Will the maximum focal length change when I use EF 24-70mm zoom lens on 600D?

brightcolours wrote:

WilbaW wrote:

brightcolours wrote:

WilbaW wrote:

When you put a 100mm lens on a 60D and set it to f/2.8 -

1. You have the same FOV of the same scene from the same position on the 60D as a 160mm lens on a 6D.
2. You have the same DOF on the 60D as a 160mm lens set to f/4.5 on a 6D focussed at the same distance.
3. You have the same shutter on the 60D as on the 6D with the 160mm lens set to f/4.5 at the same ISO?

You want to know why the ISO is the same... because the answer shows that crop factor does not apply to aperture in equivalence with respect to metering. An f/2.8 lens is always an f/2.8 lens when it comes to metering, regardless of format.

The question has nit been asked and has no place anywhere.

Okay, I accept you haven't seen the question before and insist it shouldn't be considered, but you can't stop the music!

In discussions of equivalence, crop factor is applied to aperture in respect to DOF. Crop factor is applied to focal length in respect to FOV. Crop factor is applied to ISO in respect to exposure.

That's because you have used the same shutter and a tighter aperture on the larger system to get the same blur, DOF, and total light in an equivalent image, and therefore you need to apply the crop factor to the ISO to equalise the image brightness.

We are not talking about that.

We are talking about the metering on the smaller system, the one with the f/2.8 lens. You don't use the DOF-equivalent aperture of the larger system (f/4.5) for that purpose, you use the actual aperture of the smaller system (f/2.8). That's all there is to it.

And because ISO is not about sensitivity anymore. And because the reel sensitivity between different sensors is going to be different.

You introduced "sensitivity" into the discussion, and it sounds, smells, and tastes like a strawman's red herring. It's irrelevant to metering.

Nonsense, stop wanting to muddy the discussion on purpose. Since when is sensitivity not a part of metering. One sets a meter to ISO/ASA (depending on age of the meter) to the ISO/ASA sensitivity of the film used, before metering. It is stupid to claim otherwise.

But ISO is not about sensitivity any more, the real sensitivity between different sensors is going to be different! (Sorry, couldn't resist. )

I accept you can't answer the question (point 3) about metering on the smaller system. Please leave the discussion to anyone who might get something out of it.