Apertures and DOF

[gbjune]

Ok, this might be a really easy-to-answer question, but it is something I am wondering about and trying to understand better, so please, someone, if you know, answer this...

How does the fact that the sensor is so much smaller (compared to 35mm film) change the properties of the pictures. Since 7mm (G1) = ~35mm (35mm), is there any difference of say, aperture f/2 on the G1 and f/2 on a 35mm (real 35mm) lens.

I would believe there are differences that come into play here...

How does this change DOF ?

Geir

[Grant Dixon]

There are so many areas for confusion on this subject so it is very difficult to come up with a definitive answered. But assuming that we are going to accept the same size circles of confusion for the G1 and a 35 mm camera and all else are equal. If we select the 7 mm focal length lens with G1 and view an object at given distance and also the same object viewed at the same distande using a 35 mm lenses on a 35 mm camera. If we select f2.0 on the G1 we will require f50 on the 35 mm to duplicate the same hyperfocal distance and the same depth of field. This is because the ratio are proportional to the squares of the focal length of the lenses.

[sjguenard]

In addition, shorter focal length lenses have more diffraction problems at larger F stop numbers. E.G. F11 or F16 on a digital is less "sharp" than a similiar F stop on a true 35mm camera.

Could be why G1 stops out at F8.

Good news is, you can hand hold the G1 at a lower shutter speed than your Nikon F2. (An old rule of thumb is shutter speed should be ~2 or 3x focal length.)