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06-29-2009, 06:39 PM   #16
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QuoteOriginally posted by Duck Dodgers Quote
Huh. Funny how all my Pentax exif info always states stuff like:

Focal Length In 35mm Format : 300mm

...for a 200mm lens.
Ah yes, marketing...

Well, it's been a slice - off to bed so I can get back to photography!

06-29-2009, 07:51 PM   #17
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I blame it on whoever in the long past that started the bad habit of saying FL as an expression of FOV (as in how wide/tele). To work as such the film width was implied to be an integral part of that "thought process". When the sensor size changed the FL numbers don't correspond the same way as before, still the same FL but different meaning when "read" in FOV sense.
06-30-2009, 06:57 AM   #18
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Yeah, but it's been going on since long before sensors came into play. For instance, say I have a 90mm lens. On a 35mm film camera, it's "crop factor" is 1. On my Pentax DSLR, the crop factor is 1.5. On a Pentax 67 its crop factor is 0.6. Regardless of the platform, it's a 90mm lens, agreed. On which platform does it have more "reach?" Yes, yes, I know it's not magnifying per se, but the end result to the consumer is that three full resolution 8x10 prints from each of these cameras yields three very different images. Hence, the concept of "35mm equivalency," which has been around since before the days of 110 film, like when Pentax listed the "equivalency" of their 110 SLR lenses.

The average person doesn't care that their lens "technically doesn't magnify" on a DSLR; the fact is it still appears to be longer in the end result. I don't know why there is such a debate about this... we see the opposite result at the other end of the spectrum (so to speak) when trying to find wide lenses, and we have to put up with much more distortion at the wide end because of the fight with the crop factor.
06-30-2009, 08:30 AM   #19
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QuoteOriginally posted by Marc Langille Quote
Very good points Marc! Now the OP's question is evolving into additional comments and answers, so it's beginning to go beyond the focal length issue by including pixel densities of the sensor on APS-C, etc.
True enough. But my goal was to try to cut through all that and get back to the main point that is relevant to most people who are not up on all the science and so forth and are still having a hard time wrapping their brains around the basic idea of what the crop factor is. For 99% of photographers, FOV is the only attribute of focal length that they care about, even if they don't realize up front what FOV actually is. So I'm just trying to put it into the simplest possible terms: it is how big your subject appears *on the print*. Details of viewfinder magnification, sensor resolution, lens resolution, etc just don't really matter to most people when trying to get the basic idea of what a crop factor is about, although of course it might become relevant when one is looking for ways to squeeze every last drop of image quality out of their gear.

I agree with most of your points and bottom line is that I'll stand by my post. The lenses' focal length remains unchanged regardless of sensor size and the object is no closer.
Absolutely agreed.


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