86

Through-the-lens focusing cameras had focusing screens — usually ground glass or fresnel lens (related: What is a focusing screen?). View cameras (the old-style large cameras with bellows) projected the image onto the focus screen. The photographer directly inspected the image on the focusing screen (perhaps using a loupe to magnify areas of the image), ...


60

Rarity. There were only approximately 20 of these now out of production lenses ever made. When they were in production they sold for about $90,000 (US). Due to the time needed to grow the large fluorite crystal used in the 3rd element of the lens, once ordered they took about 18 months to produce. Autofocus Capability. These lenses include auto focus ...


55

STM stands for Stepper Motor and is a applied to a new range of Canon lenses which feature a new design of focus motors which, along with a new iris mechanism are designed to eliminate (auditory) noise during video recording. Canon haven't revealed any information about how the new design works but it's probably the same type of motor used in mirrorless ...


49

You're not doing anything wrong. You're just finding the limits of the camera/lens combination you are using. The EF 50mm f/1.8 (in various versions) has been known as the "plastic fantastic" for a long time. For what it can do at what it costs, it is a fantastic value. But it isn't really a fantastic 50mm prime lens when compared to many others that, ...


33

Like many things when it comes to designing hardware for photography, there are always tradeoffs to be considered and made. STM lenses sacrifice a little speed in order to be quieter and smoother (no jerky starts and stops). This is important when using Autofocus while recording video. Lenses with USM focus designs are built for speed first and quiet ...


29

No Canon EOS body needs AF motors because every single Canon EF lens released since the EOS system was introduced since 1987 has a focus motor in the lens. Thus no Canon EOS camera has ever had a need for a focus motor in the body. There are a few manual focus lenses in the EOS system, but they are clearly designated as such by not being named as an EF lens:...


28

In actuality, a cross type AF sensor is just two "normal" AF sensors, one with the lines oriented in a vertical direction and the other with the lines oriented in a horizontal direction, that are superimposed over the same area. Non cross-type AF sensors can be either vertical, horizontal, or even diagonal. Some very early AF film cameras with a single ...


27

It is not just cheaper lenses. Many modern lenses, especially Auto Focus zoom lenses have this characteristic. There are several reasons for it: Unless a lens is parfocal the exact point of infinity focus shifts as the lens is zoomed in or out, and so obviously there will be a point where infinity for one focal length is past infinity for another. As ...


26

Having many autofocus points opens up the camera's capabilities because it can function in different ways depending upon settings and camera features: You can select a single AF point (get precise with exactly which point you want to use, without recomposing at all). You can select a group of AF points (a group of AF points means you don't need to be as ...


25

How did photography work before auto-focus was invented? Pretty well for those willing to learn how to do it with the tools we had at at the time. The same is true now. The only difference is that now we must learn how to tell an AF system to focus on the part of the frame we want it to bring into focus. Presumably everybody used manual focus. But here's ...


24

Your old D80 had a focus motor built into the body that connects to a mechanical coupling on Nikkor AF lenses to move the focus elements in the lens. Your D5300 does not have a focus motor in the body. To use autofocus your D5300 requires that you use Nikon AF-S or AF-I lenses or the equivalent third party lenses (such as Sigma's HSM or Tamron's USD and PZD ...


22

A few aspects mentioned in your question will be our starting point. Please note, we are not saying each of these issues will be determining factors for every photographer. We're not saying one system is better than the other because of... a or b. Rather they are a response to the question, "...what all should a person consider?" Once considered, each of ...


21

Phase detect autofocus in DSLRs works by comparing patterns of light coming from each side of the lens using pairs of detectors which are separated a certain distance on the AF sensor. This distance is called the baseline, and the greater the baseline the more accurately the distance can be measured. The need for a wide baseline and for light to travel from ...


21

According to it, we should first turn off the camera before turning auto-focus on/off. That's quite cumbersome obviously. That seems pretty ridiculous. Perhaps the authors are serious about their target audience being dummies. I am confused if this might harm my camera or lens in any way? You won't hurt anything. It's fine to turn AF on or off while the ...


20

Do whatever gives you the best results, don't worry about what may or may not be acceptable to others. I'd say shooting events fully manual is rare these days, though you might want to explore the aperture-priority and shutter-priority modes, each of which are very good for certain situations. I'd also investigate auto-ISO if your camera offers it. My ...


20

I can not imagine damage that would impact focusing without visible damage to the packaging or the camera. These things are pretty sturdy. you would have to damage the mirror or shutter box to really have an impact. So I suspect user error. These images appear to be in focus, but perhaps not where the photographer expected. I see areas in focus in both. ...


19

I don't think you're lacking in sharpness: at full size, the image you post shows sharp eyelashes and teeth. If you are using a large aperture (<F2), that explains the unsharp ears. When you reduce the size at which the image is displayed, apparent sharpness tends to decrease. To get the impression of sharpness back, you'd have to apply some sharpening ...


17

Major reason is that the DSLR lenses are optimized for Phase Detection. Every component of the lens is tailored towards quick movement and stopping the glass in precisely picked moment. Contrast detection on the other hand works best with stepper motors capable of quickly switching directions so that you can move lenses inside back and forth looking for ...


17

There are three parts to the answer to this, which is appropriate, because with Sony, Olympus, Panasonic, Fujifilm, and Sigma focusing on mirrorless designs, there are really only three companies making DSLRs: Pentax, Canon, and Nikon. First, all Pentax DSLRs, even the entry-level models, have built-in autofocus motors. So, if that's really your main ...


16

Phase detect autofocus works by measuring the horizontal displacement between brightness patterns projected onto the AF sensor. To measure the displacement, pairs of 1-dimensional arrays of monochrome pixels are used. This is what the AF sensor in the Canon 5D mkIII looks like: You can see lots of different lines of pixels used by different user selectable ...


16

USM is fast, STM is smooth. For still images (particularly with sports and wildlife) it is important that focus tracks quickly whereas in video the quick movements of a USM lens make the video feel jerky.


15

Lenses certainly are not optimised for the infra-red spectrum. I know this from pursuing infra-red photography with a converted camera. Chromatic aberration (well wavelength specific aberration, infrared light has no colour) is much worse, resolution is lower and some lenses exhibit "hot spots" a curious type of flair that occurs in the centre of the image. ...


15

It really depends on what you want to do with the camera. After all, there are many great photos that have been taken with older cameras, both when they were the hot new model and when they were no longer on the cutting edge. As with all equipment recommendations it comes down to the question of what do the technical demands of the photos you want to take ...


15

Your question seems to reflect the idea that a lower aperture number is for closer objects and a higher aperture number is for distant objects. This is not the case. Either aperture may be used to take photos of subjects whether they are near or far. Besides controlling how much light is allowed through a lens, the aperture setting also determines how far ...


15

No Canon EOS camera has an in-body focus motor. Canon's lens mount is 100% electric, there is no mechanical linkage. (Some mounts e.g. Pentax have a mechanical link for the aperture too, for some lenses). The EF designation of Canon's lenses stands for Electro-Focus - in other words, the focus is driven electronically. Each lens has a built in motor. There ...


15

The first image was shot wide open with what is essentially the lowest cost Canon lens (50mm f/1.8), in demanding low light conditions, and at ISO 1600. I'd say your results are exactly what I would expect. The second image, I don't see anything wrong with. My best guess is that you are overly concerned with the quality of each pixel viewed at 100% to a ...


14

A number of articles have been written about the problem with the focus and recompose technique. While the general idea they espouse is theoretically correct, most of them are really actually wrong on a number of points. First and foremost, most of them assume that you want to focus at the extreme corner of your picture. While you can do that, it's pretty ...


14

Are RAW images by nature slightly blurry prior to processing? If I open them up in Lightroom and zoom into the photo, my photos are not tack sharp but a bit blurry. Once I process, it comes out looking pretty sharp. Wait wait wait — let me stop you right there. When you open up RAW files in Lightroom, you are seeing a processed image. Lightroom does not ...


13

Many (possibly most) modern SLR lens systems return focus setting data to the camera. Potentially the precision of data returned could be high - something better than 1% of range would be possible and meaningful with modern systems. However, it appears that most if not all systems use a simple gray-coded* system with perhaps 16 steps. Number of steps ...


13

The fundamental driver of cost in a lens is not the correction of aberrations, although the correction of aberrations does add to the cost of a lens, and may be a more significant factor in wider angle lenses. Generally speaking, the primary cost of a lens is the "glass". I put glass in quotes, because sometimes it is other materials, such as Fluorite or a ...


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