at a given aperture.

smallaperture said:
If you do not print larger than 8R or A4 size, Optimum aperture is preferred to optimum sharpness. Just my 2 cents worth.
You are entitled to your opinion, however those of us who print a lot larger than 10x8" on a daily basis pay particular attention to sharpness and other factors at any given aperture we are using.


smallaperture said:
and I heard someone saying extra small aperture of F64 - another guru was saying that at smaller aperture than F22, there is a beast called diffraction to attack your pix.
It was I who made the comment about f64 and it was in relationship to 10x8 inch film cameras aka Large format.
 

Ian

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#7
fooey said:
hmm can anyone show me a picture taken with f64 aperture? heh...
Take a look at ANY of the Ansel Adams landscape photographs .. most were taken at f64
 

smallaperture

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What I have been saying is entirely from an amateur point of view, shooting in the 24x36 format and printing no larger than 8x12 Epson printer.

So, small aperture would mean F16. F22 is somewhat to the very limit.
 

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Wah Laus eh...u all talk really like gurus u know...

can shoot shoot lah...small hole , big hole ,whatever, your output is still the prints and the moments you captured...who cares so much....can take good pictures means can take lah....give you small or big aperture, you cannot take good photos also no use...

just like car gurus...wah this engine good, wha this gear good...what that steering wheel good...can drive then drive lah..compare so much for what..wah lau eh.....

start posting your pics and stop comparing lah...!

hahhahaha....no flame incurred... :D
 

erwinx

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#10
MatthewSCL said:
start posting your pics and stop comparing lah...!
:thumbsup: More meaningful to discuss actual pictures/situations than to make general statements.
 

smallaperture

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#11
MatthewSCL said:
Wah Laus eh...u all talk really like gurus u know...

can shoot shoot lah...small hole , big hole ,whatever, your output is still the prints and the moments you captured...who cares so much....can take good pictures means can take lah....give you small or big aperture, you cannot take good photos also no use...

just like car gurus...wah this engine good, wha this gear good...what that steering wheel good...can drive then drive lah..compare so much for what..wah lau eh.....

start posting your pics and stop comparing lah...!

hahhahaha....no flame incurred... :D
There is so much thrill in discovering things for yourself, learning from experience. Learning could be faster if we learn from some gurus, some experts, a professor or two and not forgetting a Tse Fu. We can also learn some theory or theorem or we call it tips here.

If you any how gasak, shoot here, shoot there, shoot everywhere, you get louzee pix. I have just learnt that there is such thing as F64! I still learn after shooting for more than 25 years.
 

ahbeng

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#12
smallaperture said:
There is so much thrill in discovering things for yourself, learning from experience. Learning could be faster if we learn from some gurus, some experts, a professor or two and not forgetting a Tse Fu. We can also learn some theory or theorem or we call it tips here.

If you any how gasak, shoot here, shoot there, shoot everywhere, you get louzee pix. I have just learnt that there is such thing as F64! I still learn after shooting for more than 25 years.
from my past experience, my landscape always look better and sharper with f/11~16 than f/22 and above. f64? never heard of it in my life.
 

#13
ahbeng said:
from my past experience, my landscape always look better and sharper with f/11~16 than f/22 and above. f64? never heard of it in my life.
You'll never come across f/64, f/128 on 35mm cameras, and possibly not even medium format. Like Ian said, it's a Large Format thing.

Regards
CK
 

Ian

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#14
ckiang said:
You'll never come across f/64, f/128 on 35mm cameras, and possibly not even medium format. Like Ian said, it's a Large Format thing.

Regards
CK
Erm CK slight correction ;)

You can encounter both f64 and f128 in 35mm photography, but only in the areas of astrophotography (eyepiece projection normally) and in photomicrography (extreme macro work, at ratios around 4-15x lifesize, when using bellows and reversed lenses etc).
 

ellery

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#15
Let me comment on one point which seems to have been over looked in this sorry mess. Sorry Ian but there is a little too much dogma floating around - I did not get to read the actuals which knowing you - there probably was more explainations. Smallapeture - most of the rules are thumb of rules which are useful as approximations - what and how you work is determined by what you are doing with the subject. That's where the creative part of photography comes in.

Irregardless of everything else, small or large appertures used, zone of focus or the effect of DOF, there is only one point of infocus in any picture; for smaller appeture those elements within the zone of focus just look almost in focus ie less unsharp enlargements show things up really fast. It applies even when you use wide angles.

Your choice of appeture should be linked to what you need to do - what is the use of the final print, what is the subject, what size is the print (never assume that a 4R is the only size you need). I did a series of shots once using flashes as light source camera on tripod, and lots of care in focusing for a many item setup. Just from 4R quick looks - the prints at the "optimum apperature" 5.6/8 are not as useable as those done on 16/11. Lens was a 80-200 2.8 AFS Nikon. The final selected for use was either the 16 or the 11 - final size of picture used was 6 x 9. Picture was still excellent at 8x12.
 

#16
Ian said:
Erm CK slight correction ;)

You can encounter both f64 and f128 in 35mm photography, but only in the areas of astrophotography (eyepiece projection normally) and in photomicrography (extreme macro work, at ratios around 4-15x lifesize, when using bellows and reversed lenses etc).
Thanks Ian for bringing those areas up, I've forgotten that extensions and such will affect the effective aperture. :embrass:

Regards
CK
 

smallaperture

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#17
ellery said:
Let me comment on one point which seems to have been over looked in this sorry mess. Sorry Ian but there is a little too much dogma floating around - I did not get to read the actuals which knowing you - there probably was more explainations. Smallapeture - most of the rules are thumb of rules which are useful as approximations - what and how you work is determined by what you are doing with the subject. That's where the creative part of photography comes in.

Irregardless of everything else, small or large appertures used, zone of focus or the effect of DOF, there is only one point of infocus in any picture; for smaller appeture those elements within the zone of focus just look almost in focus ie less unsharp enlargements show things up really fast. It applies even when you use wide angles.

Your choice of appeture should be linked to what you need to do - what is the use of the final print, what is the subject, what size is the print (never assume that a 4R is the only size you need). I did a series of shots once using flashes as light source camera on tripod, and lots of care in focusing for a many item setup. Just from 4R quick looks - the prints at the "optimum apperature" 5.6/8 are not as useable as those done on 16/11. Lens was a 80-200 2.8 AFS Nikon. The final selected for use was either the 16 or the 11 - final size of picture used was 6 x 9. Picture was still excellent at 8x12.
I would like to cite one similar incident - took some "tourist" pictures for some visitors from Penang. I didn't have my portrait lens with me. I got the Jack of all Trades lens - the Tamron 28-200XR. I set the aperture to F16, using SB50DX as fill flash, on slow sync and shoot with a tripod. What I wanted was to get the background to be somewhat sharp to be readily recognisible like the merlion and the twin durians. My subject was so sharp that I could see the pores on their face on my monitor. Outdoor portraits means we want to see the background well, or else we might as well shoot in a junk yard and use F1.8. No one would be able to recognise the location. This is just my style.
 

dbcs

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What I wanted was to get the background to be somewhat sharp to be readily recognisible like the merlion and the twin durians. My subject was so sharp that I could see the pores on their face on my monitor. Outdoor portraits means we want to see the background well, or else we might as well shoot in a junk yard and use F1.8. No one would be able to recognise the location. This is just my style.
Hmm...I tend to think that at times, there is simply no focus in a composition when everything is in focus.

That is why we go about taking panning shots and using depth etc. as tools to add interest to our photographs.

Big apertures are useful as well.
 

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