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by Aditya

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12

There is a clear difference in intent and design philosophy. The Canon 50 f/1.2L is a bokeh machine, offering not only shallower depth of field (due to the ultra wide f/1.2 aperture) but also a smoother background blur on account of the decision to leave a certain amount of spherical aberration in the design. It's a lens with character and a distinct look, ...


10

Distortion caused by a lens's optics would give you barrel distortion (objects appear to bulge outward) or pincushion distortion (squishing inward). The skewed lines you are observing are straight; this is perspective distortion, and is not a problem caused by the lens nor fixable with better optics (you can fix it with a tilt-shift lens, but that's a ...


9

A Flair for flare. Flare reduces the contrast of the image captured. It can affect the image overall or selectively. I'm going to make a great leap of faith and guess that you are after selective flare such as a round or symmetrical shape that plays across the image. Your concept of what is beautiful and desirable versus undesirable is personal and will ...


9

All lenses create a circular image, it's just that most of them have an image circle large enough that it covers the entire sensor. Vignetting at wide apertures is a manifestation of the image circle encroaching on the corners of the sensor as the circle edge is not as sharp as it would be with a narrower aperture. With a fish-eye lens, the image circle is ...


8

This not a thing that can happen. Cameras just don't work that way. For that matter, light doesn't work that way. Specifically, for digital cameras: every "photosite" — each individual pixel-level sensor — is just a counter of photons. It doesn't have any sense of the wavelength of the light received, and correspondingly no perception of color. In order to ...


7

An aperture could be closed which is effectively an infinitely large f-stop number since no light gets through. The fastest possible (smallest f number) is a bit harder. The speed of a lens is limited by the ratio of the entrance pupil to the focal length of the lens. The longer the focal length, the bigger the entrance pupil must be. In theory you could ...


7

Cost and ease of design. The main purpose of mirror telephoto lenses is to make them much more cheaply and compact than a conventional refractive lens can be produced. This is easiest to accomplish by coating the back side of a negative meniscus lens (known as a Mangin mirror) instead of creating a parabolic first surface mirror that would need to be shaped ...


7

OK i will try to actually answer this! there is a distinction between HAZE and flare - for the purposes of this I will cover FLARE only. Lens flare is caused by light from a particularly bright source such as the sun or a bulb directly striking the lens element surfaceS at an off-centre axis, and not being REFRACTED but instead being REFLECTED either off ...


6

You can find a lot of others with this problem, especially some Nikon primes. Apparently, also zooms like yours. It is reflection from the glass in front of the sensor that reflects back to the lens rear element. The colour and power of the spot depends on camera/lens combination, but often it is reddish (pink, magenta, whatever you want to call it) ...


6

You're getting what is called Perspective distortion which is most noticable in wide angle lenses. Check out this link for more info: http://en.wikipedia.org/wiki/Perspective_distortion_(photography) Basically close up objects in the center of the frame will look enlarged while objects on the sides will be stretched away from the center of the photo.


6

The "telecompressor" you mentioned is a focal reducer, a device that concentrates the image in order to project it onto a smaller sensor. This approach reduces the backfocus distance (the distance from the back of the lens to the sensor). So it only works on mirrorless cameras using lenses designed for DSLRs (which have sufficient backfocus distance to make ...


5

The lower the number after the F, the more light gets into the camera. More light means - you can get away with shorter exposure times. - you have lower depth-of-field (which is a good thing in portrait shots) The ranges given for the lenses are the values for the wide angle and the tele setting of the lens. Generally you want the numbers to be as low as ...


5

Physics plays a role in answering your question and that information is out there. The basics from that linked discussion are that the index of refraction of the lens material will affect the maximum aperture you can achieve, so for pure glass that has an index of refraction of 1.5, the maximum aperture would be f/0.5 or thereabouts. Better substances, such ...


5

Two reasons: A camera objective (made up from many lenses) needs to focus on a plane, not an arc. And we dont see the image projected on the back of our eye ball. We build up the image from features extracted by many neurons with each their specialty. That's why we don't have to show reality to the eyes for us to see the same, we just need to construct ...


5

The shape of the bokeh is related to the apparent shape of the aperture of the lens. Straight on, this will produce a bokeh that is approximately a circle. As the subject moves away from the center of the field, the bokeh starts to look like a sliver of the circle. This can be reduced by stoping down the lens. (above image from ...


5

This is not "obviously irrelevant to normal photography" at all; we just don't normally worry about the sort of precision that you'll need to deal with. There are two numbers that we ordinarily take at face value, knowing that they're slight fibs: the focal length of the lens (which is usualy rounded to a "friendly" value except on data sheets), and the ...


4

Flare is a non-standard use case for a lens, i.e. it's outside the intended operating conditions. As such it tends to be a little bit random how a lens flares as it's a side effect of various design decisions that are made without concern for how it affects flare. I have heard many times anecdotally that older lenses that are less thoroughly corrected for ...


4

Panavision offer dedicated lenses attributed to more desirable lens flare - this all comes down to the coating and treatment of the glass: http://www.panavision.com/content/spherical-specialty Additionally, in films such as Star-Trek, Super-8 etc, they have hot lights just off camera to add glares already attributed to the on-camera light sources. Though ...


4

A screw on diopter filter with a positive index number refracts light from a narrower angle of view before it strikes the front element of the original lens. It obviously adds another lens element to the optical path of the light reaching the film/sensor. This will affect overall image quality to one degree or another, depending upon the quality of the screw ...


4

Without knowing the focal length, the exact lens added to the front of the existing one can't be calculated. However, what you want is called a "closeup lens". These are usually single-element convex lenses that mechanically mount as filters. First you have to find the diameter of the filter mount on the lens. This is usually written on the front of the ...


4

Yes on normal lenses the area in focus is nearly perfectly described as a plane and the small deviations are rarely taken into account in regular photography. There are two important factors that cause these slight imperfections: the Petzval curvature and Astigmatism. The uncorrected astigmatism is usually more severe but can be over-corrected in order to ...


4

Consider this review of the Canon 8-15 f/4L USM fisheye, which can shift from circular at 8mm to diagonal at 15mm. Yes, it's circular because the lens's entire image circle is inside the area of the sensor, rather than covering the entire sensor. I'm not sure there's going to be an entire explanatory webpage other than Wikipedia on this, because it's such a ...


3

Here's the short answer: a wide angle lens on a crop sensor skews the image exactly in the way it does in the center of the frame on a full-frame sensor. In turn, this means that using a wide angle lens (small focal length) on a crop sensor gives the same perspective distortion as using a narrower lens (larger focal length) on a full frame sensor, with the ...


3

if I measure the size of the entrance pupil by looking at it, will that be equivalent to the focal length of the lens divided by the f-number Yes. F-number is defined in terms of focal length and entrance pupil diameter, so if you know any two of: entrance pupil diameter, f-number, and focal length, you can calculate the third number. The equation that ...


3

Simply put, it does, our brain corrects for it. Among other things, you can't actually see where your optic nerve attaches to the retina and your visual acuity is actually much more center focused than even a cheap camera lens, but because your eyes refocus on the fly every time you change where you are focusing, you don't notice the changes or the lack of ...


3

STM and USM are different kinds of focusing motors. Prior to STM, USM was the preferred option because it was fast and quiet (relative to other kinds of motors that are available). However, it isn't fluid which becomes an issue with video. Enter STM which is also quiet (though I'm not sure which is more quiet) and provides a smooth transition as it focuses ...


3

You can look at DxOMark's Lens Ratings, and particularly the Optical Metric Scores, which include a T stop measurement. I don't put too much stock in DxOMark's overall numbers (which don't have much practical impact for real use), but if you're interested in this particular thing, here's a way to tell. Manufacturers do not typically give this number, so the ...


3

The SLR Magic Hyper Prime is lower than that at f/0.95, and Leica's Noctilux also offers f/0.95. And then there's the brand new IBELUX 40mm f/0.85. And if rental counts, you can rent the Zeiss f/0.7 lens made for NASA and famously used by Stanley Kubrick - but only attached to a specific camera. That's often claimed to be the largest practically usable ...


3

This is because of differences in how your eyes and your camera work. In your camera, the rear element of the lens is the final optical element before the image is formed. The aperture iris is placed at or near the point of "maximum out-of-focusness" (the optical center of the lens) so that the shadow of the iris is spread evenly over the entire image. By ...


3

This is field curvature. (And a nice example of it!) Simple lenses naturally project a curved field, not a flat one to match film or digital sensors. Modern lenses attempt to correct for this, but many older designs do not. In fact, it's sometimes called the "Petzval effect" after a classic design famous for this look. Interestingly, just this week Sony ...



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