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Suns Boiling, and Black Holes Freezing… - Page 2

User Thread
 68yrs • M •
A CTL of 1 means that cturtle is a contributing member of Captain Cynic.
Being old as it is, it is rather simple too. The len is simple a magnifying glass, the light [image] shines though the glass & is bent or converges to a point (null point) then diverges forming the image on the ground glass plate at the other end.
So when you look at the glass plate, the image is inverted, upside down & backwards. If you want to see more to the right then you move {glass plate} it more to the left; if you want to see more of the top then you move it more toward the bottom. So it is easy to see why he would like his 35mm better. But then that single lense reflex works the same as the old fashion large format camera . . . except they use a hinged mirror that comes down in front of the film plane [glass plate of LF] which reflects the image upward to another mirror which reflects out the back [back of camera] out through the view finder. Right? Well, yes & no. After all when you look in the mirror, left is right & right is left but you are not upside down.
Yes, the mirror reflects the image but it also reflects the convergent-divergent nature [attribute] of the lense.
Mute point , maybe but an easy mistake to make that could mislead one to misunderstanding the nature of things.

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"Terrorist or tyrant, few may come to the Truth that both are poor choice."
 40yrs • M •
A CTL of 1 means that Wayback is a contributing member of Captain Cynic.
You like photography, how about this 1:1 macro? I used a Laarge format slide film & I measured the subject & its' image and they are the same size!



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 68yrs • M •
A CTL of 1 means that cturtle is a contributing member of Captain Cynic.
As the photo is a 1:1 macro you used bellows factor to figure the exposure?

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"Terrorist or tyrant, few may come to the Truth that both are poor choice."
 40yrs • M •
A CTL of 1 means that Wayback is a contributing member of Captain Cynic.
Yes as a matter of fact I did have to calculate the exposure factor.
http://www.largeformatphotography.info/bellows-factor.html
quote:
a) When the camera is focused at infinity, note a point on the camera and another on the lens (e.g., diaphragm) such that the distance between them is equal to the focal length (call it F). Then, when the bellows is extended for close-up focus, the extension between those two points will be greater than F (call it E). The exposure factor will be (E/F) squared. For example, extending the bellows to twice-F to focus for an object-to-image ratio of 1:1, the FACTOR will be 4.
Secondly, FACTORs of 2, 4, 8, etc. obviously correspond to 1, 2, 3, etc. stops; what about a FACTOR of 3?? To convert FACTORs to stops, use a scientific calculator; (log FACTOR/log 2) or (ln FACTOR/ln 2) equals stops. For a FACTOR of 3, (log 3/log 2) equals (.48/.3) equals 1.6 stops.

Which does bring up another interesting variation as I made two macros, 1) with a 210mm & 2) with a 150mm len. I used the full extension for both expsures so I had two diferent exposure compensations. they turned out to be close to 1:1 & 2:1 macros.
Funny thing was I realized that the inverse square as applied to the exposures seemed to vary according to the focal length of the len?

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 68yrs • M •
A CTL of 1 means that cturtle is a contributing member of Captain Cynic.
What I found interesting is related to the use of the bellows extension factor. You use the metered light reading directly over the extension (movement) of the film plane to len plane until it becomes > the focal length. On one hand, you could say that this portion has a value of unity (or 1) & therefore does not increase.
But on the other hand, as the magnifing glass concentrates (focuses) the light to a point (which increases the energy to the point of spontanteous combustion) then why shouldn't it increase?

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"Terrorist or tyrant, few may come to the Truth that both are poor choice."
 40yrs • M •
A CTL of 1 means that Wayback is a contributing member of Captain Cynic.
One thing I was thinking about is that how the glass of the len bends light?
I mean is it the [inertial] mass or the e-m field of the crystal lattice of the material structure of the glass? But then as you pointed out water tends to do the same thing but it doesn't have a crystall structure [unless it is cold enough to freeze it?

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 68yrs • M •
A CTL of 1 means that cturtle is a contributing member of Captain Cynic.
Ever heard the saying 'Once in a blue moon'; as the moon reflects the light of the sun then should not it appear red as the light would be shifted toward the infar-red region by traveling further? So what causes the 'blue moon'?
As to photography, I note that the normal lens ( giving a normal perspectus) for differs according to the format. A 35 mm normal lens is about 50mm, the 4x5 normal is about 150 mm & so forth. I wonder what format (size) would be related to our normal perspectus?

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"Terrorist or tyrant, few may come to the Truth that both are poor choice."
 40yrs • M •
A CTL of 1 means that Wayback is a contributing member of Captain Cynic.
I don't really see what you are trying to say?
I guess one could say that as light falls off with with distance that the distance that it travels in order to decrease to half it's original value (intensity) could be considered the focal length of our perspective view?
But how would that relate to the size {dimension} character of our preception?

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Suns Boiling, and Black Holes Freezing… - Page 2
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