Landscape Aperture's f/? range

Graham00

Graham00

Messages
3,145
Name
Graham Mc
Edit My Images
Yes
I've noticed some of my landscapes are apertures between f8 through to f22, but now i mainly stick to f13-f16 because f22 can sometimes makes things on the horizons soft.
I noticed it doesn't seem to make much difference in picture quality it just seems to change the light a little in AV, this being where focusing a third into the scene with single focus point. I suppose i can be guilty of being lazy trying to find where my lenses sweet spot is, do you think i should change my method or stick with what i'm doing ?
 
Most lenses perform best, as you know, "in their sweet spot".

Most people will exploit this by using hyperfocal distance to ascertain where they can focus to give a depth of focus which will fall in the area of the lens's best performance.

Only you can tell anyone if you are happy with the status quo. If you can look at your best photograph taken as you are, and it makes you smile, then why change?

Dave
 
Last edited:
As a rule of thumb the sweet spot is around 2-3 stops down from wide open. So with a F4 lens this will be around F8 to F11. Stopping down to much causes diffraction and this causes the softness you see.
 
It's not just the Lens' sweet spot you need to think about; there is a little effect called diffraction that starts to make photos soft at high apertures.

The actual aperture that diffraction starts to affect the image differs for each camera as it relates to the aperture and the pixel pitch on the sensor. Typically on a 10MP crop factor DSLR diffraction kicks in at anything above f13.

However, as with all other elements of photography you have to make your choice when taking the photograph; DoF vs non-diffraction affected images. But if you look at and understand Hyperfocal Distances you maximise your chances of getting that balance right - you may even be able to eat your cake and eat it :)
 
The sweet spot of a lens is the point where improvements in sharpness caused by raising the f/number, are crossed by the reduction in sharpness caused by diffraction. This is a physical property unrelated to lens design or quality and is format dependent. In reality, on crop format this is almost always around f/5.6, and f/8 on full frame which is not necessarily two or three stops down from maximum.

It might not be that simple though, bceause the edges of the frame are affected more by aberrations than the centre and it is quite common for this area of the frame to continue to get better even after the centre has peaked. So it's a compromise, but for sure f/22 on a crop camera like the D300 will be pretty horrible. F/16 isn't great either and it's best not to go further than f/11 if ultimate sharpness is the goal.

Depth of field is another question, and causes a lot of argument amongst landscapers. If you want maximum DoF, then you should use hyperfocal distance focusing - which is quite different to focusing 'one third in' which will not deliver maximum DoF in distant landscapes. However, by definition HFD technique places the far horizon right on the limit of acceptable sharpness, which is sometime unacceptable :eek: and hence the arguments.

Edit: example of the sweet spot from DPReview's lens testing wiget, Canon 50mm f/1.8 on full frame. Use the slider on the bottom to see how sharpness changes with f/number, and how the cenrte starts to go down while the edges and corners are still improving http://www.dpreview.com/lensreviews/canon_50_1p8_ii_c16/page4.asp
 
Last edited:
HoppyUK said:
Edit: example of the sweet spot from DPReview's lens testing wiget, Canon 50mm f/1.8 on full frame. Use the slider on the bottom to see how sharpness changes with f/number, and how the cenrte starts to go down while the edges and corners are still improving http://www.dpreview.com/lensreviews/canon_50_1p8_ii_c16/page4.asp
Click to expand...

Thats really useful - thanks!

Does anyone know where I could find a similar chart for the Sigma 18-50mm F2.8 EX DG Macro?
 
DaveKing said:
Thats really useful - thanks!

Does anyone know where I could find a similar chart for the Sigma 18-50mm F2.8 EX DG Macro?
Click to expand...

Sigma publishes MTF graphs, but they're presented differently and show different things. I would put money on it being sharpest at f/5.6 in the centre, and f/8 for the corners. And better at the wide and middle focal lengths than the longest end.

You could always shoot some pictures ;) Note also how vignetting improves as the f/number goes up, and geometric distortion changes with focal length (but not f/number).
 
F/8 usually gives the sharpest result. But sometimes it is necessary to have everything in focus, which may require f/16 or even f/22. It could be slightly softer, but not that bad as some make it sound.
 
daugirdas said:
F/8 usually gives the sharpest result. But sometimes it is necessary to have everything in focus, which may require f/16 or even f/22. It could be slightly softer, but not that bad as some make it sound.
Click to expand...

On your full frame camera yes, but diffraction gets really bad on crop cameras at f/22. It is the equivalent of f/35 in terms of diffraction on full frame :eek:
 
Thanks for the info. F22 doesnt look the sharpest, so I am going to try a few at F16
 
Why not just use f/8?

It's nearly always the sweet spot and will reduce your shutter speed and/or ISO which is always a good thing.

Assuming you're shooting wide (most landscapes are) then f/8 should offer plenty enough DOF. Only if you need a larger field would I go beyond f/8.
 
NigelPaul said:
Is my ole mate Bryan so wrong????............
http://www.youtube.com/watch?v=uQ6DqhPuPpQ&feature=related


:D:D:p
Click to expand...

Oh him. He is such a goon sometimes. He's the guy who managed to write a whole book about exposure and dismiss the histogram as the second most useless feature on a camera. That is after the white balance setting - which should always be left on cloudy. I kid you not :shrug:

F/22 on a crop camera is horrific if you are looking to get anywhere near optimum sharpness. And f/16 is very noticeably worse than f/8 or f/5.6.

You don't have to take my word for it - just take a couple of snaps.
 
HoppyUK said:
F/22 on a crop camera is horrific if you are looking to get anywhere near optimum sharpness. And f/16 is very noticeably worse than f/8 or f/5.6.

You don't have to take my word for it - just take a couple of snaps.
Click to expand...

I think that's it - I need to spend more time taking photos :bonk:
 
Yup!

Aperture settings can vary wildly depending on what you want to achieve too. You may want to isol;ate an element against the background, so a larger aperture would be better than the small aperture you'd want to get as much as possible in acceptable focus.

YOU are probably the end user so chose the settings that give YOU the results YOU are happy with.
 
You must log in or register to reply here.
Back
Top