lens magnification

[Rickjs]

I have a tamaron 70-300 lens and I see, what I call the big telephoto/zooms, the kind you need to mount on a tripod and have been wondering. Would it be the same magnification as my 70-30o zoomed out all the way to 300 but with a better aperature? Or would it be greater zoom being is it is a much lens?

 

[Designer]

What apertures are we talking about? Same focal length in both lenses.

 

[Rickjs]

The 70-300 is f5.6 @ 300 mm and the ones I see online are f4 fixed at 300mm. Like I said, I realize It would be a better aperture but is 300mm the same regardless of lens size?

 

[Ido]

No matter what, if a lens cites a 300mm focal length, once you mount it on your camera it will give the same field of view as you know 300mm gives on your lens. Barring differences caused by focus breathing, which are usually minimal.

Those lenses may differ in maximum aperture (clearly stated in the model name / specifications), optical quality, autofocus speed, and many other traits.

 

[fmw]

Also note that sometimes the lens specs can be optimistic. I have a 200-400mm zoom upstairs. When fully extended the focal length is only 350mm.