25

This is normal behavior, caused by: Imperfections of aperture. Usually there are variations from technology process which cause not to have exact size of the hole. On 50mm lens f4 you should have 12.5mm opening, but it can be 12.4mm or 12.6mm Imperfections in shutter speed. The shutter is also mechanical unit and based on some factors as temperature, how ...


18

Your observations of the lens leads you to both a correct, and incorrect, conclusion. Correct: the aperture (i.e., mechanical iris) of the lens is substantially smaller than the 10 cm it supposedly should be. Only the front element is anywhere near 10 cm diameter. Where the iris mechanism is in the lens barrel, the diameter is substantially smaller than 10 ...


17

1) Sharpness is complicated. Lens sharpness is just one aspect of the overall resolving power of a camera system. The appearance of crispness is separate from the rendition of detail. And a lens can be sharper in the center but not in the corners, or less sharp overall but consistent across the frame. And that's not even getting into other factors that ...


17

During focussing, the lens is left at full aperture. It's only when you take the picture that it closes down to the appropriate f-stop. That's so you can see what's going on and so that the camera has enough light to focus. So, yes, a lens with a maximum aperture that's two f-stops larger than another will let in four times as much light during focussing. ...


16

In theory, yes — stops are interchangeable. In practice, they do not perfectly cancel to complete precision. the standard deviation of the raw counts is ~5% of the mean In photographic terms, this is basically nothing. It is far below human perception, and even when the difference is noticeable, the generally-expected workflow involves working with each ...


15

What is the purpose ... for the existing convention? Math. It's because in many equations regarding simple optics, the ratio N = ƒ/D (where N is the ƒ-number, and D is the lens (or more often precisely, entrance pupil) diameter) pops up a lot, or the use of the ratio simplifies the expression or understanding of the expression. Example 1: The hyperfocal ...


13

Is there any reason to change the ISO manually, rather than have it set automatically? The primary reason to set ISO, along with shutter time and aperture, manually would be to totally control exposure manually rather than let the camera set exposure. Not every scene needs to be rendered with an overall average brightness of medium gray. Left to its own ...


12

The short answer is yes... they cancel. But there are some nuances. Each time the diameter of a circle increases (or decreases) by a factor equal to the square root of 2 (approximately 1.4) the area of that circle is exactly doubled (or halved if decreased). The f-stop numbers are all based on powers of the square root of 2 (e.g. f/1 = √2^0; f/1.4 = √2^1; ...


11

What did the reviewers say about why they chose one lens over the other? They have their own priorities and biases. You should evaluate the information they present and decide for yourself whether you agree with their conclusions. Everyone tests lens sharpness because it's easy. Just photograph a resolution chart and read off the numbers. However, this ...


8

I think it wasn't mentioned: with increase in exposure time comes increase in thermal Dark Shot noise. You can read more here, for example


8

Basically, no-one on earth can hold a camera still for 15 seconds. Most people struggle at anything over 100th of a second. If you need exposures at that kind of length a tripod is essential - or a wall, or a bean-bag, or something so you're not holding it. Even at that, open your aperture as far as it will go, because celestial bodies move relative to ...


7

Sometimes a picture, even a crudely drawn one, is worth a thousand words.


6

No one can really give you an answer because the answer is completely dependent on your lighting set-up, as Michael C commented. But, you have some wrong assumptions that I wanted to point out. There are two types of set-ups you might use, continuous lighting or strobes. Strobes Shutter speed is relatively slow Maybe correct, it really depends on your ...


6

You need to differentiate the camera, on where the sensor or film resides and the optical elements. This can be either lenses or mirrors. A mirror telescope is a good example of an open structure. This structure is only to hold the elements aligned. But it still needs housing at the end, to make a labyrinth so no direct light enters the last element, where ...


6

If I'm getting the question correctly, it is about whether at infinity focus you ought to use wider apertures like f/1.4 or narrower apertures like f/11 to get the sharpest results? The answer is, it depends... First let's look at what depth of field actually is at infinity focus. The depth of field depends on three things: Focus distance, focal length, ...


5

With regard to systematic problems: you are taking into account that with opening up the aperture depth of focus decreases and thus the borders of out-of-focus scene parts blur? Also with small apertures you might get some blurring due to diffraction. If you have a mechanical shutter, you actually can get diffraction with large apertures from the resulting ...


5

Most product photos simply have an overexposed background, therefore meter the subject/product, then use lights to push the background exposure two stops above the subject. My tips for a standard setup would be; Take care with the white balance if shooting jpeg. Shoot bracketed with a selection of exposures. This toy dog was ISO: 200, shutter 1/100, and ...


5

That is not entirely true: You can see better through them because the depth of field (DOF) is shallower. If you focus on the object behind, a wider aperture allows the foreground to be blurred more heavily: Legend: BG ... background; FG ... foreground. Photos were made handheld (so framing and focus might nit be 100% accurate), no post-production (except ...


5

A similar aperture numbering system called the U.S. system (Uniform System) was used by the first Kodak cameras (until around 1920s). That system originated in England (1880s). Not 1, 2, 3, 4, but those stops were numbered 1, 2, 4, 8, etc, starting from todays f/4 equivalence. It was more useful than 1, 2, 3, 4 because it represented exposure increase ...


4

At the time I'm writing this, I have completed 40 marathons, 36 half marathons and many other races. Recently, I volunteered as a photographer at a small marathon. Based on this, I would start by asking a few questions: What is the purpose of your photos? Do you want to show the general event, photograph a few friends, or get individual pictures of nearly ...


4

The moon's surface is relatively darker than Earth's, with an average albedo of 11% (our gray cards are 18%). Moon phases other than full moon are side lighted, and darker still. Yet we seem to prefer too-bright pictures of the moon, thinking that captures it shining up there against the black sky background. So f/11 more nearly captures that sensation for ...


4

The equation is: f-number² illuminance × ISO value ───────────── = ─────────────────────── exposure time incident-light meter in seconds calibration constant Or N² = E*S*t/C, as you've summarized it with N as aperture on the left. Note that the calibration constant ("C") corresponds to your meter, not to the camera,...


4

"Landscape Photography" is a somewhat nebulous term. It doesn't, in and of itself, convey any meaning about the depth of field for the shot. One could go for everything sharp, and indeed, this is what most people assume landscape means. But it's equally possible that you'd want to isolate a subject by using limited DoF. So, if it's a choice between f/2.8 ...


4

All lenses with the same aperture value (e.g. f/5.6) acquire essentially the same amount of light, because that number is relative to the focal length. The aperture of a 400mm/5.6 lens is about 71mm, while 500mm/5.6 is about 89mm. The speed of focus, however, is more related to the speed of the focus motors on the lens, and how many (and how heavy) lens ...


4

The last time Camera FV-5 was updated was in November 2017. To say it is getting a bit long in the tooth is an understatement. That was only three months after the initial public release of Android 8.0. A lot of reviews for Camera FV-5 are negative and indicate that it causes a wide variety of phones to crash when certain features are accessed. It may be ...


4

Assuming all other potential issues are eliminated (and it sounds like you've done a good job of making sure of that), I would check the following: Does the aperture close on its own smoothly? Almost all Nikon F-mount lenses (including this one) have a mechanical linkage to the camera body. So you can easily check the aperture's action by taking the lens ...


4

"its known that lenses are generally sharpest at the F/8" That is not correct. Some lenses are sharpest at f/8, most reach their max at one to two stops from wide open, and some are sharpest when wide open. You need to test your lens/combination, or find a good test online. Strictly in terms of sharpness, you should use the widest aperture that doesn't ...


3

You can not have a "standard" if you leave the main variables at random. And the main, main, main and I can not understate main is "the lighting". KEEP CALM and Define your lighting I will repeat what @Hueco said. The aperture defines the DoF. You do not want a blurry image, you want to show the product as sharp as possible, so the aperture could be around ...


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