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At what aperture is a canon f1.8 55mm sharpest? - Page 3

post #21 of 28
Quote:
Originally Posted by Ansel View Post

Quote:
Originally Posted by mz-n10 View Post

its not completely true. f stop is only the measurement of amount of light which passes through the lens. diffraction is the optical phenomenon in which edges of the blades of aperture cause light waves to "scatter". you can get diffraction at f1 if you build the lens small enough.

Diffraction is more an issue of sensor size and therefore enlargement. It has nothing to do with lens size. You still get diffraction at f/22 with a mammoth 800 mm lens just like you do at f/22 with a 50 mm pancake lens. Yes, light curling around an aperture blade is diffracted slightly, but at low f/numbers and large sensor sizes it is less of an issue than at high f/numbers and smaller sensor sizes.

Right the size of the lens does not matter (size as in length), so 14mm vs 1600 will both have the same diffraction at f22 (assuming they are the same format). that is because F stop is a measurement of light pass through the lens and not the actual size (diameter) of the aperture.
Quote:
On a full-frame sensor, diffraction tends to start becoming an issue at around f/16. On a crop-factor sensor, it starts becoming an issue around f/11. This presupposes you are printing at 12 x 8 inches or larger. The larger it is the more apparent it will be. At web size, you'd have a hard time seeing it even in a side-by-side comparison at f/22.

What you said is true, but its not because the sensor is bigger, its because the lens allows more light to pass through on larger format cameras. f11 on a 4x5 camera is letting the same amount of light through as f11 on an asp-c (with respect to sensor size) but due to the the larger diameter hole on the aperture on a 4x5 lens there is less diffraction on the sensor/film.
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post #22 of 28
I do not know if this was already stated.... If so, I apologize for being redundant....

Set your aperture for desired depth of field. Not so much overall sharpness. any good lens should be plenty sharp at any aperture. You may now return to your previous discussion...biggrin.gif
    
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post #23 of 28
Quote:
Originally Posted by Eric Barney View Post

any good lens should be plenty sharp at any aperture.

Nope. This is exactly why landscape photogs shoot 6x9, 4x5 or even 8x10.
post #24 of 28
Quote:
Originally Posted by Ansel View Post

Diffraction is more an issue of sensor size and therefore enlargement. It has nothing to do with lens size.

It has everything to do with lens size, but not focal length. mz already covered it pretty well, and it's the reason I shoot MF. f/11 on 35mm or 1.6x? No way, jose.
post #25 of 28
Quote:
Originally Posted by sub50hz View Post

This is exactly why landscape photogs shoot 6x9, 4x5 or even 8x10.

Large format lenses and to some extent also medium format lenses are not as sharp as the highest quality 35mm (DSLR / SLR) lenses. Look up the resolving powers.

The reason landscape photographers like medium and large format is because they like the larger format because it has less grain and has to be enlarged less. The lesser amount of enlargement means that the sharpness of the lens is less of an issue in total: the total result is better, especially at the very large print sizes.

The large formats have much less depth of field and this creates problems for landscape photographers who must sometimes resort to tilting and shift the film and lens planes to overcome them.
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post #26 of 28
Quote:
Originally Posted by Ansel View Post

Large format lenses and to some extent also medium format lenses are not as sharp as the highest quality 35mm (DSLR / SLR) lenses. Look up the resolving powers.

Not when shooting stopped down to f/10 and beyond. That's what this whole discussion was about, no?

Quote:
The large formats have much less depth of field and this creates problems for landscape photographers who must sometimes resort to tilting and shift the film and lens planes to overcome them.

At the same given aperture, yes, they have a smaller DoF, but since stopping way down on larger formats doesn't have as much of an impact on sharpness... I think you see where I'm going here.
post #27 of 28
Quote:
Originally Posted by mz-n10 View Post

unless my sarcasm radar is wayyyyy off......these two statements seem to contradict one and other.....

What he seems to be saying is, if he posts it in public, then there is a record of his personal life and professional life being connected. But if he PM's it, there is no public record of it.
post #28 of 28
Quote:
Originally Posted by mz-n10 View Post

unless my sarcasm radar is wayyyyy off......these two statements seem to contradict one and other.....

My business can be found online and through Google through the correct channels -- i.e what I advertise for.

But I don't want my personal life to be seen by those looking for my business.

If I post a link on here, my personal life (what I do in my spare time -- i.e over clocking), will be able to be found by searching for the latter.

I don't want that.

Make sense?

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