Aren't we just confusing ourselves?

[ken1953]

I think sometimes I understand all this and then someone brings up a good discussion like this. So...I have a question...would someone who has both full frame and c-size sensors like to post some examples of the differences in shots.
For example...set a tripod up, lock the position down as exact as possible, use same settings on both cameras and the same lens and snap away. Maybe do some landscape examples, some midrange and some closeup/macro shots.
Any takers?
I, for one, understand better with examples...all the words just confuse me sometimes.

[OldClicker]

I don't have an FF to do what you are asking, but you can do the same thing with whatever you have. Take a photo you have at, say, 3000x4000 pixels. Now crop off the edges so that you have the center 2400x3200. View them both full screen on your monitor. - TF

[Franglais]

I agree totally if you change your focal length or position to compensate for a change in sensor size, but if you simply take a given lens and change it from one camera to the next the depth of field doesn't change, all you are changing is how much of the image circle hits the sensor / film.

It would be nice to say this was true because it is simple and helps to explain things. The image cast on the sensor by the lens is exactly the same. However the depth of field might not appear to be the same for two reasons:

1. The image from the smaller sensor is enlarged more so unsharpness is more visible. The Circle of Confusion is not the same. Depth of field with a smaller sensor will apear to be less than on a bigger one
2. Image sharpening by the camera is usually stronger on a smaller sensor than with a large one. The image sharpening will correct out-of-focus unsharpness up to a certain degree then suddenly give up so you may get a more abrupt switch from in-focus to out-of-focus

[OldClicker]

It would be nice to say this was true because it is simple and helps to explain things. The image cast on the sensor by the lens is exactly the same. However the depth of field might not appear to be the same for two reasons:

1. The image from the smaller sensor is enlarged more so unsharpness is more visible. The Circle of Confusion is not the same. Depth of field with a smaller sensor will apear to be less than on a bigger one
2. Image sharpening by the camera is usually stronger on a smaller sensor than with a large one. The image sharpening will correct out-of-focus unsharpness up to a certain degree then suddenly give up so you may get a more abrupt switch from in-focus to out-of-focus

1- But we were talking about the same image taken with the same lens at the same distance and printed the same size. Since we will have to crop the FF to get the same image, they will both be enlarged the same and both prints will show the same circle of confusion.

2- In RAW?

TF

[Franglais]

1- But we were talking about the same image taken with the same lens at the same distance and printed the same size. Since we will have to crop the FF to get the same image, they will both be enlarged the same and both prints will show the same circle of confusion.

2- In RAW?

TF

1. If you crop they should be the same. I was answering the post just before the one where you published your test method

2. The RAW file contains the same sharpness settings as the JPG, the difference being you can undo them. To make the test accurate you need to shut off all sharpness enhancement on both cameras.

Ideally this test would be done between a D200 and a D3X - the D3X crops down to 10Mpix like the D200. However I don't know of anyone who has that combination.

[Loupey]

...would someone who has both full frame and c-size sensors like to post some examples of the differences in shots.

No problem.

One factor which adds to the confusion is that people try to compare the differences when outputted to the same size (screen, print).

Here is one example that I posted before. Both images are uncropped but I made their relative sizes to scale. I think the results are clear, obvious, and simple.

[Loupey]

So when uncropped images are outputted to the same size, it only appears that the smaller sensor size has a deeper DOF. Shot from the same distance, same lens, same focal length.

[Loupey]

But when enlarged to the SAME SUBJECT SIZE, we see that the DOF is identical as it should be.

[Sushigaijin]

Good posts, loupey.

The biggest problem here is output size. 10 mp is 10 mp, regardless of sensor size. Therefor, equivalent focal length makes sense. If all pixel sizes were the same it wouldn't make any difference at all. Back when we had film the output sizes were different - different size film and negatives...but with digital that isn't a consideration any more.