It was the best of times, it was the worst of times…
Well, maybe instead of Dickens we need to paraphrase Shakespeare:
Two cameras, both alike in dignity..
One of the reasons I selected the D50 was because it was so similar to my N60. The controls are almost identical, and lenses can be swapped between the two. However, there are quite a few things one must keep in mind when choose lenses for a DSLR. The image sensor in a DSLR is somewhat smaller than 35mm film. This causes some rather funky things to happen with the focal length of the lens.
Consider how regular 35mm SLRs handle various lens lengths. A film SLR using a 35mm lens has a 1:1 image ratio, since the medium that is capturing the image is also 35mm. A 70mm lens would have a 1:2 image ratio, for an effective 2X telephoto image. Since the image sensor on a DSLR is smaller, the image ratios will be different. The follow diagrams illustrate this:
The yellow circle illustrates how much of the image is captured for each type of camera. On the Nikon D50, the image is about 1.5 times smaller than a 35mm image. This means that a telephoto effect will be present on just about every lens. In order to get close to a 1:1 image ratio, you would need a 23mm lens instead of a 35mm lens. The chart below shows the three lenses I have, and the effective difference on the DSLR:
So my Celestron C90 1000mm telescope would actually act like at 1500mm lens if attached to my D50. All of the variables such as depth of field, etc, are affected by this difference, and will need to be taken into consideration when shooting. At least, now I know why the sales dude was trying to get me to buy an 18-70mm lens instead of the 28-90mm I got. I suppose I’ll just have to wait a few months for Christmas to roll around.
[tags]photography, Nikon D50, Nikon N60, SLR, DSLR, digital photography[/tags]