## [ Astronomy & Space ] Open question: How did the Crab Nebula reach 5.5 light years of radius if its supernova explosion only happened 1000 years ago?

You know, because matter can not travel at the speed of light. Something seems suspicious here …

## Flash: How long is the life of a speed light?

If it is a really economic agreement (for example, from \$ 5 to \$ 20, as it is not uncommon for the equipment not compatible with digital TTL) … buy two and you do not care if you can get a couple of thousand dollars for thousands. leaves each one. Which is very likely given that you can assume the "few million" mentioned above close to the truth.

It is statistically unlikely that you buy a gun with exactly 1% of the tube's life.

The main causes of the lack of service in old rifles used are usually compartments of poorly maintained batteries that were flooded with battery acid (usually they can be repaired, if there has not been a migration of acid to the proper electronics). said) and capacitors are worn out, aged or kept in poor condition

There is a good reason why it is not necessary to suppose that the regime in any speedlite is even close to "60% of the explosion energy": the electrolytic capacitors, as used in the flashes, are very little tolerated towards the positive ( + 20% Capacitance is found on a data sheet from a well-known manufacturer, for its photoflash products, some brands could be + 50%!). Something designed to be 50% uniform would suddenly find 60% that way occasionally, and would fail very quickly if used in the full-power manual mode.

A branded firearm that only serves a few hundred cycles quickly would leave the manufacturer in bad repute.

If a previous user used a flash to the point of a severe thermal stress, that will generally be evident as the discoloration / melting / … of the clear plastic diffuser.

## lighting – point of light unit bake in lightmap

I am developing a puzzle with a ball with cracks. Inside the ball there is a point of light. Its rays of light come out of the cracks and hit some platforms (walls / roof / floor).

To solve the puzzle, the player must turn the ball to match the light coming out of the cracks with a pre-lit pattern on the platforms.

I do not know how to make the pre-lit pattern. I do not want it to be done manually using a texture editing tool like Photoshop or GIMP. I remembered that this could probably be done using light cooking. I think what I need is to make the light become just that point of light in a map of light and use it only on those platforms, but I do not know how to do it.

Can someone help me with a solution?

## html: it is necessary to make a light hit from one point to another with svg and canvas coordinates

I have an svg file that has three areas, one is an external area with points around the edge, another is an internal area with a point halfway to the center and in the center there are randomly arranged points. A lightn animation, glow beam or some other type of animation will be used to visually connect these points, if I can find some way to use a single image as a light hit or a bright beam hit to increase performance. I can obtain the location of each point from the svg file embedded in the html by the method of the element getBoundingClientRect and getClientRects. It seems to work once and sometimes not. Someone can show me or codepen an example of svg images composed of two circles, one outer and one inner and the interior varies from points to point and hit. It can be a canvas with just drawing lines from the outside to the inside and from the inside to the variety of points in the interior closer to the center.

## nikon – How to reduce ISO in low light conditions with slow zoom lenses?

Some options to consider:

• Meditate on what it means for ISO to be high.

• Use the 35 / 1.8. You can not get the shot you want with it, but you may not get the shot you want with the zoom lens.

• Use slower shutter speeds. 1/125 may Be faster than necessary. As it indicates that you are using the zoom lens for focal lengths greater than 35mm, 1/60 should be fine. Even slower if your lens has image stabilization. Use 1/40 throughout the zoom range of my kit lens (18-55). Use 1/100 for non-stabilized lenses (up to 135 mm).

• Use a flash(with diffuser or bounce), or look for some other way to add light.

• Post process to eliminate noise or convert to black and white.

• Lower the camera and enjoy the moment.

• Get new glassesHere are some that might work:

• Try a focal reducer?Pity … They do not work on digital SLR cameras.

• Get a new camerawhich produces less noise (objectionable) at high ISOs.

The end result is that I have … many shots with ISO higher than I would like. The image quality is not terrible in those ISOs, but …

It is not clear to me if you want lower ISO values ​​because of having lower ISO values ​​or if you really find that the noise that results from high ISO values ​​is objectionable.

For example, I do not like chroma noise, as you can see in the flolyl sample image. But I do not care more about monochromatic noise, which my camera tends to produce. So even though I I like it lower ISO values, I let my camera reach ISO 12800 because I know that, otherwise, I would lose the shot. However, if I need cleaner images, I find ways to add more light.

Here is an image taken with a Sigma 18-200 / 3.5-6.3 to 69 mm F4, 1/125 sec, ISO 8000. You can see it 100% to see how the noise from my camera looks. (There are no colored spots).

Here is an image taken with a Canon FD 35-105 / 3.5 at 105mm F3.5, 1/75 sec, ISO 12800. There is an almost absence of green light, which means that the sensor was running at only 45% of your capacity. (Non-standard color matrix with green sensors that cover approximately 55% of the sensor). I turned black and white because I could not make the color work without the green channel.

## nikon – DX lens with low light at a wider angle

With any gear: the Golden Rule To get photos without a remarkable camera movement is:

``````shutter_speed[s]  ≤ 1[s] / (focal length[mm] * crop factor)
``````

Note that if you like pixel display, you will probably need shorter shutter speeds (at least 2 thirds of a stop). E.g. For your 35mm lens, it should be good with something faster than 1 / 60s.

Lenses (or bodies) with image stabilization can help with the movement of the camera; however, they will not help you if you have to deal with the movement of the subject.

Regarding the gear:

• Tripods (not allowed in many spaces, somewhat bulky to carry) or monopods (offers much less stabilization) can help because they limit camera movement.
• The faster lenses will allow less ISO and / or faster shutter speeds; however, you trade in depth of field. In addition, fast lenses are usually more expensive and heavier than the lenses of an average kit.
• A full frame sensor will generally provide better high ISO image quality.

Will you need any of them? It depends. It is important to have realistic expectations to avoid GAS.. I will give an example:

This is a 200% vintage of a picture I took inside a church. The floor is slightly underexposed because I wanted to expose the ceiling correctly. It was fabricated with a 24-105 mm f / 4 lens with image stabilization in a full-frame camera. The real parameters are: 24mm | 1 / 30s | f / 5.6 | ISO 3200. The image is not altered (that is, the noise is not eliminated, it is not compensated by the exposure).

Is this bad? No, not really, with a little bit of noise, it looks pretty good, and for A4-size prints, I would not even have to do that.

## dnd 5e – Does the release of Light, or a similar spell, have any effect when the caster is swallowed by a monster?

So you've been swallowed by a giant toad. Ups. Your companions will surely kill you soon, but you want to do something in the meantime.

"Well," you say, "maybe attack the toad from within!"

"Ah," says God (you're used to God commenting on your intentional actions), "but remember, you're blinded and restricted, so any roll you make is Disadvantaged." (You're also used to God using strange terminology to describe your life as a kind of game.

"But I'm surrounded on all sides by a toad! Surely that would imply some advantageous modifier!"

"The toad's beard restricts you," God replies, "your arms can not move well enough to attack effectively, even if you were not blind."

Phooey. You think about it for a moment. "Maybe it's better to do a spell, then" you say "Magic missile It does not even require an attack roll! Oh, but, gee, I need to see the target, right? Maybe I should take Light in any given object in my person first. "

"It's not just dark, you're blind," says God, "Light It will not do anything. Nor torches, lanterns or whatever. "

"Are you suggesting that my face is always pressed against a part of the frog's anatomy? With restriction or not, it seems that I should have at least the range of motion to remedy it. that! "

So, is there any indication that you can forever see the toad what are you inside Enough to point it with a spell?

## dnd 5e – Does the Maddening Darkness spell affect the creatures in its radius if they have level 9 light that illuminates it?

The description of the maddening darkness spell (XGtE, p.160) says [emphasis mine]:

The magical darkness extends from a point that you choose within the range to fill.
A sphere of 60 feet of radius until the spell ends. The darkness extends
around the corners A creature with dark vision can not see through this
darkness. The non-magical light, as well as the light created by the spells of the 8th.
level or lower, the area can not be illuminated.

Screams, babbles and crazy laughter can be heard inside the sphere.
Each time a creature begins its turn in the sphere., you must make a
Release of wisdom salvation, taking 8d8 psychic damage in a failed salvation, or
Half damage in a success.

If I throw continuous flame at the ninth level, it must produce a magical light capable of illuminating a sub-sphere of the maddening darkness.

I postulate that if I'm standing in the sphere of maddening darkness when it was originally released and I'm also exposing that level 9 continuous flame to illuminate the darkness, then I am no longer in the area of ​​the sphere (darkness) and the spell would not affect me.

I can see a strict RAW reading that, technically, I am still in the original radius of the spell and, because of that, it would be affected. It could be true that the intention is only that my continuous flame I would light the darkness and it would not eliminate any maddening effect.

Which of the previous interpretations is true?

## php – How to find out if a hexadecimal color is dark or light?

``````/ **
* Function that defines if a color, given the values ​​of the red, green and blue components on a scale of 0 to 1, is clear or dark.
* @param {int} r - Value of the red component on a scale of 0 to 1.
* @param {int} g - Value of the green component on a scale of 0 to 1.
* @param {int} b - Value of the blue component on a scale of 0 to 1.
* /
(), () () () () () () ()
return Math.sqrt (r * r * 0.299 + g * g * 0.587 + b * b * 0.114)> = 0.5;
}

// Map common names of colors. Source: http://www.w3schools.com/cssref/css_colors.asp
: "# FFFFFF", "AQUAMARINE": "# FFFFF", "AQUAMARINE": "# FFFFDF", "AQUAMARINE": "# F00F5DC", "BISQUE": "# FFE4C4", "BLACK": "# 000000" , "BLANCHEDALMOND": "#FFEBCD", "BLUE": "# 0000FF", "BLUEVIOLET": "#" "BOTLY": "# A52A2A", "BURLYWOOD": "# DEB887", "CADETBLUE": "# 5F9EA0 "," CHARTREUSE ":" # 7FFF00 "," CHOCOLATE ":" # D2691E "," CORAL ":" # FF7F50 "," CORNFLOWERBLUE ":" # 6495ED "," CORNSILK ":" # FFF8DC "," CRIMSON ":" # DC143C "," CYAN ":" # 00FFFF "," DARKBLUE ":" # 00008B "" DARKGREEN ":" # 008B8B "," DARKGOLDENROD ":" # B8860B "," DARKGRAY ":" # A9A9A9 " , "DARKGREY": "# A9A9A9", "DARKGREEN": "# 0064B": "# BDB76B", "DARKMAGENTA": "# 8B008B", "DARKOLIVEGREEN": "# 556B2F", "DARKORANGE": "# FF8C00" , "DARKORCHID": "# 9932CC", "DARKRED": "# 8B0000", "DARK", "DARK", "DARK", "DARKS", "DARK", "DARK", "DARK", "DARK" , "DARK" "# 00CED1", "DARKVIOLET": "# 9400D3", "DEEPPINK": "# FF1493", "DEEPSKYBLUE": "# 00BFFF", "DIMGRAY": "# 696969", "DIMGREY": " # 696969 "," DODGERBLUE ":" # 1E90FF "," FIREBRICK ":" # B22222 "," F LORALWHITE ":" "" FF00FF "," GHOSTWHITE "," GHOSTWHITE "," GHOSTWHITE ":" # F8F8FF "," GOLD ":" # FF00FF "," GFOS "" GOLDENROD ":" # DAA520 "," GRAY " : "# 808080", "GRAY": "# 808080", "GREEN": "# 008000", "GREENYELLOW": "# ADFF2F", "HONEYDEW": "" # FBB "," DIVISION ":" # FBB "," INDIVIDUAL ":" # FB "," INDICATOR "" LAVENDERBLUSH ":" # FFF0F5 "," LAWNGREEN ":" # 7CFC00 "," LEMONCHIFFON ":" #FFFACD "," LIGHTBLUE ":" # ADD8E6 ", "LIGHTCORAL": "#" "LIGHTGREEN", "LIGHTGREEN", "LIGHTGREEN", "LIGHTGREEN", "LIGHTGREEN": "# D2D3D3": "# FFB6C1", "LIGHTSALMON": "# FFA07A", "LIGHTSEAGREEN": "# 20B2AA", "LIGHTSKYBLUE": "# 87CEFA", "LIGHTSLATEGRAY": "# 778899", "LIGHTSLATEGREY": "# 778899" "," LIGHTSTEELBLUE ":" # B0C4DE "," LIGHTYELLOW ":" #FFFFE 0 "," LIME ":" # 00FF00 "," LIMEGREEN ":" # 32CD32 "," LINEN ":" # FAF0E6 "," MAGENTA ":" # FF00FF "," MAROON ":" # 800000 "," MEDIUMAQUAMARINE: "# 66CDAA", "MEDIUMBLUE": "# 0000CD", "MEDIUMORCHID": "# BA55D3", "MEDIUMPURPLE": "# 9370DB", "MEDIUMSEAGREEN": "# 3CB371", " MEDIUMSLATEBLUE ":" # 7B68EEE "", "MEDIUMSPRINGGREEN": "# 00FA9A", "MEDIUMTURQUOISE": "# 48D1CC", "MEDIUMVIOLETRED": "# C71585", "MIDNIGHTBLUE": "# 191970", "MINTCREAM": " # F5FFFA "," MISTYROSE ":" # FFE4E1 "," MOCCASIN ":" # FFE4B5 "," NAVAJOWHITE ":" #FFDEAD "," NAVY ":" # 000080 "," OLDLACE ":" # FDF5E6 "," OLIVE ":" # 808000 "," OLIVEDRAB ":" # 6B8E23 "," ORANGE ":" # FFA500 "," ORANGERED ":" # FF4500 "," ORCHID ":" # DA70D6 "," PALEGOLDENROD ":" # EEE8AA "," PALEGREEN ":": "# FFEFD5", "PEACHPUFF": "# FFDAB9", "PERU": "# CD853F": "# FFEFD5", "PF", "MOVIE" "PINK": "# FFC0CB "," PLUM ":" # DDA0DD "," POWDERBLUE ":" # B0E0E6 "," PURPLE ":" # 800080 "," REBECCAPURPLE ":" # 663399 "," RED ":" # "# FF0000", "ROSYBROWN": "# BC8F8F", "ROYALBLUE": "# 4169E1", "" SADDLEBROWN ":" # 2B4513 "," SALMON ":" # FA8072 "," SANDYBROWN ":" # F4A460 "," SEAGREEN ": "# 2E8B57", "SEASHELL": "# FFF5EE", "SIENNA": "": "# 708090", "SLATBLRE": "# 708090", "SLATBLRE": "# 708090", "SLATBLRE": "# 708090 "," SLATBLRE "" SNO W ":" #FFFAFA "," SPRINGGREEN ":" # 00FF7F "," STEELBLUE ":" # 4682B4 "," SO ":" # D2B48C "," TEAL ":" # 008080 "," THISTLE ":" # : "D", "TOMATO": "# FF6347", "TURQUOISE": "# 40E0D0", "VIOLET": "# EE82EE", "WHEAT": "# F5DEB3", "WHITE": "#FFFFFF", "WHITESMOKE" ":" # F5F5F5 "," YELLOW ":" # FFFF00 "," YELLOWGREEN ":" # 9ACD32 "};

/ **
* Function that defines if a color, given its name, is light or dark.
In the event that the name of the color, it may have one of the following formats: & # 39; # abcdef & # 39 ;, & # 39; # abc & # 39 ;, & # 39; rgb (a, b, c) & # 39 ;, & # 39; rgba (a, b, c) & # 39 ;, or be a common color name, such as & # 39; network & # 39; or & # 39; yellow & # 39 ;.
* /
color function Clara (color) {
var r, g, b;
test {
var rgb = color.trim (). toUpperCase ();
(colorMap[rgb]) rgb = colorMap[rgb];
if (rgb.startsWith ("#") && rgb.length === 7) {
r = parseInt (rgb.substring (1, 3), 16) / 255;
g = parseInt (rgb.substring (3, 5), 16) / 255;
b = parseInt (rgb.substring (5, 7), 16) / 255;
} else if (rgb.startsWith ("#") && rgb.length === 4) {
r = parseInt (rgb.substring (1, 2), 16) * 17/255;
g = parseInt (rgb.substring (2, 3), 16) * 17/255;
b = parseInt (rgb.substring (3, 4), 16) * 17/255;
} else if (rgb.startsWith ("RGB") && rgb.endsWith (")")) {
rgb = rgb.substring (3);
var a = rgb.charAt (0) === & # 39; A & # 39 ;;
yes (a) RGB = rgb.substring (1);
rgb = rgb.trim ();
if (! rgb.startsWith ("(")) throw new error ();
rgb = rgb.substring (1, rgb.length - 1);
var x = rgb.split (& # 39;, & # 39;);
if (x.length! == (a? 4: 3)) throw new error ();
r = parseInt (x)[0].trim ());
g = parseInt (x)[1].trim ());
b = parseInt (x)[2].trim ());
aa = a? parseFloat (x[3].trim ()): 0.0;
(isNaN (r) || isNaN (g) || isNaN (b) || isNaN (a) || r < 0 || r > 255 || g < 0 || g > 255 || b < 0 || b > 255 || aa < 0.0 || aa > 1.0) throw new error ();
r / = 255;
g / = 255;
b / = 255;
}} else {
returns a new error ();
}
return colorClaraRgb (r, g, b);
} catch (x) {
the new error ("Color") + color + "has not been recognized.
}
}

// Test
test function (x) {
test {
document.write ("Color" + x + "& # 39; is a color" + (colorClare (x)? "light": "dark") + ".");
} catch (e) {
document.write (e.message + "");
}
}

document.write ("These colors must be valid");
Test ("# 102030");
test ("# 0000ff");
test ("# 00f");
Test ("# 00ff00");
Test ("# FF00FF");
Test ("# 808080");
Test ("# 888");
test ("#ffffff");
test ("# fff");
Test ("# 000000");
Test ("# 000");
test ("# a000A0");
Test ("# A0A");
test ("yellow");
test ("blue");
test ("Powderblue");
test ("rgb (20, 40, 60)");
test ("rgb (100, 180, 250)");
test ("rgb (100, 180, 250)");
test ("rgb (255, 255, 255)");
test ("rgba (20, 40, 60, 0.4)");
test ("rgba (100, 180, 250, 0.7)");
test ("rgba (100, 180, 250, 0.9)");
test ("rgba (255, 255, 255, 0.33)");

document.write ("These colors must all be invalid");
test ("lol");
test ("donkey color when he flees");
test ("rgba (255, 255, 255)");
test ("rgb (255, 255, 255, 255)");
("rgb (255, 255)");
test ("rgba (255, 255, 255, 0, 0)");
test ("rgb (256, 0, 0)");
test ("rgb (-1, 0, 0)");
test ("rgba (256, 0, 0, 0.0)");
test ("rgba (-1, 0, 0, 0.0)");
test ("rgba (255, 0, 0, -1.0)");
test ("rgba (255, 0, 0, 1.1)");
test ({});
Test (1245);
test ([]);
test (undefined);
test (null);``````

## White balance: is it correct to match the light sources with the same color temperature?

For example, the color temperature of a candle flame, sunrise and sunset have the same color temperature, knowing that its color temperature is the same. Could you say that these sources are similar or equivalent? Could you say that they would produce the same image of a scene? Could you say that the pixel values ​​are the same with these three light sources? Thanks in advance