Originally posted by Muushka
PS, just wondering, how do you find the 'depth of field' on the digital compared to the 35mm? I think that is the right term-when you focus on a subject close to the camera and the background is blurry. I love that and miss it so much on my non-SLR digital. And I miss having the option of which part of the picture I want to focus on. My weenie camera does a little, but not enough to suit me.
Depth of field control is there, but it's not necessarily the same as on a 35mm SLR. Most digital SLRs have a smaller-than-35mm sensor meaning photos taken with these lenses are cropped. The crop factor depends on the camera; my D100 crops at 1.5x. So, for example, when I use a 50mm lens I get the same view as using a 75mm lens on a full-frame film SLR.
What's this got to do with depth-of-field and the price of tea in China? Well... depth of field is a function of aperture, distance to subject and focal length. For a given aperture and given distance to subject, the field of "acceptable sharpness" descreases with focal length. In other words, the blurriness of the background increases with focal length. Likewise, as distance to subject increases for a constant focal length and constant aperture, the depth of field increases.
These relationships aren't linear, at some point the depth of field ceases to increase or descrease and remains constant. Most notably, the hyper focal point refers to the distance at which everything is in focus. Hyper focal point is further away as focal length increases.
Why is all this important, you ask? Let's go back to the crop factor. Point being that in order to achieve the same field of view with the same lens on digital SLR that's not full-frame as you would with a 35mm SLR, you've either got to back up or use a wider angle lens - both of which would cause you to have a deeper depth of field or more of the background in focus.
Check out this DoF calculator to see what I mean:
http://dfleming.ameranet.com/dofjs.html
All that said, yes, you can get good depth of field with a digital SLR; just don't expect it to perform exactly like a 35mm because it is different.
Be aware there are other differences with digital SLRs that you don't have to think about with film: color management (especially when printing), white balance, buffer size and speed, and dealing with digital noise.
But it's worth it! I promise.
BTW, you can buy a full-frame DSLR but they cost big bucks. Those would behave more closely to the 35mm SLR you're used to.
I'll also add the Canon digital Rebel has a crop factor of 1.6, so the depth-of-field issue is slightly exacerbated over Nikon's crop factor of 1.5 though not nearly as much as when going from full-frame to 1.5 or 1.6.
Sam