comparable FoV (Page 2): No. While the depth of field may change (depending also on whether you change the subject to camera distance) the fstop, like the focal length, does not...

TriX Loc: Raleigh, NC

rdubreuil wrote:

...To know the equivalent on a crop body you must also multiply the f stop by the crop factor, so an f/2.8 lens on full frame would act like an f/4.2 on a crop body when one is considering the loss of light and changes to depth of field.

No. While the depth of field may change (depending also on whether you change the subject to camera distance) the fstop, like the focal length, does not change, nor does the “loss of light” (light transmission). This has been discussed and debunked multiple times in the past. You can use any of the usual DOF calculators to calculate DOF and FOV, but the f stop and light transmission remains the same (note that a light meter does not have a different scale, for crop, FF, MF, etc.)

phlash46 Loc: Westchester County, New York

jerryc41 wrote:

Actually, it is perfectly correct. Although focal... (show quote)

Quite correct Jerry! The f stop, in terms of light gathering, doesn't change, but, in terms of DOF it does. The FOV and DOF on my Olympus EM-1 of a 25mm lens set at f/1.4 equals the FOV of a 50mm lens on a full frame camera and a DOF equal to a 50mm lens at f/2.1; however, in terms of light gathering, it is an f/1.4 lens.

rdubreuil Loc: Dummer, NH USA

TriX wrote:

No. While the depth of field may change (depending also on whether you change the subject to camera distance) the fstop, like the focal length, does not change, nor does the “loss of light” (light transmission). This has been discussed and debunked multiple times in the past. You can use any of the usual DOF calculators to calculate DOF and FOV, but the f stop and light transmission remains the same (note that a light meter does not have a different scale, for crop, FF, MF, etc.)

Hi Trix, I did preface my statement that there is no change to the settings on either camera body or lens, same distance from the subject and you will see less blur in the background of the crop body shot. So again; how is it the DoF increases from one to the other if something in the mix (the crop factor) isn't acting upon the f stop and the final image? If I'm out in left field I just want to understand why.

CHG_CANON Loc: the Windy City

rdubreuil wrote:

Hi Trix, I did preface my statement that there is no change to the settings on either camera body or lens, same distance from the subject and you will see less blur in the background of the crop body shot. So again; how is it the DoF increases from one to the other if something in the mix (the crop factor) isn't acting upon the f stop and the final image? If I'm out in left field I just want to understand why.

The crop sensor does impact the apparent depth of field. It does not change the f-value of the lens nor change how much light hits the sensor for any given aperture value. This demonstration is not perfect but attempts to show the DoF and FoV aspects of comparing a FF to crop camera with the same lens on both bodies or when using FoV "equivalent" lenses on different bodies.

http://neilvn.com/tangents/full-frame-vs-crop-sensor-cameras-comparison-depth-of-field/ (the post includes a link to a DEPTH OF FIELD tutorial from Cambridge in Colour that introduces a concept of Circle of Confusion)

Depth of Field is not light gathering. period.

bmike101 Loc: Gainesville, Florida

so divide the nikon focal length by 1.5 to get the sony's apparent focal length.... Sorry for causing trouble. Well, not really trouble, rather discussion.

Notorious T.O.D. Loc: Harrisburg, North Carolina

Pegasus wrote:

This all unbelievably incorrect. The focal length and f-number of a lens do not change.

Notorious T.O.D. Loc: Harrisburg, North Carolina

TriX wrote:

No. While the depth of field may change (depending also on whether you change the subject to camera distance) the fstop, like the focal length, does not change, nor does the “loss of light” (light transmission). This has been discussed and debunked multiple times in the past. You can use any of the usual DOF calculators to calculate DOF and FOV, but the f stop and light transmission remains the same (note that a light meter does not have a different scale, for crop, FF, MF, etc.)

geezer7 Loc: Michigan

While most of us agree that actual focal length doesn't change from crop sensors to full-frame sensors and that light transmitted to the sensor also doesn't change, the DOF does change. A simplified formula for calculating DOF is
DOF = 2 * (Lens_F_number) * (circle_of_confusion) * (subject_distance)^2 / (focal_length)^2
Charts show that the circles of confusion (CoC) for aps-c and full-frame sensors are 0.019mm and 0.029mm respectively. These values are cited in Wikipedia for Nikon aps-c sensors.
Sorry for going mathematical but the formula seems to clear up the confusion about DOF. Pun intended.
Note that CoC varies approximately inversely as the crop factor and that in order to obtain the same DOF for both formats the f-numbers need to change by the crop factor.
More complex formulae are available but the formula above seems to be adequate to explain the difference in DOF.
Hope this helps.

Bill_de Loc: US

A lot of correct facts in this thread. Very few addressed the original question.

What I don't understand is the reference to "perceived" field of view. AFAIK when I look through the viewfinder everything I see is within my field of view.

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rdubreuil Loc: Dummer, NH USA

geezer7 wrote:

While most of us agree that actual focal length do... (show quote)

SusanFromVermont Loc: Southwest corner of Vermont

Bill_de wrote:

A lot of correct facts in this thread. Very few addressed the original question.

What I don't understand is the reference to "perceived" field of view. AFAIK when I look through the viewfinder everything I see is within my field of view.

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A full-frame lens has a certain field of view that can be used completely on a full-frame camera. When you put that lens on a crop-sensor camera, you see a decreased field of view. So what you see is what you perceive, but the fov of the lens has not changed.

Bill_de Loc: US

SusanFromVermont wrote:

A full-frame lens has a certain field of view that can be used completely on a full-frame camera. When you put that lens on a crop-sensor camera, you see a decreased field of view. So what you see is what you perceive, but the fov of the lens has not changed.

Thank you Susan.

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RWR Loc: La Mesa, CA

bmike101 wrote:

so divide the nikon focal length by 1.5 to get the sony's apparent focal length....

You got it!

CO

CHG_CANON wrote:

The crop sensor does impact the i apparent /i de... (show quote)

That's an excellent article by Neil Van Niekerk. I've read it a few times. After I read it I did my own testing to check it out myself. I went to a marina with a Nikon DF (full frame) and a Nikon D7000 (1.5X crop factor). I even took a 100ft. tape measure with my to check depth of field distances. I took photos from the same spot. I used a 24mm focal length on the full frame camera and a 16mm focal length on the crop sensor camera. It resulted in the same field of view but the crop sensor camera had significantly more depth of field.

ole sarg Loc: south florida

Who cares
When shooting film i never said i wonder what the fov would be if i shot this with a speed graphic