what is low light?

[mediyoga]

There has been a lot of discussion on low light and third party lenses focusing issues. Just how do we define low light?
1) Two or one flourescent lamps for a room
2) one or two yellow bulbs only
3) lets look at low light practically rather than go in tems of lux measurement which is more theoritical
4)every one's low light environment is different
6) sunlight streaming through the window with one lamp ( fluorescent or a bulb) in the room- can that be defined as low light?
5) is it defined by the need to up the iso to 400, or 800 etc
what ever we use to clean the image there is no mistaking the fact that a 2.8 lens (constant) @ 100 iso can produce a clean image than any other

I find that with natural light on the subject in a room but still causing the raise of iso gives a better pic than artifical light causing the rise of iso in the same room
krishna

[hallbilly]

In my opinion... Lens wise, anything less than a cloudy day.


Guess that pretty much gives an exact number:rolleyes:

A good question though.

[aparmley]

With out giving a exact camera settings I consider low light this:

I think it varies by lens' max aperture and focal lenght, generally, ISO 1600 at max aperture - wide open, if you can't get hand holdable shutter speeds, thats low light. . .my definition.

But one could say a universal definition might be more useful say:

ISO 800 | F2.8 meters 1/100 ??? IDK . . . this could be an interesting thread.

[mediyoga]

Aparmley

I would like to edit your "no holdable shutter speed @iso 1600 " = low light to just "no holdable shutter speed= low light?

But a constant 2.8 lens might ( in most situations) give a holdable shutter? Then all the folks in all forums who complain of focus issues on third party lenses are probably in darkness! why even canon lenses struggle in " low light"
krishna
I feel that for a camera "no holdable shutter speed" = lowlight! Hall feels cloudy day is low light . lets look at physics
I qoute from a web site:

Lumens are the standard measure of light output, but light is actually defined as energy evaluated by the eye. Standard lumen measurements define the light output response of a person only during high light levels (called photopic light), typical of daylight and interior lighting. The light meter measures photopic light as seen by the central region of the eye.
one more definition :

Lumens, also called Luminous Intensity, represents the total amount of photons emitted by a light source at any given time. Lumens is not the same as brightness, which is the maximum concentration of photons on a given location. Lumens is non-directional (unlike Candelas). (Summing this up over a surface gives total flux, but a point source has no area so you can't really calculate its intensity.

A measurement of light intensity. (1 lumen=10.76 lux).


Lux - Lux is the surface brightness per unit area (lumens/meter²). Lux measurements are taken only at the very center of the beam.

10 LUX (the light produced by a 60 watt bulb from ten feet away
so what camera settings can we do in a setting with a 60 watt bulb- that would be a starting point-

I will ferret more info as possible

[mediyoga]

With out giving a exact camera settings I consider low light this:

I think it varies by lens' max aperture and focal lenght, generally, ISO 1600 at max aperture - wide open, if you can't get hand holdable shutter speeds, thats low light. . .my definition.

But one could say a universal definition might be more useful say:

ISO 800 | F2.8 meters 1/100 ??? IDK . . . this could be an interesting thread.

Yes this could be an interesting thread, but I think many missed it:D

Krishna

[ReF]

i usually think of "low light" as 1/100, f2.8, ISO 800-1600 for a decent exposure. sometimes it's f1.4 1/60, ISO 1600 and still underexposed. darker than that and i need tripod.

regarding the AF comment, i find that my canon USM lenses, especially the L's, focus surprisingly well in dim lighting. of course there needs to be some contrast to focus on though.

[noyjimi]

Low light is when the B&G are dancing and the only thing illuminating the floor is the disco ball...

[mediyoga]

Noy
Thats a good one!!

[aparmley]

Aparmley

I would like to edit your "no holdable shutter speed @iso 1600 " = low light to just "no holdable shutter speed= low light?



Well, I've found that shooting indoors with my 50 1.4 @ 1.4 and ISO 1600 can meter shutterspeeds to slow to hand hold, but lightinging isn't exactly "darkness." I can still read in this lighting and other things. . . So its not complete darnkess, its just not bright day light. . . Its very appilcation dependent as well. For instance, I've found that at high noon on clear sunny day shooting at 200-300mm at ISO 1600 in the shade, gave me shutter speeds around 1/160 - not exactly hand holdable and not exactly "Darkness" either. Which is why I settled on my definition being, ISO 1600 max aperture and can't get hand holdable shutter speeds - Shutter speed being the only variable. For those that primary shoot bodies or objects in motion the definition for them might be - the bare minimum action stopping shutter speed while at max aperture + ISO 1600. For example F2.8 ISO 1600 meters 1/250 - this could be under the lights at a football game or a gymnasium perhaps. These places aren't what one would call "Darkness" but for their application these are probably low light venues.

In general if you aren't shooting action, the next logical limitation on shutter speeds is effective hand holding shutter speeds.

I suppose another low light definition could be stated by saying, Low light = any lighting in which the lens mounted begins showing signs of AF hunting.

But, again, the need for a constant "Standard" low light definition should really be assessed, voted on, and referrenced when people begin talking about a particular lens' performance in low lighting. It would help to eliminate a lot of uncertainty for a fair number of people who might have a "Brighter" understanding of low light than that of the person talking about the lens in question.

[mediyoga]

I suppose another low light definition could be stated by saying, Low light = any lighting in which the lens mounted begins showing signs of AF hunting.

But, again, the need for a constant "Standard" low light definition should really be assessed, voted on, and referrenced when people begin talking about a particular lens' performance in low lighting. It would help to eliminate a lot of uncertainty for a fair number of people who might have a "Brighter" understanding of low light than that of the person talking about the lens in question.[/QUOTE]

I agree with you on the last paragraph. Which is why I feretted the info from the net on definitions of lux etc. Will canon listen to our ramblings? and give a standard lux reference for every lens?

Maybe we can narrow down low light to several factors than just one?
1) unable to get a hand holdable shutter speed
2) there fore raising the ISO to 400- 800 or any thing above

[cdifoto]

To me, low light is when I need flash for both autofocus assistance and primary illumination.

Saturday's wedding metered ISO1600, f/1.4, 1/40th. I had to flash the entire event since my only fast lens is the inconveniently long at times 50mm f/1.4 and my zooms are f/2.8s and an f/4.

[mediyoga]

Therefore I am adding one more maxim to low light to help eveyone define it:
1) unable to get a hand holdable shutter speed
2) there fore raising the ISO to 400- 800 or any thing above
3) Need to use flash for auto focus and primary illumination

I feel that the definiton of low light must confine to indoors as if it becomes dark at 6pm outside we are going to use flash anyway- so even if it is extremely cloudy and like an iminent thunderstrom it is not low light ulnless it becomes like very dangerously dark and foreboding!!

Any further contributions?