Landscape & F stops

[duncan22]

I Must admit to being totally confused about the correct F stop to use in landscape photography.
Some advise the smallest aperture but if you look back at landscape photographs that appear in Photoplus Inspirations (starting from issue one) at the f stops used the main range appears to be between f5.6 to f14.
Of course a few are higher or lower than this figure but the bulk fall within this range and have been taken with almost the full range of Canon Cameras (mostly FF) along with a vast range of lenses many of these being L lenses, so if the smallest apertures are being advised for landscape photography is this information wrong? Even more important will the aperture vary for the amount of light available or should you stick with the same aperture all along and vary the exposure. (assuming a tripod is used in all cases)

[chris-p]

There is no "right" aperture for landscapes (or anything really).

The general advice is to use a smaller aperture for landscapes as the smaller aperture gives you a larger depth of field so more of the landscape is in focus.
If the light levels are low the advice would usually be to use a longer shutter speed, rather than increase the size of the aperture.

However, it's never as clear cut as that. You can calculate the exact depth of field for a given aperture, at a given focal length, at a specific focal distance on a particular camera (the sensor size does affect DoF).

There are a couple of techniques for increasing depth of field. You could try focus stacking (google it as I've never tried it and don't know much about it) and you could try using the hyperfocal distance.

It's also worth having a look at this thread where this was discussed at quite some length!

Cue Flake for a discussion about optical diffraction!

Edit: I just realised that the thread I linked to was one you started!!

[chris-p]

Just a quickie...

DOFMaster have a really simple and very helpful online DoF calculator.

Select your camera model (for the sensor size), select your focal length and the distance to the point you focus on and it'll tell you how large an area will acceptably sharp.

[matt wilson]

I usually try and avoid the extremes .Though there are times I want to create an out of focus background and will use the depth of field preview button.

Another likely reason for the range you see is a lot of lenses have a sweet spot around say f8 or f11 and it's favoured for clarity.

[jinky]

Yes Matt is right about sweet spots for each lens. You might be thinking that to get maximum dof you would have to go to F16 / 22 and the like. However at these f stops diffraction starts to kick in evidently and you lose sharpness. Varies according to camera / lens as to when diffraction kicks in but as low as f14 sometimes so that might explain why they do not go above that stop

[chris-p]

Diffraction can set in earlier than f/14 as it really depends on the size of the microlenses covering the photosites on the sensor. However (as has been discussed in the thread I linked to before) how much of an effect it has on the final image is different for every shot.

I still think that, if you're worried about not getting enough DoF, you need to try several apertures and see what gives you the sharpest and what gives you the most DoF. You will still get a greater DoF at f/22 than at f/11 but the image will be softer thanks to diffraction.
As with most things in photography, it's a balance.

[duncan22]

Thanks for that. The link to the DOF chart was very useful.

[nikonian]

Originally Posted by chris-p

There is no "right" aperture for landscapes (or anything really).

The general advice is to use a smaller aperture for landscapes as the smaller aperture gives you a larger depth of field so more of the landscape is in focus.
If the light levels are low the advice would usually be to use a longer shutter speed, rather than increase the size of the aperture.

However, it's never as clear cut as that. You can calculate the exact depth of field for a given aperture, at a given focal length, at a specific focal distance on a particular camera (the sensor size does affect DoF).

There are a couple of techniques for increasing depth of field. You could try focus stacking (google it as I've never tried it and don't know much about it) and you could try using the hyperfocal distance.

It's also worth having a look at this thread where this was discussed at quite some length!

Cue Flake for a discussion about optical diffraction!

Edit: I just realised that the thread I linked to was one you started!!

The sensor size does not alter the DOF. The lens does that. The only way that the sensor size increases the DOF is to walk back to increase the distance from subject to camera to make the image the same size. The greater the distance the greater the DOF.

[chris-p]

Originally Posted by nikonian

The sensor size does not alter the DOF. The lens does that. The only way that the sensor size increases the DOF is to walk back to increase the distance from subject to camera to make the image the same size. The greater the distance the greater the DOF.

Sensor size does affect the DoF. The smaller the sensor the larger the DoF. It's basic physics. If you use the same field of view (say a constant effective 50mm focal length) and calculate DoF figures you can see it. Having a smaller sensor effectively has a similar effect to squeezing light through a smaller aperture.

For example... Using a 50mm FoV, 15m focus distance at f/2.8 these are the DoF's for the following cameras

Nikon D3 (Full Frame) - 20.3 metres
Canon EOS 450D (1.62x APS-C) - 84.2 metres
Olympus E-520 (4/3 2x) - infinite
1/1.8" (Common Compact) - infinite

As you can see, the DoF gets larger the smaller the sensor. It's because the CoC gets larger. I've lost count of the number of times that I've seen people say that sensor size doesn't affect DoF and it's simply not true!!

[nikonian]

Originally Posted by chris-p

Sensor size does affect the DoF. The smaller the sensor the larger the DoF. It's basic physics. If you use the same field of view (say a constant effective 50mm focal length) and calculate DoF figures you can see it. Having a smaller sensor effectively has a similar effect to squeezing light through a smaller aperture.

For example... Using a 50mm FoV, 15m focus distance at f/2.8 these are the DoF's for the following cameras

Nikon D3 (Full Frame) - 20.3 metres
Canon EOS 450D (1.62x APS-C) - 84.2 metres
Olympus E-520 (4/3 2x) - infinite
1/1.8" (Common Compact) - infinite

As you can see, the DoF gets larger the smaller the sensor. It's because the CoC gets larger. I've lost count of the number of times that I've seen people say that sensor size doesn't affect DoF and it's simply not true!!

Taking a shot on a full frame sensor or cropped frame sensor leaves the C of C the same size on both sensors. IT is only the act of enlarging the small size of the cropped sensor by your PC that makes the C of C bigger.