Different lenses = different exposures?

Started 3 months ago | Discussions thread
Christi Dee Forum Member • Posts: 96
Re: Different lenses = different exposures?

stevet1 wrote:

I have not tested this yet, so I don't know the answer.

Let's say I take a camera (a DSLR) and put it in Auto. I put one lens on it and take a meter reading, or even take a picture. I take the same camera and put a different lens on it.

Taking a picture of the exact same scene, will I get the same meter reading, or get the same exposure when taking the picture, or do I get different results?

Steve Thomas

First, as well as most likely the largest: the metering considers even more of the scene with the wider angle, and also the scene is different enough that the exposure choice is likewise various. If there are actual light resources or shadow locations in the scene, this is especially likely to be the situation. You don't mention what metering setting you are utilizing. Still, if you are utilizing Evaluative Metering (matrix metering on various other brand names), the camera tries to acknowledge the scene and also do something "wise"-- yet the formulas are truly not really challenging, and also a little adjustment can often cause a large difference in what the cam believes it is seeing.

Second, the lenses may have the same f value yet various actual transmission. This is gauged in "t quits"-- even more at What is T-number/ T-stop? In this specific situation, thinking you are contrasting the EF 100mm f/2.8 USM Macro and EF 28mm f/1.8 USM, the former is about half a stop darker than the f-number would indicate, while the latter is just a 3rd darker. Presuming you're at the same f-stop, the distinction between the two is small, but enough that you may notice a metering variant. (If you have the L version of the 100mm, that's additionally concerning a 3rd of a stop darker, so the difference should be almost absolutely nothing).

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