Tag Info

58

If you just want bokeh for bokeh's sake then you can achieve this with pretty much any lens and any type of camera, even a tiny sensor compact, by focusing extremely close. Depth of field diminishes very quickly with focus distance, so much so that it becomes a major problem with macro photography getting a non blurred background (or subject!) However this ...

50

You've run over the diffraction limit. Light rays passing through a small hole will diverge and interfere with each other and a pattern emerges--a sort of banding where different frequencies/placement can cause separate rays to add up or negate each other. The smaller the opening gets, the larger this divergence/interference becomes. This pattern is called ...

46

Ok for a change I'm going to dispense with the formulas, photos of rulers and definitions of "magnification" and go with what you actually experience in practice. The major factors that actually matter to shooting are: Aperture. Wide aperture lenses give you a shallower depth of field. This is probably the least controversial factor! This is important as ...

43

Here's the list of things that influence depth of field the most (in this particular order): Subject distance, the closer the subject is, the shallower the DOF (think of macro) Focal length, the more millimeters, the shallower the DOF Aperture, the smaller the f-number, the shallower the DOF

40

As mentioned in the other answers, diffraction has led to unsharpness. To put this to the test, one can attempt to sharpen the image using deconvolution by using the point spread function that corresponds to F/29. For diffraction, we have (up to an overall normalization) P(s) = {J1[ πrs/(λF) ] / [ πrs/(λF) ] }2 where J1 is the Bessel function of the ...

36

Aperture simply means "opening", and in photography we use the term to refer to the diameter of the opening in a special adjustable diaphragm within each lens. When this diaphragm is constricted, there's less physical space for light to get in, so naturally the exposure is darker, and a more-open aperture allows more light and results in a lighter exposure. ...

36

The small degree of defocus in the background is due to the focal length used being very short (18mm). The amount of background blur depends on the size of the entrance pupil, not the f-number. The entrance pupil size is the focal length divided by f number, so in this case it would be about 5mm. This is quite small. A 100mm lens at f/3.5 would have an ...

33

This is an excellent question, and one that has different answers depending on context. You mentioned several specific questions each of which might warrant their own answers. I'll try to address them more as a unified whole here. Q. Is it just a property of the lens? A. Simply put, no, although if you ignore CoC, one could (given the math) make the ...

32

Depth of field formulas are indeed complex and nonlinear, but they still afford useful rules of thumb. For medium subject distances (not too close to the lens, compared to its focal length, and not so far away that the DoF extends to infinity), the DoF is approximately proportional to: The f-stop. The square of the distance. The inverse square of the lens'...

31

The hyperfocal distance is the distance at which everything from 1/2 the distance to infinity is in focus. For instance, if the hyperfocal distance of a particular lens at a particular aperture is 100ft, then by focusing at 100 ft you can capture anything from 50ft-infinity in clear focus. A more in depth explanation can be found at www.dofmaster.com

31

What you are looking for is large depth of field. This is an optical property, not something applied as a special effect, so it's not something you can turn on or off. The raw image captures the light focused by the lens, and inevitably there will be parts of the scene which are either too far or too close — out of the range where the rays are tightly ...

30

Firstly, the number of wells on the sensor has no bearing on where you can focus or 'how much' you can focus on. Out of focus light is still light hitting the sensor. Simply put, you have shallower depth of field with a full-frame sensor because you have to get closer to the subject (or zoom in) in order to fill the frame. Note that in your example it says ...

29

DoF preview is difficult to use well. The idea is simple, but application much less so. Without DoF preview, what you see through the viewfinder is shown with the lens "wide open" -- at its largest possible aperture. This provides no guidance about how much depth of field your picture will have, because (unless you happen to be shooting at maximum aperture) ...

29

Why the wide aperture blurs the background more Let me start with Wikipedia figure: Above we have a wide open aperture. Only point 2 is in focus. Points 1 and 3 are out of focus. Due to wide aperture, the rays coming from them through different parts of the lens intersect the screen 5 (a film or a digital sensor) in different points. We may also tell ...

28

The aperture affects not only the amount of time required to take a photo, but also the depth of field within it. With a wide aperture (so a low number, like f/1.8) gives a shallow depth of field - sometimes less than a millimetre with a macro lens. Because a lot of light is reaching the sensor (be it film or digital), this allows for fast shutter speeds ...

27

Depth of field depends not only on aperture but also on distance to the subject. Depth of field increases as the subject gets farther away. If the wave and boats were all relatively far from the camera, but not terribly far from each other, then it's not surprising that they were all reasonably sharp. You can use DOFMaster to run the numbers yourself. Some ...

26

I'm going to crib from my answer to an earlier question on aperture: When the aperture is very small, the admitted light is highly "collimated", which is a fancy way of saying "all the rays are nicely parallel to each other". This results in a sharp focus for all the light that comes in. When the aperture is more open, only the rays which closely match ...

24

There's a good answer from Brian Auer, which I'll reproduce here, as it pretty much covers the problem you're trying to solve: Ooh, good question. Yes, but how much will depend on the camera. If the camera has manual controls for aperture, that definitely helps. It also helps if the camera has zoom, as most P&S cameras do. The problem with ...

24

First of all, it was an issue on film. If Bryan Peterson wasn't aware of it at the time, it just shows what he didn't know, not that it actually wasn't a problem. There were differences though. First of all, we didn't have EXIF data, and most people didn't keep careful enough notes to really know why shot X came out quite a bit sharper than shot Y. Even for ...

24

No - the aperture is set by the physical blades in the lens when you take the photo; a RAW "image" contains the readings from the sensor when the photo was taken, so there's no way you can go back and modify the light which was captured by the sensor. While it's not as obvious, this is equivalent to asking "Can I modify what the camera was pointing at from a ...

21

While using shallow depth of field is the most common technique to get blurred background, there are some other ways: using plain background so it would not need any blurring set up your own background - you'll have full control over color and pattern shoot against sky or some other plain surface (longer lens will help you by having smaller segment of ...

20

There is NO difference at ALL because the physical aperture has not changed. The Fuji Finepix S4000 simulates a small aperture using an ND filter. When you stop-down the ND filter slides into the optical path. The Aperture written in the EXIF data is adjusted to reflect the transmittance of the ND filter, but note that since the size of the opening has not ...

20

Here's a really good case for the application of Okham's Razor. The simplest explanation is that the image was shot outdoors, under the midday sun. The blur was not added in post but is the result of the close shooting distance and relatively wide aperture of f/4. The fast shutter speed was required otherwise the shot would have been overexposed due to the ...

19

Ultimately, you want a shallow depth of field, which means a low fstop number (f/2.8 for example). The lower the fstop number, the more light that gets in, so in order to expose correctly, you need to increase your shutter speed (1/1000 is better than 1/25), lower your iso (100 is better than 400), and if all this is not enough, add a neutral density filter ...

19

The lens is nothing magical and does not have "infinite depth of field" as some have claimed. However it does achieve a very deep depth of field, by a combination of short focal length, small aperture and tilted plane of focus. It was developed by wildlife photographer/filmmaker Jim Frazier who was fed up with the limitations of traditional lenses for ...

18

Bokeh is subjective, and all cameras can create bokeh. One pre-requisite to pleasing bokeh is to have sufficiently out of focus areas. Most details that are only a bit out of focus don't look too pleasing. Something is more out of focus the further away it is from the plane of focus. In addition, the the shallower the depth of field, the quicker things ...

18

It's arguable whether this is "clear and easy to understand", but Thom Hogan has an interesting article on Hyperfocal distance - explaining that it's not quite what people think it is, and also why it's not necessarily a desirable effect. Here's a few quotes (emphasis mine): "Hyperfocal focus distance" is basically the focus distance for any given ...

18

All lenses can really only focus at one distance from the camera. Everything in front of or behind that point is increasingly blurry. In practice, there is a range of distances where the blur is imperceptible, or close enough. We call this the depth of field. It sounds like you are looking for a very large depth of field. Your older camera had a very high ...

18

The effect is called field curvature. A good discussion comes from Nikon. It is a lens aberration that can reduce the resolution of the lens when coupled with a flat sensor. In the old days, the film could be bent a little to try to follow the image plane and reduce the effect, but our sensors today are rigid. It can be reduced with lens design.

Only top voted, non community-wiki answers of a minimum length are eligible