Say I want to take a landscape-type photograph of some large object in the distant (focus at infinity); for instance a mountain range at the horizon, or even the moon. Suppose no closer objects appear in the picture and that the lighting is generous. Will there be a noticeable difference between:
wide aperture, say f/1.4, fast shutter speed
narrow aperture, say f/16, slow shutter speed
(same ISO for each & shutter speed suitably adjusted so that both pictures appear roughly as bright)
If so, which would be more advisable? Thank you to anyone who replies.
f/16 will give you sharper image than f/1.4. Yes, diffraction does kick-in at f/16, but it's still not as bad as the optical flaws that are pronounced at f/1.4 in pretty much every f/1.4 lens out there. (see: tests of your particular lens, resolution charts)
Also lens coma and astigmatism are worse when lens is wide open than when it's stopped-down. That's important when you have point light sources (stars, distant street lights), otherwise: resolution will be your major concern (point above)
f/16 will give you higher depth of field (by this: make focusing easy, which is especially important with autofocus lenses as they have can overshoot infinity (manual lenses (eg. Zeiss ZF/ZE) tend to be calibrated to end the focusing range at infinity making whole process easier).
Longer exposure times might require remote triggering (or delayed shutter release), a Mirror Lock-Up (MLU) and a tripod to avoid capturing camera shake caused by a mirror and your hand holding the camera.
When shooting during the night - you might get star trials with a (very) long exposure time (see: rule of 600)
Long exposure images will suffer from added thermal noise. Usually it's not a problem, but the closer you approach 30 seconds mark the worse it becomes. It's especially important in some low-end cameras or cameras with known flaws, where you might get a brighter/more noisy spots due to electronics radiating heat. (see: dark frame subtraction) Best way to test if your camera got a problem with thermal heat from electronics is to put the lens cap on and make a 30 sec exposure at ISO6400 or so - if your image is uniform than it's fine, but if you see that for example right corner of the image is brighter than anywhere else - you will have a problem with long exposure photos.
In general - unless you intentionally want to achieve some desired effect - avoid extremes. Extremely high ISO, extremely wide open lens (or closed down), extremely long exposure - everything negatively affects image quality. Lenses very much like middle ground (again: refer to the tests for more information).
Assuming you don't have stability or motion issues and depth of field is not a concern then f/16 would be more advisable than f/1.4 as ultra-fast lenses show several image degrading aberrations when the aperture is wide open.
However f/5.6 would probably be better still, as diffraction starts to kick in past this point which reduces sharpness (assuming an APS-C sensor, with 35mm or larger you can stop down further before diffraction is a problem).
Some lenses do improve in the corners after f/5.6 so you might want to trade central sharpness for corner performance. There are plenty of lens review sites that will be able to the optimum f/stop for centre/corner performance. A lens peaking early (at f/4 or even f/2.8) is a sign of a very good lens with few aberrations (hence smaller benefit to stopping down).
Assuming you are using a tripod, the shutter speed will make little difference in itself. If you are hand-holding, a faster shutter speed will help to eliminate shake. You also have the consideration of any moving objects in the scene, like trees, water, or clouds - a slower shutter speed will blur them.
However, image quality is rarely at its best at either extreme of aperture - f16 is often where diffraction starts to effect image sharpness, for example. In the situation you describe, you are better off shooting somewhere around the 'sweet spot' of your lens, which varies with model.
The distance of the objects is not a factor on your decision on the shutter speed. Their relative movement velocity related to the camera as well as your composition intentions and the available light is what really matters. The fact that you ask the question hints that you don't know about the artistic differences between a large aperture and a small one and between a fast shutter speed and a small one.
The fact that the object is far away makes any movement less perceptible but it may still affect your image. The best example for that is the clouds, which may be far away but can still appear "moving" on your image in a windy day.
As in 90% of landscape photography, you're best using your lens sweet spot which you can usually approximate to about double of your smallest aperture (i.e. for a lens that can do f/22, that'll be f/11) which will also produce a rich enough depth of field while maintaining sharpness.
If the question is meant literally f/1.4 vs f/16, then I would say 16, because there are only handful of lenses that are good enough at f/1.4 to shoot landscape type of photography in great technical quality. But my mindset about setting aperture (for these types of shots or others) is different.
In this kind of photography you should set your aperture to:
Get maximum resolution. This depends on the lens, but it is definitely not f/1.4 and most likely not f/16. It will be somewhere in between
Get desired depth of field. This depends on the distance of subjects you want to have in focus from the camera and each other.
To get reasonable shutter speed. For handheld photography with a FF camera it will be somewhere around 1/focal length or shorter, for tripod photography you may want to avoid "critical shutter speeds" somewhere around 1/10s.
Control motion blur. In landscape photography it may mean branches or grass moving in the wind, moon traveling across the sky, birds flying, rain dropping, water falling...
So the resultant f-stop will be a combination of the above. What the value will be in particular depends on the lens, on your vision, on the weather and since photography may be an artistic discipline for you, perhaps even on your mood.
Experimentation, tips from many talented mentors a pile of garbage images and some pure luck has resulted in a default starting setup / checklist for any Landscape, Panorama Stitch during Daytime or at Night... This also works as Middle Exposure in any HDR Bracket.
Heavy Tripod (Keep legs and neck extension to a minimum)
F-Stop -3EV from the Full Closed (Some lenses are F32 so initial would be F22)
ISO 100-160 (400+ if absolutely needed (Higher ISO = More Noise (Grain)))
2Second Shutter Delay (There is often noticeable tripod vibration from pressing shutter release)
Make sure camera is level for panorama stitches (Shoot Portrait Not Landscape)
Mirror Lockup Enabled (Mirror vibration can be felt in tripods!)
Always Shoot RAW! (+ jpg is fine for proofs only)
Check Histogram! Preview screens Lie!!!
[|__]= BAD (Under Exposed - No Details in Shadow)
[/ ]= Good
[__/|]= BAD (Over Exposed - No detail in Highlights)
Over Exposure is usually better than Under exposure... (increasing exposure in post also increases noise ... Decreasing Exposure to darken image also decreases Noise)
Shoot it right and mess it up in Post... Has anyone ever seen any good results from the 'Fix it in Post' approach? Unless the 'Fixed look' is desired' :)