andreacioci
TPF Noob!
- Joined
- Jul 29, 2013
- Messages
- 7
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Hi all,
I'm new in the forum. I've a Nikon D5000 with a 18-105mm and I'm trying to understand the use of the grey card 18%. Using it for the white balance is pretty simple and I want to use it for a correct exposure. Here is what I did:
- I put the camera on my tripod with 105mm focal length and measure the exposure with the light meter of the camera on the grey card. I took a pic and,when I open it through photoshop, the grey card is properly exposed with RGB values around 127.
- I changed the focal length to 18mm but I kept the same ISO, shutterspeed, aperture and took a second pic. If I measure the grey card, now the RGB values are around 140.
How comes that, changing only the focal length, the same object is exposed differently?
Thanks for your help.
Andrea
I'm new in the forum. I've a Nikon D5000 with a 18-105mm and I'm trying to understand the use of the grey card 18%. Using it for the white balance is pretty simple and I want to use it for a correct exposure. Here is what I did:
- I put the camera on my tripod with 105mm focal length and measure the exposure with the light meter of the camera on the grey card. I took a pic and,when I open it through photoshop, the grey card is properly exposed with RGB values around 127.
- I changed the focal length to 18mm but I kept the same ISO, shutterspeed, aperture and took a second pic. If I measure the grey card, now the RGB values are around 140.
How comes that, changing only the focal length, the same object is exposed differently?
Thanks for your help.
Andrea