# This is kinda weird NOT C&C



## zombiemann (Aug 22, 2012)

I took this shot about 20 minutes ago.  I know the composition is off, the exposure is off.  I was playing around with different F stop values and exposure times just for the heck of it.  This is a 30 second exposure.  The weird thing is, as the shot was exposing a guy rode a bicycle right down the sidewalk on the other side of the street from me.  Right through the frame of the picture.... When I opened the RAW in photoshop imagine my surprise when there isn't a trace of the guy on his bike. I resized the shot for posting but thats it.  No other processing has been done


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## MLeeK (Aug 22, 2012)

Wow. That is different! I'd expect it with longer exposures, but not that short!


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## FanBoy (Aug 22, 2012)

You'd think there would be a reflection off of the bicycle thus creating some streak. Maybe he was "ghost-riding"??


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## unpopular (Aug 22, 2012)

The composition is off. It would be nice to have the street perpendicular with the sign.

(harhar)


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## zombiemann (Aug 22, 2012)

I jokingly told my girlfriend either we would see a ghost in the pic or he was a ghost lol


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## AaronLLockhart (Aug 22, 2012)

This is not uncommon. I shoot shots that result in this all the time. I'll have to post one later of a bridge I took a 30 sec exposure of that there were about 20 or 30 people walking on... In the final result, you don't see a single trace of any of them.


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## rokvi (Aug 23, 2012)

I think it all depends on the speed at which someone goes through the frame.


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## LaFoto (Aug 23, 2012)

Well, I once took a 30-second exposure of a night street in Stockholm and a group of persons wandered THE LENGTH of the photo and they don't show - they didn't even "ghost" the picture. Nothing. As if they hadn't been there. Empty street. So yes, I've had the self same effect myself, too.


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## PhotoWrangler (Aug 23, 2012)

Think about it. The street and building had to stay still for 30 seconds for them to be lit enough to show up in the photograph. A person riding a bike wouldn't even be in the same spot for 1/2 a second if they were moving. Even reflections off the bike itself wouldn't have been bright enough to cause a ghost.


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## Jaemie (Aug 23, 2012)

It's happened to me as well. Here's a 30sec exposure in which several people walked directly in front of the camera. (ignore comp, technique, etc. - just an example)


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## unpopular (Aug 23, 2012)

Yep. The amount of time that the pedestrian was in the frame at any given position, relative to the time of exposure is not sufficient to make any _measurable_ impact. The change in accumulated luminance is there, but not likely recorded.

Remember, it takes time to allow light to accumulate on a sensor or film in order to allow sufficient electrical or chemical reactions to occur. Movement inherently takes place over a period of time. The cyclist's projected image was not in any one position long enough to make an exposure.

There's probably some way to calculate exposure value per millimeter per millisecond and determine exactly how fast something has to travel before it will be visible ... if you really wanted to get technical about it.


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## ceejtank (Aug 23, 2012)

It's not weird.. it's understanding basic light properties..


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## AaronLLockhart (Aug 23, 2012)

ceejtank said:


> It's not weird.. it's understanding basic light properties..




Man you are on a roll today.

The four basic properties of light are:

*Intensity
*How bright the light is. highly intense lights are much more attention-getting than dim ones, obviously, and you can use this to direct your viewers.

*Quality
*Whether the light is "hard" (sharp shadows) or "soft" (diffuse). Volumetric behavior, like beams of light through fog and haze, is also an aspect of quality.

_*Direction
*_Where is the source of the light in relation to the object it's lighting? Is it coming from the front, the side, from behind?

_*Color
*_This one's more subtle than you think. Is the light in your home white? If so, what about sunlight? Note that even sunlight varies greatly, from warm yellows all the way to clear blues. In addition to being red, green, or blue, we can think of light as varying from "warm" (reddish/orange/yellow) to "cool" (blue/white).




So, please elaborate how any of the above has ANYTHING to do with the exposure of the above image? It doesn't. The result you see above has to do with the aperture and the amount of light let into the lens. The light stays the same... it's the object that you're using to capture the light that is important.


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## jaicatalano (Aug 23, 2012)

This is one of my favorite lines I have read in a while. Is this your and if so would I be able to quote you? "It seems your vocabulary is bigger than your brain."

I think I want to use this one on my wife. 



AaronLLockhart said:


> ceejtank said:
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## AaronLLockhart (Aug 23, 2012)

jaicatalano said:


> This is one of my favorite lines I have read in a while. Is this your and if so would I be able to quote you? "It seems your vocabulary is bigger than your brain."
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> I think I want to use this one on my wife.
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Go for it


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## zombiemann (Aug 23, 2012)

ceejtank said:


> It's not weird.. it's understanding basic light properties..



Wow, thanks for that, I would have never thought of it all by myself.

:waiting:


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## Ballistics (Aug 23, 2012)

ceejtank said:


> It's not weird.. it's understanding basic light properties..



Yeah, no. 

Like Aaron said, knowing the properties of light would not explain why people are not showing up in the frame during a long exposure. 

It's simply understanding exposure.

A moving object that is not a light source is not being lit enough by the ambient light to be captured in the frame during a long exposure with low sensitivity settings.


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## AaronLLockhart (Aug 23, 2012)

zombiemann said:


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Dude... noooo. He's like a genius... he swears.


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## ceejtank (Aug 23, 2012)

Ballistics said:


> ceejtank said:
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And what is exposure?  Exposure is the amount of time needed to capture light.  So if you understand that the exposure is set for 30 seconsd to capture the light needed to get the buildings in that shot to appear (and the buildings clearly are standing still for 30 seconds) then the amount of light reflecting off an object not standing still to the camera will not be enough to make it appear on said photo.  As I said.  It's basic light properties.  See below for the definition of exposure for photography.

Exposure:In photography, *exposure* is the *amount of light* allowed to fall on each area unit of a photographic medium (photographic film or image sensor) during the process of taking a photograph. Exposure is measured in lux seconds, and can be computed from exposure value (EV) and scene luminance in a specified region.


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## Ballistics (Aug 23, 2012)

ceejtank said:


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That's like saying in order to drive a car, you have to understand how combustion works. Sure, it's important to the act of driving, but the lack of knowledge about combustion does not affect your ability to drive.

Like I said, it's not understanding the properties of light, it's understanding exposure. 

To take it a step further, you are essentially saying that understanding the properties of light will allow you to know how to properly expose an image.


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## ceejtank (Aug 23, 2012)

Ballistics said:


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Exposure is literally getting the correct amount of light into the picture.  They're basically interchangable words.  Too much light and you're overexposed, not enough light and you're underexposed.  Changing the length of your exposure is simply controlling the amount of light you let in to your sensor (or film).


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## AaronLLockhart (Aug 23, 2012)

ceejtank said:


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Right, but it's not altering the properties of the light entering the lens. So, knowing the properties of the light has nothing to do with knowing how to capture it. 

I don't have to know the anatomy of a lightning bug to be able to capture it in a jar.


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## ceejtank (Aug 23, 2012)

AaronLLockhart said:


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Actually understanding the properties of light has everything to do with it.  The light reflecting off the buildings to your camera sensor means it needed 30 seconds to produce that image.  Understanding not enough light is reflecting off a moving bike to make it appear on the picture is not understanding basic light principles.

Either way - you don't understand light, or exposure if you think it's weird.. and both are very simple to understand.


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## unpopular (Aug 23, 2012)

Holy bucket**** people!
(i like adding the f word to random things)

It's not like this is rocket science! All objects occupy any given area for a period of time. How long that period of time relative to the time the shutter is open influences how much influence it has in the recorded image.

Some things, like the buildings sit there motionless allowing the light which they represent to accumulate in the same place on the sensor, the image is concentrated to one specific region on the sensor. Others, like the cyclist, diffuse that image over a larger area and only for a fraction of of the total exposure time. If the cyclist is moving fast enough, then his or her influence is not significant enough to measure and theirfor is not recorded.

If you sat up an exposure for 700 billion years, the buildings also would be invisible. It's just averaging people!


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## Ballistics (Aug 23, 2012)

ceejtank said:


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Right, so by teaching someone who has never used a camera in their life the properties of light, then they should be able to put the camera on manual and know how to use f/stops, ISO, and shutter speed properly right? 

Because after all, exposure and light properties are the same thing.

Too much light, and you change your exposure.
Too little light, and you change your exposure.



> Changing the length of your exposure is simply controlling the amount of light you let in to your sensor (or film)



Bingo. So tell me how knowing the properties of light helps you understand why people walking in the frame do not show up.

Intensity,Quality,Direction,Color. Where do these fit in to the explanation?


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## AaronLLockhart (Aug 23, 2012)

ceejtank said:


> The light reflecting off the buildings to your camera sensor means it needed 30 seconds to produce that image.




No it doesn't.

At ISO 3200 and f/1.8, I could capture that image in 1/60th shutter speed. 

Once gain, you are not gaining ground in your argument. The settings on the camera are what controls how fast or how slow it will catch the light.

I'd bet that at 30 seconds, this image was set on ISO 100 with an aperture of f/19 or f/22. Once again, having nothing to do with the properties of the light, and EVERYTHING to do with the settings on the camera.


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## ceejtank (Aug 23, 2012)

Ballistics said:


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To answer your question(For Quality, Direction, Intensity) I'll just quote the guy above you.. "Some things, like the buildings sit there motionless allowing the light which they represent to accumulate in the same place on the sensor, the image is concentrated to one specific region on the sensor. *Others, like the cyclist, diffuse that image over a larger area and only for a fraction of of the total exposure time*. If the cyclist is moving fast enough, then his or her influence is not significant enough to measure and theirfor is not recorded."

As for color you would need to understand that the light spectrum is not picked up by sensors and is added in afterwards.


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## Ballistics (Aug 23, 2012)

ceejtank said:


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Yikes.


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## Ballistics (Aug 23, 2012)

So, long story short, you have no idea what you are talking about.


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## AaronLLockhart (Aug 23, 2012)

Ballistics said:


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Ballistics said:


> So, long story short, you have no idea what you are talking about.



+2 on both of these. 

This guy thinks he understands light, but then doesn't understand that color is simply reflection & absorption of light. The "color" doesn't ever have to be added in, because the colors are contained in the light itself, which is being captured initially by the imaging sensor.

If color was added in "afterwards," There would be absolutely NO NEED for white balance, as the camera would get it right every single time.


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## unpopular (Aug 23, 2012)

WAIT A MINUTE HERE!

Ceej is much more accurate than you're giving him credit. I can't explain now, but he he. Digital cameras do not directly record spectra, and there has never been a imaging system that has.


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## tirediron (Aug 23, 2012)

*Okay everyone, back to your own sand-boxes.  We're done here.*


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