slr film vs digital lenses

tom beard

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Mar 2, 2009
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So. Cal mountains east of LA
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I am used to 35mm slr film photography and lenses. I am interested in switching to a nikon d-90 with a couple of zoom lenses. When looking at nikkor lenses such as an 18-135 mm zoom, the discription says,"This 18-135mm zoom lens approzimates the picture angle of a 28-200mm lens on 35mm slr." Is the digital format different from that of 35mm? Do I need a conversion chart? Not all nikkor lenses carry this caveat. I am really confused. HELP!

Tom Beard
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Most digital cameras have a "crop factor" -- the difference between the size of the sensor and the size of a full 35mm film frame. Because the exposure area is smaller, it is effectively like cropping all of your pictures by a certain amount. (There are full frame cameras as well -- but they're super-expensive.) As a result of that cropping, you get something approximating an extra amount of zoom at all focal lengths.

The D-90 has a "crop factor" of 1.5x. That means that any focal length must be multiplied by 1.5 to get an approximation of what the lenses would be like on a full frame camera. So, for example, an 18mm lens on a full frame is pretty wide -- 18mm. But on a crop camera, it's 18mm x 1.5 -- around 27mm. (The crop factor is consistent across all focal lengths.)

This is true for all lenses, and any 18mm lens on a crop camera will always look like a 27mm lens. However, some lenses are specially made for crop cameras -- the 18-135 is such a lens -- a so-called "DX" lens. These cannot be used on film cameras, I don't believe, though others may know better -- but they're designed to take the place of the roughly equivalent lenses used for film.
TheotherBob has pretty much covered it, but ill expand just a little. Because most DSLRs have a a smaller "aps-c" sensor. Yes its the same size as the short lived "Advanced Photo System" film, or "Advantix" as branded by Kodak. So just think of a it as another format size, A "normal" lens for 35mm Film is a 50mm lens, normal for aps-c is about 30mm, and normal for medium format 6x6 is about 75mm. Each of these combinations give the same angle of view.

Also "AF-S, DC, canons EF-S" all just mean that the lenses are built more compact to project a smaller image circle for the smaller apsc format. 50mm is still 50mm, but the lens wont project a large enough area to cover an entire frame of 35mm film, the coners would be cut off.

All 35mm film lenses will work fine on a digital camera, But the fesult will look like you are using a longer lens. It's the same thing when people adapt medium format lenses to 35mm or digital slrs.
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I own two amazing Nikon cameras. A D80 and an N80 I swap both my digital and film lenses back and forth between the cameras. Both lenses fit on both bodies. The DX format allows for the lenses to be interchangeable between digital and film bodies. In all honesty I dont think it matters at all. Who cares what a chart says when you are making dynamic photographs while in a tropical wonderland such as Hawaii. Plus the lenses might give you something creative. Though I have never noticed any difference in the quality of my images.

Get the D90 it is a great camera! Here are a few videos that you should watch, they will entice you into buying the D90.

LenShare.Com: Nikon News: D90 Tutorials
It's not something you need to think about while shooting. What you see in the viewfinder is still what you get in your photo.
One thing to keep in mind: older film lenses without cpu connections will not meter on the lower range of nikon dslrs, you'd need a d200 or d300 for that.

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