Anyone keen to photograph some candles, for scientific experiment?

[christop]

Can't you accomplish the same effect with cars on a highway at night?

http://image1.masterfile.com/em_w/00/53/02/700-00530279w.jpg

Or am I missing the point?

But all those lights are overexposed!

I think we've just concluded the discussion about candles and the inverse square law.

 

[480sparky41 40]

Can't you accomplish the same effect with cars on a highway at night?

http://image1.masterfile.com/em_w/00/53/02/700-00530279w.jpg

Or am I missing the point?

[h=1]Referral Denied[/h] You don't have permission to access "http://image1.masterfile.com/em_w/00/53/02/700-00530279w.jpg" on this server. Reference #24.e836d83f.1352931550.265fb872

 

[tris_d]

Can't you accomplish the same effect with cars on a highway at night?

http://image1.masterfile.com/em_w/00/53/02/700-00530279w.jpg

Or am I missing the point?

I can not open that image, it says: "Referral Denied". Can you please upload it here?

 

[tris_d]

Ok, I think that sounds good to me.

Greater magnification is a somewhat problematic phrase as well, but I think we can work with it. There are two factors in play here, focal length, and aperture. Aperture is normally measured as the ratio of the lens opening to the focal length. So, if when we increase the focal length, we normally decrease the aperture. The answer to your question is, it depends.

Greater magnification is associated with longer focal lengths. When imaging the sky, this simply means that we're placing less of the area of the sky onto the sensor.

If you double the focal length (increasing magnification) while keeping aperture the same (for example, for from a 300mm f/2.8 lens to a 600mm f/2.8 lens), several things occur:

- less of the sky is imaged on to the sensor, 1/4 as much, to be exact.
- the size of the lens opening has doubled, which means the area of that opening has quadrupled, which means the light-gathering power has quadrupled.

The effect is that the apparent brightness of the stars will indeed quadruple. This is why building a bigger telescope is actually a helpful thing to do. Stars not previously visible are now visible, if you can build a telescope with a bigger hole for light to pass through, with more light gathering capability.

If you double the focal length but do not change the light gathering power of the system (for instance, inserting elements into a telescope system to increase the magnification) you will effectively cut the aperture in half. The will also have some effects:

- less of the sky is imaged on the sensor, 1/4 as much. Same as last time.
- the size of the lens opening is the SAME, the light gathering power is the SAME. The infinitesimal points which are the images of stars will remain at the same brightness.


This is why, in order to see deeper into the night sky, you cannot simply add elements on to the viewing end of the telescope. You must build a bigger telescope, with more light gathering power -- with a larger physical aperture through which light can pass.

I think I understand. Let me see, would that mean that Hubble telescope does not use any magnification when taking photos of deep space? And if it does, how would that make anything look "better"?

 

[480sparky41 40]

I can not open that image, it says: "Referral Denied". Can you please upload it here?

Only if you have rights. Posting images w/o rights is a no-no 'round here.

 

[christop]

Magnification is a somewhat meaningless term when discussing camera lenses. Magnification is a ratio. The primary lenses used in cameras are defined by their focal length. A focal length is measured in millimeters (sometimes centimeters, or meters in the case of the Hubble telescope).

Hubble has a 57.6 meter focal length and a 2.4 meter aperture. So it has an aperture of f/24. Its sensor size is 4.5 m[sup]2[/sup] (4500000 mm[sup]2[/sup]).

Hubble Space Telescope - Wikipedia, the free encyclopedia

In comparison, my Canon DSLR has a sensor of about 337 mm[sup]2[/sup]. I currently have a "normal" lens on it which is 28mm f/2.5.

The Hubble lens would be roughly equivalent to a 500mm lens on my Canon, which could be used for wildlife photography (except an f/24 aperture would make it terrible for almost anything but space observation).

By the way, I can view the picture of cars on a highway by copying and pasting the link in my browser.

 

[runnah]

Can't you accomplish the same effect with cars on a highway at night?

http://image1.masterfile.com/em_w/00/53/02/700-00530279w.jpg

Or am I missing the point?

I can not open that image, it says: "Referral Denied". Can you please upload it here?

a long highway shot with car headlights in the foreground and half a mile in the background.

 

[tris_d]

Magnification is a somewhat meaningless term when discussing camera lenses. Magnification is a ratio. The primary lenses used in cameras are defined by their focal length. A focal length is measured in millimeters (sometimes centimeters, or meters in the case of the Hubble telescope).

Hubble has a 57.6 meter focal length and a 2.4 meter aperture. So it has an aperture of f/24. Its sensor size is 4.5 m[SUP]2[/SUP] (4500000 mm[SUP]2[/SUP]).

Hubble Space Telescope - Wikipedia, the free encyclopedia

In comparison, my Canon DSLR has a sensor of about 337 mm[SUP]2[/SUP]. I currently have a "normal" lens on it which is 28mm f/2.5.

The Hubble lens would be roughly equivalent to a 500mm lens on my Canon, which could be used for wildlife photography (except an f/24 aperture would make it terrible for almost anything but space observation).

By the way, I can view the picture of cars on a highway by copying and pasting the link in my browser.

Having focal length, does that automatically imply there is some magnification, built in the lens itself? And if yes, then what other parameters could be changed to nullify that magnification?


(I managed to open the picture of cars as per your instructions)

 

[tris_d]

Stars on the left image representing closer stars are bright, and stars on the right image representing further away stars are less bright. And if we go on like that the stars from any further away shell can only get even dimmer. Now, it seems to me no matter how many of those less bright stars are, they could not appear any more bright than what their individual brightness is. Where is the paradox?

 

[480sparky41 40]

........ Where is the paradox?

Try understanding 'infinity'.

 

[tris_d]

........ Where is the paradox?

Try understanding 'infinity'.

Whaaa...you want my head to explode?! Fortunately however there is no any infinity here. If every line of sight ends at some star, well that's where that line of sight ENDS, and if every line of sight ends at some point, then there is nothing infinite about it. Even if there are infinite number of lines of sight. Which brings me to the question, are there infinite number of lines of sight per some certain area in the sky?


Hey, the original Olbers' paradox thread is open again! Maybe we should move there?

 

[480sparky41 40]

....... If every line of sight ends at some star, well that's where that line of sight ENDS, ...........

New flash..... they all don't.

 

[tris_d]

....... If every line of sight ends at some star, well that's where that line of sight ENDS, ...........

New flash..... they all don't.

I have no idea what point you are trying to make. I think it's the premise of Olbers' paradox that every line of sight ends at some star, so I don't see how what you said makes sense, or how it matters to what I originally said about those two pictures.

 

[480sparky41 40]

....... If every line of sight ends at some star, well that's where that line of sight ENDS, ...........

New flash..... they all don't.

Please make a statement in a full sentence, I have no idea what are you referring to. I think it's the premise of Olbers' paradox that every line of sight ends at some star, so I don't see how what you said makes sense, or how it matters to what I originally said about those two pictures.

I'm referring to what I quoted. It's not that hard to figure out.

Olbers' Paradox doesn't state every line of sight ends in a star. It stated that IF the universe was infinite, then that would be true. Of course, his observation was made during a time when the universe was assumed to be static, and not expanding as is the current model. Given an infinite universe, every line of sight will end in a star, but we may not be able to see it with the visible spectrum because if a star is far enough away, the Doppler Effect will render it invisible to our eyes.


That said, since whatever doesn't make sense to you, you immediately and summarily dismiss based on your own prejudices and preconceived notions, I'm done here.

 

[Derrel]

If somebody can arrange for 8,10,12,or even up to 24 bikini-clad women to show up in one location, I will gladly buy a bunch of candles and will undertake this challenge, and will photograph the chit outta this here candle thing...but otherwise,without the bikinis...it's a non-starter...