Why don't DX and EF-s lenses show appropriate focal length?

alohadave · 09-09-2009, 01:25 PM

Originally posted by legacyb4

Marketing departments were probably too slow to try and manipulate the mindset of consumers when the first DSLR bodies hit the market that were using existing "built for film" lenses. By the time "digital only" came around, it was probably already too late to try and create a new set of measurements...

There are no new measurements to create. The focal length is what it is.

GLXLR · 09-09-2009, 02:59 PM

Originally posted by jct us101

Considering the highly debated 1.6x crop "factor" in crop cameras, how come the focal lengths still show the original film focal lengths on them? Wouldn't it be appropriate to have them show the cropped numbers on them?

I pondered on this to, but after thinkin about it more, I realized it really wouldn't do much good at all to change the FL on the lenses fit for APS-C, simply b/c it would cause more confusion when people buy a "24-120mm lens" (the 16-85mm Nikkor) and then they get the Sigma 100-300mm and yet the difference is so huge b/c the APS-C sensor crops the Sigma out to 150-450mm lens.

Sure it would make sense for the short term, but for the rich/ experienced, when they buy a FF designated lens for their cropped body, they will certainly be even more confused.

pingflood · 09-09-2009, 03:24 PM

You have to be rich to buy FF glass now?

Eruditass · 09-09-2009, 03:36 PM

focal length is a physical measurement and should be reported. crop factor does not make a 50mm lens a 75mm lens on a 1.5x camera - perspective (from the focal length) is still 50mm, it is just cropped in the middle. In addition, some sensors can be slightly bigger / smaller, making 1.5 more like 1.51837211.

Do we really want to add another number to the lens title?

RBellavance · 09-09-2009, 03:45 PM

Originally posted by GLXLR

Sure it would make sense for the short term

It would make no sense at all, the focal length of a lens is the focal length of a lens, and does not change with the size of the device it's projecting an image on.

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09-09-2009, 01:25 PM	#16
alohadave Veteran Member Join Date: Jan 2008 Location: Quincy, MA Photos: Gallery \| Albums Posts: 2,024	Originally posted by legacyb4 Marketing departments were probably too slow to try and manipulate the mindset of consumers when the first DSLR bodies hit the market that were using existing "built for film" lenses. By the time "digital only" came around, it was probably already too late to try and create a new set of measurements... There are no new measurements to create. The focal length is what it is.

09-09-2009, 02:59 PM	#17
GLXLR Veteran Member Join Date: Feb 2009 Location: Sugar Land, TX Photos: Gallery Posts: 684	Originally posted by jct us101 Considering the highly debated 1.6x crop "factor" in crop cameras, how come the focal lengths still show the original film focal lengths on them? Wouldn't it be appropriate to have them show the cropped numbers on them? I pondered on this to, but after thinkin about it more, I realized it really wouldn't do much good at all to change the FL on the lenses fit for APS-C, simply b/c it would cause more confusion when people buy a "24-120mm lens" (the 16-85mm Nikkor) and then they get the Sigma 100-300mm and yet the difference is so huge b/c the APS-C sensor crops the Sigma out to 150-450mm lens. Sure it would make sense for the short term, but for the rich/ experienced, when they buy a FF designated lens for their cropped body, they will certainly be even more confused.

09-09-2009, 03:24 PM	#18
pingflood Veteran Member Join Date: Jun 2008 Location: Borås, Sweden Photos: Gallery Posts: 3,169	You have to be rich to buy FF glass now?

09-09-2009, 03:36 PM	#19
Eruditass Veteran Member Join Date: Jul 2009 Photos: Gallery Posts: 2,207	focal length is a physical measurement and should be reported. crop factor does not make a 50mm lens a 75mm lens on a 1.5x camera - perspective (from the focal length) is still 50mm, it is just cropped in the middle. In addition, some sensors can be slightly bigger / smaller, making 1.5 more like 1.51837211. Do we really want to add another number to the lens title?

09-09-2009, 03:45 PM	#20
RBellavance Veteran Member Join Date: Nov 2006 Location: Near Montréal, Canada Photos: Gallery Posts: 1,716	Originally posted by GLXLR Sure it would make sense for the short term It would make no sense at all, the focal length of a lens is the focal length of a lens, and does not change with the size of the device it's projecting an image on.

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