Quick Question: 50GM Actual Focal Length?

Started 2 months ago | Discussions thread
Tristimulus Veteran Member • Posts: 8,175
Re: Quick Question: 50GM Actual Focal Length?

Magnar W wrote:

rofl wrote:

Magnar W wrote:

rofl wrote:

Hi All. I heard 50gm is actually wider than 50mm. Does anyone know its actual fl? Thank you.

Few lenses have exactly the focal lenght stated. Usually focal lenghts are off within 5 % or so. That is common.

If you intend to use the lens for precision measurements then you need to calibrate the lens anyway as the focal lenght varies across the field of view. Else the lens would not be  rectilinear.

How important is a few millimeters plus or minus from 50? If this is important, you probably should take a look at how the latent image is projected on the sensor, since this too might slightly affect the angle of view.

Important or not I'm just curious. Do you have a link for the info about 'the latent image projected on the sensor'?

I don't have a specific link now, but a little web searching should answer this.

There is no latent image projected on the image sensor.

There is a real image projected on the image sensor.

The photographic latent image is the image stored in a photographic film after exposure and before processing is done. Film days termonology.

Digital image sensors convert the projected image instantly into electric signals (which goes down the processing pipeline and is stored as a digital image on a memory card). There is no latent image, just data stored digitally.

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