With a modern Sony, what does "f/8" at 1X mean?

[rjlittlefield]

I know that modern Nikon cameras and macro lenses work directly in effective f-number, already corrected for magnification.

Do modern Sony systems work the same way?

Or are they like Canon systems where you still have to calculate effective f# = nominal f# * (magnification+1) ?

--Rik

[RobertOToole]

I know that modern Nikon cameras and macro lenses work directly in effective f-number, already corrected for magnification.

Do modern Sony systems work the same way?

Or are they like Canon systems where you still have to calculate effective f# = nominal f# * (magnification+1) ?

--Rik

Hi Rik,

My Sony bodies, A7RIV and A6300 will display nominal, you have to calculate effective f.

Best,

[RobertOToole]

I know that modern Nikon cameras and macro lenses work directly in effective f-number, already corrected for magnification.

I believe the camera body displays the F/number data that the lens reports. I don't know exactly how it works but as far as I've read some lenses would overestimate the value for various reasons and report the figure wider than actual.

Do you how the displayed effective f-number reporting works Rik?

Best,

Robert

[rjlittlefield]

Do you how the displayed effective f-number reporting works Rik?

On Nikon, my understanding is that one can set a macro lens to closest focus and see what the widest settable aperture is there. If it is substantially narrower than the lens's rating, say f/4.5 instead of f/2.8, then that's a good indication that the system has already corrected for magnification.

I would expect the same procedure to work on Sony, but that's based only on general principles and not experience. I have no hands-on experience with Sony cameras or lenses.

--Rik

[RobertOToole]

Do you how the displayed effective f-number reporting works Rik?

On Nikon, my understanding is that one can set a macro lens to closest focus and see what the widest settable aperture is there. If it is substantially narrower than the lens's rating, say f/4.5 instead of f/2.8, then that's a good indication that the system has already corrected for magnification.

I would expect the same procedure to work on Sony, but that's based only on general principles and not experience. I have no hands-on experience with Sony cameras or lenses.

--Rik

Thanks, got it!

When shooting with a lens with electronic contacts, and I am shooting at f/2.8 @ 1x. The body LCD and Exif will report f/2.8. Not effective. Both bodies display the same way.

I've read the Nikon system is very sensitive and is pretty much accurate to within 1/12th a stop. Someone found the spec in a Nikon lens patent. In the real world this means it reports f/3.0-f/3.1-f/3.2 etc in Exif as you focus closer. Also its interesting that due to lens breathing its usually not a full 2 stop drop at 1x.

Best,

Robert

[rjlittlefield]

Also its interesting that due to lens breathing its usually not a full 2 stop drop at 1x.

Even with lenses that don't have movable elements, the *(m+1) formula only applies when pupil ratio is 1, and often it is not.

Add in movable elements and the situation gets even more variable. The mechanisms that cause effective focal length to shrink at close focus can also cause the effective aperture to shrink slower than *(m+1).

Thanks for the info about your Sonys.

--Rik

[Joaquim F.]

I know that modern Nikon cameras and macro lenses work directly in effective f-number, already corrected for magnification.

I believe the camera body displays the F/number data that the lens reports. I don't know exactly how it works but as far as I've read some lenses would overestimate the value for various reasons and report the figure wider than actual.

Do you how the displayed effective f-number reporting works Rik?

Best,

Robert

Also its interesting that due to lens breathing its usually not a full 2 stop drop at 1x.

Even with lenses that don't have movable elements, the *(m+1) formula only applies when pupil ratio is 1, and often it is not.

Add in movable elements and the situation gets even more variable. The mechanisms that cause effective focal length to shrink at close focus can also cause the effective aperture to shrink slower than *(m+1).

Thanks for the info about your Sonys.

--Rik

Hi, I remember seeing a website where the internal focus movement of the Micro-Nikkor 60mm and 105mm AF D was described, the luminosity gain with respect to an "focus by extension" lens was due to the fact that in its optical design there is an integrated teleconverter, a 3 element 1.4X on 105mm and a weak 2 element 1.2X on 60mm, when this fixed rear objective part are away from the frontal base objective combined with the decrease on effective focal length create a gain in brightness. I remember the gain is about f/5 respect to a normal f/5.6 at 1:1. Not long ago I read some posts from gardenerassistant ? that dealt with this optical behavior in depth and at more large magnification scale.
The real aperture indexing works very nice in situations like macro with flash where the objective reports the focus distance and real F number to exposure system for better performance.

Best

Joaquim

[enricosavazzi]

Same here, Sony Alpha 7R II, Sony 90 mm f/2.8 macro. In aperture priority mode (changing aperture with the front wheel on the camera) the camera displays the nominal aperture, from f/2.8 to f/22, regardless of the focus position from infinity to 1x.