Focal length 35mm equivalent, but not F-stop?

Started Jul 24, 2014 | Discussions thread
Great Bustard Forum Pro • Posts: 43,650
Re: because they don't want you to know

mostlyboringphotog wrote:

tko wrote:

Multiplying focal length isn't a bad thing. A 1000MM equivalent lens can be very useful.

But do you think they want to know that aperture gets multiplied as well? All of the sudden that F2.8 lens you thought was really fast is really only F10 equivalent?

Of course not! Because people might figure out that a true F2.8 FF lens is actually a pretty good deal compared to a smaller format equivalent F10 lens. And the public would know the lenses are smaller because they do less, not because of any magic dust.

What advertise your shortcomings? It's all about marketing.

Neither the focal length nor the aperture is multiplied. A 1000mm with image circle of FF and FL equivalent lens with the image circle of CX format is not an equivalent thing, even if FOV looks the same. BTW, this is MY point of view.

f/2.8 on iphone is still f/2.8 unless the new math is different than the old math. If you are told that iphone can give you the same image quality as FF camera and you believed it, because both can do f/2.8, you need to know more about photography (Of course, this is not true of you).

There are no true f/2.8 FF or false f/2.8 iphone as it's just a ratio.

http://www.josephjamesphotography.com/equivalence/#onthequick

  • Neither the focal length nor the f-ratio of a lens change as a function of format: 50mm = 50mm and f/2 = f/2 regardless of the format the lens is used on.
  • The effect of the focal length and f-ratio of a lens, however, do change as a function of format.
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