Do lens affect camera metering ?

anupmathur

Super Moderator
Staff member
I would consider it logical that since an SLR views things 'through the lens' its metering and any other function would depend on the lens entirely.
 

Ankur003

UltraWideLife.com
I would consider it logical that since an SLR views things 'through the lens' its metering and any other function would depend on the lens entirely.
Anup Sir, you mean to say , some lens will underexpose or over expose a picture, yet showing correctly exposed in camera meter?
 

anupmathur

Super Moderator
Staff member
Anup Sir, you mean to say , some lens will underexpose or over expose a picture, yet showing correctly exposed in camera meter?
No, the frame should not turn out under or over exposed. If it does then the metering is not quite doing its job! The camera meter should show correct exposure of what is viewed through the lens that is in use.
This is just my (educated) guess; as you know I am not an expert on Photography.
Maybe we should shout out to some major experts. @pushpinder, for starters! And we have @hensil , @kdacharya and @Yogesh Sarkar , and so many more!
 

Yogesh Sarkar

Administrator
Each lens is different, some under expose, some over. Aperture mentioned on lens isn’t consistent across the board either; it varies from lens to lens. That is why you have to learn your gear and work accordingly.
 

Ankur003

UltraWideLife.com
Each lens is different, some under expose, some over. Aperture mentioned on lens isn’t consistent across the board either; it varies from lens to lens. That is why you have to learn your gear and work accordingly.
Yes YS I agree. each lens is different. even aperture ratings are not consistent.
I think metering is a function of data gathered from CPU lens + light distribution of frame. It is the function of light meter to evaluate lens data (and light pattern) to get optimum metering value. So if one lens has smaller aperture opening for f/2.8 , camera meter to show underexposed as compared to a lens with larger aperture opening (Every other parameter remaining constant, namely frame, shutter speed and ISO)

PS: I have not done any study in camera meter working. This is all my understanding.
 

hensil

Guru
No. Lens does not affect light metering.
Yes the focal length which gives different field of view will affect light metering.
Consider incident light meter, it does not have lens but a dome instead.
Light meter is only concerned with the amount of light falling on its sensor.
This is what I know.
Henry
 

Ankur003

UltraWideLife.com
No. Lens does not affect light metering.
Yes the focal length which gives different field of view will affect light metering.
Consider incident light meter, it does not have lens but a dome instead.
Light meter is only concerned with the amount of light falling on its sensor.
This is what I know.
Henry
Thats what I thought Henry...
 

nishchaya

Dreamer
And why wouldn't a lens play a role in metering? I think it should.
Since the SLR metering is through the lens, the light would reach sensor only through the lens. The camera meter is a reflective one and doesn't depend upon the incident light. So if metering is dependent on the light that comes through the lens, it should indeed effect the metering.
 

nishchaya

Dreamer
On a second thought, I realized that the lens shouldn't effect the metering. Since DSLR in camera meter is caliberated to read 18% grey, any change in luminance of light would only alter the values around 18% grey. The scene might look a bit dark or a bit light but since the camera meter is designed to read only the pre defined values around 18% gray, any lens should not effect the metering.

Henry, why should focal length change the metering, especially if you spot meter?
 
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