damned truths
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Why is focal length measured in millimeters?
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23 votes

Firstly, distance is used for focal length because it measures the distance between the plane of the lens and the point at which refracted rays meet at a point, when the incident rays were parallel. ...

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What's the reason for red eye in photo?
16 votes

Red eye is caused when light, almost always from flash, bounces off the retina of the eye and reflects back to the camera. Because the retina has lots of blood in it, the light appears red. In case ...

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Why don't I see a difference in the brightness through my viewfinder when I change the aperture?
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14 votes

You will not see a change of brightness through the viewfinder as the aperture is only stopped down when the photo is taken. This allows the auto focus sensors to focus accurately as many cannot focus ...

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Why are my printed photos coming out smudged and crazy looking?
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10 votes

I have seen this before when printing on the wrong side of the paper. Photo paper has a specific side that it needs to be printed on to keep the ink from spreading as only one side is usually ...

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Why don't DSLR cameras have internal memory to save images?
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9 votes

There is nothing technical stopping DSLRs from having internal storage (in fact, they already have a small amount). One reason for not including internal storage would be that it cannot be replaced, ...

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Is a 3rd party (Tamron) lens safe to use on a Canon EOS 600D?
9 votes

Third party lenses are generally safe to use. The only situation that is likely to damage the camera is if the lens focuses light weirdly and so creates a part of the camera a lot hotter than usually ...

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How can I get dramatic shallow DOF with a kit lens?
8 votes

To maximize background blur with a kit lens (Canon EF-S 18–55mm f/3.5 for example), you will need to zoom in as much as possible and use the widest aperture possible at that zoom. This will increase ...

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Can one tell, just by looking at a picture, if it's a sunset or a sunrise?
8 votes

From my (family's) observations, generally sunsets have a larger spread of light. Also sunsets have more colour depth. For example: Sunrise (from Wikipedia) Sunset (from wikipedia) This is from our ...

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Should I buy a compact, SLR, or DSLR camera?
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7 votes

Before I start: Past a certain point (where the camera does not limit the ability of the photographer to take the photos they want to), it is the photographer who makes a photograph good (with ...

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Question about legal usage of stock and photos with attribution
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5 votes

Even if it wasn't illegal in pretty much every legal jurisdiction in the world (maybe with the exception of the countries that are currently in a state of semi-anarchy), it is certainly a moral issue. ...

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Is there a name for artifacts for taking a photo of LCD / LED screens and how to remove or avoid it?
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5 votes

The effect is called Moire. It is caused by the grid pattern of the photosites in your sensor and the grid of pixels in the screen interacting. It happens when the grids do not exactly line up. It can ...

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What kind of lens is typically used for these type of night street shots?
4 votes

The lens used would have a reasonably large aperture (low F number). This gives the effect of a relatively narrow depth of field and also allows more light to get to the sensor, making it easier to ...

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Is there any reason to prefer a T3i if a T4i has the same price?
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4 votes

You should almost certainly go for the T4i if the price is the same or similar. The T4i has better technical specs and features, including video auto focus, cross-type focus points and faster ...

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Is there a formula to calculate DOF?
4 votes

Yes, there are formulas. One can be found at http://www.dofmaster.com/equations.html. These formulas are used on this calculator, it also explains depth of field in more detail. I have used this site ...

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How does "designed for APS-C" affect focal length?
3 votes

The advertised focal length is the actual focal length of the lens and not the Full frame equivalent focal length. The focal lengths are reported like this as the focal length of a lens is a physical ...

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Why doesn't a drastic change in aperture seem to have an effect on this city skyline photo?
3 votes

So since there is no difference between that two extreme presets, does it make any sense to use them, if Auto mode (the first image) already looks fine? That depends. If you are interested in the ...

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Do I get more detail from a shorter focal length by being physically closer?
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3 votes

Theoretically, assuming two perfect lenses, which do not distort the image at all, but just achieve different fields of view, then the wider angle, from closer should have better image quality, ...

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Is the weird red and yellow patch near the center of my photo chromatic aberration?
3 votes

The strip of colour near the centre of the image is the result of what is known as lens flare. This occurs due to light directly from a bright source within, or just outside, the field of view being ...

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How should I respond to a lowball offer for commercial use of one of my photographs?
3 votes

Disclaimer: I have NO professional experience at all. The best response is the response that you feel most comfortable with, and the response that most fits your purpose as a photographer. If you ...

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Improve photo resolution
3 votes

The act of adding pixels to make the image larger (without adding extra information (this is an important point)) is a basic function of any image processor. There are any number of applications that ...

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why it is showing two pictures of a picture
3 votes

This is a .GIF (Graphics Interchange Format) image. This format allows the creator to have the images swap (although this only happens on preset time intervals). This format is one of the formats ...

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What are the exact pixel values (or ranges) for shadows/midtones/highlights in Lightroom?
2 votes

From casual observation it would appear that each slider affects all values, however each slider affects each value to a different degree. From slightly more detailed observation: The Exposure ...

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how to capture snowflakes like this
2 votes

As you say, normally the flakes would be nearly invisible, however, the photographer has used a bright flash to illuminate the flakes, so that they are much brighter than the surrounding environment. ...

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How can I get tack-sharp portraits with the focus perfectly on my subject's eye?
2 votes

Ensure your subject is well lit and try to use a fast enough shutter speed that you have no chance of motion blur (i.e. mush faster than the usually suggested 1/focal length). Or use a tripod, remote ...

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What is the better material choice for a gorillapod? Metal or plastic?
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2 votes

I own both the metal ("Focus") and plastic ("SLR Zoom") variants of the gorilla pod. I found that on the plastic one, one of the cups (for want of a better word) broke, and then again after ...

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Which is better: a smaller f-number lens or a bigger sensor size?
2 votes

The bigger the sensor (not to be confused with size of image (number of pixels)), the greater the area there is for collecting light, and so there is less noise produced when the signal from the ...

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Are there any reasons to use film cameras anymore?
2 votes

Certainly. The process of developing film into prints can be what attracts photographers. Also using film can help a photographer get it right "in-camera" as film is expensive and photos can only be ...

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Resizing large size images retaining good quality for the web
2 votes

To create the size image that you want you will need to crop the image first , then re-size it. After you have cropped the image to your desired aspect ratio, you can resize it to what ever size you ...

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Why does storing a long exposure photo take almost as long as the exposure time itself?
2 votes

The extra time that the camera takes to store long exposure shots is caused by the extra processing that the camera has to do to reduce noise. It may help to turn off long exposure noise reduction if ...

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Is there a better macro lens for the Canon EOS system than the MP-E 65mm?
2 votes

This lens is the only lens that can magnify subjects so much, so close. It has the unique ability to magnify subjects to 5times their actual size. The definition of better would vary from person to ...

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