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#1
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A Rant re Focal Length Multipliers
Is anyone else bothered by the frequent use of "focal length multipliers" or
"crop factors" when describing digital cameras and their lenses? Why don't the manufacturers just tell us what a "normal" lens is for a particular camera. If, for example, the manufacturers would tell us that a 35mm lens is a normal lens for a particular digital camera we would know that we would need shorter lenses than that if we expected to get wide-angle. You would also know, of course, that anything longer than that would be moving toward telephoto. After all a 50mm lens is a 50mm lens is a 50mm lens (a rose is a rose is a rose)! It does not magically change to a 75mm lens on a digital camera with a focal length multiplier of 1.5. No one publishes the 35mm camera equivalent for an 80mm lens on a Hasselblad; no one publishes the 35mm camera equivalent for a 150mm lens on a 4x5 view camera! All of this I think adds to the confusion of new comers to the digital world who may go around thinking, for example, that the 200mm lens that they want to buy is really a 320mm lens on their 1.6 focal length multiplier camera. No it's not, it's a 200mm lens! The fact is that if you put that lens on a 'full frame' 35mm camera and cropped a picture to the same size as a camera with a 1.6 focal length multiplier you would have exactly the same picture. There, I feel better! Chuck |
#2
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In article ,
C Wright wrote: Is anyone else bothered by the frequent use of "focal length multipliers" or "crop factors" when describing digital cameras and their lenses? Why don't the manufacturers just tell us what a "normal" lens is for a particular camera. Some people can't get their head out of the 35mm mindset. Those of us who shoot multiple formats (digital "APS-C", 35mm, 6*6, 6*7 and 6*9 in my case) have no problem with the concept that a normal lens scales with capture diagonal, but the concept seems utterly alien to some. Witness the occasional person who thinks you can't use a 50mm lens as a portrait lens on a 24*16mm DSLR because "it will still have the perspective of a standard lens", or some such nonsense. Some of these people seem quite unshakable in their strange beliefs about the magical properties of various focal lengths. No one publishes the 35mm camera equivalent for an 80mm lens on a Hasselblad; no one publishes the 35mm camera equivalent for a 150mm lens on a 4x5 view camera! Quite, but there seems to be an assumption amongst the camera manufacturers that those buying medium and large format equipment are generally not ignorant when it comes to this sort of thing (almost certainly justified), and that those who buy DSLRs might be (maybe justified, maybe not). Call it more evidence of "dumbing down" if you like, but I agree with you. If someone really can't understand the concept of focal length and how it relates to field of view, given varying format sizes, or just wants a camera for casual use and isn't interested in photography as an art form or occupation, you have to wonder if a sophisticated interchangable lens camera is really the right choice for them. Having said that, the manufacturers seem to think so, as many of them continue to put those point and shoot modes with the strange little icons of skiers and what-have-you on really quite high-end camera equipment. |
#3
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C Wright wrote in
: Is anyone else bothered by the frequent use of "focal length multipliers" or "crop factors" when describing digital cameras and their lenses? I think it's an easy to understand shorthand. So many people have so much experience with 35mm that understanding how the field of view will be different is a pretty useful thing. If you stipulate that 50mm is "normal" for 35mm film, then a Nikon D70 would have a 33mm "normal" lens. If you already own a Nikon 24mm lens, and you want to know what kind of pictures to expect from a D70, what system would you suggest that would allow a person to know, other than a 1.5 factor of some sort? Bob |
#4
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"C Wright" wrote in message . .. Is anyone else bothered by the frequent use of "focal length multipliers" or "crop factors" when describing digital cameras and their lenses? Not particularly. Why don't the manufacturers just tell us what a "normal" lens is for a particular camera. Because they feel that their customers only understand the effect on the photo in terms of 35mm focal lengths. Jim |
#5
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C Wright wrote: Is anyone else bothered by the frequent use of "focal length multipliers" or "crop factors" when describing digital cameras and their lenses? Why don't the manufacturers just tell us what a "normal" lens is for a particular camera. If, for example, the manufacturers would tell us that a 35mm lens is a normal lens for a particular digital camera we would know that we would need shorter lenses than that if we expected to get wide-angle. You would also know, of course, that anything longer than that would be moving toward telephoto. After all a 50mm lens is a 50mm lens is a 50mm lens (a rose is a rose is a rose)! It does not magically change to a 75mm lens on a digital camera with a focal length multiplier of 1.5. No one publishes the 35mm camera equivalent for an 80mm lens on a Hasselblad; no one publishes the 35mm camera equivalent for a 150mm lens on a 4x5 view camera! All of this I think adds to the confusion of new comers to the digital world who may go around thinking, for example, that the 200mm lens that they want to buy is really a 320mm lens on their 1.6 focal length multiplier camera. No it's not, it's a 200mm lens! The fact is that if you put that lens on a 'full frame' 35mm camera and cropped a picture to the same size as a camera with a 1.6 focal length multiplier you would have exactly the same picture. There, I feel better! Chuck On all 35 mm film cameras the sensor size is FIXED at 24 x 36 mm. So all 35 mm camera users know immediately and instinctively whether a certain focal length lens is super wide angle, extreme telephoto or something in between. With Digicams the sensor size varies all over the place, from 24 x 35 mm in the Canon D1s to 3.34 x 4.45 mm in the Canon A400. So just telling you the focal length of your lens without also telling you the sensor size, doesn't give you a clue whether the lens is wide angle or tele when used with that particular camera. For instance, a F.L. of 28 mm on a D1s is a wide angle lens. On a Canon A400 that same focal length would be a strong telephoto. Bob Williams |
#6
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Bob Williams wrote: C Wright wrote: Is anyone else bothered by the frequent use of "focal length multipliers" or "crop factors" when describing digital cameras and their lenses? Why don't the manufacturers just tell us what a "normal" lens is for a particular camera. If, for example, the manufacturers would tell us that a 35mm lens is a normal lens for a particular digital camera we would know that we would need shorter lenses than that if we expected to get wide-angle. You would also know, of course, that anything longer than that would be moving toward telephoto. After all a 50mm lens is a 50mm lens is a 50mm lens (a rose is a rose is a rose)! It does not magically change to a 75mm lens on a digital camera with a focal length multiplier of 1.5. No one publishes the 35mm camera equivalent for an 80mm lens on a Hasselblad; no one publishes the 35mm camera equivalent for a 150mm lens on a 4x5 view camera! All of this I think adds to the confusion of new comers to the digital world who may go around thinking, for example, that the 200mm lens that they want to buy is really a 320mm lens on their 1.6 focal length multiplier camera. No it's not, it's a 200mm lens! The fact is that if you put that lens on a 'full frame' 35mm camera and cropped a picture to the same size as a camera with a 1.6 focal length multiplier you would have exactly the same picture. There, I feel better! Chuck On all 35 mm film cameras the sensor size is FIXED at 24 x 36 mm. So all 35 mm camera users know immediately and instinctively whether a certain focal length lens is super wide angle, extreme telephoto or something in between. With Digicams the sensor size varies all over the place, from 24 x 35 mm in the Canon D1s to 3.34 x 4.45 mm in the Canon A400. So just telling you the focal length of your lens without also telling you the sensor size, doesn't give you a clue whether the lens is wide angle or tele when used with that particular camera. For instance, a F.L. of 28 mm on a D1s is a wide angle lens. On a Canon A400 that same focal length would be a strong telephoto. Bob Williams Errata; The full frame Canon EOS Digital SLR is called the 1Ds not the D1s Its sensor size is 24x36mm not 24x35mm Bob |
#7
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C Wright writes:
Is anyone else bothered by the frequent use of "focal length multipliers" or "crop factors" when describing digital cameras and their lenses? Why don't the manufacturers just tell us what a "normal" lens is for a particular camera. If, for example, the manufacturers would tell us that a 35mm lens is a normal lens for a particular digital camera we would know that we would need shorter lenses than that if we expected to get wide-angle. You would also know, of course, that anything longer than that would be moving toward telephoto. I find the way they do it much more useful. After all a 50mm lens is a 50mm lens is a 50mm lens (a rose is a rose is a rose)! It does not magically change to a 75mm lens on a digital camera with a focal length multiplier of 1.5. And the lens is labeled right on the front as a 50mm lens, so no problem there. And since I know my crop factor is 1.5 (Fuji S2), I can very quickly find that I get the angle of view I'd normally expect from a 75mm lens on a 35mm camera. No one publishes the 35mm camera equivalent for an 80mm lens on a Hasselblad; no one publishes the 35mm camera equivalent for a 150mm lens on a 4x5 view camera! I've been photographing with cameras I could swap lenses on since 1969. I currently own one 4x5 and two medium format, in addition to my 35mm equipment (5 film bodies plus the S2). I've previously owned several other medium format cameras. But you know what? I've never actually had a second lens for *any* of them except the 35mm cameras. Like the vast majority of photographers, my experience with focal lengths (as a decision) is 100% tied to 35mm work. I've got those numbers burned into my brain. Giving me the 35mm-equivalent numbers is the easiest way to give me that information. All of this I think adds to the confusion of new comers to the digital world who may go around thinking, for example, that the 200mm lens that they want to buy is really a 320mm lens on their 1.6 focal length multiplier camera. No it's not, it's a 200mm lens! The fact is that if you put that lens on a 'full frame' 35mm camera and cropped a picture to the same size as a camera with a 1.6 focal length multiplier you would have exactly the same picture. There, I feel better! Chuck Glad you feel better. And of course anybody who really gets confused about focal lengths as opposed to angle of view has been badly served by their education and by the system. Which is why I prefer "crop factor" rather than "focal length multiplier". Meanwhile, I really enjoy my 450mm f2.8 lens and my 87.5 f1.2 NOCT. :-) -- David Dyer-Bennet, , http://www.dd-b.net/dd-b/ RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/ Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/ Dragaera/Steven Brust: http://dragaera.info/ |
#9
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#10
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In message ,
C Wright wrote: Is anyone else bothered by the frequent use of "focal length multipliers" or "crop factors" when describing digital cameras and their lenses? Why don't the manufacturers just tell us what a "normal" lens is for a particular camera. Why aren't we using angles? That would make a lot more sense then refering to the focal length of lenses when what we are really interested in is the angle of view. The manufacturer could state the angle of view with a 50mm lens, or something like that. I hadn't used 35mm SLRs for almost 20 years when I started using 1.6x DSLRs. I relate directly to the absolute focal length in the context of these cameras, and I cringe when people refer to the "35-mm equivalent Angle of View" without stating such. Cropping does not effect focal length. -- John P Sheehy |
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