 Kevin J.L. Figueira |
Film Camera Lenses for a Digital SLR I currently own a Nikon N90 film camera, but I might be going digital in the next little while. Can I still use the lenses I now use on my N90 on a digital SLR?
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robert G. Fately |
Yes, Kevin, you should be able to use any of the more current lenses made for your Nikon N90 on the Nikon or Fuji DSLRs. Be aware of the so-called 'crop factor", though - because the image chip in the DSLR is smaller than the 24x36MM image area of the 35MM film format ... only the central portion of a given lens' image is captured. The factor for the Nikon DSLRs is 1.5. This means that to get a close approximation of how a lens will look on the DSLR, you multiply its focal length by 1.5. So, your 200MM lens suddenly seems like a 300MM lens! It's like free telephoto length. (Remember that the rule of thumb about slowest hand-held shutter speed also implies that you need to use a tripod below 1/300th second). That's the good news. The bad news is on the wide-angle side - your 24MM lens on the DSLR is going to be like using a 36MM lens on the N90.
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Dean Huggins |
I am not an expert in this field but all the data I have ever gleaned from professionals indicates that you should use a tripod below 1/30 th of a second. Bob's response said 1/300 th of a second. Perhaps a typo?? Dean
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Brendan Knell |
Dean, if you hand hold the camera, the slowest shutterspeed for a 300mm lens, is indeed 1/300th of a second. If you go any slower than that, you should use a tripod.
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robert G. Fately |
Well, you're both sort of wrong. Here's the deal: The focal length of a lens on a given format camera ascribes its "magnification", if you will. A longer focal length will hav a narrower field of view, meaning that what it DOES see appears closer. Now, again, what constitutes a telephoto lens depends entirely on the size of the imaging area (film or digital chip). A "normal" lens for a 35MM film camera was a 50MM focal length, but on a 2-1/4 inch film camera 50MM is a wide angle (80MM is considered normal). And on a 4x5 view camera 50MM is an ultra-wide angle (in fact, they're not made). Meanwhile, in the other direction, for an APS sensor a 35MM lens really provides a normal view; a 50MM lens is actually a short telephoto. For point & shoot digitial cameras, where the sensor is even tinier, the lenses are something like 8-23MM (but the marketing materials always relate thee focal lengths to the 35MM "equivalents". On a traditional 35MM film camera, the "rule of thumb" was the slowest shutter speed to use handheld is 1 over the focal length. So, unless you were very steady, on a 35MM film camera you would not want to shoot at less than 1/200th of a second using a 200MM lens. Since 35MM SLRs were ubiquitous, and many shooters can relate to lenses for them, the DSLR makers have used the term "cropping factor" to describe the fact that the smaller CCD size would essentially make a 50MM lens, say, appear to be something longer. that is, when you put a 50MM lens on a Nikon DSLR (with a crop factor of 1.5) the angle of view you see is actually much like a 75MM lens would be on a film camera. Get it? So, the 200MM lens on the DSLR behaves like a 300MM lens would on a film camera (200x1.5 factor). The rule of thumb, then would indicate 1/300th second to be the slowest you should handhold without getting noticeable blur due to your motion (as opposed to the subject's motion). Hope that made sense...
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