Hello,
I recently adapted an 85mm 1.5 lens, and a 50mm 1.4 lens to my Sigma SD-9. I noticed that my focus was off and realized that my depth of field was perhaps one half or one third of what my viewfinder image displayed. I am viewing the image with the lens stopped down and believe what I see should translate onto the image. I placed a row of about 10 nails into a board. They were about 2-3 centimeters apart, and I focused on the center nail. My viewfinder showed 1 or 2 nails in front of my focal point to be sharp, and about 3 or 4 behind the focal point. This coincides with my knowledge of depth of field (1/3 in front and 2/3 behind focal point) ...But, my image showed FAR less depth of field, with a total of 2, and sometimes 3 nails appearing focused. My shooting distance was about two meters.
...Can anybody explain this to me? I can also be reached at: bnsnphoto@aol.com Sincerely, Neil Benson